COMMISSION DIRECTIVE of 25 April 1984 adapting to technical progress for the sixth time Council Directive 67/548/EEC on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances (84/449/EEC)

THE COMMISSION OF THE EUROPEAN COMMUNITIES,

Having regard to the Treaty establishing the European Economic Community,

Having regard to Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances (1), as amended for the sixth time by Council Directive 79/831/EEC (2), and in particular Articles 19, 20 and 21 thereof,

Whereas Article 3 (1) of Directive 79/831/EEC provides that the physico-chemical properties, toxicity and ecotoxicity of the substances and preparations shall be determined according to the methods specified in Annex V;

Whereas Article 19 of Directive 79/831/EEC of 18 September 1979 provides that Annex V comes under the procedure, involving the Committee for Adaptation to Technical Progress ; whereas due regard should be given, in particular, to any methods recognized and recommended by competent international organizations;

Whereas the provisions of this Directive are in accordance with the opinion of the Committee for the Adaptation to Technical Progress of the Directives on the Removal of Technical Barriers to Trade in Dangerous Substances and Preparations,

HAS ADOPTED THIS DIRECTIVE:

Article 1

The text of Annex V to Directive 67/548/EEC is hereby replaced by the text of the Annex to this Directive.

Article 2

Member States shall adopt and publish before 1 July 1985 the measures needed to comply with this Directive and immediately inform the Commission thereof. They shall apply these measures by 1 July 1986 at the latest.

Article 3

This Directive is adressed to the Member States.

Done at Brussels, 25 April 1984.

For the Commission

Karl-Heinz NARJES

Member of the Commission (1) OJ No L 196, 16.8.1967, p. 1. (2) OJ No L 259, 15.10.1979, p. 10.

ANNEX

The Annex sets out test methods for the determination of physicochemical, toxicological and ecotoxicological properties listed in Annexes VII and VIII to Directive 79/831/EEC. The methods are based on those recognized and recommended by competent international bodies (in particular OECD).

When such methods were not available, national standards or scientific consensus methods have been adopted. Generally, tests should be performed with the substance as marketed. Attention should be given to the possible influence of impurities on the test results.

When the methods of this Annex are inappropriate for the investigation of a certain property, the notifier must justify the alternate method used.

Animal tests and studies shall be conducted in accordance with national regulations and shall take into account humane principles and international developments in the field of animal welfare.

Among equivalent testing methods, the method using the minimum number of animals is chosen.

CONTENTS

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PART A : METHODS FOR THE DETERMINATION OF PHYSICO-CHEMICAL PROPERTIES

A. 1. MELTING POINT/MELTING RANGE

1. METHOD

The methods described are based on the OECD Test Guideline (1). 1.1. Introduction

The methods and devices described are to be applied for the determination of the melting point of chemical substances, without any restriction in respect to their degree of purity.

The selection of the method is dependent on the nature of the substance to be tested.

In consequence the limiting factor will be according to whether the substance can be pulverized easily, with difficulty, or not at all.

For some substances, the determination of the freezing or solidification point is more appropriate and the standards for these determinations have also been included in the guideline.

1.2. Definitions and units

The melting point is defined as the temperature at which the phase transition from solid to liquid state at normal atmospheric pressure takes place.

This temperature ideally corresponds to the temperature at the solidification point or the freezing point.

As the phase transition of many substances takes place over a large temperature range, it is often described as the melting range.

Conversion of units (K to °C):

t = T - 273,15

with t in °C, T in K.

1.3. Reference substances

Reference substances do not need to be employed in all cases when investigating a new substance. This should primarily serve to calibrate the method from time to time and to allow a comparison of results when another method is applied.

Some calibration substances are listed in the references (2).

1.4. Principle of the test method

The temperature (temperature range) of the phase transition from the solid to the liquid state is determined. In practice while heating a sample of the test substance at atmospheric pressure the temperatures of the initial melting and the final stage of melting are determined. Three types of methods are described, namely capillary method, hot stages method and freezing point determinations. 1.4.1. Capillary method 1.4.1.1. Melting point devices with liquid bath

A small amount of the finely ground substance is charged in a capillary tube and packed tightly. The tube is heated together with a thermometer and the temperature rise is adjusted to less than about 1 K/min during the actual melting. The initial and final melting temperatures are determined.

1.4.1.2. Metal block

As described under 1.4.1.1, except that the capillary tube and the thermometer are situated in a heated metal block, and can be observed through holes in the block.

1.4.1.3. Photocell detection

The sample in the capillary tube is heated automatically in a metal cylinder. A beam of light is directed through the substance, by way of a hole in the cylinder, to a precisely calibrated photocell. The optical properties of most substances change from opaque to transparent when they are melting. The intensity of light reaching the photocell increases and sends a stop signal to the digital indicator reading out the temperature of a platinum resistance thermometer located in the heat chamber. This method is not suitable for some highly coloured substances.

1.4.2. Hot stages 1.4.2.1. Kofler hot bar

The Kofler hot bar uses two pieces of metal of different thermal conductivity, heated electrically, with the bar designed so that the temperature gradient is almost linear along its length. The temperature of the hot bar can range from 283 to 543 K with a special temperature-reading device including a runner with a pointer and tab designed for the specific bar. In order to determine a melting point, the substance is laid in a thin layer directly on the surface of the hot bar. In a few seconds a sharp dividing line between the fluid and solid phase develops. The temperature at the dividing line is read by adjusting the pointer to rest at the line.

1.4.2.2. Melt microscope

Several microscope hot stages are in use for the determination of melting points with very small quantities of material. In most of the hot stages the temperature is measured with a sensitive thermocouple but sometimes mercury thermometers are also used. A typical microscope hot stage melting point apparatus has a heating chamber which contains a metal plate upon which the sample is placed on a slide. The centre of the metal plate contains a hole permitting the entrance of light from the illuminating mirror of the microscope. When in use, the chamber is closed by a glass plate to cut off air from the working area.

The heating of the sample is regulated by a rheostat. For very precise measurements, polarized light may be used for optically anisotropic substances.

1.4.2.3. Meniscus method

This method is specifically used for polyamides.

Determination of the temperature at which the displacement of a meniscus of silicone oil, enclosed between a hot stage and a cover-glass supported by the polyamide test specimen, is observed visually.

1.4.3. Method to determine the freezing point

The sample is filled in a special test tube and placed in an apparatus for the determination of the crystallizing point. The sample is stirred gently and continuously during cooling and the temperature is read and recorded at 30-second intervals. As soon as the temperature remains constant for a few readings this temperature (corrected for thermometer error) is recorded as the crystallizing point.

1.5. Quality criteria

The applicability and accuracy of the different methods used for the determination of the melting point/melting range are listed in the following table:

TABLE : APPLICABILITY OF THE METHODS

A. Capillary methods

>PIC FILE= "T0027347">

B. Hot stages and freezing methods

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1.6. Description of the methods

The procedures of nearly all the test methods have been described in international and national standards (see Appendix 1). 1.6.1. Methods with capillary tube

Finely pulverized substances usually show the stages of melting shown in figure 1 during a slow temperature rise. >PIC FILE= "T0027349">

During the determination of the melting point the temperatures are recorded at the beginning of melting and at the final stage. 1.6.1.1. Melting point devices with liquid bath apparatus

Figure 2 shows a type of standardized melting-point apparatus made of glass (JIS K 0064), all specifications are in millimetres.

>PIC FILE= "T0027350">

Bath liquid:

The suitable liquid should be chosen from below depending on the melting point. Liquid paraffin for melting points not higher than 473 K, concentrated sulphuric acid or silicone oil for melting points not higher than 573 K.

For melting points above 523 K, a mixture consisting of three parts sulphuric acid and two parts potassium sulphate (in weight ratio) can be used.

Thermometer:

Only those thermometers should be used which fulfil the requirements of the following or equivalent standards : ASTM E 1-71, DIN 12770, JIS K 8001.

Procedure:

The dry substance is finely pulverized in a mortar and is put into the capillary tube, fused at one end, so that the filling level is approximately 3 mm after being tightly packed. To obtain a uniform packed sample, the capillary tube should be dropped from a height of approximately 700 mm through a glass tube vertically onto a watch glass.

The filled capillary tubes are placed in the bath so that the middle part of the mercury bulb of the thermometer touches the capillary tube at the part where the sample is located. Usually the capillary tube is introduced into the apparatus about 10 K below the melting point.

The bath liquid is heated so that the temperature rise is approximately 3 K/min. The liquid must be stirred. At about 10 K below the expected melting temperature the rate of temperature rise is adjusted to a maximum of 1 K/min.

Calculation:

The calculation of the melting point is as follows:

T = TD + 0,00016(TD - TE) n where:

T = corrected melting temperature in K

TD = temperature reading of thermometer D in K

TE = temperature reading of thermometer E in K

n = number of graduations of mercury thread on thermometer D at emergent stem.

1.6.1.2. Metal block

Apparatus:

This consists of: - a cylindrical metal block, the upper part of which is hollow and forms a chamber (see figure 3),

- a metal plug, with two or more holes, allowing tubes to be mounted into the metal block,

- a heating system, for the metal block, provided for example by an electrical resistance enclosed in the block,

- a rheostat for regulation of power input, if electric heating is used,

- four windows of heat-resistant glass on the lateral walls of the chamber, diametrically disposed at right-angles to each other. In front of one of these windows is mounted an eye-piece for observing the capillary tube. The other three windows are used for illuminating the inside of the enclosure by means of lamps,

- a capillary tube of heat-resistant glass closed at one end (see 1.6.1.1).

Thermometer:

See standards 1.6.1.1.

Thermoelectrical instruments with comparable accuracy are also applicable. >PIC FILE= "T0027351">

Procedure:

See 1.6.1.1. A thermometer correction must not be applied in this case. The recorded temperature indicates the melting point.

1.6.1.3. Photocell detection

Apparatus and procedure:

The apparatus consists of a metal chamber with automated heating system. Three capillary tubes are filled according to 1.6.1.1 and placed in the oven.

