NBSIR 75-958

Simulated Precipitation Reference

Materials

J. K. Taylor, E. R. Deardorff, R. A. Durst, E. J. Maienthal,

T. C. Rains, and E. P. Scheide

National Bureau of Standards

Department of Commerce

Washington, D. C. 20234

October 1 975

Final Report

Prepared for The Environmental Protection Agency

Office of Research and Development

Research Triangle Park, North Carolina 2771

NBSIR 75-958

SIMULATED PRECIPITATION REFERENCE

MATERIALS

J. K. Taylor, E. R. Deardorff, R. A. Durst, E. J. Maienthal,

T. C. Rains, and E. P. Scheide

National Bureau of Standards

Department of Commerce

Washington, D. C. 20234

October 1 975

Final Report

Prepared for The Environmental Protection Agency

Office of Research and Development

Research Triangle Park, North Carolina 2771

f v \

U.S. DEPARTMENT OF COMMERCE, Rogers C.B. Morton, Secretary

James A. Baker, III, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

TABLE OF CONTENTS

Page

1. INTRODUCTION 1

2. EXPERIMENTAL DETAILS 2

2.1 General Considerations 2 2.2 Preparation of Reference Materials 3

2.3 Ampouling 3

2.4 Numbering Sequence 4

2.5 Analysis of Bulk Solutions 4

2.6 Analysis of Ampoules 4

2.6.1 pH Measurements 5

2.6.2 Conductivity Measurements 5

2.6.3 Acidity Measurements 5

2.6.4 Analysis of Anions 6

2.6.4.1 Measurement for Sulfate Ion . 6

2.6.4.2 Measurement for Nitrate Ion . 6

2.6.4.3 Measurement for Fluoride Ion. 6

2.6.4.4 Measurement for Chloride Ion. 7 2.6.5 Analysis for Cations 7 2.6.5.1 Measurement of Ammonium Ion . 7 2.6.5.2 Metals by Atomic Absorption

and Flame Emission 8

2.6.5.3 Metals by Polarographic

Analysis 8

3. ANALYTICAL RESULTS 8

4. DISCUSSION 10

5. RECOMMENDED DILUTION PROCEDURE . . 11

6. ACKNOWLEDGEMENTS 11

i

Simulated Precipitation Reference Materials

John K. Taylor, E. R. Deardorff, R. A. Durst,

E. J. Maienthal, T. C. Rains, and E. P. Scheide

ABSTRACT

The preparation of a series of reference

materials for chemical analysis of natural precipitation is described. The materials consist of

ampoules of concentrates which can be diluted to

simulate naturally collected samples of rainwater.

The analytical measurements made to verify the

composition of the samples are also described.

KEY WORDS

Chemical analysis; rainwater analysis;

reference materials.

1. INTRODUCTION

This report describes work done at the National Bureau

of Standards to prepare reference materials needed for the

evaluation of methodology and for the verification of data

concerned with the analysis of rainwater and other forms of

precipitation. Such measurements can provide valuable

information on global pollution levels, atmospheric circulation, and geophysical phenomena when the data are validated.

However, the reliability of such measurements is presently

unknown

.

In recognition of this situation, the National Bureau

of Standards has investigated the problems of producing

synthetic aqueous concentrates which simulate natural

precipitation samples when quantitatively diluted.

The work reported here was initiated at the request of

and supported by the Environmental Protection Agency under

an Interagency Agreement and resulted in the preparation and

analysis of a series of four concentrates of graded composition,

and two additional sets of "unknowns" within the compositional

range

.

CONTRIBUTION OF THE NATIONAL BUREAU OF STANDARDS. NOT

SUBJECT TO COPYRIGHT.
2. EXPERIMENTAL DETAILS

2 . 1 General Considerations

A decision was made to produce four concentrates which

could be diluted to simulate natural precipitation samples.

The reference materials would consist of 10 ml of appropriate

solutions, sealed in ampoules, which would be quantitatively

diluted to a final volume of 500 ml by the user. The four

concentration levels were chosen to represent the range of

composition of samples ordinarily encountered in rainwater

analysis

.

The constituents and compositional levels recommended

by EPA are given in table 1. However, some compromises had

to be made in preparing the reference samples. From materials

balance considerations, it was evident that there were

missing constituents. There were also problems concerned

with achieving specified values for gross parameters such as

pH, conductivity, and acidity when chemical constituents are

specified

.

