Techniques of Water-Resources Investigations 

of the United States Geological Survey 

Chapter Al 

MEiHODS FOR DETERMINATION 

OF INORGANIC SUBSTANCES 

IN WATER 

AND FLUVIAL SEDIMENTS 

By Marvin J. Flshman and Linda C. Friedman, Editors 

First Edition 1970 

Second Edition 1979 

Third Edition 1989 

Book 5 

LABORATORY ANALYSIS 
Bromide, titrimetric, hypochlorite oxidatbn 

Parameter and Code: 

Bromide, dissolved, I-1125-85 (mg/L as Br): 71870 

1. Application 

This method may be used to analyze any 

natural or treated water or brine containing at 

least 1 .O mg/L of bromide. Highly concentrated 

brines may require dilution. 

2. Summary of method 

2.1 The determination of bromide involves 

the determination of bromide and iodide colle& 

ively, and then the determination of iodide 

alone; bromide is calculated by difference. 

Bromide and iodide are oxidixed to bromate and 

iodate, respectively. by hypochlorite, and the 

excess hypochlorite is subsequently decomposed with sodium formate (Kolthoff and 

others, 1969). 

3OCl-1 + Br-1 + BrCgl + 3Cl-1 

3OCl-’ + I-’ - IOjl + 3Cl-1 

Iodine equivalent to the combined iodate and 

bromate is then liberated by addition of 

potassium iodide to an acid solution. 

Broil + 61-l + 6H+1+ 31, + 3H,O + Br-1 

IOjl + 51-l + 6H+l-, 31, + 3H,O 

The liberated iodine is titrated with standard 

thiosulfate with use of starch as the indicator. 

I, + 2s,og2 - s4052 + 21-l 

2.2 Iodide alone is determined by oxidation 

to iodate with bromine in a buffered solution. 

Iodine equivalent to the iodate is then liberated 

from added potassium iodide and titrated with 

thiosulfate as in the combined determination. 

3. Interferences 

Iron, manganese, and organic material interfere with the basic reactions of the method, 

but their interferences are removed by preliminary treatment with calcium oxide. 

4. Apparatus 

4.1 Buret, 10-n& capacity. 

4.2 Iodine mks, 250-n& capacity. 

5. Reagents 

5.1 Acetic acid, 2.2Mz Mix 125 mL glacial 

HC,HsO, (sp gr 1.069) with demineralized 

water and dilute to 1 L. 

5.2 Bromine water, saturated: Add to approx 260 mL demineralized water slightly more 

liquid Br2 than will dissolve when mixed. Store 

in a glass-stoppered, a&ink-glass bottle. 

6.3 Cal&m carbonate, powder, CaCO,. 

5.4 Calcium oxide, a&y&us powder, CaO. 

6.5 Hydrochloric acid, W Mix 50 mL 

concentrated HCl (sp gr 1.19) with demineralized water and dilute to 100 mL. 

5.6 Meth$l red indicator solution, 0.01 g/l00 

mL: Dissolve 0.01 g water-soluble methyl red 

in 100 mL d,emineralized water. 

5.7 Potassium fluor&, crystals, KF*2H20. 

5.6 Potassium hypochbrite solution, 4.4 gL: 

Dissolve 6.2 g KOH in 109 mL demineralixed 

water; then saturate the solutiea with bromidefree Cl, while continually cooling and stirring. 

Store in a glass-s-, a&i&-glass bottle. 

Prepare fresh daily. 

6.9 Potassium iodide, crystals, IOil-free: 

The KI can be tested for 1091 by dissolving 

about 0.1 g in 5 mL demineralized water, acidifying with 1 or 2 drops concentrated H2SOd (sp 

gr 1.84), and adding 2 to 3 mL starch indicator 

solution. Immediate apeearawe of a bIue color 

111 
112 TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS 

indicates the presence of 10~~; slow color formation is due to atmospheric oxidation. 

5.10 Sodium acetate solution, 165 g/L: 

Dissolve 273 g NaC,H30,-3H,O in demineralized water and dilute to 1 L. 

5.11 Sodium chloride, crystals: Free from 1-l. 

IOgl, Br-l, and BrOgl. The NaCl can be tested 

for IO$ and BrOgl by dissolving about 0.1 g 

in 5 mL demineralized water, acidifying with 1 

or 2 drops concentrated H,SO, (sp gr 1.84), and 

adding 2 to 3 mL starch indicator solution. Immediate appearance of a blue color indicates 

presence of IOil or BrCgl; slow color formation 

is caused by atmospheric oxidation. 

5.12 Sodium fonnate solution, 50 g/l00 mL: 

Dissolve 50 g NaHCO, in hot demineralized 

water and dilute to 100 mL. Prepare fresh daily. 

5.13 Sodium molybdute solution, 1.0 g/l00 

mL: Dissolve 1.2 g Na2Mo0,-2H20 in demineralized water and dilute to 100 mL. 

5.14 Sodium thiosulfate solution, O.lON: 

Dissolve 25.0 g Na,S,03-5H,O in carbon dioxide-free, demineralized water; add 1 g Na,COs 

and dilute to 1 L. 

5.15 Sodium thiosulfate standard solution, 

O.OlOiVz Dilute 100.0 mL O.lOiV Na,S,O, solution to 950 mL with carbon dioxide-free, 

demineralized water and standardize against 

KIO, as follows: Dry approx 0.5 g KIO, for 2 

h at 180°C. Cool and dissolve 0.3567 g in 

demineralized water, and dilute to 1,000 mL. 

Pipet 25.00 mL of the KIO, solution into a 

250-n& iodine flask; then add successively 75 

mL demineralized water and 0.5 g KI crystals. 

After solution is complete, add ,lO mL 3.6M 

H,SO,. Allow the stoppered flask to stand 5 

min in the dark, and then titrate with standard 

Na#,Os solution, adding 2 mL starch indicator 

solution as the end point is approached (light 

straw color). 

Normality of Na,S,O,= 0.25 

mL Na,S,O, 

5.16 Starch indicator solution, stable or 

“thyodene,” powdered (Fisher No. T138 or 

equivalent). 

5.17 Sulfuric acid, 3.6M: CAUTIOUSLY add 

200 mL concentrated H@O, (sp gr 1.84) to 

demineralized water, cool, and dilute to 1 L. 

6.1 Remove soluble iron, manganese, and 

organic matter by adding a slight excess of CaO 

to approx 400 mL sample; mix, let stand about 

1 h, and filter through a dry, moderately retentive filter paper. Discard the first 75 mL of 

filtrate. 

6.2 For the combined Br-1 and 1-l determination, pipet a volume of the filtrate containing 

less than 5.0 mg Br-l and 1-l (100.0 mL max) 

into a 250-n& iodine flask, and adjust the 

volume to approx 100 mL. 

6.3 Prepare a blank of approx 100 mL 

demineralized water, and carry it through the 

procedure along with the sample. 

6.4 Add sufficient NaCl to produce a 3.0 g 

Cl-l content. 

6.5 Add a drop of methyl red indicator solution, and make the solution just acidic with 6M 

HCl. 

6.6 Add 10 mL KC10 solution, 0.5 mL 6M 

HCI, and sufficient CaCO, to produce an excess 

of approx 0.1 g. 

6.7 Heat the solution to boiling and maintain this temperature for about 8 min. 

6.8 Reduce the excess KC10 by adding 2 mL c 

NaI-ICO, solution, taking precaution to wash 

down the sides of the flask with a small amount 

of hot water. Keep the solution hot for an additional 8 min. 

6.9 Cool and add several drops of NapMoO 

solution. If any iron precipitates at this point, 

add 0.5 g KF*SH,O. 