Five linear increases of temperature are available for calibrating the apparatus and the suitable temperature rise is electrically adjusted at a pre-selected constant and linear rate. Recorders show the actual oven temperature and the melting point of the substance in the capillary tubes.

1.6.2. Hot stages 1.6.2.1. Kofler hot bar

See Appendix.

1.6.2.2. Melt microscope

See Appendix.

1.6.2.3. Meniscus method (polyamides)

See Appendix.

The heating rate through the melting point should be less than 1 K/min.

1.6.3. Methods for the determination of the freezing point

See Appendix.

2. DATA

A thermometer correction is necessary in some cases.

3. REPORTING

The method used shall be stated.

The reported melting point is the mean of at least two measurements which are in the range of the approximate accuracy (see table). An estimate of the accuracy should be provided. If the difference between the temperature at the beginning and at the final stage of melting is within the limits of the accuracy of the method, the temperature at the final stage of melting is taken as the melting point, otherwise the two temperatures are reported.

Some substances will decompose or sublime before the melting point is reached. In these circumstances this should be reported.

All information and remarks relevant for the interpretation of results have to be reported, especially with regard to impurities and physical state of the substance.

4. REFERENCES (1) OECD, Paris, 1981, Test Guideline 102, Decision of the Council C(81) 30 final.

(2) IUPAC, Physicochemical measurements : Catalogue of reference materials from national laboratories, Pure and applied chemistry, vol. 48, 1976, pp. 505 to 515.

Appendix For additional technical details, the following standards may be consulted for example:

1. Capillary methods >PIC FILE= "T0027352">

2. Hot stages >PIC FILE= "T0027353">

3. Methods for the determination of the freezing point >PIC FILE= "T0027354">

>PIC FILE= "T0027355">

A. 2. BOILING POINT/BOILING RANGE

1. METHOD

The methods described are based on the OECD Test Guideline (1). 1.1. Introduction

The methods and devices described here can be applied to liquid substances, provided that these do not undergo chemical reaction below the boiling point (for example : auto-oxidation, rearrangement, degradation, etc.). The methods can be applied to pure and to impure liquid substances.

Emphasis is put on the method using photocell detection, because this method allows the determination of melting as well as boiling points. Moreover, measurements can be performed automatically.

The "dynamic method" has the advantage that it can also be applied to the determination of the vapour pressure and it is not necessary to correct the boiling temperature to the normal pressure (101,325 kPa) because the standard pressure can be adjusted during the measurement. But this method is not at present automated.

Remarks

The influence of impurities on the determination of the boiling point depends greatly upon the nature of the impurity. The effect can be considerable if a highly volatile solvent is present in the sample.

The composition of the investigated sample changes from measurement to measurement due to the volatilization of low boiling components : continuously increasing values are obtained in these circumstances.

1.2. Definitions and units

The standard boiling temperature is described as the temperature at which the pressure of the saturated vapour of a liquid is the same as the standard pressure.

The measured boiling point is dependent on the atmospheric pressure. This dependence can be described quantitatively by the Clausius-Clapeyron equation as follows: >PIC FILE= "T0027356">

where:

p = the vapour pressure of the substance in Pascals >PIC FILE= "T0027357">

R = the universal molar gas constant = 8,31 J mol-1 K-1

(The temperature T is expressed in K).

The temperature at the boiling point (boiling temperature) is stated with regard to the ambient pressure during the measurement.

Conversions:

Pressure (units : kPa)

100 kPa = 1 bar = 0,1 MPa ("bar" units are still permissible but not recommended);

133 Pa = 1 mm Hg = 1 Torr (the units "mm Hg" and "Torr" are not permitted).

Temperature (units : K)

t = T - 273,15

(t in °C, and T in K).

1.3. Reference substances

Reference substances do not need to be employed in all cases when investigating a new substance. This should primarily serve to calibrate the method from time to time and to allow a comparison of results.

Some calibration substances can be found in the methods listed in the Appendix.

1.4. Principle of the test method

All methods for the determination of the boiling point (boiling range) are based on the measurement of the boiling temperature. Five methods are described. 1.4.1. Determination by use of the Ebulliometer

Ebulliometers were originally developed for the determination of the molecular weight by boiling point elevation, but they are also suited for exact boiling point measurements. A very simple apparatus is described in ASTM D 1120-72 (see Appendix). The liquid is heated in this apparatus under equilibrium conditions at atmospheric pressure until it is boiling.

1.4.2. Dynamic method

This method involves the measurement of the vapour recondensation temperature by means of a thermocouple in the reflux while boiling. The pressure can be varied in this method.

1.4.3. Distillation method for boiling point and boiling range

This method involves distillation of the liquid and measurement of the vapour recondensation temperature and determination of the amount of distillate.

1.4.4. Method according to Siwoloboff

A sample is heated in a sample tube, which is immersed in a liquid in a heat-bath. A fused capillary, containing an air bubble in the lower part, is dipped in the sample tube.

The temperature at which a regular string of bubbles escapes from the capillary or the temperature at which, on momentary cooling, the string of bubbles stops and the fluid suddenly starts rising in the capillary (Siwoloboff) is determined.

1.4.5. Photocell detection

Following the principle according to Siwoloboff, automatic photo-electrical measurement is made using rising bubbles.

1.5. Quality criteria

The applicability and accuracy of the different methods used for the determination of the boiling point/boiling range are listed in table 1.

1.6. Description of the methods

The procedures of some test methods have been described in international and national standards (see Appendix). 1.6.1. Ebulliometer

See Appendix.

1.6.2. Dynamic method

See test method A. 4 for the determination of the vapour pressure.

The boiling temperature observed with an applied pressure of 101,325 kPa is recorded.

1.6.3. Distillation process (boiling range)

See Appendix.

TABLE 1 : COMPARISON OF THE METHODS >PIC FILE= "T0027358">

1.6.4. Method according to Siwoloboff

The sample is heated in a melting point apparatus in a sample tube, with a diameter of approximately 5 mm (figure 1).

Figure 1 shows a type of standardized melting and boiling point apparatus (JIS K 0064) (made of glass, all specifications in millimetres).

>PIC FILE= "T0027359">

A capillary tube (boiling capillary) which is fused about 1 cm above the lower end is placed in the sample tube. The level to which the test substance is added is such that the fused section of the capillary is below the surface of the liquid. The sample tube containing the boiling capillary is fastened either to the thermometer with a rubber band or is fixed with a support from the side (see figure 2).

>PIC FILE= "T0027360">

The bath liquid is chosen according to boiling temperature. At temperatures up to 573 K, sulphuric acid or silicone oil can be used. Liquid paraffin may only be used up to 473 K. The heating of the bath liquid should be adjusted to a temperature rise of 3 K/min at first. The bath liquid must be stirred. At about 10 K below the expected boiling point, the heating is reduced so that the rate of temperature rise is less than 1 K/min. Upon approach of the boiling temperature, bubbles begin to emerge from the boiling capillary.

The boiling point is that point when, on momentary cooling, the string of bubbles stops and fluid suddenly starts rising in the capillary. The corresponding thermometer reading is the boiling temperature of the substance.

In the modified principle (figure 3) the boiling point is determined in a melting point capillary. It is stretched to a fine point about 2 cm in length (a) and a small amount of the sample is sucked up. The open end of the fine capillary is closed by melting, so that a small air bubble is located at the end. While heating in the melting point apparatus (b), the air bubble expands. The boiling point corresponds to the temperature at which the substance plug reaches the level of the surface of the bath liquid (c).

1.6.5. Photocell detection

The sample is heated in a capillary tube inside a heated metal block.

A light beam is directed, via suitable holes in the block, through the substance onto a precisely calibrated photocell.

During the increase of the sample temperature, single air bubbles emerge from the boiling capillary. When the boiling temperature is reached the number of bubbles increases immensely. This causes a change in the intensity of light, recorded by a photocell, and gives a stop signal to the indicator reading out the temperature of a platinum resistance thermometer located in the block.

This method is especially useful because it allows determinations below room temperature down to 253,15 K (- 20 °C) without any changes in the apparatus. The instrument merely has to be placed in a cold room or cooling bath. The exact execution of the boiling point determination can be obtained from the instrument manual.

2. DATA

At small deviations from the normal pressure (maximum ± 5 kPa) the boiling point temperatures are normalized to Tn by means of the following number-value equation by Sidney Young: >PIC FILE= "T0027361">

where: >PIC FILE= "T0027362">

p = pressure measurement in kPa

fT = rate of change of boiling point with pressure in K/kPa

T = measured boiling temperature in K

Tn = boiling temperature corrected to normal pressure in K

The temperature-correction factors, fT, and equations for their approximation are included in the international and national standards mentioned above for many substances.

For example, the DIN 53171 method mentions the following rough corrections for solvents included in paints:

TABLE 2 : TEMPERATURE-CORRECTION FACTORS fT >PIC FILE= "T0027363">

3. REPORTING

The method used shall be stated. The reported boiling point is the mean of at least two measurements, which are in the range of approximate accuracy indicated in table 1. If determinations are not reproducible, other methods shall be considered.

The measured boiling points and their mean shall be stated and the pressure(s) at which the measurements were made shall be reported in kPa.

The pressure should preferably be close to normal pressure. Where a test substance boils over a temperature range this range should be indicated. Estimates of accuracy shall be provided for all results.

All information and remarks relevant for the interpretation of results have to be reported, especially with regard to impurities and physical state of the substance.

4. REFERENCES (1) OECD, Paris, 1981, Test Guideline 103, Decision of the Council C(81) 30 final.

Appendix

For additional technical details, the following standards may be consulted for example: >PIC FILE= "T0027469">

A. 3. RELATIVE DENSITY

1. METHOD

The methods described are based on the OECD Test Guideline (1). 1.1. Introduction

The methods for determining relative density described are applicable to solid and to liquid substances, without any restriction in respect to their degree of purity. The various methods to be used are listed in table 1.

1.2. Definitions and units

The relative density (D420) of solids or liquids is the ratio between the mass of a volume of substance to be examined, determined at 20 °C and the mass of the same volume of water, determined at 4 °C. The relative density has no dimension. >PIC FILE= "T0027592">

The density is given, in SI units, in kg/m3.