A further problem is concerned with the actual synthesis

of the samples. Natural processes cannot be duplicated in

the laboratory. Hence, incompatibilities can occur during

mixing of constituents which would not occur under natural

conditions

.

The recommended compositions were found to be deficient

in anions. This could be rectified by addition of other

anions but this would disturb the cation balance and also

could conceivably cause compatibility problems. Furthermore,

the basis for choice of the balancing anion was not clear.

Accordingly, it was decided to use the values in table 1 as

guidelines and to prepare the reference samples with the

cationic constituents as the major consideration. The

anionic constituents would approach the recommended levels

as far as possible. The gross parameters would be permitted

to assume values consistent with this approach.

A further complication is that of compatibility of

constituents which is influenced by the order, rate of

addition, and concentration of the individual constituents

at time of addition to the bulk solution. The fact that

the reference samples were to be 50 times more concentrated

than the final solutions also complicated this problem,

since compatibility needs to be achieved for the concentrates.

2
2 . 2 Preparation of Reference Materials

In consideration of the problems outlined in Section

2.1, compromise concentration levels were adopted and

experimental work was undertaken to investigate their

feasibility. During this work, two problems were identified

It was found difficult to retain iron at anywhere near the

recommended level, so it was eliminated. Also there was

some precipitation of lead in the most concentrated solution.

Since this did not appear to be a major problem, it was

decided to tolerate it, but to filter the solution before

ampouling

.

The chemicals used to prepare the reference materials

are listed in table 2. In general, they were reagent grade

chemicals and were believed to be of sufficient purity to

permit calculation of the amount of constituent added without

assaying them. However, it was later found that several of

the hydrated salts were not the nominal compositions. Trace

impurities in the chemicals are of no significance for the

present situation. The selection of the chemicals was

somewhat arbitrary to attain the desired anionic and cationic

compositions. Laboratory grade distilled water was used for

dilution purposes.

The amounts of chemicals used to prepare the bulk

solutions are given in tables 3, 4, 5, and 6. For Solutions

A, C, and D, half of the constituents were added to approximately 2 1 of water in a volumetric flask and then diluted

to the mark. A second solution was prepared containing the

remaining constituents. These solutions were combined and

the resulting solution was filtered through a quantitative

paper (S § S 589 Blue Ribbon)*. In the case of Solution B,

an additional volume of 2 1 of distilled water was added

before filtering. The final solutions were stored in pyrex

bottles of appropriate size prior to ampouling. No visible

precipitation occurred during the storage period which was

about 30 days.

2 . 3 Ampouling

The bulk solutions were transferred to ampoules using

the automatic dispensing and sealing equipment of the Office

of Standard Reference Materials. The ampoules used (Wheaton

Cat. No. 176780) are made from borosilicate glass formulated

to prevent a change of pH and to maintain the purity of the

contents. They are pre-scored to eliminate the need for

filing

.

^Certain commercial materials and equipment are identified in

this paper in order to adequately specify the experimental

procedure. In no case does such identification imply recommendation or endorsement by the National Bureau of Standards, nor

does it imply that the material or equipment identified is

necessarily the best available for the purpose.
The dispensing equipment pumps the solution from the

storage vessel and reproducibility injects a pre-set volume

into the ampoules. Ampoules randomly selected for analysis

were also weighed to verify the reproducibility of the

filling operation. No significant changes were detected

during the entire filling operation for the four solutions,

which was done during a three-hour period.

The dispensing equipment automatically flame-sealed the

ampoules. These were then placed in their original shipping

boxes, in the order of filling.

2 . 4 Numbering Sequence

The ampoules were labeled and numbered in the following

sequences

:

Twenty samples were randomly selected from each lot for

chemical analysis. The remainder of the ampoules were

delivered to EPA.

In addition to the ampoules noted above, additional

ampoules amounting to approximately 40 in each lot were

filled, depending upon the amount of solution available.

These ampoules were also numbered in a continuation of the

same sequences and will be retained at NBS for further

study.

2 . 5 Analysis of Bulk Solutions

The bulk solutions were analyzed for their cationic

constituents by atomic absorbtion and flame emission spectrometry. The results, reported in tables 7 to 10 indicate

that the desired concentration levels had been acheived,

except in the case of lead in Solution D where it was known

that some initial precipitation had occurred. The data are

also useful to evaluate any long-term deterioration of the

samples, either by loss or leaching processes.