6.10 Add approx 1 g KI and 10 mL 3.6M 

H,SO,, and let stand 5 min in the dark. 

6.11 Titrate the Liberated I, with O.OlN 

Na$,O, standard solution, adding 2 to 3 mL 

starch indicator solution as the end point is approached. Disregard a return of the blue color 

after the end point has been reached. 

6.12 For the I-1 determination, pipet a 

volume of filtrate (step 6.1) containing less 

than 5.0 mg 1-l (100.0 mL max) into a 250~mL 

iodine flask, and adjust the volume to approx 

100 mL. 

6.13 Prepare a blank of 100.0 mL demineralized water and carry through the procedure 

along with the sample. 

6.14 Add a drop of methyl red indicator solution, and make the solution just acidic with 

3.6M H,SO,. c 
METHODS FOR DETERMINATION OF INORGANIC SUBSTANCES 113 

6.15 Add 15.0 solution, 

mL 2.2M HC2H302, and-sufficient bromine 

water to produce a light-yellow color; mix and 

allow to stand 5 min. 

6.16 Reduce the excess Br, by adding 

NaHCO, solution drop by drop until the yehow 

tinge in the sample disappears; then add an excess of 1 mL. 

6.17 Wash the sides of the flask with a small 

amount of water, and blow out Br, vapors with 

a syringe and a glass tube inserted into the 

mouth of the flask. If any iron precipitates at 

this point, add 0.5 g KI*BH,O. 

6.18 Add approx 1 g KI and 10 mL 3.6M 

H&JO,, and let stand 5 min in the dark. 

6.19 Titrate the liberated I, with O.OlOiV 

Na,S,OS standard solution, adding 2 to 3 mL 

starch indicator solution as the end point is ap 

proached (light-straw color). Disregard a return 

of the blue color after the end point has been 

reached. 

7. Calculations 

7.1 Determine Br-l+I-l in epL as follows: 

Br-1 + I-l(epL) = 

1,000 0.01 

XmL sample 6 

X (mL,-mLb) 

7.2 Determine 1-l in epL as follows: 

I-l(epL)= 

1,000 0.01 X - X(mLi-mL& 

mL sample 6 

7.3 Determine Br-l in mg/L as follows: 

Br-l(mg/L)=79.91X[epL (H-l+ Br-l)-epL I-‘] 

where 

epL= equivalents per liter, 

mL,= titrant volume for blank determination, 

mL,= titrant volume for combined determination, 

and 

mLi= titrant volume for 1-l determination. 

8. Report 

Report bromide, dissolved (71870). concentrations as follows: less than 10 mg/L, one decimal; 

10 mg/L and above, two significant figures. 

9. Precision 

Single-operator precision of this method 

(American Society for Testing and Materials, 

1984) may be expressed as follows: 

where 

s* = 0.0044x 

S,= single-operator precision, milligrams per 

liter, 

and 

X= concentration of bromide, milligrsms per 

liter. 

References 

American Society for Testing and Materials, 1984, Annual 

book of ASTM standards, section 11, water: Philadelphia, v. 11.01, p. 482-90. 

Kolthoff, I. M., Sandell, E. B., Meehan, E. J., and Bruckenstein, S., 1969, Quantitative chemical analysis (4th ed.): 

New York, Macmillan, 1199 p. 
Bromide, ion-exchange chromatographic, automated 

Parameters and Codes: 

Bromide, dissolved, I-2057-85 (mg/L as Br): 71870 

Bromide, dissolved, I-2058-85 (mg/L as Br): 71870 

2. Summary of method 

Bromide is determined sequentially with 

six other anions by ion-exchange chromatography. Ions are separated based on their 

aifinity for the exchange sites of the resin. 

The separated anions in their acid form are 

measured using an electrical-conductivity 

cell. See method I-2067, anions, ion-exchange chromatographic, automated, and 

method I-2058, anions, ion-exchange chromatographic, low ionic-strength water, 

automated. 

11s 
Bromide, ion-exchange chromatographic-electrochemical, automated 

Parameter and Code: 

Bromide, dissolved, l-2128-85 (mg/L as Br): 71870 

1. Application 

1.1 This method may be used to analyze atmospheric precipitation and natural water containing at least 0.01 mg/L of bromide. Samples 

containing more than 1 mg/L need to be diluted. 

1.2 Analyses need to be performed on 

filtered and unacidified samples. 

2. Summary of method 

Bromide is determined with an ion chromatograph using an ion-exchange resin in combination with a specific eluent to separate the 

anions. After the solution has passed through 

the separator column, the sample stream flows 

through an electrochemical cell, where a fixed 

potential is applied. Any electroactive species 

such as bromide having an oxidation-reduction 

potential near the applied potential will generate a current, which is directly proportional 

to the concentration of the electroactive 

species. 

3. Interferences 

3.1 Chloride is an interference. When chloride ion passes through the detector, a current 

generates because of the formation of silver 

chloride on the surface of the silver-working 

electrode. The eluent stream, which removes 

silver chloride, generates a negative peak. The 

higher the chloride concentration, the longer it 

takes for the peak to return to baseline conditions. The effects of chloride at various levels 

of bromide are shown in tables 5 and 6. Chloride 

interferes with bromide if the chloridetobromide ratio is greater than 1,OOO:l for the 

analytical range of 0.01 to 0.1 mg/L of bromide. 

A similar interference is present when the 

chloridetobromide ratio exceeds 5,00&l for the 

0.1 to 1.0 mg/L analytical range. Samples 

containing greater than 2,000 mg/L of chloride 

must first be diluted. 

3.2 Sulfite elutes at almost the same time as 

bromide, however, this interference will not affect bromide since any sulfite in the sample will 

have had time to oxidize to sulfate before analysis. For example, 10 mg/L of sulfite usually oxidizes to sulfate within 120 h. 

4. Apparatus 

4.1 Ion Chmmatogmph, Dionex Model 12 or 

equivalent, using the following operating conditions: 

Sample loop -------- 200 PL 

Eluent flow rate ---- 138 n&/h (30 

percent of 

full capacity) 

Sample pump flow rate 50 percent of 

full capacity 

4.1.1 Precolumn, 4X50 mm, fast-run, anionresin column (Dionex P/N 030831 or equivalent) 

placed before the separator column to protect 

the separator column from being fouled by particulates or species strongly retained by the ionexchange resin. 

4.1.2 Separator column, 4X250 mm, fast-run, 

anion separator column packed with low-capacity, pellicular, anion-exchange resin (Dionex P/N 

030830 or equivalent) that is styrene divinylbenzene based. This has been found to be suitable for resolving fluoride, chloride, nitrite, 

orthophosphate, bromide, nitrate, and sulfate. 

4.2 Pulse dumper, installed just before the 

injection valve to reduce flow pulsation. 

4.3 Electrochemical detector, Dionex or 

equivalent, consisting of cell and potentiostat. 

4.3.1 The electrochemical cell is installed after 

the separator ion-exchange column. The cell 

is composed of a silver-working electrode, a 

117 
118 TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS 

Table S-Recovery of bromide in the presence of chloride for 0.01 to 0.09 mg/L bromide 

Bromide 

O-wW 

0.01 .02 

.03 

.05 

.07 

.09 

10 

100 

100 

100 

100 

100 

20 

1El 

100 

100 

100 

100 

Chloride (me/L) 

30 50 

Recovery of bromide 

(percent) 

50 65 40 50 

loo 60 

100 100 

100 100 

100 100 

70 90 

10 50 :5 

si 40 

60 

100 66 

100 100 

Table 6.--Recovery.of bromide in the presence of chloride for 0.01 to 0.09 mg/L bromide 

Chloride (mgll) 

Bromide 

O-wW 

0.1 

.2 

.3 

:: 

.6 

.7 

500 700 

100 60 

100 100 

100 100 

100 100 

100 100 

100 100 

100 100 

100 100 

1000 1500 

Recovery of bromide 

(percent) 

70 10 

100 75 

100 100 

100 100 

100 100 

100 100 

100 100 

100 100 

2mo 2500 

0 0 

50 10 

70 17 

100 26 50

100 53 

100 57 

loo 60 

100 61 

stainless steel counter electrode and a AglAgCl 

reference electrode (NOTE 1). CAUTION: 

Samples containing oil and grease damage the 

membrane. 

NOTE 1. It is necessary to refill the reference 

electrode with NaCl solution saturated with 

AgCl and to replace the ion-exchange membrane 

and membrane gasket when the potentiostat 

cannot be zeroed (high detector output). This 

happens when the AgCl in the reference electrode cell is depleted and (or) the membrane is 

damaged. It is important not to introduce any 

air bubbles while refilling the reference electrode 

and replacing the membrane; this causes a loss 

of sensitivity. The silver-working electrode 

needs to be cleaned once a month. Polish the 

surface with a small amount of toothpaste on 

a Kimwipe to remove the gray tarnish, and then 

rinse with deionized water. It is desirable to 

have a spare reference electrode to avoid 

downtime. If there is difficulty in refilling the 

reference electrode, contact the manufacturer. 

4.3.2 The potentiostat operating conditions 

are as follows: 

Applied potential --- 0.10 V (NOTE 2) 

Select mode MEAS - ON 

Select mode +I- -- + 

Off set multiplier --- Xl uA 

Meter select ------- Out Put 

Output range ------ 100 nA/V 

NOTE 2. The applied potiential setting of the 

potentiostat that gives the optimum sensitivity for bromide will vary with age and condition 

of the reference electrode, and needs to be de 

termined. 

4.4 Autosampkr, Technicon IV or equivalent, using a proportioning pump to deliver 

water to the wash receptacle. 

4.5 Integrator, Spectra Physics SP-4100 or 

equivalent, using the following operating conditions: 

Bromide Bromide 

0.01 to 0.1 mg/L 0.1 to 1.0 mgiL 

Input range 1v 10 v 

Chart speed 1 cmlmin 1 cmlmin 

Calibration 0 (linear) 2 (quadratic fit) 

PT (Peak threshold) 60,000 1,500 

AT (Attenuation) 512 126 

PH (Peak height) 

PW (No. of data A0 A0 

samples per bunch) c 
METHODS FOR DETERMINATION OF INORGANIC SUBSTANCES 119 

4.6 For additional information refer 

manufacturer’s instruction manual 

6. Reagents 

5.1 Bromide standard solution I, 1.00 mL= 

1.00 mg Br-l: Dissolve 1.2877 g NaBr in demineralized water and dilute to 1,000 mL. 

5.2 Bromide sturzcihnl solution II, 1.00 mL= 

0.01 mg Br-‘: Dilute 10.0 mL bromide standard solution I to 1,000 mL with demineralized 

water. 

5.3 Bromide standard solution III, 1.00 

mL= 0.001 mg Br-l: Dilute 100 mL bromide 

standard solution II to 1,000 mL with 

demineralized water. 

5.4 Bromide working standards: Prepare 

1,000 mL each of a series of bromide working 

standards by appropriate quantitative dilution 

of bromide standard solutions II and III. 

Bromide standard solutions 

(W 

10 of III 

50 10 of of III 

5oof II 

100 of II 

Bromide concentration 

@w/L) 

0.01 

.05 

:A 

1.0 

5.5 Eluent, 0.003M sodium bicarbonate0.0024M sodium carbonate (NOTE 3): Dissolve 

0.2520 g NaHC03 and 0.2544 g Na,C03 in 

demineralized water and dilute to 1 L. 

NOTE 3. Eluent concentration may be varied 

slightly to obtain the same retention times for 

each anion when a new separator column is 

used. The NaHC03 is subject to thermal 

decomposition and must be weighed without 

prior drying. 

6. Procedure 

6.1 Set up ion chromatographic system 

according to manufacturer’s instructions. 

Equilibrate the column with eluent until a 

stable baseline is obtained. AIIow approx 30 min 

for equilibration. 

6.2 Enter appropriate program into the 

main program controller of the ion chromatograph according to the manufacturer’s instruction. The system is configured so that the ion 

chromatograph, controls the autosampler and 

starts the integrator at the beginning of each 

sample injection. 

6.3 Press the LEVEL key of the integrator, 

which causes the display of the input voltage. 

Level the integrator at 10 mV or display 1000 

by adjusting coarse dial of potentiostat. 

6.4 Press the PT EVAL (peak threshold 

evaluation) key for integrator to evaluate the 

detector signal for noise and drift. 

6.5 Create an information file in the integrator by pressing the DIALOG key. Create 

File 1 for bromide concentrations between 0.1 

to 1.0 mg/L using a quadratic fit. Create File 

2 for bromide concentrations less than 0.1 mg/L 

using a single-point calibration with intercept 

of zero. 

6.6 Place a complete set of standards in the 

first positions of the tray, beginning with the 

least concentrated standard, followed by samples. Place individual standards of differing 

concentrations in every tenth position of the remainder of the tray. 

7. Calculations 

The integrator automatically computes the 

concentration of bromide in each sample by 

comparing its peak height or peak area to the 

analytical curve. Retention time for bromide is 

approximately 5.4 min. 

8. Report 

Report bromide, dissolved (71870), concentrations as follows: less than 1.0 r&L, nearest 0.01 

mg/L; 1.0 mg/L and above, two significant 

figures. 

9. Precision and accuracy 

9.1 Analysis of six test samples 10 times 

each by a single operator over a period of one 

month resulted in the following: 

Mean Standard deviation 

(fw3W mLw 

0.32 0.005 

.22 .005 

.24 .005 

.30 .008 

.50 .008 

.049 .002 

Relative standard devlatlon 

(percent) 

:f 

2.2 

2.6 

1.6 

4.7 

9.2 Recovery of bromide added to ten water 

samples resulted in the following: 
120 TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS 

Chloride 

present 

VwW 

- 

4 

ii 

2.28 

5.95 

4.59 

4.78 

4.89 

5.05 

Bromide Bromlds 

present added 

(meW (meW 

0.59 

.49 

.33 

.30 

.22 

.040 

.037 

.031 

.029 

.031 

.05 

.03 

.Ol 

.03 

found ReCOVery 

(meW (percent) 

1.13 

1.03 

.85 

.61 

51 

.089 

.086 

.062 

.039 

.064 

108 

108 

107 

103 

ii 

98 

103 

100 

110 

References 

Fishman, M. J., and F’yen, G. S., 1979, Determination of 

selected anions in water by ion chromatography: U.S. 

Geological Survey Water-Resources Investigations, 

79-101, 30 p. 

Johnson, E. L., and Cathers, E., 1981, Applications of 

simultaneous detection in IC: 23rd Ftocky Mountain 

Conference, Denver, Colorado. 

Small, H., Stevens, T. S., and Bauman, W. C., 1975, Novel 

ion exchange chromatographic method using conductimetric detection: Analytical Chemistry, v. 47, 

p. 1801-09. 

c 
Bromide, calorimetric, fluorescein, automated-segmented flow 

Parameter and Code: 

Bromide, dissolved, l-2129-85 (mg/L as Br): 71870 

1. Application 

This method may be used to analyze natural 

water containing from 0.010 to 0.40 mg/L of 

bromide. Samples containing greater concentrations need to be diluted. 

2. Summary of method 

The sample is buffered to pH 5.6 with an 

acetic acid buffer solution and then reacted with 

chloramine T to oxidize the bromide to hypobromous acid. The hypobromous acid formed 

then reacts with fluorescein to form the pink 

eosin (tetrabromo fluorescein), which is proportional to the bromide concentration. 

Br-l + HOC1 -, BrOH + Cl-l 

BrOH + Fluorescein -t Tetrabromo 

Fluorescein (pink) 

3. Interferences 

Iodide interferes quantitatively, but in most 

waters the iodide concentration is negligible. It 

is recommended that a determination for iodide 

be performed and that the concentration that 

is found be subtracted from the apparent bromide concentration. Cyanide, as much as 0.50 

mg/L, and chloride, as much as 500 mg/L, do not 

interfere. Thiocyanate interferes linearly, but in 

most waters its concentration is negligible. 

4. Apparatus 

4.1 Technicon AutoAnalyzer II, consisting 

of a sampler, proportioning pump, cartridge 

manifold, calorimeter, voltage stabilizer, recorder, and printer. 

4.2 With this equipment the following operating conditions have been found satisfactory 

for the range from 0.010 to 0.40 mg/L bromide. 

Absorption cell ----- 50 mm 

Wavelength _____--- 520 nm 

Cm _---- ________-- 3()/h (‘J/l) 

5. Reagents 

5.1 Bromide standard solution I, 1.00 mL= 

0.100 mg Br-l: Dissolve 0.149 g KBr, dried 

overnight over concentrated H,SO,, in 

demineralized water and dilute to 1,000 mL with 

demineralized water. 

5.2 Bromide stundurd solution II, 1.00 mL= 

0.010 mg Br-l: Dilute 100.0 mL bromide standard solution I to 1,000 mL with demineralized 

water. 

5.3 Bromide working standards: Prepare a 

blank and 1000 mL each of a series of bromide 

working standards by appropriate quantitative 

dilution of bromide standard solution II as 

follows: 

Bromide standard solution II Sromlde concentration 

(mL) OWL) 

1.0 0.010 

5.0 .050 

10.0 .lOO 

25.0 .250 

40.0 .400 

5.4 Buffer solution: Dissolve 9.426 g NH&l 

in 500 mL demineralized water and add 67 mL 

glacial acetic acid (sp. gr. 1.06). Add dropwise, 5N 

KOH solution until the pH of the solution is 5.6. 

Dilute to 1,000 mL with demineralized water. 

5.5 Chloramine-T solution, 0.5 g/l00 mL: 

Dissolve 0.500 g chloram.ineT in 100 mL of 

demineralized water. Prepare fresh daily. 

5.6 Fluorescein stock solution, 0.125 g/100 

mL: Dissolve 0.125 g fluorescein in 25 mL O.lN 

NaOH and dilute to 100 mL with demineralized 

water. This solution is stable for one week if 

stored in a light-proof bottle. 

121 
122 TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS 

5.7 Fluorescein working solution: Pipet 10 

mL Fluorescein stock solution into a lOO-mL 

volumetric flask; dilute to the mark with demineralized water. This solution must be prepared 

fresh daily. 

5.0 Sodium hydroxide solution, 0.1N: 

Dissolve 4.0 g NaOH in demineralized water 

and dilute to 1 L with demineralized water. 

5.9 Potassium hyclroxide solution, 5.ON: 

CAUTIOUSLY dissolve 280 g KOH in demineralized water, cool, and dilute to 1 L with 

demineralized water. 

6. Procedure 

6.1 Set up manifold (fig. 18). 

6.2 Allow calorimeter and recorder to warm 

up for at least 30 min. 

6.3 Adjust the baseline to read zero scale 

divisions on the recorder with all reagents, but 

with demineralized water in the sample line. 

6.4 Place a complete set of standards and a 

blank in the first positions of the first sample 

tray, beginning with the most concentrated 

standard. Place individual standards of differing concentrations in every eighth position of 

the remainder of this and subsequent sample 

trays. Fill remainder of each sample tray with 

unknown samples. 

6.5 Begin analysis. When the peak from the 

most concentrated standard appears on the 

recorder, adjust the STD CAL control until the 

flat portion of the peak reads full scale. 

7. Calculations 

7.1 Prepare an analytical curve by plotting 

the height of each standard peak versus its 

respective empirical bromide concentration. 

S-Turn 5 

Dil 

I 0.0301n Air \ 0 32mL/min 

6.051 in I 4 4AA Waste -I ,-* n II I I .uumw ml 

’ Air 

k.32mL/min InI 

0.08Oin I wr...p7.8v 

250mLImin 

I 

Sampler 4 

30/h 

P/lcam 

0.0 loin 1 Chloramine T 

O.O5mL/njin I O.OlOin I Fluorescein 

Calorimeter --- ~0 0.05 mL/min 

n 

- -,I. Wapte sampler n-1 WMn I Water 150-mm CWII I wazh 3.40 mL/min -~ 

receptacle 0 05lin 

* 1 .OOml 

I Waste 

Jmin I 

I I I Recorder Proportioning pump I 

c 

Figure 18.- Bromide, fluorescein manifold c 
METHODS FOR DETERMINATION OF INORGANIC SUBSTANCES 123 

7.2 Compute the apparent bromide concentration of each sample by comparing its peak 

height to the analytical curve. Any baseline 

drift that may occur must be taken into account 

when computing the height of a sample or 

standard peak. 

7.3 Compute the iodide concentration of 

each sample in accordance with method I- 2371. 

7.4 Compute the bromide concentration as 

follows: 

Br-l(mg/L)= 

mg/L apparent concentration-mg/L iodide 

concentration 

8. Report 

Report bromide, dissolved (71870), concentrations as follows: less than 0.1 mg/L, two 

decimals; 0.1 mg/L and above, two significant 

figures. 

9. Precision 

Single-operator precision for dissolved 

bromide for six samples expressed in terms 

of percent relative standard deviation is as 

follows: 

Number of 

replicates 

10 

10 1 

10 

10 

Concentration 

mW 

0.010 

.050 

.lOO 

.3!x 

550 .860 

Relative standard deviation 

(percent) 

15.0 

10.0 

f:8 

::: 

References 

Marti, V. C., and Arozarena, C. E.. 1981, Automated detarmination of bromide in water: proceedings Pittsburgh 

Conference, No. 734. 

Thomas, L. C., and ChamberIin. G. J., 1980. Calorimetric 

chemical analytical methods, 9th: England, The Tinto 

meter Ltd., p. 111-12. 

Stager, V. A., and Kolthorf, I. M., 1935, The detection and 

calorimetric estimation of micro quantities of bromide: 

Journal of the American Chemical Society, v. LVll. 

p. 831-3. 

Zitomer, F. and Lambert, J. L., 1963, Spectrophotometric 

determination of bromide ion in water: Analytical 

Chemistry, v. 35, p. 1731-34. 
Cadmium, atomic absorption spectrometric, chelation-extraction 

Parameters and Codes: 

Cadmium, dissolved, l-1136-85 kg/L as Cd): 01025 

Cadmium, total recoverable, l-3136-85 Gg/L as Cd): 01027 

Cadmium, suspended recoverable, l-7136-85 bg/L as Cd): 01026 

1. Application 

1.1 This method may be used to analyze 

water and water-suspended sediment containing from 1 to 25 pg/L of cadmium. Sample solutions containing more than 25 pg/L need either 

to be diluted prior to chelation-extraction or to 

be analyzed by the atomic absorption spectrometric direct method. 

1.2 Suspended recoverable cadmium is calculated by subtracting dissolved cadmium from 

total recoverable cadmium. 

1.3 Total-recoverable cadmium in watersuspended sediment needs to undergo a preliminary digestion-solubilization by method I-3485 

before being determined. 

1.4 If the iron concentration of the sample 

solution exceeds 25,000 pg/L, determine cadmium by the atomic absorption spectrometric 

direct method. 

2. Summary of method 

Cadmium is determined by atomic absorption 

spectrometry following chelation with ammonium pyrrolidine dithiocarbamate (APDC) 

and extraction with methyl isobutyl ketone 

(MIBK). The extract is aspirated into the airacetylene flame of the spectrometer. 

3. Interferences 

Concentrations of iron greater than 25,000 

pg/L interfere by depressing the cadmium absorption. 

4. Apparatus 

4.1 Atomic absorption spectrometer 

equipped with electronic digital readout and 

automatic zero and concentration controls. 

4.2 Refer to the manufacturer’s manual to 

optimize instrument for the following: 

Grating ------------ Ultraviolet 

Wavelength -------- 228.8 nm 

Source (hollow-cathode 

or electrodeless-discharge lamp) ----- Cadmium 

Ofi,-Jmt _a__ - _______ & 

Fuel ________- ---_-- Acetylene 

Type of flame ------- Oxidizing 

4.3 Different burners may be used according 

to manufacturers’ instructions. 

5. Reagents 

5.1 Ammonium pyr&dine dithiocarbamate 

solution, 1 g/l00 mL: Dissolve 1 g APDC in 100 

mL demineralized water. Prepare fresh daily. 

5.2 Cadmium stunduti solution I, 1.00 mL= 

100 pg Cd: Dissolve 0.1000 g Cd splatters in a 

minimum of dilute HNO,. Heat to increase rate 

of dissolution. Add 10 mL concentrated HNO, 

(sp gr 1.41) and dilute to 1000 mL with demineralized water. 

5.3 Cad&m standard solution II, 1.00 

mL= 0.50 pg Cd: Dilute 5.0 mL cadmium standard solution I and 1 mL concentrated HNOz (sp 

gr 1.41) to 1,000 mL with demineralized water. 

5.4 Cadmium standard solution III, 1.00 

mL=O.O5 pg Cd: Immediately before use, dilute 

10.0 mL cadmium standard solution II to 100.0 

mL with acidified water. This standard is used 

to prepare working standards at time of 

analysis. 

5.5 citric acid-sodium citrate buffer solution: 

Dissolve 126 g citric acid monohydrate and 44 

g sodium citrate dihydrate in demineralized 

water and dilute to 1 L with demineralized 

water. See NOTE 3 before preparation. 

5.6 Methyl isobutyl ketone (MIBK). 

125 
126 TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS 

5.7 Potassium hydroxide, 1OM Dissolve 56 

g KOH in demineralized water, cool, and dilute 

to 100 mL. 

5.8 Potassium hydroxide solution, 2.5M: 

Dissolve 14 g KOH in demineralized water and 

dilute to 100 mL (NOTE 1). 

NOTE 1. Alternately, a 2.5M NH,OH solution 

may be used. Add 167 mL concentrated 

NH,OH (sp gr 0.90) to 600 mL demineralized 

water. Cool and dilute to 1 L. 

5.9 Water, acidified: Add 1.5 mL concentrated HNO, (sp gr 1.41) to 1 L of demineralized water. 

6. Procedure 

6.1 Clean all glassware used in this determination with warm, dilute HNO, (1+9) and 

rinse with demineralized water immediately 

before use. 

6.2 Pipet a volume of sample solution containing less than 2.5 pg Cd (100 mL max) into 

a 200-n& volumetric flask, and adjust the 

volume to approx 100 mL. 

6.3 Prepare a blank of acidified water and 

sufficient standards, and adjust the volume 

of each to approx 100 mL with acidified 

water. 

6.4 With a pH meter, adjust the pH of each 

solution to 2.7 (NOTES 2 and 3) with 2.5M 

KOH. Shake for 3 min. 

NOTE 2. For water-suspended sediment samples which have been digested, add 1 to 2 mL 

1OM KOH or concentrated NH,OH (sp gr 0.90) 

before pH adjustment. 

NOTE 3. If an automated titration system is 

used to adjust the pH, add 2.5 mL citric acidsodium citrate buffer solution prior to pH 

adjustment. This will prevent over-shooting the 

end point in poorly buffered samples. 

6.5 Add 2.5 mL APDC solution and mix. 

6.6 Add 10.0 mL MIBK and shake vigorously for 3 min. 

6.7 Allow the layers to separate and add 

demineralized water until the ketone layer is 

completely in the neck of the flask. 

6.8 Aspirate the ketone layer within 1 h. 

Aspirate the ketone layer of the blank to set the 

automatic zero control. Use the automatic concentration control to set the concentrations of 

standards. Use at least six standards. Calibrate 

the instrument each time a set of samples is 

analyzed and check calibration at reasonable 

intervals. 

7. Calculations 

7.1 Determine the micrograms per liter of 

dissolved or total recoverable cadmium in each 

sample from the digital display or printer while 

aspirating each sample. Dilute those samples 

containing concentrations of cadmium that exceed the working range of the method; repeat 

the chelation-extraction and multiply by the 

proper dilution factors. 

7.2 To determine the micrograms per liter of 

suspended recoverable cadmium, subtract dissolved-cadmium concentration from totalrecoverable-cadmium concentration. 

6. Report 

Report cadmium, dissolved (01025), totalrecoverable (01027), and suspended-recoverable 

(01026). concentrations as follows: less than 10 

pg/L, nearest microgram per liter, 10 ClglL and 

above, two significant figures. 

9. Precision 

9.1 Precision for dissolved cadmium for 22 

samples within the range of 2 to 17 pg/L may 

be expressed as follows: 

S,= 0.213X - 0.111 

where 

s,= overall precision, micrograms per liter, 

and 

X= concentration of cadmium, micrograms 

per liter. 

The correlation coefficient is 0.6914. 

9.2 Precision for dissolved cadmium for four 

of the 22 samples expressed in terms of the percent relative standard deviation is as follows: 

Number of 

laL7oratorles 

6 

11 

6 

12 

Relative standard deviation (percent) 

;: 

17 

34 

9.3 It is estimated that the percent relative 

standard deviation for total recoverable and 

suspended recoverable cadmium will be greater 

than that reported for dissolved cadmium. 
Cadmium, atomic absorption spectrometric, direct 

Parameters and Codes: 

Cadmium, dissolved, l-l 135-85 bg/L as Cd): 01025 

Cadmium, total recoverable, l-3135-85 bg/L as Cd): 01027 

Cadmium, suspended recoverable, l-7135-85 bg/L as Cd): 01028 

Cadmium, recoverable-from-bottom-material, l-5135-85 bglg as Cd): 01028 

1. Application 

1.1 This method may be used to analyze 

water and water-suspended sediment containing at least 10 pg/L of cadmium. Sample solutions containing more than 250 pg/L need either 

to be diluted or to be read on a less expanded 

scale. Sample solutions containing less than 10 

pg/L need to be analyzed by the atomic absorp 

tion spectrometric chelationextraction method, 

providing that the interference limits discussed 

in that method are not exceeded. 

1.2 Suspended recoverable cadmium is 

calculated by subtracting dissolved cadmium 

from total recoverable cadmium. 

1.3 This method may be used to analyxe hottom material containing at least 1 pg/g of 

cadmium. 

1.4 Total recoverable cadmium in watersuspended sediment needs to undergo preliminary digestion-solubilization by method 

I-3486, and recoverable cadmium in bottom 

material needs to undergo preliminary digestion-solubilixation by method I-5486 before be 

ing determined. 

2. Summary of method 

Cadmium is determined by atomic absorption 

spectrometry by direct aspiration of the sample into an air-acetylene flame without preconcentration or pretreatment of the sample. 

3. Interferences 

3.1 Individual concentrations of sodium 

(9,000 mg/L), potassium (9,000 mg/L), magnesium (4,500 mg/L), sulfate (9,000 mg/L), chloride 

(9,000 mg/L), nitrate (100 mg/L), iron (4X10” 

rg/L), and cobalt, nickel, copper, zinc, lead, and 

chromium (10,000 M/L each) do not interfere. 

Greater concentrations of each constituent were 

not investigated. 

3.2 Calcium at concentrations greater than 

1,000 mg/L suppresses the cadmium absorp 

tion. At 2,000 mg per liter of calcium, the suppression is approximately 19 percent. 

4. Apparatus 

4.1 Atomic absorption spectrometer 

equipped with electronic digital readout and 

automatic zero and concentration controls. 

4.2 Refer to the manufacturer’s manual to 

optimize instrument for the following: 

Grating ,----------- Ultraviolet 

Wavelength ----- --- 253.8 m 

Source (hollow-cathode 

lamp) A,,- _---_ -_- Cadmium 

Oi&& I,--e---w--- fi 

fiel --- --___--__-__ Acetylene 

Type of flame ------- Oxidizing 

4.3 The Perkin-Elmer, flathead, single-slot 

burner allows a working range of 10 to 250 pg/L. 

Different burners may be used according to 

manufacturers’ instructions. 

5. Reagents 

6.1 Cadmium standad solution I, 1.00 mL= 

100 pg Cd: Dissolve 0.1000 g Cd splatters in a 

minimun of dilute HNOs. Heat to increase rate 

of dissolution. Add 10 mL concentrated HNOa 

(sp gr 1.41) and dilute to 1,000 mL with demineralized water. 

5.2 Cadmium standard solution II, 1.00 

mL= 1.0 pgmcd: Dilute 10.0 mL cadmium standard solution I and 1 mL concentrated HNO, (sp 

gr 1.41) to 1,000 mL with demineralized water. 

127 
128 TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS 

5.3 Cadmium working standards: Prepare a (01026), concentrations as follows: less than 

series of at least six working standards containing from 10 to 250 pg/L of cadmium by appropriate dilution of cadmium standard solutions 

I and II with acidified water. Prepare fresh daily. 

5.4 Water, acidified: Add 1.5 mL concentrated HNO, (sp gr 1.41) to a liter of deminerslized water. 

1,000 ClglL, nearest 10 rg/L; 1,000 pg/L and 

above, two significant figures. 

8.2 Report cadmium, recoverable-frombottom-material (01028), concentrations as 

follows: less than 10 pglg, nearest microgram 

per gram; 10 pglg and above, two significant 

figUlW. 

6. Procedure 

Aspirate the blank (acidified water) to set the 

automatic zero control. Use the automatic concentration control to set the concentrations of 

standards. Use at least six standards. Calibrate 

the instrument each time a set of samples is 

analyzed and check calibration at reasonable intC?rVdS. 

7. Calculations 

7.1 Determine the micrograms per liter of 

dissolved or total recoverable cadmium in each 

sample from the digital display or printer while 

aspirating each sample Dilute those samples 

containing cadmium concentrations that exceed 

the working range of the method and multiply 

by the proper dilution factors. 

7.2 lb determine micrograms per liter suspended mcoverable cadmium, subtract dissolvedcadmium concentration from total-recoverablecadmium concentration. 

7.3 lb determine micrograms per gram of 

cadmium in bottom-material samples, first 

determine the micrograms per liter of cadmium 

in each sample as in paragraph 7.1; then 

9. Precision 

9.1 The standard deviation for dissolved cadmium within the range of 2.8 to 18.4 pg/L for 

21 samples was found to be independent of 

concentration. The 95-percent confidence inter 

val for the average standard deviation of 3.57 

pg/L ranged from 3.24 to 3.95 pg/L. 

9.2 Precision for dissolved cadmium for five 

of the 21 samples expressed in terms of the 

percent relative standard deviation is as 

follows: 

Number of Mean Ralatlve standard deviation 

laboratories .&gQ (percent) 

12 2.8 124 

17 4.8 50 

15 10.7 19 

15 15.7 24 

5 18.4 71 

m/L CdX 

mL of original digest 

Cd klg)= 1,000 

wt of sample (g) 

9.3 It is estimated that the percent relative 

standard deviation for total recoverable and 

suspended recoverable cadmium and for recoverable cadmium from bottom material will be 

greater than that reported for dissolved 

cadmium. 

9.4 Precision for total recoverable cadmium 

expressed in terms of the percent relative standard deviation for two watersuspended sediment 

mixtures is as follows: 

a. Report 

8.1 Report cadmium, dissolved (01025), totalrecoverable (01027), and suspended-recoverable 

Number of 

laboratorles 

13 

9 

Mean 

&gg5.4 

15.8 

Relative standard davlatlon 

(percent) 

ii 

c, 

c 
Cadmium, atomic absorption spectrometric, graphite furnace 

Parameter and Code: 

Cadmium, dissolved, l-1137-85 (pa/L as Cd): 01025 

1. Application 

1.1 This method may be used to determine 

cadmium in low ionic-strength water and pre 

cipitation. With deuterium background correction and a 20-rL sample, the method is 

applicable in the range from 0.02 to 1.0 pg/L. 

With Zeeman background correction and a 

20-rL sample, the method is applicable in the 

range from 0.1 to 3.0 pg/L. Sample solutions 

that contain cadmium concentrations exceeding 

the upper limits must be diluted or preferably 

be analyzed by the atomic absorption spectrometric direct or chelation- extraction method 

or by the atomic emission spectrometric ICP 

method. 

1.2 The analytical range and detection limits 

can be increased or possibly decreased by varying the volume of sample injected or the instrumental settings. Purification of reagents and 

use of ASTM Type 1 water (Method D-1193, 

American Society for Testing and Materials, 

1984) may result in lower detection limits. 

2. Summary of method 

Cadmium is determined by atomic absorption 

spectrometry in conjunction with a graphite furnace containing a graphite platform (Hinderberger and others, 1981). A sample is placed on 

the graphite platform and a matrix modifier is 

added. The sample is then evaporated to dryness, charred, and atomized using high-temperature ramping. The absorption signal generated 

during atomization is recorded and compared 

with standards. 

3. Interferences 

3.1 Interferences in low ionic-strength samples, such as precipitation, normally are quite 

low. In addition, the use of the graphite platform reduces the effects of many interferences. 

Cslcium (25 mg/L), magnesium (8 n&L), sodium 

(20 mg/L), sulfate (34 mg/L), and chloride (25 

mg/L) do not interfere. Greater concentrations 

of these constituents were not investigated. 

3.2 Precipitation samples ususlly contain 

very low concentrations of cadmium. Special 

precautionary measures must be employed during both sample collection and laboratory 

determination to prevent contribution from 

contamination. 

4. Apparatus 

4.1 Atomic absorption spectrometer, for use 

at 228.8 nm and equipped with background correction, digital integrator to quantitate peak 

areas, graphite furnace with temperature programmer, and automatic sample injector. The 

programmer must have high-temperature ramping and stopped-flow capabilities. 

4.1.1 Refer to the manufacturer’s manual to 

optimize instrumental performance. The aualytical ranges reported in paragraph 1.1 are for a 

20-PL sample with 5 CCL of matrix modifier 

(NOTE 1). 

NOTE 1. A 20-rL sample generally requires 30 

s to dry. Samples that have a complex matrix 

may require a longer drying and charring time. 

4.1.2 Graphite furnace, capable of reaching 

temperatures sufficient to atomize the element 

of interest. Warning: dial settings frequently 

are inaccurate and newly conditioned furnaces 

require temperature calibration. 

4.1.3 Graphite tubes and platforms. Pyrolyt 

ically coated graphite tubes and solid pyrolytic 

graphite platforms are recommended. 

4.2 Labware. Many trace metals at very 

low concentrations have been found to sorb 

very rapidly to glassware. To preclude this, 

129 
130 TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS 

fluorinated ethylene propylene (FEP) or Teflon 

labware may be used. Alternately, glassware, 

particularly flasks and pipets, may be treated 

with silicone anti-wetting agent such as Surfacil 

(Pierce Chemical Co., Rockford, IL, 61105) according to the manufacturer’s instructions. 

Autosampler cups must be checked for contamination. Lancer (1831 Olive St., St. Louis, MO, 

63103) polystyrene disposable cups have been 

found to be satisfactory after acid rinsing. 

Alternately, reuseable Teflon or FEP cups may 

be used. 

4.3 Argon, standard, welder’s grade, commercially available. Nitrogen may also be 

used if recommended by the instrument 

manufacturer. 

5. Reagents 

5.1 Cadmium standu~ solution I, 1.00 mL= 

1,000 pg Cd: Dissolve 1.0000 g Cd splatters in 

a minimum of dilute HNO,. Heat to increase 

rate of dissolution. Add 10 mL high-purity 

concentrated HNO, (sp gr 1.41). Ultrex or 

equivalent, and dilute to 1,000 mL with Type 

1 water. 

5.2 Cadmium standard solution II, 1.00 

mL= 10.0 pg Cd: Dilute 10.0 mL cadmium 

standard solution I to 1,000 mL (NOTE 2). 

NOTE 2. Use acidified Type 1 water (paragraph 

5.7) to make dilutions. All standards must be 

stored in sealed Teflon or FEP containers. Each 

container must be rinsed twice with a small 

volume of standard before being filled. Standards stored for 6 months in FEP containers 

yielded values equal to those of freshly prepared 

standards. 

5.3 Cadmium standard solution III, 1.00 

mL= 0.100 pg Cd: Dilute 10.0 mL cadmium 

standard solution II to 1,000 mL. This standard is used to prepare working standards serially at time of analysis. 

5.4 Cadmium standard solution IV, 1.00 

mL= 0.001 pg Cd: Dilute 10.0 mL cadmium 

standard solution III to 1,000 mL. This standard also is used to prepare working standards 

serially at time, of analysis. 

5.5 Matrix modifier solution, 40g 

NH4HzP04/L: Add 40.0 g NH,H,P04 to 950 

mL Type 1 water, mix, and dilute to 1,000 mL. 

Analyze 20 CCL of matrix modifier for cadmium 

contamination. If the cadmium reading is more 

absorbanceseconds, purify the solution by chelation with ammonium pyrrolidine 

dithiocarbamate (APDC) and extraction with 

methyl isobutyl ketone (MIBK) (NOTE 3). 

Analyze 20 rL of the purified solution. Repeat 

extractions until the cadmium level is reduced 

to the acceptable level. DO NOT ADD ACID 

TO THE PURIFIED MATRIX MODIFIER 

SOLUTION. 

NOTE 3. To purify matrix modifier solution, 

pour the solution into a Teflon or FEP container. Add 0.25g APDC for each liter of solution. While stirring, adjust the solution to pH 

2.9 by dropwise addition of concentrated HNO, 

(sp gr 1.41). Transfer portions of the solution 

to a separatory funnel, add 100 mL MIBK/liter 

of solution, and shake vigorously for at least 5 

min. Frequently, vent the funnel in a hood. Collect the extracted solution in the FEP container. 

Repeat the extraction with 50 mL MIBK/liter 

of solution. Because MIBK can dissolve some 

plastic autosampler cups, boil the solution for 

at least 10 min in a silicone-treated or acidrinsed container covered with a watchglass to 

remove MIBK. 

5.6 Nitric acid, concentrated, high-purity, c _ 

(sp gr 1.41): J. T. Baker “Ultrex” brand HNOs 

has been found to be adequately pure; however, 

each lot must be checked for contamination. 

Analyze acidified Type 1 water for cadmium. 

Add an additional 1.5 mL of concentrated 

HNO,/liter of water, and repeat analysis. The 

integrated signal should not increase by more 

than 0.001 absorbance-seconds. 

5.7 Watet, acidified, Type 1: Add 1.5 mL 

high-purity, concentrated HNO, (sp gr 1.41) to 

each liter of water. 

5.8 Water, Type 1 

6. Procedure 

6.1 Systematically clean and rinse work 

areas with deionized water on a regular schedule. Use a laminar flow hood or a “clean room” 

environment during sample transfers. Ideally, 

the autosampler and the graphite furnace 

should be in a clean environment. 

6.2 Soak autosampler cups at least overnight in a 1 +l solution of Type 1 water and 

high-purity nitric acid. 

6.3 Rinse the sample cups twice with sample before filling. Place cups in sample tray and 

c 
METHODS FOR DETERMINATION OF INORGANIC SUBSTANCES 131 

cover. Adjust sampler so that only the injection 

tip contacts the sample. 

6.4 In sequence, inject 20-PL aliquots of 

blank and working standards plus 5 CCL of 

modifier each and analyze. Analyze the blank 

and working standards twice. Construct the 

analytical curve from the integrated peak areas 

(absorbance-seconds). Generally, the curve 

should be linear to a peak-absorbance (peakheight) value of 0.40 absorbance units. 

6.5 Similarly, inject and analyze the samples 

twice. Every tenth sample cup should contain 

either a standard or a reference material. 

6.6 Restandatdize as required. Minor changes 

of values for known samples usually indicate 

deterioration of the furnace tube, contact rings, 

and/or platform. A major variation usually indicates either autosampler malfunction or residue 

buildup from a complex matrix in a previous 

sample. 

7. Calculations 

Determine the micrograms per liter of cadmium in each sample from the digital display 

or printer output. Dilute those samples containing concentrations of cadmium that exceed the 

working range of the method; repeat the analysis, and multiply by the proper dilution factors. 

8. Report 

Report cadmium, dissolved (01025), concentrations as follows: less than 1.0 pg/L, nearest 

0.01 CcglL for deuterium background correction 

or nearest 0.1 pg/L for Zeeman background correction; 1.0 pg/L and above, two significant 

figures for both deuterium background correction and Zeeman background correction. 

9. Precision 

9.1 Analysis of five samples six times each 

by a single operator using deuterium background correction is as follows: 

Mean Standard deviation Relative standard deviation 

WL) &BU (percent) 

0.030 0.004 6.9 

.106 .004 4.0 

,249 .009 3.4 

.499 .OlO 2.0 

1.005 .013 1.3 

9.2 Analysis of four samples by a single 

operator using Zeeman background correction 

B is as follows: 

Relative standard 

Number of Mean Standard deviation devlatlon 

replicates be/L) WL) (percent) 

~~ 

4 0.50 0.115 23 

12 1.60 .060 3.6 

6 2.10 .089 4.2 

14 3.14 .074 2.4 

9.3 The precision and bias for the Zeeman 

background correction were tested on deionized 

water and tap water (specific conductance 280 

PSIcm). A known amount of cadmium was 

added to each sample, and single-operator precision and bias for six replicates are as follows: 

Amount Amount 

added found 

bw) (rsw 

Deionized water 

Standard 

devlatlon 

biw 

Relative 

standard 

devlatlon 

(percent) 

Recovery 

(percent) 

5f5 

E 

6:5 

Tap water 

2.2577 0.05 .05 2.2 t; 

4.5342 .157 i:X 3.0 91 85

5.63 .08 1.4 87 

f:!5 2.055 .0841 3.9 72 

5.00 4.52 .12 90 

X:E 3.90 522.1541 f.i 7:9 75 80

9.4 The precision and bias for the deuterium 

background method were tested on deionized 

water and tap water (specific conductance 280 

@/cm). A known amount of cadmium was 

added to each sample, and singleoperator precision and bias for six replicates are as follows: 

Amount Amount 

added found 

(rm be/L) 

Deionized water 

::825 2.5572 

tx 4.7097 

6:5 5.83 

Tap water 

Standard 

deviation 

be-) 

0.31 .15 

.3044 

.33 

Relative 

standard 

deviation 

(percent) 

12 

i:: 

::: 

Recovery 

(percent) 

98 

t: 

it 

2.6 ‘3.03 1.0 33 117 

3.25 50 ,2.83 4.53 .257 if 

::: ,5.48 4.23 .2115 5:o 2.7

t: 

814 

9.5 Interlaboratory precision for dissolved 

cadmium for 16 samples within the range of 
132 TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS 

0.62 to 16.2 PglL, without regard to type of 

background correction and use of matrix modifiers, if any, may be expressed as follows: 

ST= 0.282X + 0.022 

where 

S,= overall precision, micrograms per liter, 

and 

X= concentration of cadmium, micrograms 

per liter. 

The correlation coefficient is 0.9157. 

References 

American Society for Testing and Materials, 1984, Annual 

book of ASTM standards, section 11, water: PhiIadelphi4 v. 11.01, p. 39-41. 

Cooksey, M., and Bamett. W. B., 1979, Matrix modification 

and the method of additions in fhuneless atomic absorption: Atomic Absorption Newsletter, v. 18, p. 101-6. 

Femandez, F. J., Beatty, M. M., and Bamett, W. B., 1981, 

Use of the L’vov platform for furnace atomic absorp 

tion applications: Atomic Spectroscopy, v. 2, p. 16-21. 

Hinderberger, E. J., Kaiser, M. L., and Koirtyohann, S. It., 

1981, Furnace atomic absorption analysis of biological 

samples using the L’vov platform and matrix modi% 

ation: Atomic Spectroscopy, v. 2, p. l-11. 

Manning, D. C., and Slavin, W., 1983, The determination 

of trace elements in natural waters using the stabihred 

temperature platform furnace: Applied Spectroscopy, 

v. 37. p. l-11. 

Ottaway, J. M., 1982, A revolutionary development in 

graphite furnace atomic absorption: Atomic Spectra 

scopy, v. 3, p. 89-92. 

Slavin, W., Carnrick, G. R., and Marming, D. C., 1982, 

Magnesium nitrate as a matrix modifier In the stabilised temperature platform furnace: AnaIyticai Chemistry, v. 54. p. 621-4. 

c 

c 
Cadmium, atomic emission spectrometric, ICP 

Parameter and Code: 

Cadmium, dissolved, l-1472-85 (pg/L as Cd): 01025 

2. Summary of method metric method utilizing an induction-coupled 

Cadmium is determined simultaneously argon plasma as an excitation source. See 

with several other constituents on a single method I-1472, metals, atomic emission specsample by a direct-reading emission spectro- trometric, ICP. 

133 
Cadmium, total-in-sediment, atomic absorption spectrometric, direct 

Parameter and Code: 

Cadmium, total, l-5474-55 (mglkg as Cd): none assigned 

2. Summary of method hotplate at 200°C. Cadmium is determined on 

A sediment sample is dried, ground, and the resulting solution by atomic absorption 

homogenized. The sample is digested with a spectrometry. See method I-5474, metals, macombination of nitric, hydrofluoric, and per- jor and minor, total-in-sediment, atomic absorpchloric acids in a Teflon beaker heated on a tion spectrometric, direct. 

135 
Calcium, atomic absorption spectrometric, direct 

Parameters and Codes: 

Calcium, dissolved, l-1152-85 (mg/L as Ca): 00915 

Calcium, total recoverable, l-3152-85 (mg/L as Ca): none assigned 

Calcium, suspended recoverable, l-7152-85 (mg/L as Ca): 81357 

Calcium, recoverable-from-bottom-material, dry wt l-5152-85 (mglkg as Ca): 00917 

1. Application 

1.1 This method may be used to analyze atmospheric precipitation, water, brines, and 

water-suspended sediment. 

1.2 Two analytical ranges for calcium are included: from 0.01 to 5.0 mg/L and from 1.0 to 

60 mg/L. Sample solutions containing calcium 

concentrations greater than 60 mg/L need to be 

diluted. 

1.3 Suspended recoverable calcium is calculated by subtracting dissolved calcium from 

total recoverable calcium. 

1.4 This method may be used to analyze bottom material containing at least 10 mglkg of 

calcium. 

1.5 Total recoverable calcium in water-suspended sediment needs to undergo preliminary 

digestion-solubilization by method I-3485, and 

To aspirator 

recoverable calcium in bottom material needs 

to undergo preliminary digestion-solubilization 

by method I-5485 before being determined. 

2. Summary of method 

2.1 Calcium is determined by atomic absorption spectrometry (Fishman and Downs, 1966). 

Lanthanum chloride is added to mask interferences. 

2.2 This procedure may be automated by the 

addition of a sampler, a proportioning pump, 

and a strip-chart recorder or printer or both 

(fig. 19). 

3. Interferences 

3.1 Phosphate, sulfate, and aluminum interfere but are masked by the addition of lanthanum. Silica also reportedly interferes. Because 

Waste 

wash receptacle 

Figure lg.-Calcium manifold 

137 
138 TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS 

low calcium values result if the pH of the sample is above 7, standards are prepared in hydra 

chloric acid solution and samples are preserved 

in the field with use of nitric acid solution. 

Concentrations of magnesium greater than 

1,000 mg/L also cause low calcium values. 

3.2 Nitrate interferes, but in the presence of 

lanthanum chloride-hydrochloric acid solution 

at least 2,000 mg/L can be tolerated. The addition of nitric acid to the sample causes no prob. 

lem in the following procedure. 

4. Apparatus 

4.1 Atomic absorption spectrometer 

equipped with electronic digital readout and 

automatic zero and concentration controls. 

4.2 Refer to the manufacturer’s manual to 

optimize instrument for the following: 

Grating __-_- _______ Visible 

Wavelength -------- 422.7 nm 

Source (hollow-cathode 

lamp) -------- ____ C&urn 

Oxidant --- _________ Ah 

Fuel ______ ---- _____ Acetylene 

Type of flame ------- Slightly 

reducing 

4.3 The 50.mm (2-m.), flathead burner allows 

a working range of 0.01 to 5.0 mg/L. This 

burner, rotated 90 “, allows a working range of 

1.0 to 60 mg/L. 

4.4 Different burners may be used according 

to manufacturers’ instructions. A nitrous oxide-acetylene flame will provide two to five 

times greater analytical sensitivity and freedom 

from chemical interferences; however, sodium 

or potassium chloride must be added to control 

ionization of calcium. 

5. