FINAL REPORT

Study Title

DETERMINATION OF PHYSICO-CHEMICAL PROPERTIES OF 

CASTOR OIL, SULFATED, SODIUM SALT, 75%

 Melting and boiling temperature

 Water content Karl Fischer

 Content Sodium Sulphate

 Content SO3

 Purity / composition

Author

I. van Doormalen - Schaap, BSc.

Test Facility

WIL Research Europe B.V.

Hambakenwetering 7

5231 DD ‘s-Hertogenbosch

The Netherlands

 Laboratory Project Identification

Project 503335

Substance 205003/A

- Page 1 of 27 -
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

Final report - Page 2 - 

1. CONTENTS

1. CONTENTS ......................................................................................................................................2

2. STATEMENT OF GLP COMPLIANCE.............................................................................................4

3. QUALITY ASSURANCE STATEMENT ............................................................................................5

4. SUMMARY........................................................................................................................................6

5. INTRODUCTION ..............................................................................................................................7

5.1. Preface ...................................................................................................................................7

5.2. Aim of the study......................................................................................................................7

5.3. Storage and retention of records and materials .....................................................................7

6. MATERIALS......................................................................................................................................8

6.1. Test substance .......................................................................................................................8

6.2. Electronic data capture...........................................................................................................8

6.3. List of deviations .....................................................................................................................8

7. MELTING AND BOILING TEMPERATURE .....................................................................................9

7.1. Guidelines...............................................................................................................................9

7.2. Performance of the test ..........................................................................................................9

7.3. Analytical method ................................................................................................................ 10

7.4. Interpretation........................................................................................................................ 10

7.5. Results................................................................................................................................. 11

7.6. Conclusion ........................................................................................................................... 12

7.7. Figures................................................................................................................................. 12

8. WATER CONTENT KARL FISCHER ............................................................................................ 15

8.1. Reagents ............................................................................................................................. 15

8.2. Performance of the test ....................................................................................................... 15

8.3. Analytical method ................................................................................................................ 16

8.4. Interpretation........................................................................................................................ 16

8.5. Results................................................................................................................................. 17

8.6. Conclusion ........................................................................................................................... 17

9. CONTENT SODIUM SULPHATE.................................................................................................. 18

9.1. Guidelines............................................................................................................................ 18

9.2. Reagents ............................................................................................................................. 18

9.3. Reagent solutions ................................................................................................................ 18

9.4. Performance of the study .................................................................................................... 18

9.5. Analytical method ................................................................................................................ 19

9.6. Interpretation........................................................................................................................ 20

9.7. Results................................................................................................................................. 21

9.8. Conclusion ........................................................................................................................... 22

10. CONTENT SO3 .............................................................................................................................. 23

10.1. Guidelines............................................................................................................................ 23

10.2. Reagents ............................................................................................................................. 23

10.3. Reagent solutions ................................................................................................................ 23

10.4. Performance of the study .................................................................................................... 23

10.5. Analytical method ................................................................................................................ 24

10.6. Interpretation........................................................................................................................ 24

10.7. Results................................................................................................................................. 25

10.8. Conclusion ........................................................................................................................... 26

11. PURITY / COMPOSITION ............................................................................................................. 26
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

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TABLES

Table 1 Calibration of Karl Fischer apparatus................................................................................ 17

Table 2 Water content of the solvent solution................................................................................ 17

Table 3 Water content of the test substance ................................................................................. 17

Table 4 Content Sodium Sulphate ................................................................................................. 21

Table 5 Relative standard deviation............................................................................................... 21

Table 6 Accuracy samples ............................................................................................................. 22

Table 7 SO3 content....................................................................................................................... 25

Table 8 Relative standard deviation............................................................................................... 25

Table 9 Accuracy samples ............................................................................................................. 26

FIGURES

Figure 1 TGA curve of the test substance....................................................................................... 12

Figure 2 DSC curve of the test substance obtained with Experiment 1.......................................... 13

Figure 3 DSC curve of the test substance obtained with Experiment 2.......................................... 13

Figure 4 DSC curve of the test substance obtained with Experiment 3.......................................... 14

APPENDICES

Appendix 1 Certificate of analysis ........................................................................................................ 27


Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

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4. SUMMARY

The results of the physico-chemical properties of the test substance are given below. 

