NBSIR 77-1315

Simulated Precipitation

Reference Materials II

J. K. Taylor, E. R. Deardorff, and T. C. Rains

National Bureau of Standards

Department of Commerce

Washington, D.C. 20234

September 1977

Final Report

Prepared for The Environmental Protection Agency

Environmental Monitoring and Support Laboratory

Research Triangle Park, North Carolina 27711

NBSIR 77-1315

SIMULATED PRECIPITATION

REFERENCE MATERIALS II

J. K. Taylor, E. R. Deardorff, and T. C. Rains

National Bureau of Standards

Department of Commerce

Washington, D.C. 20234

September 1977

Final Report

Prepared for The Environmental Protection Agency

Environmental Monitoring and Support Laboratory

Research Triangle Park, North Carolina 27711

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Sidney Harman, Under Secretary

Jordan J. Baruch, 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 2 2.3. Ampouling 3

2.4 Numbering Sequence 4

2.5 Analysis of Ampoules 5 2.5.1 pH Measurements 5

2.5.2 Conductivity Measurements 5

2.5.3 Acidity Measurements 5 2.5.4 Analysis of Anions 6

2. 5. 4.1 Measurement for Sulfate Ion . 6

2. 5. 4.

Measurement for Nitrate Ion . 7 2. 5. 4.

Measurement for Fluoride Ion. 7 2. 5. 4.

Measurement for Chloride Ion. 7 2.5.5 Analysis for Cations 7 2. 5. 5.1 Measurement for Ammonium Ion. 7 2. 5. 5.

Metals by Atomic Absorption

and Flame Emission 8

3. ANALTYICAL RESULTS 8

4. DISCUSSION 9

5. RE-EXAMINATION OF FY 76 SAMPLES. 10

6. INSTRUCTIONS FOR USE . 10

6.1 Series 710000, Series 720000, Series 730000 . 10

6.2 Series 740000 11

6.2.1 Acidity Measurement 11

6.2.2 Conductivity and pH Measurements ... 11

7. ACKNOWLEDGEMENTS 12

l
TABLES

Page

1. Target Compositions 13

2. Preparation of Stock Solutions 14

3. Precision of Ampouling 15

4. Analytical Data for Series 710000 16

5. Analytical Data for Series 720000 17

6. Analytical Data for Series 730000 18

7. Compositional Data for Series 740000 19

8. Re-examination of FY76 Samples 20

FIGURE

1 . Titration Curves for Acidity Measurements

Page

21
Simulated Precipitation Reference Materials, II

John K. Taylor, E. R. Deardorff, and T. C. Rains

ABSTRACT

This report describes the preparation of a series of

reference materials for chemical analysis of natural precipitation. This is the second series of such materials

prepared by NBS, under the sponsorship of EPA, and will be

distributed by the latter as a means to intercalibrate

atmospheric monitoring stations. The materials consist of

ampoules of concentrates which can be diluted to simulate

natural rainwater. A separate reference sample, to be used

undiluted, is provided for evaluation of acidity measurements.

The analytical measurements made to establish the composition

of the samples are also described.

1. INTRODUCTION

The analysis of the composition of rainfall and other

forms of precipitation is an excellent means to monitor

global atmospheric pollution. Such measurements must necessarily be made at widely spaced geographical locations,

over extended periods of time, and by many independent

investigators. It is imperative that the measuring stations

be intercalibrated if the data obtained are to be correlated

and combined for environmental interpretation. The measurement of a series of substantially identical samples by

stations in a measurement system is an accepted method of

evaluating laboratory performance for intercalibration

purposes

This report describes work done at the National Bureau

of Standards under the sponsorship of EPA to prepare and

establish the composition of a series of reference materials

intended to be used for the intercalibration of precipitation measurement stations 1

. The materials consist of

ampoules containing aqueous concentrates that simulate

natural precipitation when accurately diluted. Three multicomponent solutions and one solution specifically designated

for acidity measurement were prepared.

1 This work was performed at the National Bureau of Standards

for the Environmental Protection Agency under Interagency

Agreement EPA- IAG-D7-F1069

CONTRIBUTION OF THE NATIONAL BUREAU OF STANDARDS. NOT

SUBJECT TO COPYRIGHT.
This is the second series of solutions prepared for the

above described purpose. The details of the first series

are contained in a report, NBSIR 75-958, "Simulated Precipitation Reference Materials", October 1975.