1.3. Reference substances (1) (2)

Reference substances do not need to be employed in all cases when investigating a new substance.

They should primarily serve to calibrate the method from time to time and to allow a comparison of results.

1.4. Principle of the methods

Four methods are used. 1.4.1. Buoyancy methods 1.4.1.1. Hydrometer (for liquid substances)

Sufficiently accurate and quick determinations of density may be obtained by floating hydrometers, which allow the density of a liquid to be deduced from the depth of immersion by reading of a graduated scale.

1.4.1.2. Hydrostatic balance (for liquid and solid substances)

The difference between the weight of a test sample measured in air and in water can be employed to determine its density.

For solids, the measured density is only representative of the particular sample employed. For the determination of density of liquids, a body of known volume, v, is weighed first in air and then in the liquid.

1.4.1.3. Immersed ball method (for liquid substances) (3)

In this method, the density of a liquid is determined from the difference between the results of weighing the liquid before and after immersing a ball of known volume in the test liquid.

1.4.2. Pycnometer methods

For solids or liquids, pycnometers of various shapes and with known volumes may be employed. The density is calculated from the difference in weight between the full and empty pycnometer and its known volume.

1.4.3. Air comparison pycnometer (for solids)

The density of a solid in any form can be measured at room temperature with the gas comparison pyconometer. The volume of a substance is measured in air or in an inert gas in a cylinder of variable calibrated volume. For the calculation of density one mass measurement is taken after concluding the volume measurement.

1.4.4. Oscillating densitometer (4) (5) (6)

The density of a liquid can be measured by an oscillating densitometer. A mechanical oscillator constructed in the form of a U-tube is vibrated at a specific frequency that depends on the mass of the oscillator. Introducing a sample changes the resonance frequency of the oscillator. The apparatus has to be calibrated by two liquid substances of known densities.

These substances should preferably be chosen such that their densities span the range to be measured.

1.5. Quality criteria

The applicability of the different methods used for the determination of the relative density is listed in the table.

The accuracy as cited in the ISO standard refers only to pure substances.

1.6. Description of the methods

The standards given as examples, which are to be consulted for additional technical details, are attached in the Appendix.

The tests have to be run at 20 °C, and at least two measurements performed.

2. DATA

See standards.

3. REPORTING

The method/standard used shall be reported.

The relative density (D420) shall be reported as defined in 1.2, along with the physical state of the measured substance.

All information and remarks relevant for the interpretation of results have to be reported, especially with regard to impurities and physical state of the substance.

TABLE : APPLICABILITY OF METHODS >PIC FILE= "T0027364">

4. REFERENCES (1) OECD, Paris, 1981, Test Guideline 109, Decision of the Council C(81) 30 final.

(2) IUPAC, Recommended reference materials for realization of physico-chemical properties, Pure and applied chemistry, vol. 48, 1976, pp. 508.

(3) Wagenbreth, H., Die Tauchkugel zur Bestimmung der Dichte von Flüssigkeiten, Technisches Messen tm, vol. 11, 1979, pp. 427 to 430.

(4) Leopold, H., Die digitale Messung von Flüssigkeiten, Elektronik, vol. 19, 1970, p. 297 to 302.

(5) Baumgarten, D., Füllmengenkontrolle bei vorgepackten Erzeugnissen - Verfahren zur Dichtebestimmung bei flüssigen Produkten und ihre praktische Anwendung, Die Pharmazeutische Industrie, vol. 37, 1975, pp. 717 to 726.

(6) Riemann, J., Der Einsatz der digitalen Dichtemessung im Brauereilaboratorium, Brauwissenschaft, vol. 9, 1976, pp. 253 to 255.

Appendix

For additional technical details, the following standards may be consulted for example: 1. Buoyancy methods >PIC FILE= "T0027365">

2. Pycnometer methods >PIC FILE= "T0027366">

>PIC FILE= "T0027367">

3. Air comparison pycnometer >PIC FILE= "T0027368">

A. 4. VAPOUR PRESSURE

1. METHOD

The methods described are based on the OECD Test Guideline (1). 1.1. Introduction

It is useful to have preliminary information on the structure, the melting point and the boiling point of the substance to perform this test.

There is no single measurement procedure applicable to the entire range of vapour pressures. Therefore, several methods are recommended to be used for the measurement of vapour pressure from -3 to 105 Pa.

Impurities will usually affect the vapour pressure. The influence of impurities on the determination of the vapour pressure depends greatly upon the kind of impurity. The effect can be considerable if a highly volatile solvent is present in the sample.

1.2. Definitions and units

The vapour pressure of a substance is defined as the saturation pressure above a solid or liquid substance. At the thermodynamic equilibrium, the vapour pressure of a pure substance is a function of temperature only.

The SI unit of pressure which should be used is the Pascal (Newton/m2).

Units which have been employed historically, together with their conversion factors, are: >PIC FILE= "T0027369">

The SI unit of temperature is the degree Kelvin (K).

1.3. Reference substances

Reference substances do not need to be employed in all cases when investigating a new substance. They should primarily serve to check the performance of the method from time to time and to offer the possibility to compare results when another method is applied.

1.4. Principle of the test methods

For determining the vapour pressure, five methods are proposed which can be applied in different vapour pressure ranges. For each method, the vapour pressure is determined at various temperatures. In a limited temperature range, the logarithm of the vapour pressure of a pure substance is a linear function of the inverse of the temperature. 1.4.1. Dynamic method

In the dynamic method, the boiling temperature which pertains to a specified pressure is measured.

Recommended range:

103 up to 105 Pa, between 20 and 100 °C.

This method has also been recommended for boiling point determination and is useful for that purpose up to 350 °C.

1.4.2. Static method

In the static process, at thermodynamic equilibrium, the vapour pressure established in a closed system is determined at a specified temperature.

This method is suitable for one component and multicomponent solids and liquids.

Recommended range:

10 up to 105 7Pa, between 0 and 100 °C.

1.4.3. Isoteniscope

This standardized method is also a static method but is usually not suitable for multicomponent systems. Additional information is available in ASTM method D-2879-75.

Recommended range:

from 100 to 105 Pa between 0 and 100 °C.

1.4.4. Vapour pressure balance

The quantity of substance leaving a cell per unit time through an aperture of known size is determined under vacuum conditions such that return of substance into the cell is negligible (e.g. by measurement of the pulse generated on a sensitive balance by a vapour jet or by measuring the weight loss).

Recommended range:

10-3 to 1 Pa, between 0 and 100 °C.

1.4.5. Gas saturation method

A stream of inert carrier gas is passed over the substance in such a way that it becomes saturated with its vapour and the vapour is then collected in a suitable trap. Measurement of the amount of material transported by a known amount of carrier gas is used to calculate the vapour pressure at a given temperature.

Recommended range:

up to 1 Pa.

1.5. Quality criteria

The various methods of determining the vapour pressure are compared as to application, repeatability, reproducibility, measuring range, existing standard. This is done in the following table.

TABLE : QUALITY CRITERIA >PIC FILE= "T0027370">

1.6. Description of the methods 1.6.1. Dynamic measurement 1.6.1.1. Apparatus

The measuring apparatus typically consists of a boiling vessel with attached cooler made of glass or metal (figure 1), equipment for regulating and measuring the temperature and equipment for regulating and measuring the pressure. A typical measuring apparatus shown in the drawing is made from heat-resistant glass and is composed of five parts:

The large, partially double-walled tube consists of a ground jacket joint, a cooler, a cooling vessel and an inlet.

The glass cylinder with a Cottrell pump is mounted in the boiling section of the tube and has a rough surface of crushed glass to avoid "bumping" in the boiling process.

The temperature is measured by using a thermocouple or resistance thermometer which is immersed in a small quantity of oil. It is inserted into the charging tube which has a male ground joint and is sealed on the bottom.

The crosspiece makes the necessary connections to the pressure regulation and measurement equipment.

The bulb, which acts as a buffer volume, is connected with the measuring apparatus by means of a capillary tube.

A cartridge heater, which is inserted into the glass apparatus externally from below, is used for heating the boiling vessel. The desired heating current is set by means of a voltage-regulating transformer, and is monitored by means of an ammeter.

An oil pump is used for setting the desired vacuum between 102 Pa and roughly 105 Pa.

A nitrogen cylinder is used for setting a desired pressure and is connected via a valve which is also used for ventilating the apparatus.

A precision pressure gauge which is connected to the crosspiece is used for pressure measurement.

1.6.1.2. Measurement procedure

The vapour pressure is measured by determining the boiling point of the sample at various specified pressures between roughly 103 and 105 Pa. A steady temperature under constant pressure indicates that the boiling point (boiling equilibrium in case of a mixture) has been reached. Frothing substances cannot be measured using this method.

In order to perform the measurement, all glass parts are first thoroughly cleaned and dried and then evacuated under a gas ballast. The substance is then introduced into the apparatus. If solids are not in a powdered form, problems may occur during the filling process, but they can be circumvented by heating the cooling water jacket. After filling, the apparatus is flanged together and the substance degassed. The lowest desired pressure is then set, and the heating system is switched on. Simultaneously the thermocouple or the resistance thermometer is connected to a recorder. Equilibrium is reached when a constant boiling temperature can be read off at a given constant pressure. After recording this equilibrium point, a higher pressure is set. The process is continued in this manner until 105 Pa has been reached (approximately 5 to 10 measuring points in all). As a check, equilibrium points must be repeated at decreasing pressures.

1.6.2. Static measurement 1.6.2.1. Apparatus

A typical measuring apparatus (figure 2) includes a heating and a cooling system consisting of glass and metal, for bringing the sample to a regulated temperature, as well as equipment for setting and measuring the pressure and temperature.

The sample chamber has on one side a high-vacuum valve made of stainless steel, and on the other side a U-tube containing a suitable manometric fluid. The other end of the U-tube is joined to a crosspiece, one branch of which leads to the vacuum pump, another to the nitrogen cylinder and the third to the pressure gauge.

For bringing the substance to a regulated temperature, the entire sample chamber including the valve poppet and a sufficiently large section of the U-tube (for practical purposes, up to the height of the valve poppet) is placed in an appropriate constant temperature bath. The temperature is measured using a thermocouple or resistance-thermometer very close to the outside of the sample chamber and can be recorded.