Parameter Guideline(s) Result Comment

Melting temperature EC A.1 

OECD 102

OPPTS 830.7200

-4°C (269K) most likely due to 

water in the test 

substance

Boiling temperature EC A.2 

OECD 103

OPPTS 830.7220

113°C (386K) most likely due to 

water in the test 

substance

Water content - 24.3% w/w by Karl Fischer 

coulometric titration

Content Sodium Sulphate FAO

SANCO/3030/99

1.25% w/w colorimetric titration

Content SO3 FAO

SANCO/3030/99

5.58% w/w colorimetric titration

Purity / composition - 74.4% (100% minus water 

and sodium sulphate

content)
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

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5. INTRODUCTION

5.1. Preface

Sponsor Sulfated Castor Oil Consortium, Society of Chemical 

Manufacturers & Affiliates

1850 M Street NW, Suite 700

Washington, DC 20036

USA

Study Monitor Rodney Boatman

PCA Services

2704 Trail Wood Drive

Durham, NC 27705

USA

Test Facility WIL Research Europe B.V.

Hambakenwetering 7

5231 DD ‘s-Hertogenbosch

The Netherlands

Study Director I. van Doormalen - Schaap, BSc.

Study Plan Start : 12 October 2013

Completion : 07 November 2013

5.2. Aim of the study

The aim of the study was to determine the following physico-chemical properties for Castor Oil, 

Sulfated, Sodium Salt, 75%.

 Melting and boiling temperature

 Water content Karl Fischer

 Content Sodium Sulphate

 Content SO3

 Purity / composition

5.3. Storage and retention of records and materials

Records and materials pertaining to the study including protocol, raw data, specimens (except 

specimens requiring refrigeration or freezing) and the final report are retained in the WIL Research 

Europe archives for a period of at least 2 years after finalization of the report. After this period, the 

sponsor will be contacted to determine how the records and materials should be handled. WIL 

Research Europe will retain information concerning decisions made.

Those specimens requiring refrigeration or freezing will be retained by WIL Research Europe for as 

long as the quality of the specimens permits evaluation but no longer than three months after 

finalization of the report.

WIL Research Europe will retain a test substance sample until the expiry date, but no longer than 

10 years after finalization of the report. After this period the sample will be destroyed.
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

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6. MATERIALS

6.1. Test substance

6.1.1. Test substance information

Identification Castor Oil, Sulfated, Sodium Salt, 75%

CAS Number 68187-76-8

Description Clear amber liquid

Batch R-10135-064

Purity/Composition To be determined in this project

Test substance storage At room temperature in the dark

Stable under storage conditions until 18 July 2014 (expiry date) 

The certificate of analysis is shown in Appendix 1.

6.1.2. Study specific test substance information

Purity/composition correction factor required No

6.2. Electronic data capture

System control, data acquisition and data processing were performed using the following programme:

- Advantage Integrity Software version 3.0 (TA Instruments, New Castle, DE, USA)

Temperature, relative humidity and/or atmospheric pressure during sample storage and/or 

performance of the studies was monitored continuously using the following programmes:

- REES Centron Environmental Monitoring system version SQL 2.0 (REES Scientific, Trenton, NJ, 

USA)

6.3. List of deviations

6.3.1. List of protocol deviations

There were no deviations from the protocol.

6.3.2. List of standard operating procedures deviations

Any deviations from standard operating procedures (SOPs) were evaluated and filed in the study file. 

There were no deviations from SOPs that affected the integrity of the study. 
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7. MELTING AND BOILING TEMPERATURE

7.1. Guidelines

European Community (EC), EC no. 440/2008, Part A: Methods for the Determination of PhysicoChemical Properties, Guideline A.1: “Melting/Freezing Temperature”, Official Journal of the European 

Union no. L142, May 31, 2008.

European Community (EC), EC no. 440/2008, Part A: Methods for the Determination of PhysicoChemical Properties, Guideline A.2: “Boiling Temperature”, Official Journal of the European Union no. 

L142, May 31, 2008.

Organization for Economic Co-operation and Development (OECD), OECD Guidelines for the Testing 

of Chemicals no. 102: "Melting Point / Melting Range", July 27, 1995.

Organization for Economic Co-operation and Development (OECD), OECD Guidelines for the Testing 

of Chemicals no. 103: "Boiling Point", July 27, 1995.

United States Environmental Protection Agency (EPA), Product Properties Test Guidelines no. 

OPPTS 830.7200: "Melting Point/Melting Range", March 1998.

United States Environmental Protection Agency (EPA), Product Properties Test Guidelines no. 

OPPTS 830.7220: "Boiling Point/Boiling Range", August 1996.