2. EXPERIMENTAL DETAILS

2 . 1 General Considerations

The reference materials are similar in concept to those

prepared previously. While the former were satisfactory in

most respects, laboratories had particular problems with the

measurement of pH, conductivity and acidity. Accordingly,

it was decided to prepare one reference material specifically

intended for the measurement of these parameters. In addition,

a series of three solutions was prepared containing a number

of components at concentrations similar to those expected in

natural samples.

The target compositions are given in Table 1. The

solutions were prepared according to instructions furnished

by EPA. Two of the solutions contain acids to stabilize

them, while all three contain complexing agents to stabilize

the iron, particularly. Although directions were followed

implicitly, the third solution showed both immediate and

long-term precipitation, so that the objectives were only

partly realized.

2 . 2 Preparation of Reference Materials

The reference materials were prepared from high quality

distilled water and reagent grade chemicals. The chemicals

and quantities used are given in Table 2.

The instructions followed for preparation of Series

710000 and Series 720000 are as follows:

Dissolve all except the Pb salt in 1 liter of water.

Mix well. Pipet 200 mL of this solution into each of two

2000 mL volumetric flasks, and dilute each solution to

approximately 1800 mL . Dissolve the Pb salt in 100 mL

water. Pipet 20 mL of the lead solution into each 2000 mL

volumetric flask and dilute to volume. Mix well. Filter

the two final solutions through Whatman 42 paper into four

liter bottles.

Instructions for Series 730000:

Dissolve all except the Pb salt in approximately 3200

mL water. Dissolve the Pb salt in a separate portion of 200

mL water. Add the Pb solution to the first solution and

dilute to four liters. Mix well. Filter the final solution

through Whatman 42 paper into a four liter bottle.

2
The Series 730000 solution became cloudy when the

sodium fluoride was added and a definite precipitate settled

out. This was filtered off and analyzed spectrographically

with the following result:

Ca >> 201; Cu 1%; Fe 5%; Na 2 %; Ni II , Si II; Zn II

The bulk solution was filtered before ampouling and appeared

to be homogeneous at that time. However, a small amount of

precipitate has settled out in the ampoules. Analysts are

requested to shake the ampoules before opening and using.

While there appears to be no difficulty with most of the

constituents, the iron values appear to be questionable.

The Series 740000 bulk solution was prepared by dilution

of the appropriate volume of 0.06N H 2 S0 4 to a final volume

of 20 liters. The sulfuric acid solution was standardized

by titration with a 0.05 N NaOH solution that had been

standardized with potassium acid phthalate, SRM 84. The

acid was also standardized with respect to THAM, SRM 723.

The original intention was to deliver 20 mL of the bulk

solution into ampoules. However, as explained in Section

2.3 it was necessary to dispense a smaller volume. The

volume finally dispensed was 18.7 mL per ampoule so that

each ampoule should contain 4.66 yeq of acid.

2 . 3 Ampouling

The bulk solutions were transferred to ampoules using

an automatic dispensing and sealing machine 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

The dispensing equipment pumps the solution from the

storage vessel and reproduceably 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 in

the four solutions during the three hour filling operation.

The dispensing equipment automatically flame-sealed the

ampoules

3
The ampoules used for Series 710000, Series 720000, and

Series 730000 were of 10 mL capacity while 20 mL ampoules

were used for the Series 740000 samples. The dispensing

equipment was adjusted to deliver approximately 10 mL in the

first group. It was intended to deliver 20 mL of the Series

740000 solution but a problem was encountered when the

liquid splashed up into the necks of the ampoules during

filling. This was eliminated when the volume was decreased

to 18.7 mL

The ampouling operation was very precise as indicated

by the data of Table 3. The upward trend in mass delivered

is due to the density differences in the respective solutions.

The densities of the solutions were measured and the volumes

calculated (which is the important parameter since the

dispenser is a displacement device) are seen to be constant.

The standard deviations for the first three series were

pooled to calculate a two-sided tolerance interval of ± 0.2%

at the 99% level. This means that there is a 99% confidence

that 99% of the ampoules are within ± 0.2 percent of each

other. The same tolerance level was found for the Series

740000 samples, which is to be expected, if the variation is

based upon performance of the dispenser alone.