Liquid nitrogen or a dry-ice/alcohol mixture is suitable for supercooling the sample. An ultracryostat is used for measuring at low temperatures.

A suitable pump is used to evacuate the apparatus to the required pressure.

The vapour pressure of a substance is usually measured indirectly via a zero indicator. This zero indicator can be a U-tube containing a liquid, as specified below, or, among others, a membrane manometer. In a temperature-controlled bath, the vapour pressure moves the liquid in the U-tube out of equilibrium. Nitrogen is now let into the apparatus from a connected nitrogen cylinder via a valve to compensate the effect of the vapour pressure and bring the pressure gauge back to zero. The nitrogen pressure required for this is read off at a precision pressure gauge which is at ambient temperature and corresponds to the vapour pressure of the substance at the corresponding steady temperature. Various liquids such as mercury, silicone oils, phthalates, according to pressure range and the chemical behaviour of a substance, can be used as U-tube liquids for zero balancing.

Mercury can be used from atmospheric pressure down to 102 Pa, silicone oils and phthalates also below 102 Pa down to 10 Pa ; the membrane manometer can even be applied below 10-1 Pa.

1.6.2.2. Measurement procedure

Before measurement, all parts of the apparatus in figure 2 are thoroughly cleaned with solvents and then dried in a vacuum. The U-tube is then filled with the desired fluid, which should be degassed at elevated temperature prior to filling.

After filling with the substance, the apparatus is flanged together and the sample chamber sufficiently supercooled. Then with the valve open above the sample chamber, the enclosed air is pumped out of the apparatus for several minutes. The valve above the substance is then closed, the sample is brought to the selected temperature, and during this, the resulting displacement of the columns is observed and compensated to the zero position with nitrogen, if necessary, until temperature constancy is reached. The sample chamber is then again supercooled. If residual pressure is observed in the supercooled condition, it is caused either by air contained in the sample which is released during the heating process which can be drawn off, or by the cooling temperature not being low enough. Liquid nitrogen must then be used as a coolant.

After the sample has been sufficiently degassed, the temperature dependency of the vapour pressure is determined at sufficiently small temperature intervals.

1.6.3. Isoteniscope

A complete description of this method can be found in reference 2. The principle of the measuring device is shown in figure 3. Similarly to the static method described in 1.6.2, the isoteniscope is appropriate for the investigation of solids or liquids.

In the case of liquids, the substance itself serves as the fluid in the auxiliary manometer. In the case of solids, depending on the pressure and temperature range, the manometer liquids listed in 1.6.2 are used. For liquids, the sphere of the isoteniscope is filled with the substance to be investigated which is degassed at elevated temperature during boiling.

Simultaneously, a part of the liquid is distilled out of the sphere and is condensed in the upper cooled sphere and returns to the U-tube. When this is filled sufficiently with degassed liquid, the lower sphere with the U-tube in a thermostated bath is brought up to the chosen temperature and the resulting vapour pressure is indirectly measured just as in the method described in 1.6.2.

In the case of solids the degassed manometer liquid is filled into the bulge on the long arm of the isoteniscope. Then the solid to be investigated is filled into the lower sphere and is degassed at elevated temperature. After that the isoteniscope is inclined so that the manometer liquid can flow into the U-tube. The measurement of vapour pressure as a function of temperature is done according to 1.6.2.

1.6.4. Vapour pressure balance 1.6.4.1. Apparatus

There are several different designs available in the literature (1). The one described here illustrates the principles involved. A number of parts are shown in figure 4. These are base plate and bell jar, a pump with a vacuum measuring device and equipment for measuring the vapour pressure by a pointer deflection. The following built-in equipment is mounted on the base plate: - An evaporator furnace with flange and rotary feedthrough. The evaporator furnace is a flat, cylindrical copper vessel. (The furnace can also be made of glass surrounded by a copper wall.) It sits in a copper retainer which is screwed onto a piece of stainless steel at its lower protruding edge. The piece of stainless steel, in turn, is mounted on the base plate by means of a flange so that it can be rotated about the axis of the furnace. Heating is provided by a heater coil which sits inside the piece of stainless steel, and is thus closed off from the vacuum chamber.

- The furnace lid is made of copper, and has three evaporation openings of various cross-sections which are located at 90 degrees to one another. By rotating the furnace, the desired furnace opening or an intermediate position can be placed under the slot in the cooler which is positioned eccentrically to the furnace, thus aiming the molecular beam at the balance pan or diverting it. A thermocouple or resistance thermometer is mounted in the furnace wall for temperature measurement.

- The balance is a moving-coil instrument. The pointer is replaced by a small tube on which are mounted the balance beam and counterweight. The balance beam has a replaceable pan made of a thin piece of gold-plated aluminium. A 0,1 mm thick constantan wire, onto which calibration weights can be set, is attached to the approximate centre of the balance beam. The vapour pressure can be recorded using a photoelectric zero-point instrument.

- A cylindrical brass pot surrounds the balance pan on all sides with the exception of the two slots for the movement of the balance beam and a narrow opening for the entrance of the molecular beam. Heat dissipation to the outside is provided by a copper bar on top of the brass pot and is routed via a stainless steel tube through the base plate and thermally insulated from it. The bar is immersed in a Dewar flask containing liquid nitrogen under the base plate.

1.6.4.2. Measurement procedure

The copper furnace is filled with the substance, the lid closed, and the plate orifice, shield and cooler slid over the furnace. The bell is mounted, and the vacuum pumps are switched on. The final pressure before beginning measurement is roughly 10-4 Pa. From 10-2 Pa downwards, the cooling of the refrigeration box is started.

After a period of time, the balance will have attained a sufficiently low temperature so that the escaping vapour jet can condense on the scale pan. This condensation produces a signal on the connected recorder. This signal can be used in two ways : for the particular apparatus described here the vapour pressure is determined directly from the pressure on the scale pan (the molecular mass is not required). At the same time the mass condensed is determined and the evaporation rate can therefore be calculated from the time of deposition. This latter applies to more general apparatus. The vapour pressure may also then be calculated from the evaporation rate and molecular mass using the Herz relationship: >PIC FILE= "T0027371">

where:

G = evaporation rate (kg/s m2)

M = molar mass (g/mol)

T = temperature (K)

R = universal molar gas constant (J/mol K)

p = vapour pressure (Pa)

After the necessary vacuum is reached, the series of measurements commence at the lowest desired measuring temperature. The necessary orifice is opened and the vapour jet passes the shield directly mounted above the cover and then strikes the cooled scale pan. The scale pan is dimensioned so that the entire jet is collected in its cosinal distribution. The momentum of the vapour jet causes a force onto the scale pan where the condensation takes place on its cooled surface. By the force of the vapour jet the scale beam will be deflected from the equilibrium state. At the end of the scale beam is a small tab which is registered optically via a prism system and two photodiodes. A connected control circuit then momentarily regulates and resets the scale beam to the balanced state. The required torque is recorded and after a counterweighting it corresponds to the vapour pressure of the substance.

For further measurements, the temperature is increased by small intervals until the maximum desired temperature value is reached. The sample is then cooled again and a second curve of the vapour pressure may be recorded. The two series will only be reproducible if the sample being measured is sufficiently pure. If the third run fails to confirm the results of the second run, then it is possible that the substance may be decomposing in the temperature range being measured.

1.6.5. Gas saturation method 1.6.5.1. Apparatus

A typical apparatus used to perform this test comprises a number of components given in figure 5 and described below (1).

Inert gas:

The carrier gas must not react chemically with the test substance. Nitrogen is usually sufficient for this purpose but occasionally other gases may be required. The gas employed must be dry (see figure 5, key 4 : relative humidity sensor).

Flow control:

A suitable gas-control system is required to ensure a constant and selected flow through the saturator column.

Traps to collect vapour:

These are dependent on the particular sample characteristics and the chosen method of analysis. The vapour should be trapped quantitatively and in a form which permits subsequent analysis. For some test substances, traps containing liquids such as hexane or ethylene glycol will be suitable. For others, solid absorbents may be applicable.

Heat exchanger:

For measurements at different temperatures it may be necessary to include a heat-exchanger in the assembly.

Saturator column:

The test substance is solution coated onto a suitable inert support. The coated support is packed into the saturator column, the dimensions of which and the flow rate should be such that complete saturation of the carrier gas is ensured. The saturator column must be thermostated. For measurements at temperatures above 20 °C, the region between the saturator column and the traps should be heated to prevent condensation of the test substance.

1.6.5.2. Measurement procedure

Preparation of the saturator column:

A solution of the test substance in a highly volatile solvent is added to a suitable amount of support. Sufficient test substance should be added to maintain saturation for the duration of the test. The solvent is totally evaporated in air or in a rotary evaporator, and the thoroughly mixed material is added to the saturator column. After thermostating the sample, dry nitrogen is passed through the apparatus.

Measurement:

The traps are connected to the column effluent line and the time recorded. The flow rate is checked at the beginning and at regular intervals during the experiment, using a bubble meter (or continuously with a mass flow-meter).

The pressure at the outlet to the saturator must be measured. This may be done either: (a) by including a pressure gauge between the saturator and traps (this because of increased dead space and adsorptive surface) ; or

(b) by determining the pressure drops across the particular trapping system used as a function of flow rate in a separate experiment (may be not very satisfactory for liquid traps).

The time required for collecting the quantity of test substance that is necessary for the different methods of analysis is determined in preliminary runs or by estimates. Before calculating the vapour pressure at a given temperature, preliminary runs are to be carried out to determine the maximum flow rate that will completely saturate the carrier gas with substance vapour. This is guaranteed if the carrier gas is passed through the saturator sufficiently slowly so that a lower rate gives no greater calculated vapour pressure.

The specific analytical method will be determined by the nature of the substance being tested (e.g. gas chromatography or gravimetry).

The quantity of substance transported by a known volume of carrier gas is determined.

1.6.5.3. Calculation of vapour pressure

Vapour pressure is calculated from the vapour density, W/V, through the equation: >PIC FILE= "T0027372">

where:

p = vapour pressure (Pa)

W = mass of adsorbed test substance (g)

V = volume of saturated gas (m3)

R = universal molar gas constant (J/mol K)

T = temperature (K)

M = molar mass (g/mol)

Measured volumes must be corrected for pressure and temperature differences between the flow meter and the thermostated saturator. If the flow meter is located downstream from the vapour trap, corrections may be necessary to account for any vaporized trap ingredients (1).

2. DATA

The vapour pressure from any of the preceding methods should be determined for at least two temperatures. Three or more are preferred in the range 0 to 50 °C, in order to check the linearity of the vapour pressure curve.

3. REPORTING

The following information shall if possible be included in the report:

Precise specification of the substance (identity and impurities): - At least two vapour pressure and temperature values, preferably in the range 0 to 50 °C. It should also include all of the raw data and a log p versus 1/T curve. In addition, an estimate of the vapour pressure at 20 or 25 °C should be given.

If a transition (change of state, decomposition) is observed, the following information should be noted: - nature of the change,

- temperature at which the change occurs at atmospheric pressure,

- vapour pressure at 10 and 20 °C below the transition temperature and 10 and 20 °C above this temperature (unless the transition is from solid to gas).

All information and remarks relevant for the interpretation of results have to be reported.

The method used shall be stated.

4. REFERENCES (1) OECD, Paris, 1981, Test Guideline 104, Decision of the Council C(81) 30 final.

(2) OECD, Paris, 1981, Test Guideline 104, reference 4, Decision of the Council C(81) 30 final.

Appendix

>PIC FILE= "T0027373">

>PIC FILE= "T0027374">

>PIC FILE= "T0027375">

>PIC FILE= "T0027376">

A. 5. SURFACE TENSION

1. METHOD

The methods described are based on the OECD Test Guideline (1). 1.1. Introduction

The described methods are to be applied to the measurement of the surface tension of aqueous solutions.

It is useful to have preliminary information on the water solubility, the structure, the hydrolysis properties and the critical concentration for micelles formation of the substance before performing these tests.

The following methods are applicable to most chemical substances, without any restriction in respect to their degree of purity.

The measurement of the surface tension by the ring tensiometer method is restricted to aqueous solutions with a dynamic viscosity of less than approximately 200 mPa s.

1.2. Definitions and units

The free surface enthalpy per unit of surface area is referred to as surface tension.

The surface tension is given as:

N/m (SI unit) or

mN/m (SI sub-unit)

1 N/m = 103 dyn/cm

1 mN/m = dyn/cm in the obsolete cgs system

1.3. Reference substances

Reference substances do not need to be employed in all cases when investigating a new substance. This shall primarily serve to calibrate the method from time to time and to offer a chance to compare results when another method is applied.

Reference substances which cover a wide range of surface tensions are given in references 1 and 2.

1.4. Principle of the methods

The methods are based on the measurement of the maximum force which it is necessary to exert vertically, on a stirrup or a ring in contact with the surface of the liquid being examined placed in a measuring cup, in order to separate it from this surface, or on a plate, with an edge in contact with the surface, in order to draw up the film that has formed.

1.5. Quality criteria

These methods are capable of greater precision than is likely to be required for environmental assessment.

1.6. Description of the methods 1.6.1. Plate method

See ISO-304 (Surface active agents - determination of surface tension by drawing up liquid films).

1.6.2. Stirrup method

See ISO 304 (Surface active agents - determination of surface tension by drawing up liquid films).

1.6.3. Ring method

See ISO 304 (Surface active agents - determination of surface tension by drawing up liquid films).

1.6.4. OECD harmonized ring method 1.6.4.1. Apparatus

Commercially available tensiometers are adequate for this measurement. They consist of the following elements: - mobile sample table,

- force measuring system,

- measuring body (ring),

- measurement vessel.

1.6.4.1.1. Mobile sample table

The mobile sample table is used as a support for the temperature-controlled measurement vessel holding the liquid to be tested. Together with the force measuring system, it is mounted on a stand.

1.6.4.1.2. Force measuring system

The force measuring system (see figure 1) is located above the sample table. The error of the force measurement shall not exceed ± 10-6 N, corresponding to an error limit of ± 0,1 mg in a mass measurement. In most cases, the measuring scale of commercially available tensiometers is calibrated in mN/m so that the surface tension can be read directly in mN/m with an accuracy of 0,1 mN/m.

1.6.4.1.3. Measuring body (ring)

The ring is usually made of a platinum-iridium wire of about 0,4 mm thickness and a mean circumference of 60 mm. The wire ring is suspended horizontally from a metal pin and a wire mounting bracket to establish the connection to the force measuring system (see figure).

>PIC FILE= "T0027377">

1.6.4.1.4. Measurement vessel

The measurement vessel holding the test solution to be measured shall be a temperature-controlled glass vessel. It shall be designed so that during the measurement the temperature of the test solution liquid and the gas phase above its surface remains constant and that the sample cannot evaporate. Cylindrical glass vessels having an inside diameter of not less than 45 mm are acceptable.

1.6.4.2. Preparation of the apparatus 1.6.4.2.1. Cleaning

Glass vessels shall be cleaned carefully. If necessary they shall be washed with hot chromo-sulphuric acid and subsequently with syrupy phosphoric acid (83 to 98 % by weight of H3PO4), thoroughly rinsed in tap water and finally washed with double-distilled water until a neutral reaction is obtained and subsequently dried or rinsed with part of the sample liquid to be measured.

The ring shall first be rinsed thoroughly in water to remove any substances which are soluble in water, briefly immersed in chromo-sulphuric acid, washed in double-distilled water until a neutral reaction is obtained and finally heated briefly above a methanol flame.

Note:

Contamination by substances which are not dissolved or destroyed by chromo-sulphuric acid or phosphoric acid, such as silicones, shall be removed by means of a suitable organic solvent.

1.6.4.2.2. Calibration of the apparatus

The verification of the apparatus consists of verifying the zero point and adjusting it so that the indication of the instrument allows reliable determination in mN/m.

Mounting:

The apparatus shall be levelled, for instance by means of a spirit level on the tensiometer base, by adjusting the levelling screws in the base.

Zero point adjustment:

After mounting the ring on the apparatus and prior to immersion in the liquid, the tensiometer indication shall be adjusted to zero and the ring checked for parallelism to the liquid surface. For this purpose, the liquid surface can be used as a mirror.

Calibrations:

The actual test calibration can be accomplished by means of either of two procedures: >PIC FILE= "T0027378">

1.6.4.3. Preparation of samples

Aqueous solutions shall be prepared of the substances to be tested, using the required concentrations in water, and shall not contain any non-dissolved substances.

The solution must be maintained at a constant temperature (± 0,5 °C). Since the surface tension of a solution in the measurement vessel alters over a period of time, several measurements shall be made at various times and a curve plotted showing surface tension as a function of time. When no further change occurs, a state of equilibrium has been reached.

Dust and gaseous contamination by other substances interfere with the measurement. The work shall therefore be carried out under a protective cover.

1.6.5. Test conditions

The measurement shall be made at approximately 20 °C and shall be controlled to within ± 0,5 °C.

1.6.6. Performance of test

The solutions to be measured shall be fixed into the carefully cleaned measuring vessel, taking care to avoid foaming, and subsequently the measuring vessel shall be placed onto the table of the test apparatus. The table-top with measuring vessel shall be raised until the ring is immersed below the surface of the solution to be measured. Subsequently, the table-top shall be lowered gradually and evenly (at a rate of approximately 0,5 cm/min) to detach the ring from the surface until the maximum force has been reached. The liquid layer attached to the ring must not separate from the ring. After completing the measurements, the ring shall be immersed below the surface again and the measurements repeated until a constant surface tension value is reached. The time from transferring the solution in the measurement vessel shall be recorded for each determination. Readings shall be taken at the maximum force required to detach the ring from the liquid surface.

2. DATA >PIC FILE= "T0027379">

Harkins and Jordan (3) have empirically determined correction factors for surface-tension values measured by the ring method which are dependent on ring dimensions, the density of the liquid and its surface tension.

Since it is laborious to determine the correction factor for each individual measurement from the Harkins and Jordan tables, in order to calculate the surface tension for aqueous solutions the simplified procedure of reading the corrected surface-tension values directly from table may be used. (Interpolation shall be used for readings ranging between the tabular values.) TABLE : CORRECTION OF THE MEASURED SURFACE TENSION >PIC FILE= "T0027380">

where:

F = the force measured on the dynamometer at the breakpoint of the film

R = the radius of the ring

f = the correction factor (1)

3. REPORTING

The test report shall if possible contain at least the following information: - method used : ISO or OECD harmonized ring tensiometer method,

- type of water or solution used,

- precise specification of the substance (identity and impurities),

- measurement results : surface tension (reading) stating both the individual readings and their arithmetic mean as well as the corrected mean (taking into consideration the equipment factor and the correction table),

- concentration of the solution,

- test temperature,

- age of solution used ; in particular the time between preparation and measurement of the solution,

- description of time dependence of surface tension after transferring the solution to the measurement vessel,

- all information and remarks relevant for the interpretation of results have to be reported, especially with regard to impurities and physical state of the substance.

4. REFERENCES (1) OECD, Paris, 1981, Test Guideline 115, Decision of the Council C(81) 30 final.

(2) Pure and applied chemistry, vol. 48, 1976, p. 511.

(3) Harkins, W.D., Jordan, H.F., J. Amer. Chem. Soc., vol. 52, 1930, p. 1751.

A. 6. WATER SOLUBILITY

1. METHOD

The methods described are based on the OECD Test Guideline (1). 1.1. Introduction

It is useful to have preliminary information on the structural formula, the vapour pressure, the dissociation constant and the hydrolysis (as a function of pH) of the substance to perform this test.

No single method is available to cover the whole range of solubilities in water.

The method is not applicable to volatile substances.

The two test methods described below cover the whole range of solubilities: - one which applies to essentially pure substances with low solubilities (-2 grams per litre), and which are stable in water, referred to as the "column elution method",

- the other which applies to essentially pure substances with higher solubilities (> 10-2 grams per litre), and which are stable in water, referred to as the "flask method".