2 . 6 Analysis of Ampoules

Twenty ampoules randomly selected from each lot, and

addicional ampoules randomly selected from the excess of the

lots were analyzed as will be described in the following sections.

The analysts also weighed the ampoules before and after

delivery of their contents to evaluate the reproducibility

of the filling operation.

Solution A

Solution B

Solution C

Solution D

75001A to 75320A

75001B to 75520B

75001C to 75320C

75001D to 75320D

4
2.6.1 pH Measurements

The pH measurements were made on diluted samples of the

concentrate (1 ml sample + 49 ml H 2 0) . The combination pH

electrode was calibrated with pH 4.01 and 7.00 buffers and

the sample pH readings were taken directly from the digital

pH meter display. Since the water used for diluting the

samples was in approximate equilibrium with ambient CO2,

the values found for the pH were consistent with what would

be expected for air-equilibrated water, i.e., pH 5.6 to 6.0,

and indicate that there is little acid-base character

to the samples themselves.

2.6.2 Conductivity Measurements

The conductivity measurements were made on the same

diluted samples as the pH determinations. The cell constant,

k, was determined using 0.01 M and 0.001 M KC1 solutions

having specific conductances, L, of 0.00141 and 0.000147

S*cm- . The specific conductance of the sample solutions

was calculated from the measured resistance at a frequency

of 1 kHz by the equation:

. k 0.0307 cm' 1 R R

2.6.3 Acidity Measurements

Measurement of acidity was made by the method described

in the EPA Manual of Methods for Chemical Analysis of Water

and Wastes. The pH of a 10 ml sample was measured followed

by addition of standardized sulfuric acid to pH 4. Hydrogen

peroxide (30%) was added and the solution was boiled for

several minutes. After cooling, it was titrated with

standardized sodium hydroxide to pH 8.2 and the acidity was

calculated as mg/liter CaC0 3. Measurements were made on the concentrates to obtain

increased precision and also on the reconstituted rainwater

in the case of Solution D. The latter measurements were

consistent with calculations based on a 50 fold dilution of

the concentrate. The values reported in tables 7-10 are

calculated for the reconstituted sample on the basis of a 50 fold dilution of the concentrate.

5
2.6.4 Analysis for Anions

2.6.4.1 Measurements for Sulfate Ion

The sulfate determinations were accomplished by

titration with lead nitrate solution using the lead ionselective electrode as the end-point detector. The indirect

determination of sulfate is based on the formation of PbSOt,

which is quantified by measurements with a lead electrode.

The measurements were carried out in 80 percent by volume

isopropanol using a double- junction reference electrode. The

sulfate analyses were performed using a Gran plot of the

titration standards of known amounts of sulfate with standard

lead nitrate. These were compared to the unknown samples. The

Gran plot technique permits titrat ion + measurements to be taken

beyond the equivalence point where Pb is in excess and the

electrode responds optimally. It also results in a linear

extrapolation to the end-point which simplifies the data

interpretation. Before each sulfate determination, a blank

was run to check the electrode response and to determine the

blank correction. Also, the electrode was repolished after

each sample was run to remove surface contamination. Without

re-polishing, the electrode response becomes progressively

slower and non-ideal. The concentrates were initially diluted,

if necessary, to a sulfate concentration of approximately 10" 5 M.

Two milliliters of these were diluted with 8 ml of isopropanol

prior to titration. Triplicate analyses were done on each

sample and standard.

2.6.4.2 Measurements for Nitrate

Measurements for nitrate were made by the Brucine

Method following the procedure in ASTM Method D 992-71, Nitrate

Ion in Water. Nitrate ion reacts with brucine in strong sulfuric

acid to develop a yellow color. A calibration curve was made with

pure potassium nitrate to obtain a smooth curve in the range 0

to 250 yg/25 ml where the solution does not follow Beer's Law.

The absorbance was read at 410 nm, using 1 cm cells. A sample

size of 5 ml was used in these measurements.

2.6.4.3 Measurement of Fluoride Ion

The fluoride determinations were performed by direct

potentiometry on ampoule samples diluted 1:2 with TISAB

(total ionic strength adjustment buffer) . Calibration standards

containing 2, 20, and 100 ppm F" were also prepared by 1:2

dilution with TISAB to permit direct reading of the sample

fluoride concentrations. The electrode response was Nernstian

over this range and the emf readings on both samples and

standards were generally stable.