7.2. Performance of the test

The melting and boiling temperature of the test substance were determined using differential scanning 

calorimetry (DSC). This technique records the difference in heat flow of two crucibles, one filled with 

test substance and the other left empty as reference, while these crucibles are subjected to a 

controlled temperature programme. When the test substance undergoes a transition, such as melting 

or evaporation, is indicated by a deviation from the base line of the heat-flow record. Because melting 

and evaporation are processes in which heat is consumed, for these processes the deviation from the 

base line is in the endothermic direction. The melting temperature or boiling temperature (if any) of the 

test substance is evaluated from the DSC curve as the extrapolated onset temperature of the 

endothermic melting or evaporation peak. 

The test substance is a liquid at room temperature. To determine the melting temperature, the test 

substance was cooled to -90°C and then heated. 

As a safety precaution for the DSC cell a preliminary test was performed using a thermogravimetric 

analyzer (TGA). 

7.2.1. Preliminary test

11.0 mg test substance was heated at a rate of 20°C/minute from 25°C to 431°C. At this point 70% 

weight loss of the test substance was observed. After the experiment, the sample was cooled to and 

equilibrated at 50°C and the consistency of the test substance was determined.
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7.2.2. Main study

An overview of the experimental conditions of the main study is given below. 

Experiment 1 2 3 4

Sample amount (mg) 11.16 8.58 9.72 8.44

Initial temperature (°C) 25 25 25 25

Rate (°C/minute) -5 -5 -5 -5

Temperature 2 (°C) -90 -90 -90 -90

Rate (°C/minute) 20 20 20 20

End temperature (°C) 168 168 168 400

The atmospheric pressure was 974.7 - 1012 hPa. The experiments were performed under a flow of 

nitrogen. 

7.3. Analytical method

Preliminary test

Instrument Q50 thermogravimetricanalyzer (TGA) (TA Instruments, New 

Castle, DE, USA)

Sample container aluminium; closed with a lid in which a small hole was drilled

Main study

Instrument Q100 differential scanning calorimeter (TA Instruments)

Sample container aluminium; closed (Experiment 2) or closed with a lid in which a 

small hole was drilled (Experiments 1, 3 and 4)

Reference empty sample container

7.4. Interpretation

The melting temperature is defined as the temperature at which the phase transition from solid to 

liquid state takes place at normal atmospheric pressure. This temperature ideally corresponds to the 

solidification or freezing temperature. 

The standard boiling temperature is defined as the temperature at which the vapour pressure of a 

liquid is the same as the standard pressure (1013.25 hPa). 
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

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7.5. Results

7.5.1. Preliminary test

The TGA-curve of the test substance is shown in Figure 1. Starting at 50°C, the weight of the sample 

decreased significantly. At 168°C the sample weight had decreased by 25%. This was most likely due 

to the evaporation of water in the test substance.

After the experiment, a yellow/brown solid residue remained in the sample container and on the lid of 

the container. (original colour: clear amber liquid). The slight change of the colour indicated some 

reaction and/or decomposition of the test substance.

7.5.2. Main study

The DSC-curve obtained with Experiment 1 is shown in Figure 2. In the cooling curve, an exothermic 

peak between -25°C and -50°C was observed. The effect was most likely obtained due to 

crystallization of water in the test substance. In the heating curve, an endothermic peak between 

-25°C and 25°C was observed with a maximum at -4.27°C. The effect was most likely obtained due to 

melting of water in the test substance. Starting at 75°C a broad endothermic effect with a maximum at 

113.28°C was observed most likely obtained due to evaporation/boiling. After the experiment, a light 

yellow very viscous almost solid residue, remained in the sample container and on the lid of the 

sample container. 

To investigate the evaporation peak a closed sample container was used in Experiment 2. Figure 3

shows the DSC-curve obtained. The temperature program was a duplicate of Experiment 1. Melting 

was observed with a maximum at -4.71°C. The extrapolated onset temperature of the evaporation 

peak was 149.41°C. The endothermic peak shifted to higher temperatures. It demonstrated that 

evaporation, most likely due to water in the test substance, was the reason for the endothermic effect. 

After the experiment, a yellow residue remained in the sample container. 

Experiment 3 was performed as a duplicate of Experiment 1. Figure 4 shows the DSC-curve obtained. 

Melting was observed with a maximum at -3.12°C. The maximum of the evaporation peak was at 

113.41°C. After the experiment, a light yellow very viscous almost solid residue remained in the 

sample container and on the lid of the sample container. 

Experiment 4 was performed to investigate any effects after the water had evaporated. Similar results 

as with Experiment 1 were obtained. Figure 5 shows the DSC curve. Melting was observed with a 

maximum at -4.94°C. The maximum of the evaporation peak was at 112.52°C. A small, broad 

endothermic effect was observed from 225°C to 300 °C, most likely due to reaction/decomposition. No 

further evaporation/boiling effects were observed. After the experiment, the container was empty. On 

the lid of the container, a brown residue remained.