The water solubility of the tested substance can be considerably affected by the presence of impurities.

1.2. Definition and units

The solubility in water of a substance is specified by the saturation mass concentration of the substance in water at a given temperature. The solubility in water is specified in units of mass per volume of solution. The SI unit is kg/m3 (grams per litre may also be used).

1.3. Reference substances

Reference substances do not need to be employed in all cases when investigating a new substance. They should primarily serve to check the performance of the method from time to time and to offer the possibility to compare results when another method is applied.

1.4. Principle of the test method

The approximate amount of the sample and the time necessary to achieve the saturation mass concentration should be determined in a simple preliminary test. 1.4.1. Column elution method

This method is based on the elution of a test substance with water from a micro-column which is charged with an inert support material such as glass beads, silica gel or sand and an excess of test substance. The water solubility is determined when the mass concentration of the eluate is constant. This is shown by a concentration plateau as a function of time.

1.4.2. Flask method

In this method, the substance (solids must be pulverized) is dissolved in water at a temperature somewhat above the test temperature. When saturation is achieved the mixture is cooled and kept at the test temperature, stirring as long as necessary to reach equilibrium (2). Subsequently, the mass concentration of the substance in the aqueous solution, which must not contain any undissolved particles, is determined by a suitable analytical method.

1.5. Quality criteria 1.5.1. Repeatability

For the column elution method, 1.5.2. Sensitivity

This depends upon the method of analysis, but mass concentration determinations down to at least 10-6 grams per litre can be determined.

1.6. Description of the method 1.6.1. Test conditions

The test is preferably run at 20 ± 0,5 °C. If a temperature dependence is suspected in the solubility (> 3 % per °C), two other temperatures at least 10 °C above and below the initially chosen temperature should also be used. In this case, the temperature control should be ± 0,1 °C. The chosen temperature should be kept constant in all relevant parts of the equipment.

1.6.2. Preliminary test

To approximately 0,1 g of the sample (solid substances must be pulverized) in a glass-stoppered 10 ml graduated cylinder increasing volumes of distilled water at room temperature are added according to the steps shown in the table below: >PIC FILE= "T0027381">

After each addition of the indicated amount of water, the mixture is shaken vigorously for 10 minutes and is visually checked for any undissolved parts of the sample. If, after addition of 10 ml of water, the sample or parts of it remain undissolved, the contents of the measuring cylinder are transferred to a 100 ml measuring cylinder which is then filled up with water to 100 ml and shaken. At lower solubilities the time required to dissolve a substance can be considerably longer (24 hours should be allowed). The approximate solubility is given in the table under that volume of added water in which complete dissolution of the sample occurs. If the substance is still apparently insoluble, further dilution should be undertaken to ascertain whether the column elution or flask solubility method should be used.

1.6.3. Column elution method 1.6.3.1. Support material, solvent and eluent

The support material for the column elution method should be inert. Possible materials which can be employed are glass beads and silica. A suitable volatile solvent of analytical reagent quality should be used to apply the test substance to the support material. Double distilled water from glass or quartz apparatus should be employed as the eluent or solvent.

Note

Water directly from an organic ion exchanger must not be used.

1.6.3.2. Loading of the support

Approximately 600 mg of support material is weighed and transferred to a 50 ml round-bottom flask.

A suitable, weighed amount of test substance is dissolved in the chosen solvent. An appropriate amount of the test substance solution is added to the support material. The solvent must be completely evaporated, e.g. in a rotary evaporator ; otherwise water saturation of the support is not achieved due to partition effects on the surface of the support material.

The loading of support material may cause problems (erroneous results) if the test substance is deposited as an oil or a different crystal phase. The problem should be examined experimentally.

The loaded support material is allowed to soak for about two hours in approximately 5 ml of water, and then the suspension is added to the microcolumn. Alternatively, dry loaded support material may be poured into the microcolumn, which has been filled with water, and then equilibrated for approximately two hours.

Test procedure

The elution of the substance from the support material can be carried out in one of two different ways: - recirculating pump (see figure 1),

- levelling vessel (see figure 4).

1.6.3.3. Column elution method with recirculating pump

Apparatus

A schematic arrangement of a typical system is presented in figure 1. A suitable microcolumn is shown in figure 2, although any size is acceptable, provided it meets the criteria for reproducibility and sensitivity. The column should provide for a headspace of at least five bed volumes of water plus a minimum of five samples. Alternatively, the size can be reduced if make-up solvent is employed to replace the initial five bed volumes removed with impurities.

The column should be connected to a recirculating pump capable of controlling flows of approximately 25 ml/hr. The pump is connected with polytetrafluoroethylene and/or glass connections. The column and pump, when assembled, should have provision for sampling the effluent and equilibrating the headspace at atmospheric pressure. The column material is supported with a small (5 mm) plug of glass wool, which also serves to filter out particles. The recirculating pump can be, for example, a peristaltic pump (care must be taken that no contamination and/or adsorption occurs with the tube material) or a membrane pump.

Measurement procedure

The flow through the column is started. It is recommended that a flow rate of approximately 25 ml/hr be used (approximately 10 bed volumes/hr for the described column). The first five bed volumes (minimum) are discarded to remove water soluble impurities. Following this, the recirculating pump is allowed to run until equilibration is established, as defined by five successive samples whose concentrations do not differ by more than ± 30 % in a random fashion. These samples should be separated from each other by time intervals corresponding to the passage of at least 10 bed volumes of the eluent.

1.6.3.4. Column elution method with levelling vessel

Apparatus (see figures 4 and 3)

Levelling vessel : The connection to the levelling vessel is made by using a ground glass joint which is connected by PTFE tubing. It is recommended that a flow rate of approximately 25 ml/hr be used. Successive eluate fractions should be collected and analyzed by the chosen method.

Measurement procedure

Fractions from the middle eluate range where the concentrations are constant (± 30 %) in at least five consecutive fractions are used to determine the solubility in water.

A second run is to be performed at half the flow rate of the first. If the results of the two runs are in agreement, the test is satisfactory ; if there is a higher apparent solubility with the lower flow rate, then the halving of the flow rate must continue until two successive runs give the same solubility.

In both cases (using a recirculating pump or a levelling vessel) the fractions should be checked for the presence of colloidal matter by examination for the Tyndall effect (light scattering). Presence of such particles invalidates the results, and the test should be repeated with improvements in the filtering action of the column. The pH of each sample should be recorded. A second run should be performed at the same temperature.

1.6.4. Flask method 1.6.4.1. Apparatus

For the flask method the following material is needed: - normal laboratory glassware and instrumentation,

- a device suitable for the agitation of solutions under controlled constant temperatures,

- a centrifuge (preferably thermostated), if required with emulsions, and

- equipment for analytical determination.

1.6.4.2. Measurement procedure

The quantity of material necessary to saturate the desired volume of water is estimated from the preliminary test. The volume of water required will depend on the analytical method and the solubility range. About five times the quantity of material determined above is weighed into each of three glass vessels fitted with glass stoppers (e.g. centrifuge tubes, flasks). The chosen volume of water is added to each vessel, and the vessels are tightly stoppered. The closed vessels are then agitated at 30 °C. (A shaking or stirring device capable of operating at constant temperature should be used, e.g. magnetic stirring in a thermostatically controlled water bath). After one day, one of the vessels is removed and re-equilibrated for 24 hours at the test temperature with occasional shaking. The contents of the vessel are then centrifuged at the test temperature, and the concentration of compound in the clear aqueous phase is determined by a suitable analytical method. The other two flasks are treated similarly after initial equilibration at 30 °C for two and three days, respectively. If the concentration results from at least the last two vessels agree with the required reproducibility, the test is satisfactory. The whole test should be repeated, using longer equilibration times, if the results from vessels 1, 2 and 3 show a tendency to increasing values.

The pH of each sample should be recorded.

1.6.5. Analysis

A substance-specific analytical method is preferred for these determinations, since small amounts of soluble impurities can cause large errors in the measured solubility. Examples of such methods are : gas or liquid chromatography, titration methods, photometric methods, voltametric methods.

2. DATA 2.1. Column elution method

The mean value from at least five consecutive samples taken from the saturation plateau should be calculated for each run, as should the standard deviation.

2.2. Flask method

The individual results should be given for each of the three flasks and those results deemed to be constant (repeatability less than 15 %) should be averaged and given in units of mass per volume of solution. This may require the reconversion of mass units to volume units, using the density when the solubility is very high (>100 grams per litre).

3. REPORTING 3.1. Column elution method

The report shall if possible contain an indication of the results of the preliminary test plus the following information: - precise specification of the substance (identity and impurities),

- the individual concentrations, flow rates and pH of each sample,

- the means and standard deviations from at least five samples from the saturation plateau of each run,

- the average of the two successive, acceptable runs,

- the temperature of the water during the saturation process,

- the method of analysis employed,

- the nature of the support material employed,

- loading of support material,

- solvent used,

- evidence of any chemical instability of the substance during the test and the method used,

- all information relevant for the interpretation of the results.

3.2. Flask method

The report shall if possible include the following information: - precise specification of the substance (identity and impurities),

- the individual analytical determinations and the average where more than one value was determined for each flask,

- the pH of each sample,

- the average of the value for the different flasks which were in agreement,

- the test temperature,

- the analytical method employed,

- evidence of any chemical instability of the substance during the test and the method used,

- all information relevant for the interpretation of the results.

4. REFERENCES (1) OECD, Paris, 1981, Test Guideline 105, Decision of the Council C(81) 30 final.

(2) OECD, Paris, 1981, Test Guideline 116, Decision of the Council C(81) 30 final.

Appendix

>PIC FILE= "T0027382">

>PIC FILE= "T0027383">

>PIC FILE= "T0027384">

>PIC FILE= "T0027385">

A. 7. FAT SOLUBILITY

1. METHOD

The method described is based on the OECD Test Guideline (1) 1.1. Introduction

It is useful to have preliminary information on the partition coefficient, water solubility, structural formula and stability at 50 °C of the substance to perform this test. This method is applicable only to those substances which are essentially pure, which are stable at 50 °C and which are not appreciably volatile under the same conditions.