6
2.6.4.4 Measurement of Chloride Ion

Two analytical techniques were used to determine the

chloride content of these samples. For the higher concentrations (samples "C", "D") , an automatic chloride titrator

was used. This method is based on the amperometric generation

of silver ions in situ which is automatically stopped at the

end point by a potentiometr ic detector. Duplicate, and

sometimes triplicate, 100- ul samples were used and the

reproducibility between duplicates was generally better than

1 percent. The chloride titrator was calibrated with 500

and 1000 ppm standards.

Samples "A" and "B" did not contain sufficient chloride

to activate the potentiometr ic sensor in the titrator, and

it was necessary to determine the chloride in these samples

by direct potentiometry using a chloride ion- selective

electrode. Calibration standards containing 1, 10, and

100 ppm were used and, over the sample concentration range,

the response was linear and approximatly Nernstian (54.2 mV/pCl)

.

The precision of these measurements was not good, being

about ±5 percent for the "B" samples and ±10 percent for the

"AM samples. It is assumed that the observed deviations are due to

measurement imprecision rather than actual differences

between ampoules.

2.6.5 Analysis for Cations

2.6.5.1 Measurement of Ammonium Ion

Measurement for ammonium ion were made by two methods.

An ammonia electrode was used to determine ion concentration by direct potentiometry. The sample and standard

solutions (2, 20, and 200 ppm) were diluted 1:2 with 1.0 M

NaOH to convert all of the NH£ to NH 3 which is measured by

the electrode. Although the electrode response over the

concentration range of interest was good (55.5 mV/pNH 3 ),

there was excessive electrode drift during the measurements,

possibly due to the difficulty in measuring a volatile

component in a very small volume of solution. As a result,

little confidence was ascribed to the data.

The second technique consisted of chemical measurement

according to the procedure given in the following reference:

C. 0. Willits and C. L. Ogg, "1949 Report of Standardization

of Microchemical Methods, Micro Kjeldahl Nitrogen Determinations,"

USDA Eastern Regional Research Laboratory, Philadelphia, PA.

A micro-Kj eldahl steam distillation apparatus was used to

separate the ammonia released by sodium hydroxide, which was

trapped in boric acid. The ammonia was titrated with

standardized 0.01 N hydrochloric acid using methyl purple

indicator. Both 5 ml and 10 ml samples were used for these

measurements

.

7
Because of the problems which were encountered in the

analysis using the ion- select ive electrode, the values obtained

using this method were used only for evaluation of homogeneity.

Accordingly, the values reported in tables 7 to 10 are based

on the second method only.

2.6.5.2 Metals by Atomic Absorption and Flame Emission

Spectrometry

All of the metallic cations were measured by atomic

absorption or flame emission spectrometry. Measurements

were made both on the bulk solution and on the ampoules.

The contents of an ampoule were quantitatively transferred

to a 100 ml volumetric flask. After addition of 1 ml of

purified nitric acid, the solution was diluted to the

calibrated volume. Emission or absorption measurements were

made in duplicate. Calibration standards were made by

dissolution of pure salts or pure metals.

2.6.5.3 Metals by Polarographic Analysis

Polarographic measurements were made for selected

elements, on reconstituted samples, i.e. a solution resulting

from dilution of the contents of an ampoule to a final

volume of 500 ml.

Measurements of copper, lead, cadmium, nickel and zinc

were made on the diluted samples in the following manner.

Aliquots of 100 ml of the diluted samples were evaporated to

dryness in quartz beakers, after addition of a few drops of

perchloric acid. After a second evaporation with hydrochloric acid, the residues were redissolved in 2 ml of

supporting electrolyte. For the case of copper, lead, and

cadmium, the supporting electrolyte was ammonium acetate - acetic acid. A supporting electrolyte of pyridine - pyridinium sulfate was used for measurement of nickel and

zinc. Measurements were made with a cathode-ray polarograph.

Calibration standards and blanks were carried through the

procedure

Additional ampoules were analyzed similarly, except

they were also rinsed with nitric acid and these rinsings

were included in the analysis.