The melting temperature was determined as the average peak temperature obtained from 

Experiment 1 (-4.27°C), Experiment 2 (-4.71°C), Experiment 3 (-3.12°C) and Experiment 4 (-4.94°C). 

The boiling temperature was determined as the average peak temperature obtained from 

Experiment 1 (113.28°C), Experiment 3 (113.41°C) and Experiment 4 (112.52°C).

These values are most likely due to water in the test substance (i.e. 24.3%, see chapter 8). 
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

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7.6. Conclusion

The melting and boiling temperature of Castor Oil, Sulfated, Sodium Salt, 75% were determined using 

DSC. 

The melting temperature of the test substance was -4°C (269K)

The boiling temperature of the test substance was 113°C (386K).

The values are most likely due to water in the test substance.

The atmospheric pressure was 974.7 – 1012 hPa.

7.7. Figures

Figure 1 TGA curve of the test substance.

167.59°C 25.00% Loss

431.33°C 70.00% Loss

20

40

60

80

100

120

Weight (%)

0 100 200 300 400 500

Temperature (°C)

 File: NOTOX2010 13822 62665

Universal V4.7A TA Instruments
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

Final report - Page 13 -

Figure 2 DSC curve of the test substance obtained with Experiment 1.

Figure 3 DSC curve of the test substance obtained with Experiment 2.

-4.27°C

113.28°C

-150

-100

-50

0

50

Heat Flow (mW)

-100 -50 0 50 100 150 200

Temperature (°C)

 File: NOTOX2010 13829 67430

Exo Up Universal V4.7A TA Instruments

-4.71°C

149.41°C

-30

-20

-10

0

10

Heat Flow (mW)

-100 -50 0 50 100 150 200

Temperature (°C)

 File: NOTOX2010 13829 67587

Exo Up Universal V4.7A TA Instruments
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

Final report - Page 14 -

Figure 4 DSC curve of the test substance obtained with Experiment 3.

 

Figure 5 DSC curve of the test substance obtained with Experiment 4.

-3.12°C

113.41°C

-80

-60

-40

-20

0

20

Heat Flow (mW)

-100 -50 0 50 100 150 200

Temperature (°C)

 File: NOTOX2010 13829 67734

Exo Up Universal V4.7A TA Instruments

112.52°C

-4.94°C

-100

-80

-60

-40

-20

0

20

Heat Flow (mW)

-100 0 100 200 300 400

Temperature (°C)

 File: NOTOX2010 13836 45342

Exo Up Universal V4.7A TA Instruments
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

Final report - Page 15 - 

8. WATER CONTENT KARL FISCHER

8.1. Reagents

Hydranal® Coulomat AK Sigma Aldrich, Steinheim, Germany

Art.nr. 34820, Batch SZBC3050V

Hydranal® Coulomat CG-K Sigma Aldrich

Art.nr. 34821, Batch SZBB084A

Hydranal® Water standard 0.1 mg/g = 0.01% H2O Sigma-Aldrich

Art.nr. 34847, Batch SZBA3070

Hydranal® Water standard 1.0 mg/g = 0.1% H2O Sigma-Aldrich

Art.nr. 34828, Batch SZBD0090

All reagents were of analytical grade, unless specified otherwise. 

8.2. Performance of the test

The water content was determined by a Coulometric Karl Fischer titration using a Metrohm 831 KF 

Coulometer (Metrohm, Herisau, Switzerland). 

The system consisted of a reaction vessel which was equipped with a double platinum electrode used 

for the instrumental end point indication. In addition to the double platinum electrode, a generator 

electrode was also present in the reaction vessel. Prior to titration, the reaction vessel was filled with 

100 ml Hydranal Coulomat AK reagent and the generator electrode was filled with one ampoule of 

Hydranal Coulomat CG-K reagent. The generator electrode and the reaction vessel were connected 

via a porous membrane which facilitated the conduction of electrical current between the two 

compartments but prevented the exchange of fluids. The reaction vessel was equipped with a septum 

via which liquid samples were introduced using a syringe. Titration was performed by applying a 

current to the generator electrode which resulted in the formation of iodine (I2) in the reaction vessel 

which was consumed in the Karl Fischer titration process. 

The test substance was dissolved in a suitable solvent. Prior to analysis of the test sample, the system 

was first titrated water free. Subsequently the test sample was introduced and titrated.

The results were corrected for the water content in the solvent used for preparation of the test solution. 

Calculations of the water content (in %) of the test substance is described in paragraph 8.4.1.