2 . 4 Numbering Sequence

The ampoules are labeled and numbered in the following

sequences

Series 710000 - 710001 to 710200

Series 720000 - 720001 to 720200

Series 730000 - 730001 to 730200

Series 740000 - 740001 to 740600

The rational of the numbering sequence is illustrated

as follows:

710001

First digit: Fiscal year 197^7

Second digit: Sample type 1,2,3, or 4

Remaining digits: Sample serial number, e.g., 0001

The samples were replaced in the individually compartmented boxes in which the ampoules were received from the

manufacturer. Care was exercised to place them in the box

in the order of filling. Samples for measurement were

selected from these by a random number process. Altogether,

56 ampoules were selected from each Series 710000, Series

720000 and Series 730000 for this purpose, while 21 were

4
selected from the Series 740000. No differences were found

in either mass content or composition that could be attributed

to sequence of preparation. Accordingly, it is believed

that the samples in each series are substantially uniform

with respect to composition and total content.

The samples delivered to EPA were numbered sequentially,

ignoring the gaps resulting from removal of the test samples.

However, the actual production sequence could be ascertained

should the need arise.

2 . 5 Analysis of Ampoules

Essentially seven ampoules were analyzed for each

specific determination. However, for purposes of convenience,

all measurements were not made on the same ampoule. The

measurement data are summarized in Tables 4, 5, and 6. The

methods used for measurement are summarized in the following

subsections

2.5.1 pH Measurements

The pH measurements were made on diluted samples of the

concentrates for the 710000, 720000, and 730000 series; undiluted

samples were used for the 740000 series. The combination pH

electrode was calibrated with pH 4.01 and 7.00 buffers and

the sample readings were taken directly from the digital pH

meter display.

2.5.2 Conductivity Measurements

The conductivity measurements were made on samples similar

to those used in the pH determinations. The cell constant,

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

haying specific conductances, L, of 0.00141 and 0.000147 S

cm 1

. The specific conductance of the sample solutions was

calculated from the measured resistance at a frequency of 1

kHz by the equation:

T _k_ 0.307 cm 1 L R R

2.5.3 Acidity Measurements

Two ampoules of 740000 were broken open and emptied

into a clean 100 mL beaker without washing the ampoules.

This solution was titrated with standarized 0.01N NaOH to pH

8.3 using a research pH meter.

Each ampoule of 710000, 720000, and 730000 was diluted

to 500 mL with distilled water and titrated with standarized

0.01N NaOH to pH 8.3 using a research pH meter. A blank

correction was determined by titrating 500 mL of distilled

water

5
Typical titration curves are reproduced in figure 1.

Curve 1 is for Series 710000, curve 2 is for Series 720000,

and curve 3 is for Series 730000. The curve obtained when

30 yeq of acid is added to Series 730000 is also shown.

It is evident that the end point of pH 8.3 specified by

water acidity methods does not correspond to the inflection

point of the titration curve. The quantities of salts

present exert a buffering effect and/or hydrolyze to distort

the upper part of the titration curve. The values for

acidity reported here are based on an arbitrary end point of

pH 8.3, as specified by water analysis methods. However, the

behavior shown in Figure 1 raises questions as to the meaning

of such values.

Wien the Series 740000 ampoules were analyzed, the data

appeared to fall into two groups. The acidity values for

one of them was in close agreement with that for the bulk

solution while the second group showed decreased acidity.

In visual inspection some of the ampoules appeared to be

slightly "brown" while the others appeared to be slightly

"green". The ampoules with the "green" tinge showed the

decreased acidity values.

The ampoules were supposedly from the same manufacturing

lot and the producer has been unable to furnish an explanation

for the color differences. While the difference in acidity

was small, it could be predicted based on color selection of

the ampoule. Accordingly, it was decided to remake the

Series 740000 samples, using only one type of ampoule. The

"brown" ampoules were used and the lot was screened before

hand to exclude any of the "green" type.

The remarks above pertain only to the 20 mL ampoules

used for containment of the Series 740000 samples. The 10

mL ampoules used for the other series appeared to be essentially

colorless and no differential behavior was observed.