The method is not suitable for test substances which are reactive with triglycerides.

1.2. Definitions and units

The mass fraction of a substance which forms a homogeneous phase with a liquid fat (oil) without giving rise to chemical reactions is defined as fat solubility. The maximum of such mass fraction is called the saturation mass fraction, and this is a function of temperature.

The saturation mass fraction of a substance should be given in milligrams per 100 g of standard fat at 37 ± 0,5 °C.

The following relationship exists between the solubility in grams per 100 g of solution (S') and the solubility in grams per 100 g of solvent (S): >PIC FILE= "T0027386">

Multiplication of the S value with 1 000 gives milligrams per 100 g of standard fat.

1.3. Reference substances

Reference substances do not need to be employed in all cases when investigating a new substance. They should primarily serve to check the performance of the method from time to time and to offer the possibility to compare results when another method is applied.

1.4. Principle of the method

The substance is added to a liquid "standard fat" and stirred. A sufficient amount of substance is added to ensure an excess. The dissolved amount of test substance should be determined by a suitable analytical method.

1.5. Quality criteria 1.5.1. Specificity

The repeatability of the measurement is unknown at present.

Results should apply to standard fats and are appropriate for relatively pure substances. Even at 37 °C, fats may form emulsions or fine suspension of solid substances. Since these will interfere with subsequent determination of mass fraction, the formation of these must be avoided.

1.6. Description of the method 1.6.1. Preparation 1.6.1.1. Apparatus

The following items of equipment are required: - normal laboratory glassware,

- balance,

- centrifuge with thermostat,

- a stirrer which can be used in combination with a temperature control system,

- thermostat.

1.6.1.2. Standard fats

The use of standard fats is necessary. These standards fats should be easily definable and an example of such a standard fat is given in the Appendix.

1.6.1.3. Preliminary test

A simplified preliminary test should be run to determine the approximate amount of substance necessary for the establishment of the saturation mass fraction at the test temperature (37 °C).

Note

The rate of establishment of the saturation equilibrium may be greatly dependent upon the particle size in the case of solid substances. For this reason, such materials should be pulverized.

1.6.1.4. Preparation of the substance

Weigh eight samples into 50 ml flasks. Normally each should be of twice the quantity necessary for saturation as determined in the preliminary test.

After adding a weighed amount of approximately 25 g of liquefied and mixed standard fat, the flasks, fitted with the stirrers, are tightly closed with ground glass stoppers. One half (group I) is stirred at 30 °C, and the other half (group II) at approximately 50 °C, each for at least one hour.

1.6.2. Test conditions

The determination of fat solubility is carried out at 37 ± 0,5 °C.

1.6.3. Measurement procedure

Stir the contents of the flasks in both groups at 37 ± 0,5 °C, until thoroughly mixed.

The stirring time required to establish equilibrium cannot be predicted in general. In the case of liquid substances, saturation may be reached within minutes ; in the case of solid substances it may take hours. In general no more than three hours of stirring will be needed ; after this time, stirring should be stopped for two of the flasks in both groups and these two flasks allowed to stand for at least one hour at 37 °C in order to separate the undissolved amount of substance and to allow the formation of homogeneous phase. In the event of emulsion or suspension formation (e.g. Tyndall effect), this must be eliminated by a suitable method such as thermostated centrifugation.

The third and fourth flask in both groups should be stirred for at least 24 hours before standing for one hour at 37 ± 0,5 °C.

Note

If no bottom sediment (for solid substances) has formed or no phase separation (for liquid substances) has occurred after this period, the test must be repeated with a greater amount of substance.

1.6.4. Analysis

One sample is taken from each saturated fat phase for analysis. This sample is weighed, and the mass fraction is determined.

Any suitable analytical method may be applied either directly or after extraction with water or an organic solvent or any other separation technique.

Examples of such methods are: - spectrophotometry

- gas or liquid chromatography

- voltammetry

2. DATA

If there are significant differences in results from either under- or over-saturation or short and long time periods, the test should be repeated with longer stirring times.

3. REPORTING

The following information shall if possible be included in the test report: - precise specification of the substance (identity and impurities),

- precise specification of the fat (e.g. description, characteristics, origin, composition),

- method of analysis, deviations and special features.

The results must be evaluated as described above and they are part of the test report. If there were no significant differences between the various observed values in milligrams per 100 g, the individual values, the mean value and the standard deviation should be reported. If there are significant differences, even after retesting, then only the individual results should be reported.

All information and remarks relevant for the interpretation of results have to be reported.

4. REFERENCE (1) OECD, Paris 1981, Test Guideline 116, Decision of the Council C(81) 30 final.

Appendix EXAMPLE FOR STANDARD FATS

The following table shows the composition of a typical standard fat. >PIC FILE= "T0027387">

A. 8. PARTITION COEFFICIENT

1. METHOD

The method described is based on the OECD Test Guideline (1). 1.1. Introduction

It is useful to have preliminary information on dissociation constant, water solubility, and surface tension of the substance to perform this test.

This method applies only to essentially pure substance soluble in water and octanol. It is not applicable to surface active material.

1.2. Definition and units

The partition coefficient (P) is defined as the ratio of the equilibrium concentrations (ci) of a dissolved substance in a two-phase system consisting of two largely immiscible solvents. In the case n-octanol and water: >PIC FILE= "T0027388">

The partition coefficient (P) therefore is the quotient of two concentrations and is usually given in the form of its logarithm to base 10 (log P).

1.3. Reference substances

Reference substances do not need to be employed in all cases when investigating a new substance. They should primarily serve to check the performance of the method from time to time and to offer the possibility to compare results when another method is applied.

1.4. Principle of the method

In order to determine a partition coefficient, equilibrium between all interacting components of the system must be achieved, and the concentrations of the substances dissolved in the two phases must be determined. A study of the literature on this subject indicates that there are many different techniques which can be used to solve this problem, i.e. the thorough mixing of the two phases followed by their separation in order to determine the equilibrium concentration for the substance being examined.

1.5. Quality criteria 1.5.1. Repeatability

In order to assure the precision of the partition coefficient, duplicate determinations are to be made under three different test conditions, whereby the quantity of substance specified as well as the ratio of the solvent volumes may be varied. The determined values of the partition coefficient expressed as their common logarithms should fall within a range of ± 0,3 log units.

1.5.2. Sensitivity

The measuring range of the method is determined by the limit of detection of the analytical procedure. This should be sufficient to permit the assessment of values of Pow up to 105 when the concentration of the solute in either phase is not more than 0,01 mol per litre.

1.5.3. Specificity

The Nernst Partition Law applies only at constant temperature, pressure and pH for dilute solutions. It strictly applies to a pure substance dispersed between two pure solvents. If several different solutes occur in one or both phases at the same time, this may affect the results.

Dissociation or association of the dissolved molecules result in deviations from the Nernst Partition Law. Such deviations are indicated by the fact that the partition coefficient becomes dependent upon the concentration of the solution.

Because of the multiple equilibria involved, this test method should not be applied to ionizable compounds without applying correction. (The use of buffer solutions in place of water should be considered for such compounds.)

1.6. Description of the method 1.6.1. Preliminary estimate of the partition coefficient

The value of the partition coefficient can be estimated either by means of a simple calculation (2) or by use of the solubilities of the test substance in the pure solvents (1):

For this: >PIC FILE= "T0027389">

Alternatively, it may be roughly determined by performing a simplified preliminary test.

1.6.2. Preparation

n-octanol : The determination of the partition coefficient should be carried out with high purity analytical grade reagent.

Water : Distilled or double distilled water from glass or quartz apparatus should be employed.

Note

Water taken directly from an ion exchanger should not be used. 1.6.2.1. Presaturation of the solvents

Before a partition coefficient is determined, the phases of the solvent system are mutually saturated by shaking at the temperature of the experiment. For doing this, it is practical to shake two large stock bottles of high purity analytical grade n-octanol or water each with a sufficient quantity of the other solvent for 24 hours on a mechanical shaker and then to let them stand long enough to allow the phases to separate and to achieve a saturation state.

1.6.2.2. Preparation for the test

The entire volume of the two-phase system should nearly fill the test vessel. This will help prevent loss of material due to volatilization. The volume ratio and quantities of substance to be used are fixed by the following: - the preliminary assessment of the partition coefficient (see above),

- the minimum quantity of test substance required for the analytical procedure ; and

- the limitation of a maximum concentration in either phase of 0,01 mol per litre.

Three tests are carried out. In the first, the calculated volume ratio is added ; in the second, twice the volume of n-octanol is added ; and in the third, half the volume of n-octanol is added.

1.6.2.3. Test substance

For a material balance during the test, a stock solution is prepared in n-octanol with a mass concentration between 1 and 100 mg/ml. The actual mass concentration of this stock solution should be precisely determined before it is employed in the determination of the partition coefficient. This solution should be stored under stable conditions.

1.6.3. Test Conditions

The test temperature should be kept constant (± 1 °C) and lie in the range of 20 to 25 °C.

1.6.4. Measurement procedure 1.6.4.1. Establishment of the partition equilibrium

Duplicate test vessels containing the required, accurately measured amounts of the two solvents together with the necessary quantity of the stock solution should be prepared for each of the test conditions.

The octanol parts should be measured by volume. The test vessels should either be placed in a suitable shaker or shaken by hand. A recommended method is to rotate the centrifuge tube quickly through 180° about its transverse axis so that any trapped air rises through the two phases.

1.6.4.2. Phase separation

In order to separate the phases, centrifugation of the mixture should be carried out. This should be done in a laboratory centrifuge maintained at room temperature, or, if a non-temperature controlled centrifuge is used, the centrifuge tubes should be re-equilibrated at the test temperature for at least one hour before analysis.

1.6.5. Analysis

For the determination of the partition coefficient, it is necessary to determine the concentrations of the test substance in both phases. This may be done by taking an aliquot of each of the two phases from each tube for each test condition and analyzing them by the chosen procedure. The total quantity of substance present in both phases should be calculated and compared with the quantity of the substance originally introduced.

The aqueous phase should be sampled by a procedure that minimizes the risk of including traces of octanol : a glass syringe with a removable needle can be used to sample the water phase. The syringe should initially be partially filled with air. Air should be gently expelled while inserting the needle through the octanol layer. An adequate volume of aqueous phase is withdrawn into the syringe. The syringe is quickly removed from the solution and the needle detached. The contents of the syringe may then be used as the aqueous sample. The concentration in the two separated phases should preferably be determined by a substance specific method. Examples of physico-chemical determinations which may be appropriate are: - photometric methods,

- gas chromatography,

- high-pressure liquid chromatography.

2. DATA

If the measured Pow is greater than 104, it is recommended that the results be compared with a calculated Pow value, as for example one obtained by the method given in reference 3.

The reliability of the determined values of P can be tested by comparison of the means of the duplicate determinations with the overall mean.

3. REPORTING

The following information shall if possible be included in the report: - Precise specification of the substance (identity and impurities).

- Temperature of the determination.

- Data on the analytical procedures used in determining concentrations.

- The measured concentrations in both phases for each determination. (This means that a total of 12 concentrations will be reported.)

- The weight of the test substance, the volume of each phase employed in each test vessel and the total calculated amount of test substance present in each phase after equilibration.

- The calculated values of the partition coefficient (P) and the mean should be reported for each set of test conditions as should the mean for all determinations. If there is a suggestion of concentration dependency of the partition coefficient, this should be noted in the report.

- The standard deviation of individual P values about their mean should be reported.

- The mean P from all determinations should also be expressed as its logarithm (base 10).

- The calculated theoretical Pow when this value has been determined or when the measured value is > 104.

- pH of water used and aqueous phase during the experiment.

- All information and remarks relevant for the interpretation of results.

4. REFERENCES (1) OECD, Paris, 1981, Test Guideline 107, Decision of the Council C(81) 30 final.

(2) OECD, Paris, 1981, Test Guideline 107, reference 2, Decision of the Council C(81) 30 final

(3) OECD, Paris, 1981, Test Guideline 107, reference 10, Decision of the Council C(81) 30 final.

A. 9. FLASH POINT

1. METHOD 1.1. Introduction

It is useful to have preliminary information on flammability of the substance to perform this test. The test procedure is applicable to liquid substances, as marketed, whose vapours can be ignited by ignition sources. The test methods described in this text are only reliable for flashpoint ranges which are specified in the individual methods.

1.2. Definitions and units

The flashpoint is the lowest temperature, corrected at a pressure of 101,325 kPa, at which the test liquid in a closed test vessel evolves vapours, under the conditions defined in the test method, in such amount that a flammable vapour/air mixture is produced in the test vessel.

Units : °C

t = T - 273,15

(t in °C and T in K)

1.3. Reference substances

Reference substances do not need to be used in all cases when investigating a new substance. They should primarily serve to calibrate the method from time to time and to offer a chance to compare results when another method is applied.

1.4. Principle of the method

The substance is placed in a test vessel which is progressively heated until the vapour reaches a sufficiently high concentration in air to produce a flammable mixture which can be ignited.

1.5. Quality criteria 1.5.1. Repeatability

The repeatability varies according to flashpoint range and the test method used ; maximum ± 2 °C.

1.5.2. Sensitivity

The sensitivity depends on the test method used.

1.5.3. Specificity

The specificity of some test methods is limited to certain flashpoint ranges and subject to substance-related data (e.g. high viscosity).

1.6. Description of the method 1.6.1. Preparations

A sample of the test substance is placed in a test apparatus according to 1.6.3.1 and/or 1.6.3.2.

1.6.2. Test conditions

The apparatus is preferably placed in a draught-free position.

1.6.3. Performance of the test 1.6.3.1. Equilibrium method

See ISO 1516, ISO 3680, ISO 1523, ISO 3679.

1.6.3.2. Non-equilibrium method

Abel apparatus:

See BS 2000 part 170, NF M07-011, NF T66-009.

Abel-Pensky apparatus:

See (EN 57), DIN 51755 part 1 (for temperature from 5 to 65 °C), DIN 51755 part 2 (for temperature below 5 °C), NF M07-036.

Tag apparatus:

See ASTM D 56, ISO 2719.

Pensky-Martens apparatus:

See ISO 2719, (EN 11), DIN 51758, ASTM 8013, ASTM D 93, BS 2000-34, NF M07-019.

Remarks

When the flashpoint, determined by a non-equilibrium method in 1.6.3.2, is found to be : 0 ± 2 °C, 21 ± 2 °C, 55 ± 2 °C, it should be confirmed by an equilibrium method using the same apparatus.

Only the methods which can give the temperature of the flashpoint may be used for a notification.

To determine the flashpoint of viscous liquids (paints, gums and similar) containing solvents, only apparatus and test methods suitable for determining the flashpoint of viscous liquids may be used.

See ISO 3679, ISO 3680, ISO 1523, DIN 53213 part 1.

2. DATA

3. REPORTING

The report shall, if possible, include the following information: - The precise specification of the substance (identification and impurities).

- The method used should be stated as well as any possible deviations.

- The results and all information and remarks relevant for the interpretation of results have to be reported.

4. REFERENCES

None.

A. 10. FLAMMABILITY (SOLIDS)

1. METHOD 1.1. Introduction

It is useful to have preliminary information on potentially explosive properties of the substance before performing this test.

This test should only be applied to powder, granular and pasty substances.

In order not to include all substances which can be ignited but only those which burn rapidly or those whose burning behaviour is in any way especially dangerous, only substances whose burning velocity exceeds a certain limiting value are considered to be highly flammable. Moreover, metal powders which can incandesce should also be considered to be highly flammable, if incandescence propagates throughout the sample. Such incandescence, and the associated difficulties in extinguishing a fire, are the main reason why metal powders are especially dangerous. Normal extinguishing agents such as carbon dioxide and/or water can increase the hazard considerably.

1.2. Definition and units

Burning time expressed in seconds.

1.3. Reference compounds

Not specified.

1.4. Principle of the method

The substance in its commercial form is made into a pile of 250 mm length. An attempt is then made to ignite the sample under the conditions defined in 1.6.3, and the burning time is measured.

1.5. Quality criteria

1.6. Description of method 1.6.1. Preparation

In the case of powder and granular substances the product in its commercial form is loosely filled into a mould. The mould is made of metal, has a length of 250 mm and a triangular cross section with an inner height of 10 mm and an inner width of 20 mm. On both sides of the mould in a longitudinal direction two metal sheets are mounted as lateral limitations which project 2 mm beyond the upper edge of the triangular cross section (figure). The mould is then dropped three times from a height of 2 cm onto a solid surface. If necessary the mould is then filled up again. Then the lateral limitations are removed and the excess substance scraped off. A non-combustible and non-porous plate is placed on top of the mould, the apparatus inverted and the mould removed.

Pasty substances are spread on a non-combustible surface in the form of a rope 250 mm length with a cross section of about 1 cm2.

Any suitable ignition source such as a small flame or a hot wire of minimum temperature of 1 000 °C is used to ignite the pile at one end.

1.6.2. Test conditions

In the case of a moisture-sensitive substance, the test should be carried out as quickly as possible after its removal from the container.

1.6.3. Performance of the test

Ignite one end of the pile. When the pile has burned a distance of 80 mm, measure the rate of burning over the next 100 mm. The test is performed six times, using a clean cool plate each time.

2. DATA

The values of burning time determined within six tests are necessary for the evaluation.

3. REPORTING 3.1. Test report

The report shall if possible include the following information: - The precise specification of the substance (identification and impurities).

- A description of the substance to be tested, its physical state including moisture content.

- The measurement results.

- All additional remarks relevant to the interpretation of results.

3.2. Interpretation of the result

Powders, granular or pasty substances are to be considered as highly flammable when the time of burning in one of the six tests carried out according to the test procedure described in 1.6 is less than 45 seconds. Powders of metals or metal-alloys are considered to be highly flammable when they can be ignited and the flame or the zone of reaction spreads over the whole sample.

4. REFERENCES

None

Appendix

>PIC FILE= "T0027390">

A. 11. FLAMMABILITY (GASES)

1. METHOD 1.1. Introduction

This method allows a determination of whether gases mixed with air at room temperature and atmospheric pressure have a range of flammability. Mixtures of increasing concentrations of the test gas with air are exposed to an electrical spark and it is observed whether ignition occurs.

1.2. Definition and units

The range of flammability is the range of concentration between the lower and the upper explosion limits. The lower and the upper explosion limits are those limits of concentration of the flammable gas in admixture with air at which propagation of a flame does not occur.

1.3. Reference substance

Not specified.

1.4. Principle of the method

The concentration of gas in air is increased step by step and the mixture is exposed at each stage to an electrical spark.

1.5. Quality criteria

Not stated.

1.6. Description of the method 1.6.1. Apparatus

The test vessel is an upright glass cylinder having a minimum inner diameter of 50 mm and a minimum height of 300 mm. The ignition electrodes are separated by a distance of 3 to 5 mm and are placed 60 mm above the bottom of the cylinder. The cylinder is fitted with a pressure-release opening. The apparatus has to be shielded to restrict any explosion damage.

A standing induction spark of 0,5 sec. duration, which is generated from a high voltage transformer with an output voltage of 10 to 15 kV (maximum of power input 300 W), is used as the ignition source.

1.6.2. Test conditions

The test must be performed at room temperature.

1.6.3. Performance of the test

Using proportioning pumps, a known concentration of gas in air is introduced into the glass cylinder. A spark is passed through the mixture and it is observed whether a flame detaches itself from the ignition source and propagates independently. The concentration of gas is varied in steps of 1 % vol. until ignition occurs as described above.

2. DATA

The occurrence of flame propagation is the only relevant information data for the determination of this property.

3. REPORTING

The report shall if possible include the following information: - The precise specification of the substance (identification and impurities).

- A description, with dimensions of the apparatus used.

- The room temperature at which the test is performed.

- The tested concentrations and the results obtained.

- The result of the test : non-flammable gas or highly flammable gas.

- In the case of a "non-flammable" conclusion, it sho