The water content was included in a certificate of analysis, issued based on these measurements. The 

certificate of analysis is shown in Appendix 1. 
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

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8.3. Analytical method

8.3.1. Analytical conditions

Instrument 831 KF Coulometer (Metrohm, Herisau, Switzerland)

Magnetic stirrer Ti Stand 703 (Metrohm)

8.3.2. Calibration

The validity of the system was verified using two water standards with a certified water amount of 0.1 

and 1.0 mg/g (Sigma-Aldrich). 

Duplicate samples of each standard were weighed and the water content was determined by titration. 

8.3.3. Preparation of solutions

22.2 and 40.2 mg test substance was dissolved in approximately 6 g solvent Hydranal® Coulomat AK

in a 10 ml vial.

For determination the water content in the solvent, Hydranal® Coulomat AK was used .

8.4. Interpretation

8.4.1. formulas

Test substance fraction of the sample solution * %

w w

w f

M TS

TS

TS 100

+ =

where:

fTS : fraction of test substance in the sample solution [%]

wTS : weight of test substance in the sample solution [g]

wM : weight of solvent in the sample solution [g]

Solvent fraction of the sample solution * %

w w

w f

M TS

M

M 100

+ =

where:

fM : fraction of solvent in the sample solution [%]

Water content of test substance * %

f

f

wc wc

wc

TS

M ss M

TS 100 100 



 



 −

=

where:

wcTS : water content of the test substance [%]

wcSS : water content of the sample solution [%]

wcM : water content of solvent [%]
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

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8.5. Results

Table 1 show the calibration results. The results of the Karl Fischer titrations of the solvent and test 

substance are given in Table 2 and Table 3, respectively. 

Table 1 Calibration of Karl Fischer apparatus 

Date of 

analysis

Water 

standard

[mg/g]

Certified 

water content

[mg/g]

Analysed

water content

[mg/g]

Recovery

[%]

Mean 

recovery

[%]

12-Oct-2013 0.1 0.104 0.106 102 1 114

0.119 114 

0.119 114

0.119 115

1.0 1.00 1.01 101 102

1.03 103

1 Outlier according to the Dixon’s Q-test at 95% confidence level.

The results of the 0.1 mg/g standard are somewhat higher than expected (i.e. 114%). The recovery of 

the 1.0 mg/g standard however is 102%. The concentrations of the sample solutions were in the range 

of the 1.0 mg/g standard. The results were therefore accepted. The system was found to be accurate 

for the determination of the water content of the test substance.

Table 2 Water content of the solvent solution 

Date of 

analysis

Weight solvent

[g]

Analysed

water 

[ppm]

Mean Analysed

water 

[ppm]

12-Oct-2013 1.631 62.9 71.1

1.545 79.2

Table 3 Water content of the test substance 

Date of 

analysis

Weight test 

substance

[g]

Weight solvent

[g]

Analysed

water 

[ppm]

Analysed 

water content

[% w/w]

Mean water 

content

[% w/w]

12-Oct-2013 40.2 5851.0 1731.7 24.3 24.3

22.2 5894.6 982.1 24.3

8.6. Conclusion

The water content of Castor Oil, Sulfated, Sodium Salt, 75% was determined by a Coulometric Karl 

Fischer titration.

The water content was 24.3% w/w (n = 2). 
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

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9. CONTENT SODIUM SULPHATE

9.1. Guidelines

Food and Agriculture Organization of the United Nations (FAO): Manual on development and use of 

FAO and WHO specifications for pesticides, March 2006 revision of the first edition, prepared by the 

FAO/WHO joint meeting on pesticide specifications (JMPS), Rome, 2006.

European Commission: Guidance for generating and reporting methods of analysis in support of preand post-registration data requirements for Annex II (part A, Section 4) and Annex III (part A, Section 

5) of Directive 91/414, SANCO/3030/99 rev. 4 (11/07/00).

9.2. Reagents

Water Tap water purified by a Milli-Q water purification system 

(Millipore, Bedford, MA, USA)

Lead(II)nitrate Sigma Aldrich, Steinheim, Germany

Art.nr. 228621, Batch BCBL4721V

Potassium sulphate Sigma Aldrich

Art.nr. 221325, Batch MKBM2228V

Hydroxylamine hydrochloride Sigma Aldrich

Art.nr. 379921, Batch MKBP1350V

Dithizone Sigma Aldrich

Art.nr. 33154, Batch BCBK0249V

Hydrochloric acid 1 M Merck, Darmstadt, Germany

Art.nr.1.09057, Batch HC260857

Sodium hydroxide 1 M Merck

Art.nr. 1.09137, Batch HC394982

2-Propanol Merck

Art.nr.1.01040, Batch K44623040.324

All reagents were of analytical grade, unless specified otherwise.