2.5.4 Analysis for Anions

2. 5.4.1 Measurement of Sulfate Ion

Sulfate was determined by the Turbidimetric Barium

Sulfate Method, developed by the Air and Industrial Hygiene

Laboratory, State Department of Health, Berkeley, California.

This method is similar to ASTM Method D 516-68 except a glycerol-alcohol-HCl solution is used to stabilize and

promote precipitation of barium sulfate, instead of a glycerol

and a sodium chloride solution.

6
2. 5. 4.

Measurement of Nitrate Ion

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 pg/25 mL where the solution

does not follow Beer’s Law. The absorbance was read at 410

nm, using 1 cm cells. Undiluted samples were used in these

measurements

2. 5.4.3 Measurement of Fluoride Ion

The fluoride determinations were performed by direct

potentiometry on samples diluted 1:1 with TISAB (total ionic

strength adjustment buffer) . Calibration standards containing

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

2. 5. 4.Measurement of Chloride Ion

Chloride was determined 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 approximately

Nernstian

2.5.5 Analysis for Cations

2. 5. 5.1 Measurement of Ammonium Ions

The technique used consisted of chemical measurement

according to the procedure given in the following reference:

C. 0. Willits and C. L. Ogg, ”1949 Report of Standar i zation

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.

7
2. 5.5.2 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.

3. ANALYTICAL RESULTS

The analytical results for Series 710000, Series 720000

and Series 730000 are summarized in Tables 4, 5, and 6.

Each table contains the values calculated from the method of

preparation where appropriate, and those obtained by measurement. The symbols used are as follows:

n = number of samples analyzed

x = average value by measurement

s = standard deviation of a single measurement —t s = 95% confidence interval of the average value

/n

% = confidence interval expressed as percent of measured

value

The values listed under x are the best estimates of various

compositional parameters of the solution resulting from

dilution of the concentrate of an ampoule to 500 ml.

The analytical values for Series 740000 samples are

given in Table 7. The values reported are for samples as

contained in the ampoules, without further dilution. The

acidity values are based upon combining the contents of two

ampoules. The pH and conductivity values are for undiluted

samples but of course they are independent of the quantity

of sample measured.

8
4. DISCUSSION

The samples in each series are believed to be substantially uniform in composition. Every ampoule in each

series contains the same total amount of sample within

narrow limits. Furthermore, the dilution of the contents,

as indicated, should introduce no errors, provided high

quality water is used for this purpose. Accordingly, the

samples should be capable of evaluating between- laboratory

variability within any requirement for precipitation

analysis

The various analysts at the National Bureau of Standards

who examined the samples have had considerable experience

with the methods used or ones very similar to them. Furthermore, the measurements were made as part of an ongoing

program in trace analysis. Accordingly, the values indicated

by x are believed to be unbiased and represent the best

estimates of the compositional parameters.

When the measured values are compared with those based

upon preparation of the solutions, the agreement is found to

be good in most cases. The largest discrepancies are as

follows

Series Constituent Expected Found

710000 K . 10 .199

710000 Na .10 .151

720000 Na 2.0 2.86

730000 Fe .18 .076

Because of the visible brown precipitate in the Series

730000 ampoules, the value obtained for Fe is probably meaningless. The data for the other discrepant values were reexamined but no fault could be found in them. Accordingly,

the measured values are believed to be valid.

The negligible variation in the total contents of the

ampoules, and the fact that they are filled with true

solutions (except as already noted for Series 740000) , leads

to the conclusion that there are no systematic differences

between ampoules in each series. Random errors can arise

from possible instability of the solution during long-term

storage, although advance precautions have been taken to

minimize this source of error. A number of ampoules have

been reserved at the National Bureau of Standards for future

study, should this appear to be desirable.

9
5. RE-EXAMINATION OF FY 76 SAMPLES

During the course of analysis of the present samples, a limited number of measurements were made on ampoules remaining

from the lot prepared in October 1975. The results are

given in Table 8 under the columns identified as 7/77. The

values reported in October 1975, in the columns identified

10/75, are given for comparison.

The results for SO 4 and N0 3 were measured on the ion

chromatograph and kindly furnished to us by Mr. James Mulick,

EPA, Research Triangle Park, NC, while the remainder were

obtained at NBS. The only constituents that have shown

large decreases are lead and copper. This is constistent

with the results reported earlier and predicted at the time

of preparation of the samples. There has been an apparent

small decrease in the calcium concentrations but the sodium

concentrations have shown only a small increase. These

solutions had all shown a slight initial increase in sodium,

presumably from interaction with the ampoules, but this

change has apparently not continued.

The overall conclusion that may be drawn is that

concentrates of this kind show sufficient stability, with

several exceptions, for use as intercalibration samples.

These samples contained no stabilizers. The present samples,

containing acid as a stabilizer, are expected to be more

stable than the previous ones.

6 . INSTRUCTIONS FOR USE

6 . 1 Series 710000, Series 720000, Series 750000

The samples consist of ampoules of concentrates 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 over

and back, and gently tap to transfer any liquid

from the tip to the body of the ampoule.

10
3. Hold ampoule with a paper towel (a 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 gentle 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 . 2 Series 740000

The solutions are intended for use without additional

dilution.

6.2.1 Acidity Measurement

Empty the contents of two ampoules into a clean 100 mL

beaker, according to instructions 1, 2, and 3 in Section

6.1. Hold the inverted ampoule over the beaker until

contents have drained as much as possible. Check for visible

inclusions of solution in the ampoule and shake again, if

required. Any film of solution remaining in the ampoule

will not cause significant error.

6.2.2 Conductivity and pH Measurements

Empty the contents of one ampoule into a clean 30 mL

beaker. Remove substantially all the contents by shaking as

directed before. However, the measurements are not influenced by the quantity of sample used, hence quantitative

delivery is not required. It is convenient to measure

sample conductivity, followed by measurement of pH on the

same sample.

11
7. ACKNOWLEDGEMENTS

The participation of the following members of the Staff

of the Analyical Chemistry Division in analysis of these

reference materials is gratefully acknowledged: R. A.

Durst; J. D. Messman; T. J. Brady. Mr. W. P. Reed of the

NBS Office of Standard Reference Materials was responsible

for ampouling the samples.

The work was performed for the Environmental Protection

Agency under Interagency Agreement EPA- IAG-D7-F1069.

Informative discussions with Mr. Vance R. Highsmith, EPA

Project Officer, and with Dr. Richard Thompson, Chief,

Environmental Support Laboratory, EPA, are gratefully

acknowledged

.

12
Table 1. Target Compositions

Unit of Concentration: mg/L

Constituent Series 710000 Series 720000 Series 730000

PH — — —

Conductivity — — —

Acidity — — —

so

4

(S) 2.9 (.96) 8.8 (2.9) 9.8 (3.23)

no

3

(N) .37 (.083) 3.2 (.71) 15.0 (3.4)

nh

4

(N) .11 (.085) 1.07 (.83) 10.4 (8.1)

Cl 1.0 6.4 40.0

F .048 .095 .30

Ca .10 1.0 8.0

Cd .022 .056 .10

Cu .032 .19 .98

Fe .022 .068 .18

K .10 .98 5.0

Mg .10 1.0 —

Mn .027 .055 .083

Na .10 2.0 10.0

Ni .029 .088 .50

Pb .021 .10 1.0

Zn .033 .20 1.0

13
Table 2. Preparation of Stock Solutions

710000 720000 730000

Chemical Grams Grams Grams

CaCl

2 «2H20 0.1838 1.8375 5.8652

NaCl 0.0585 3.060 1.9892

NaF 0.0525 0.105 .1344

MgS0

4

*7H

2

0 0.5043 5.043 —

kno

3

0.2525 1.2625 2.5664

NH.C1

4

0.154 1.540 6.1160

Zn(N0

3

) 2

*6H

2 0 0.0744 0.4463 .9224

Cd(N0

3

) 2

*4H

2

0 0.0309 0.0771 .0616

Cu(N0

3

) 2

*3H

2 0 0.0604 0.3624 .7488

Ferric Ammonium Citrate 0.0648 0.1945 .2076

MnCl

2 *4H20 0.495 0.099 .0496

Ni(N0

3

) 2

*6H

2 0 0.0728 0.2183

\ .4948

PbAc

2 ‘3H20 0.0190 0.0948 .3792

NaN0

3

0.425 .5952

Na o S0

.