3. ANALYTICAL RESULTS

The analytical results obtained for the four reference

mat3rials are summarized in tables 7, 8, 9, and 10. These

include data for the bulk solutions, analysis of individual

ampoules, and measurements on the reconstituted solutions in

several cases. However, all data are reported on the basis

of the reconstituted solutions (dilution of 10 ml to a final

volume of 500 ml) . The columns labelled "Synthesis" contain

values calculated from the composition of the solutions as

prepared
The last column of each table lists the recommended

values for each parameter based on a "best estimate" in

consideration of the synthesis values and the analytical

limits of uncertainty. When the two values are in essential

agreement, the synthesis values are recommended. This is

the case for most of the parameters. The analytic values

are recommended in several cases where uncertainties in the

compositions of the starting materials, or loss or gain of a constituent was found or believed to be a reasonable

explanation of the discrepancy.

All of the cadmium values are larger than expected. In

view of the good agreement between the two measurement

techniques, the discrepancy is believed to be due to nonstoichiometery of the hydrates used for preparation of the

solutions, hence the measured values are recommended. The

values found by polarographic measurement of copper in the

reconstituted solutions are slightly smaller than expected.

Since the synthesis values were found for solutions resulting

from rinsing the ampoules with acid, it is concluded that a small loss of copper has resulted from interaction with the

ampoules. Because acid rinsing is not permissible, the

measured values are recommended. The values found for lead

by two techniques are also lower than expected. Again,

values in agreement with the bulk solution were found for

ampoules rinsed with acid. Accordingly, it is concluded

that losses have occurred as the result of interaction with

the ampoule walls, so the measured values are again recommended

The values found for calcium in samples B and D are

somewhat lower than expected but agreement was found in the

case of samples A and C. In view of this latter agreement

and the confidence in the analytical procedure, the measured

values are recommended for solutions B and D.

The measured values for fluoride are low by a few

percent for all solutions except A although the differences

are barely significant. However, in view of the care exercised

in making the measurements, it is believed that the measured

values are more likely and they are recommended for these

solutions

.

The only other significant departure from the expected

values is that for sulfate in solution B. When the discrepancy

was noticed, the measurement was repeated to verify the

analytical value which is recommended.

It is not possible to assign uncertainty limits to the

recommended values, because of limited experience with these

materials. In most cases, the analytical measurements were

9
made with techniques used at NBS that are capable of providing

data reliable to within 2 percent. However, stability

problems may be an overriding factor of unknown magnitude.

The best statement that can be made at present is that the

data are believed to be useful to two significant figures.

4. DISCUSSION

The suitability of the samples to serve as reference

materials or for intercalibration of measurement laboratories

is based upon several types of information. Each ampoule

contains the same weight of solution within close limits.

Weighing of eighty ampoules indicated an average weight

content of 9.963 g with a standard deviation of 0.005 g.

Accordingly, it is clear that variations in the total amount

of the contents are of no concern.

Measurements on replicate ampoules in each series were

also made for most of the parameters to obtain information

on possible variation between samples. These ranged from

duplicates for 2 parameters to septuplicates on 9 parameters.

No variations larger than the expected measurement variations

were found. Accordingly, it is believed that all of the

samples in a given series are reasonably identical in

composition.

Because the materials consist of filtered solutions,

uniformity of composition between ampoules would be expected,

provided the contents are stable. It would have been

preferred to study the stability over an extended period of

time but the time schedule did not permit this. Accordingly,

the long-term stability has not been established.

A few minor stability problems are evident from inspection of the data in tables 7 to 10. The values for

sodium appear to be increasing, perhaps due to leaching from

the walls of the ampoules. The values for copper and lead

appear to have decreased since ampouling. It was found that

the loss can be regained by an acid wash but this is not a permissible operation. However, the samples appear to be

satisfactory for collaborative studies, especially if all

measurements are carried out within a reasonably comparable

period of time.

Samples have been retained by NBS and these will be

analyzed after a suitable period of time to further evaluate

their stability.

10
5. RECOMMENDED DILUTION PROCEDURE

The samples consist of ampoules of concentrate which

simulate rainwater, when diluted to 500 ml. The ampoules

are pre-scored at the constriction to facilitate breaking

off the tip. Glassware should be thoroughly cleaned and

rinsed with distilled water before use. The distilled water

used for rinsing and dilution should be of the highest

quality since any impurity will add to the constituents of

the sample. The recommended procedure for preparation of

the test sample is as follows:

1. Rinse the outside of the ampoule to remove dust

and allow to air dry.

2. Hold ampoule in a vertical position, tip up, and

gently tap to transfer any liquid from the tip to

the body of the ampoule.

3. Hold ampoule with a paper towel (precaution to

prevent injury to hand) and snap off the tip at

the scored constriction.

4. Place a clean funnel in the neck of a clean 500 ml

volumetric flask and transfer the contents of the

ampoule, with gently shaking as required to facilitate removal of liquid.

5. Rinse the ampoule two times with distilled water

and transfer the rinsings to the flask.

6. Add distilled water to the flask to dilute to the

graduation mark, and mix contents thoroughly.

7. Treat the resulting solution with the same care

and in the same manner as a sample of natural

rainwater

.

6. ACKNOWLEDGEMENTS

This work was done under the general supervision of

John K. Taylor. Mr. Erie R. Deardorff prepared the solutions

and performed analyses for nitrate, ammonia, and acidity.

Mr. T. C. Rains and Ms. M. A. Waguespack performed the

atomic absorbtion and flame emission measurements. Dr. R. A.

Durst made the measurements of pH, conductance, and analyses

for fluoride, chloride, and ammonium by the ion- selective

electrode. Dr. E. P. Scheide anlyzed the samples for

sulfate ion. Ms. E. J. Maienthal made polarographic measurements

on the diluates for five metals. Mr. W. P. Reed of the NBS

Office of Standard Reference Materials was responsible for

the ampouling of the samples.

USCOMM-NBS DC 11
Table 1. Proposed Reference Standards

Sample A B C D

Constituent (unit

of measurement) Value Value Value Value

pH 5.70 4.90 4. 50 4.00

Conductivity (yScm"l) 35.0 50. 0 65.0 90.0

Acidity (yeq) . 1 1.0 5.0 10.0

S0= (S) 1 (mg/1) 1.0 3.0 5.0 10.0

NO" (N)

2 (mg/1) .1 1.0 5.0 10.0

NH+ (N)

2 (mg/1) .1 1.0 5.0 10. 0

F" (mg/1) .1 .1 .2 .3

CI" (mg/1) .1 1.0 5.0 10. 0

Na + (mg/1) .1 1.0 5.0 10.0

K

+ (mg/1) . 05 .1 1.0 5.0

Ca ++ (mg/1) .1 1.0 5.0 10. 0

Mg ++ (mg/1) .05 1.0 5.0 10.0

Zn ++ (mg/1) .02 .1 .3 .6

Cd ++ (mg/1) .03 .1 . 5 1.0

Cu ++ (mg/1) .05 .1 . 2 .4

Ni ++ (mg/1) .02 .1 . 5 1.0

Fe (mg/1) .05 .1 .2 . 5

Pb + + (mg/1) .02 .1 .2 .3

Mn ++ (mg/1) .05 .08 .1 .2

12
Table 2. Chemicals Used for Preparation

of Reference Solutions

Chemical Formula Source

Calcium Chloride CaCl

2

« 2H

2

0 Mallinckrodt Analytical Reagent

Calcium Sulfate CaS0

4

Hammond Drierite Company

Magnesium Chloride MgCl

2

-6H

2

0 Mallinckrodt Analytical Reagent

Magnesium Sulfate MgS0

4

B § A Reagent

Zinc Chloride ZnCl

2

Fisher Certified

Zinc Nitrate Zn(N0

3

) 2

-6H

2 0 Baker Analyzed

Cadmium Chloride CdCl

2

« 2htt

2

0 Baker Analyzed

Cadmium Nitrate Cd(N0

3

) 2

.4H

2

0 Fisher Certified

Cupric Chloride CuCl

2

- 2H

2 0 Fisher Certified

Cupric Nitrate Cu(N0

3

) 2 -3H

2

0 Baker Analyzed

Cupric Sulfate CuSO. • 5H-0

4 2

Fisher Certified

Nickel Nitrate Ni(N0

3

) 2

' 6H

2 0 Mallinckrodt Analytical Reagent

Nickelous Sulfate NiS0

4

-6H

2

0 B § A Reagent

Lead Nitrate Pb (N0

3

) 2

Baker Analyzed

Manganese Chloride MnCl

2 '4H

2 0 Mallinckrodt Analytical Reagent

Ammonium Chloride NH

4

C1 Baker Analyzed

Ammonium Sulfate (NH

4

) 2

S0

4

Mallinckrodt Analytical Reagent

Sodium Fluoride NaF Fisher Certified

Sodium Nitrate NaN0

3

Baker Analyzed

Sodium Sulfate Na

2 S04

Mallinckrodt Analytical Reagent

Potassium Chloride KC1 Fisher Certified

Potassium Nitrate KN0

3

Baker Analyzed

Potassium Sulfate K

2 S0

4

Fisher Certified

13
Table 3. Chemicals Used to Prepare Solution A

(Weight in mg to prepare 4 liters)

mg mg mg mg mg

mg_ S0*_ N0"_ F_2_ CT Reagent

Ca ++ 19.77 47.38 67.15

Mg ++ 20.83 82.32 103.15

Zn ++ 4.25 4.60 8.85

Cd ++ 5.18 3.27 10.53

Cu ++ 10.33 15.61 40.59

Ni ++ 4.11 6.72 18.40

Pb ++ 4.51 2.70 7.21

Mn++ 10.35 13.36 37.30

NH

4

+ 22.71 60.60 83.31

Na + 25.53 21.10 46.64

K

+ 12.51 19.83 32.34

14
Table 4. Chemicals Used to Prepare Solution B

(Weight in mg to prepare 6 liters)

mg

Ca+ + 150. 54

Mg + + 162. 17

Zn+ + 29. 86

Cd + + 29. 64

Cu+ + 30. 67

Ni + + 31. 11

Pb + + 31. 72

Mn+ + 24. 37

NH+ 147. 62

Na + 93. 49

K

+ 30. 62

Na + 20. 59

Na+ 36. 91

mg mg mg mg mg

S0=_ N0"_ r_ CI" Reagent

266.32 552.1

640.93 803.1

32.39 62.26

18.69 60.21

59.84 116.6

65.71 154.1

18.98 50.70

31.45 87.79

393.91 541.9

195.31 288.8

27.76 58.38

55.52 76.12

30.50 67.43

15
Table 5. Chemicals Used to Prepare Solution C

(Weight in mg to prepare 4 liters)

mg_ mg mg mg mg

m& SO" N0-_ ClZ. Reagent

Ca ++ 246.15 589.95 836.1

Mg ++ 145.71 425.09 1219.0

Zn++ 61.29 116.25 278.9

Cd ++ 100.80 63.59 204.8

Cu ++ 39.88 44.50 107.0

Ni ++ 101.27 165.70 453.4

Pb ++ 39.23 23.48 62.71

Mn++ 19.96 25.77 71.92

NHt 490.77 966.5 1458.4

4

Na + 440.60 1188.23 1629.0

K

+ 201.35 247.33 448.7

Na+ 48.50 40.08 88.6

16
Table 6. Chemicals Used to Prepare Solution D

(Weight in mg to prepare 4 liters)

Ca+ +

Mg + +

Zn+ +

Cd + +

Cu ++

Ni + +

Pb + +

Mn++

nh;

Na+

K

+

Na +

Na+

m£

640.8

189.3

122.1

200. 7

80.2

201.4

58.8

40.

1

924.3

597. 7

611.5

410. 3

72.8

mg

§0=.

mg

NO:

mg

F"

1249.0

751.1

231.6

221.4

156.6

425.5

35.2

1106.6

mg

ci1133.7

552.4

51.8

1821

60. 2

mg

Reagent

2350.1

1584.0

555.6

550. 7

305.1

997. 9

93.99

144. 5

2747.0

1846.9

1362.6

1517.1

133.0

17
Table 7. Analytical Values for Reconstituted Samples

Sample A

Analytical Values

* Recommended

Measured Synthesis Bulk Ampoules Diluate Val has*

pH 6.18 6.18

Conductivity** 5.8 5

Acidity*** 0.49 0

SOJ (S) 361 342 361

NO" (N) 26 26 26 26

NH+ (N) 89 81 84 89

F" 102 103 102

ci- 106 136 106

Na+ 128 134 153 153

K

+ 63 68 63

Ca + + 99 96 99

Mg + + 104 86 86

Zn + + 21 19 20 21

Cd + + 26 30 30

Cu + + 52 53 52

Ni + + 21 23 21

Pb + + 23 20 18 18

Mn+ + 52 55 53 52

* Data believed useful to 2 significant figures

** yS'cm" 1 reconstituted solution

*** mg/1 CaC0

3

All other units, yg/1 reconstituted solution

18
Table 8. Analytical Values for Reconstituted Samples

Sample B

Analytical Values

Acid Recommended

Measured Synthesis Bulk Ampoules Diluate Rinse Values*

Pn 6.15 6

C An rli if + "i A7"i 1" v 18 3 18

r\\—L Li x l y o 50 n

so

= rsi 1367 1188 1188

MO" iNU fNl

3

^i' J 150 152 150 150

NH + TNI 382 *J398ZJ \J 364 382

F" 102 96 96

12 5 5 1 080 12A. Li *J55*J

Mo *

iNa ^ n ^ 48 n JlU JlU 516

in? l -L U L

La C ft ? A A ? A A?

Mg D^41t J. too 4 %J56\J

Zn+ + 100 95 94 94P

96P

95

Cd*

+ 99 113 116P 116P 116

Cu 102 107 88P 101P

88

Ni + + 104 109 103 104 104

Pb + + 106 99 92 88P 104P

88

Mn++ 81 84 83 81

Data believed useful to

** yS'cm

- ''' *** mg/1 CaCC<

2 significant figures

All other units, ug/1 reconstituted solution

p Polarographic measurement

19
Table 9. Analytical Values for Reconstituted Samples

Sample C

Analytical Values

Measured Synthesis Bulk Ampoules Diluate

Acid

Rinse

Recommended

Values *

pH 6. 20 6.20

Conductivity * it 59.8 59.8

Acidity** * 2.46 2.46

S0= (S) 1672 1645 1672

NO: (N)

3

v J 1499 1500 1480 1499

NHt (N)

4 ^

' 1909 1890 1858 1909

F" 200 195 195

CI" 7627 7666 7627

Na + 2446 2420 2460 2460

K

+ 1007 1020 1007

Ca ++ 1231 1216 1231

Mg ++ 729 722 729

Zn+ + 307 314 312 309P 30913 307

Cd + + 500 574 578 P 578 P 578

r-i 4-4- Cu + + 200 198 1 9 L r iy o r inn

Ni + + 506 518 506p 507 p 506

Pb + + 196 170 164 152 p 169 p 152

Mn+ + 100 102 101 100

* * *

Data believed useful to 2 significant figures

c "I

yS • cm

mg/1 CaC0

3

All other units, yg/1 reconstituted solution

p Polarographic measurement

20
Table 10. Analytical Values for Reconstituted Samples

Sample D

Measured Synthesis Bulk

Analytical Values

Acid Recommended

Ampoules Diluate Rinse Values*

pH 6.07 6.07

Conductivity** 117 117

Acidity*** 4.71 4

SOJ (S) 3333 3374 3333

NO" (N) 2457 2440 2500 2457

NH+ (N) 3595 3590 3524 3595

F" 301 296 296

ci- 17790 16922 17790

Na+ 5404 5260 5444 5444

K

+ 3058 3100 3058

Ca + + 3204 2840 2840

Mg++ 947 922 922

Zn + + 610 638 632 610 P 610P 610

Cd + + 1004 1010 1010P 1010P 1010

Cu + + 401 418 393P 410P 393

Ni ++ 1007 1080 1040P 1040P 1007

Pb + + 294 125 110

p 110F 120P 110

Mn+ + 200 204 200 200

**

Data believed useful to 2 significant figures

1

yS • cm

*** mg/1 CaC0

3

All other units, yg/1 reconstituted solution

p Polarographic measurement

21
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBSIR 75-958

2. Gov't Accession

No.

4. TITLE AND SUBTITLE

Simulated Precipitation Reference Materials

7. author(S) J. K. Taylor, E. K. Dearaortt, K. A. Durst,

E. J. Maienthal, T. C. Rains, and E. P. Scheide

3. Recipient's Accession No.

5. Publication Date October 1975

6. Performing Organization Code

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 31 n

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Office of Research and Development

National Environmental Research Center

Environmental Protection AgencyResearch Triangle Park, NC 27711

13. Type of Report & Period

Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less {actual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

The preparation of a series of reference materials for chemical

analysis of natural precipitation is described. The materials consist

of ampoules of concentrates which can be diluted to simulate naturally

collected samples of rainwater. The analytical measurements made to

verify the composition of the samples are also described.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons) Chemical analysis; rainwater analysis; reference

materials

18. AVAILABILITY " [JCX Unlimited

|

' For Official Dist ribution. Do Not Release to NTIS

I

1 Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. CI 3 XX Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

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21. NO. OF PAGES

23

22. Price

$ 4.00

USCOMM-DC 29042-P74