9.3. Reagent solutions

Lead(II)nitrate solution 0.039 M 13.25 g lead(II)nitrate was dissolved in 1000 ml water

Potassium sulphate solution 0.025 M 4.359 g potassium sulphate was dissolved in 1000 ml water

9.4. Performance of the study

A titration method for the quantitative analysis of the available sodium sulphate content supplied by the 

sponsor (Cognis No N-149B “sulfate (IRAM method)”) was implemented. Validation of the analytical 

method was performed for the following parameters. 

Specificity

A blank sample was prepared in three-fold. The analytical method was found to be specific if the 

interferences in the blank did not contribute more than 3% to the volume titrated for the test substance.
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

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Precision (repeatability)

The content of sodium sulphate in the test substance was determined by analysing five independent

solutions of the test substance using the analytical method, expressed in % w/w content sodium 

sulphate. The mean content, the standard deviation and the % RSD of the test samples were 

calculated. 

A certificate of analysis (see appendix I) was prepared based on the results of the five independent 

samples of the test substance.

Accuracy

Five independent accuracy samples were prepared by addition of an amount of potassium sulphate 

solution to the test substance. The mixtures were analyzed by the analytical method. 

9.5. Analytical method 

9.5.1. Analytical conditions

Titrator Titrino 716 DMS (Metrohm, Herisau, Switzerland)

Stirrer 703 TI Stand (Metrohm)

Titration solution Lead(II)nitrate solution

9.5.2. Calibration

The titer of the lead(II)nitrate solution was determined with a potassium sulphate solution. 

4.359 g potassium sulphate was accurately weighed and dissolved in 1000 ml water (i.e. 0.025 M).

To a beaker of 250 ml, 20 ml potassium sulphate solution was added. Subsequently 70 ml 2-propanol 

and 100 mg hydroxylamine hydrochloride were transferred into the beaker. Just enough dithizone

indicator was added to give the mixture sufficient color after adjusting the pH to 3.1 with hydrochloric 

acid 1 M. During titration with lead(II)nitrate solution, the pH of the solution was kept between 

2.9 - 3.1 with sodium hydroxide 1 M. The endpoint of the titration was reached when a first violet color 

was permanently observed.

9.5.3. Preparation of solutions

Test samples

To a beaker of 250 ml containing approximately 3000 mg accurately weighed test substance, 30 ml 

water was added. The mixture was stirred until dissolution was complete. 

Accuracy samples

To a beaker of 250 ml containing approximately 3000 mg accurately weighed test substance, 20 ml 

water and 11.6 ml of the 0.025 M potassium sulphate solution were added. The mixture was stirred

until dissolution was complete. 

Blank sample

In a beaker of 250 ml 30 ml water was added.

9.5.4. Sample analysis

To each sample, 70 ml 2-propanol and 100 mg hydroxylamine hydrochloride were added. Dithizone

indicator was added just enough to give the solution sufficient color after adjusting the pH to 3.1 with 

hydrochloric acid 1 M. The solution was titrated with lead(II)nitrate solution. During titration with 

lead(II)nitrate solution, the pH of the solution was kept between 2.9 - 3.1 with sodium hydroxide 1 M. 

The endpoint of the titration was reached when a first violet color was permanently observed.
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

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9.6. Interpretation

9.6.1. Formulas

Titer (Lead(II)nitrate solution) tPb = 

( ) VPb −Vbl

VSO4×CSO4

where:

tPb : titer of the Lead(II)nitrate solution (M)

VSO4 : volume potassium sulphate solution (ml)

CSO4 : concentration potassium sulphate solution (M)

VPb : volume Lead(II)nitrate solution added to sample (ml)

Vbl : volume Lead(II)nitrate solution added to blank (ml)

Content Sodium sulphate (CT) CT = w ×1000

(VPb −Vbl) × t Pb ×142.04×100% [% w/w]

where:

tPb = molarity of lead(II)nitrate (0.039 M)

w = sample weight (g)

Analysed sulphate content (CA) Analysed sulphate content of the accuracy samples.

Accuracy 100%

C

C

N

A ×

where:

CA = analysed sulphate content [mmol]

CN = calculated sulphate content [mmol]

9.6.2. Precision (repeatability)

The relative standard deviation (% RSD) on the results of the test samples analysed was determined. 

Acceptability of this value was based on the Horwitz equation: 

(1- 0.5 log C) R

10

predicted %RSD = 2

where:

% RSDR = the predicted among-laboratory RSD

C = mean content in g/g

For estimation of the repeatability (% RSDr) of the titration method the predicted among-laboratory 

RSD is modified to:

predicted %RSDr = %RSDR × 0.67

The results of the test samples were accepted if the % RSD for the content sodium sulphate in the 

substance was less than the predicted repeatability of the analytical method. 
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

Final report - Page 21 - 

9.7. Results

9.7.1. Content Sodium Sulphate

The results of the sodium sulphate content in the test samples are given in Table 5.

Table 4 Content Sodium Sulphate

Code Titration volume

Lead(II)nitrate

[ml]

Sample

weight

[mg]

Content

Sodium sulphate 

[% w/w]

I 6.692 2996.7 1.22

II 6.912 2996.2 1.26

III 6.910 3004.6 1.26

IV 6.869 2999.0 1.25

V 6.879 3001.1 1.25

Mean content 1.25

Standard deviation 0.02

9.7.2. Specificity

For the blank samples a mean amount of 0.102 ml lead(II)nitrate solution was needed. This volume is 

less than 3% (i.e. 1.6%), calculated on the lowest titration volume lead(II)nitrate (see Table 4). 

Therefore the analytical method was found to be specific for the test substance.

9.7.3. Precision (repeatability)

The relative standard deviation (RSD) of the test samples and the predicted % RSDR and % RSDr are 

given in Table 5. Since the % RSD for the content sodium sulphate in the test substance was less than 

the predicted % RSDr the results of the test samples were considered precise. 

Table 5 Relative standard deviation

% RSDR 3.9 

% RSDr 2.6

% RSD of the test samples 1.3 
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9.7.4. Accuracy

The results of the accuracy samples are given in Table 6. The mean recovery result of 97% was

considered accurate and was therefore accepted. 

Table 6 Accuracy samples

Code Calculated

spiked 

sulphate

[mmol]

Calculated 1

content 

sulphate

[mmol]

Calculated total 

sulphate content

expected

[mmol]

Analysed 

sulphate

content

[mmol]

Recovery 

[%]

I 0.290 0.263 0.554 0.536 97

II 0.290 0.264 0.554 0.534 96

III 0.290 0.263 0.554 0.539 97

IV 0.290 0.263 0.554 0.535 97

V 0.290 0.263 0.553 0.537 97

Mean recovery 97

1 based on sample weight and sodium sulphate content determined (i.e. 1.25% w/w)

9.8. Conclusion

The sodium sulphate content in Castor Oil, Sulfated, Sodium Salt, 75% was determined to be

1.25 ± 0.02% w/w ( 5n;sx −1n =± ). 
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

Final report - Page 23 -

10. CONTENT SO3

10.1. Guidelines

Food and Agriculture Organization of the United Nations (FAO): Manual on development and use of 

FAO and WHO specifications for pesticides, March 2006 revision of the first edition, prepared by the 

FAO/WHO joint meeting on pesticide specifications (JMPS), Rome, 2006.

European Commission: Guidance for generating and reporting methods of analysis in support of preand post-registration data requirements for Annex II (part A, Section 4) and Annex III (part A, Section 

5) of Directive 91/414, SANCO/3030/99 rev. 4 (11/07/00).

10.2. Reagents

Water Tap water purified by a Milli-Q water purification system 

(Millipore, Bedford, MA, USA)

Benzethonium chloride (Hyamine) Sigma Aldrich, Steinheim, Germany

Art.nr. B8879, Batch SLBC7904V

Methylene blue Sigma Aldrich

Art.nr. M9140, Batch SLBF3786V

Sodium dodecyl sulphate (SDS) Sigma Aldrich

Art.nr. L4390, Batch 129K0187

Sodium sulphate Merck, Darmstadt, Germany

Art.nr. 1.06649, Batch A0177249 111

Sulphuric acid 96% Merck

Art.nr. 1.00714, Batch K43188714 206

Chloroform VWR International, Leuven, Belgium

Art.nr. 83626.320, Batch 13Z4042

All reagents were of analytical grade, unless specified otherwise.

10.3. Reagent solutions

Hyamine solution (0.004 M) 1849 mg hyamine was dissolved in 1000 ml water

Methylene blue solution 60.2 mg methylene blue, 100 g sodium sulphate and 13 ml 

sulphuric acid 96% were dissolved to 2000 ml with water.

SDS solution 568.4 mg Sodium Dodecyl Sulphate was dissolved to 100.0 ml 

with water.

10.4. Performance of the study

A titration method for the quantitative analysis of the SO3 content supplied by the sponsor (CTMC-89A 

”Determination of SO3”) was implemented. Validation of the analytical method was performed for the 

following parameters. 

Precision (repeatability)

The SO3 content in the test substance was determined by analysing five independent solutions of the 

test substance using the analytical method, expressed in % w/w SO3 content. The mean content, the 

standard deviation and the % RSD of the test samples were calculated. 
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

Final report - Page 24 -

A certificate of analysis (see appendix I) was prepared based on the results of the five independent 

samples of the test substance.

Accuracy

Two independent accuracy samples were prepared by addition of an amount of SDS solution to the 

test substance. The mixtures were analyzed by the analytical method. 

10.5. Analytical method 

10.5.1. Analytical conditions

Titrator Titrino 716 DMS (Metrohm, Herisau, Switzerland)

Stirrer 703 TI Stand (Metrohm)

Titration solution Hyamine solution

10.5.2. Preparation of solutions

Test samples

An accurately weighed amount of approximately 100 mg test substance was quantitatively transferred 

with approximately 50 ml water, into a conical flask of 250 ml. 

Accuracy samples

An accurately weighed amount of approximately 100 mg test substance was quantitatively transferred 

with approximately 50 ml water, into a conical flask of 250 ml. The solution was spiked with 2.0 ml

SDS solution. 

10.5.3. Sample analysis

To each sample, 75 ml chloroform and 30 ml methylene blue solution were added. Stirring of the 

mixture was started. An aliquot hyamine solution, 3 ml less than the calculated end volume, was 

added. The mixing was stopped to allow the two layers to separate. The addition of the hyamine 

solution was repeated until both layers had the same intensity of the blue coloration. Then the 

endpoint of titration was reached.

10.6. Interpretation

10.6.1. Formulas

% SO3 content (CT) CT = w ×1000

V × t ×80.07×100% [%w/w]

where:

V = ml hyamine solution

t = titer of hyamine solution (0.004 M)

w = sample weight (g)

Analysed concentration (CA) Analysed concentration of the accuracy samples.

Accuracy 100%

C

C

N

A ×

where:

CA = analysed concentration SO3 [mmol]

CN = calculated concentration SO3 [mmol]
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Final report - Page 25 - 

10.6.2. Precision (repeatability)

The relative standard deviation (% RSD) on the results of the test samples analysed was determined. 

Acceptability of this value was based on the Horwitz equation: 

(1 - log0.5 C) R

10

 % predicted RSD = 2 

where:

% RSDR = the predicted among-laboratory RSD

C = mean content in g/g

For estimation of the repeatability (% RSDr) of the titration method the predicted among-laboratory 

RSD is modified to:

 % predicted RSD % RSDR 0.67 r = ×

The results of the test samples were accepted if the % RSD for the analysis of the active ingredient in 

the test substance was less than the predicted repeatability of the analytical method. 

10.7. Results

10.7.1. SO3 content

The results of the test samples are given in Table 7.

Table 7 SO3 content

Code Titration volume

hyamine solution

[ml]

Sample

weight

[mg]

SO3 content

[% w/w]

I 17.523 104.5 5.54

II 18.134 107.5 5.58

III 16.988 100.5 5.59

IV 16.126 95.7 5.57

V 17.441 102.2 5.64

Mean content 5.58

Standard deviation 0.04

10.7.2. Precision (repeatability)

The relative standard deviation (RSD) of the test samples and the predicted % RSDR and % RSDr are 

given in Table 8. Since the % RSD for the analysis of the active ingredient in the test substance was 

less than the predicted % RSDr the results of the test samples were considered precise. 

Table 8 Relative standard deviation

% RSDR 3.1 

% RSDr 2.1

% RSD of the test samples 0.65
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10.7.3. Accuracy

The results of the accuracy samples are given in Table 6. The mean recovery result of 104% was

considered accurate and was therefore accepted.

Table 9 Accuracy samples

Code Spiked 

SO3 content

[mmol]

Sample 

contribution

SO3 content

[mmol ]

Total 

SO3 content

[mmol]

Analysed 

SO3 content

[mmol]

Recovery 

[%]

I 0.0394 0.0717 0.111 0.119 107

II 0.0394 0.0710 0.110 0.112 102

Mean recovery 104

10.8. Conclusion

The SO3 content in Castor Oil, Sulfated, Sodium Salt, 75% was determined to be 

5.58 ± 0.04% w/w ( 5n;sx −1n =± ). 

11. PURITY / COMPOSITION 

The purity / composition of Castor Oil, Sulfated, Sodium Salt, 75% was calculated as 100% minus the 

water and sodium sulphate content. 

Using a water content of 24.3% and a sodium sulphate content of 1.25%, purity / composition is 

calculated to be 74.4%.
Castor Oil, Sulfated, Sodium Salt, 75% Project 503335

Final report - Page 27 -

Appendix 1 Certificate of analysis