2 4

.2982

710000

H

2

S0

4 26,900 micro-equivalents added from a standard solution

HC1 7,300 micro-equivalents added from a standard solution

720000

H

2 S04 51,000 micro-equivalents added from a standard solution

14
Table 3. Precision of Ampouling

ts

Series n Volume, mL Pooled s %

710000 7 9.975 .0027 10.01

720000 7 9.980 .0042 10.01 .0039 .024 0.24

730000 7 10.003 .0045 10.02

740000 7 18.7012 .0081 18.7 .039 .21

15
Table 4. Analytical Data for Series 710000

By Measurement

Constituent Unit

By

Preparation n X s

ts

%

PH 5 4.48 .13 .17 3.7

Conductivity _ -1

yS*cm 5 28.84 .48 .62 2.1

Acidity yeq /ampoule 7 37.57 1.10 1.06 2.8

SO.

4 mg/L 2.9 5 2.66 .17 .22 8.2

S0

4 (S) mg/L .96 5 .89 .05 .06 8.2

no

3 mg/L .37 3 .503 .005 .011 2.2

N0

3

(N) mg/L .083 3 .114 .001 .0023 2.2

NH.

4 mg/L .11 7 .107 .0028 .0027 2.5

nh

4

(n) mg/L .085 7 .084 .0021 .0020 2.5

Cl mg/L 1.0 8 1.35 .092 .080 5.9

F mg/L .048 7 .0461 .00069 .00067 1.4

Ca mg/L .078 7 .0766 .00090 .00086 1.1

Cd mg/L .022 7 .0230 .00010 ,00010 .4

Cu mg/L .032 7 .0360 .00046 .00044 1.2

Fe mg/L .022 7 .0214 .00018 .00018 .8

K mg/L .10 7 .199 .00111 .0010 .5

Mg mg/L .10 7 .110 .00034 .00032 .3

Mn mg/L .027 7 .0296 .00024 .00022 .7

Na mg/L .10 7 .151 .0060 .0058 3.8

Ni mg/L .029 7 .0338 .00056 .00054 1.6

Pb mg/L .021 7 .0232 .00062 .00060 2.5

Zn mg/L .033 7 .0344 .00024 .00022 . 6

16
Table 5 . Analytical Data for Series 720000

By Measurement

Constituent Unit

By

Preparation n X s_ ts

%

pH 7 4.08 .029 .028 0.7

Conductivity yS’cm

^

7 77.9 .65 .63 .8

Acidity yeq /ampoule 7 59.94 .35 .34 .6

SO,

4 mg/L 8.8 6 7.90 .58 .64 8.0

so

4 (s) mg/L 2.9 6 2.64 .20 .21 8.3

no

3

mg/L 3.2 6 3.02 .0 0 -

no

3

(n) mg/L .71 6 .68 .0 0 -

NH,

4

mg/L 1.07 7 1.07 .0049 .0047 .4

nh

4

(n) mg/L .83 7 .82 .0049 .0047 .5

Cl mg/L 6.4 8 7.22 .22 .19 2.6

F mg/L .095 7 .0997 .0026 .0025 2.5

Ca mg/L .78 7 .766 .0072 .0070 .9

Cd mg/L .056 7 .0572 .00046 .00044 .8

Cu mg/L .19 7 .192 .0013 .00012 . 6

Fe mg/L .068 7 .0612 .00058 .00056 .9

K mg/L .98 7 .994 .0084 .0082 .8

Mg mg/L 1.0 7 1.12 .0040 .0038 .3

Mn mg/L .055 7 .0586 .00026 .00026 .4

Na mg/L 2.0 7 .286 .014 .014 .5

Ni mg/L .088 7 .0948 .0011 .0011 1.1

Pb mg/L .10 7 .0988 .00028 .00028 2.8

Zn mg/L .20 7 .198 .00028 .00028 1.4

17
Table 6. Analytical Data for Series 730000

By Measurement

Constituent Unit Preparation n X s & %

pH 7 5.98 .026 .025 4.2

Conductivity yS cm

^

7 190.5 8.8 8.5 4.5

Acidity yeq/ampoule 7 52.5 1.8 1.7 3.3

SO.

4 mg/L 9.8 4 9.94 .44 .70 7.1

so

4 (s) mg/L 3.23 4 3.32 .14 .22 6.8

N0

3

mg/L 15.0 4 14.50 .082 .131 .9

N0

3

(N) mg/L 3.4 4 3.27 .021 .034 1.0

NH.

4 mg/L 10.4 7 10.18 .034 .032 3.1

NH. (N)

4

mg/L 8.1 7 7.93 .028 .027 3.4

Cl mg/L 40 7 42.4 3.3 3.2 7.5

F mg/L .30 7 .103 .0032 .0031 3.0

Ca mg/L 6.24 7 5.98 .048 .046 .8

Cd mg/L .10 7 .114 .00048 .00046 .4

Cu mg/L .98 7 1.012 .0102 .0098 1.0

Fe mg/L .18 7 .076 .017 .016 20

K mg/L 5.0 7 4.94 .056 .054 1.1

Mg mg/L —

Mn mg/L .083 7 .0846 .0003 .00028 .3

Na mg/L 10.0 7 9.66 .042 .040 .4

Ni mg/L .50 7 .518 .0072 .0070 1.3

Pb mg/L 1.0 7 1.04 .0088 .0084 .8

Zn mg/L 1.0 7 1.05 .0096 .0092 .9

18
Table 7. Compositional Data for Series 740000

Constituent Unit n X s

ts

PH 7 3.81 .037 .036

Conductivity yS cm

^

7 8.00 5.9 5.7

Acidity yeq/ampSu?es 7 9.32 i—

00 .17
Table 3. Re- examination of FY76 Samples

A B C D

Constitutent 10/75 7/77 10/75 7/77 10/75 7/77 10/75 7/77

so

4

(s> yg/L 342 365 1188 1267 1672 1667 3333 3300

no

3 (n) yg/L 26 33 150 158 1499 1501 2457 2461

Na yg/L 153 166 516 546 2460 2540 5444 5460

K yg/L 63 66 102 107 1007 1010 3058 2920

Ca yg/L 99 84 442 370 1230 1040 2840 2420

Mg yg/L 86 86 456 454 729 712 922 936

Zn yg/L 21 20 95 89 307 284 610 626

Cd yg/L 30 30 116 115 578 576 1010 990

Cu yg/L 52 40 88 35 200 104 393 174

Ni yg/L 21 22 104 113 506 560 1007 1034

Pb yg/L 18 8.8 88 58 152 105 110 62

Mn yg/L 52 54 81 85 100 103 200 204

20
MILLILITERS 0.01 N NaOH

Figure 1. Titration curves for acidity measurements

21
NBS-1 14A (REV. 7-73) U S. DEPT, of COMM. 1. PUBLICATION OR REPORT NO. BIBLIOGRAPHIC DATA

SHEET NBSIR 77-1315

2. Gov’t Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Simulated Precipitation Reference Materials II

5. Publication Date

6. Performing Organization Code

7. AUTHOR(S)

John K. Taylor F. . R. Dearrlorff T. C. Rainc;

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. 3105411

11. Contract/Grant No. EPA-IAG-D7-F1069

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

Enviromental Protection Agency

Enviromental Monitoring and Support Laboratory

Research 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.) This report describes the preparation of a series of reference

materials for chemical analysis of natural precipitation. This is

the second series of such materials prepared by NBS , under the

sponsorship of EPA, and will be distributed by the latter as a means

to intercalibrate atmospheric monitoring stations. The materials consist of ampoules of concentrates which can be diluted to simulate

natural rainwater. A separate reference sample, to be used undiluted,

is provided for evaluation acidity measurements. The analytical

measurements made to establish 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 [^_ Unlimited 19. SECURITY CLASS 21. NO. OF PAGES

(THIS REPORT)

~

' For Official Distribution. Do Not Release to NT1S

UNCLASSIFIED 25

1

: Order From Sup. of Doc., U.S. Government Printing Office 20. SECURITY CLASS 22. Price Washington. D.C. 20402. SD Cat. No. CIS (THIS PAGE)

Hx1 Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151 UNCLASSIFIED $3.00

USCOMM.DC 29042-P74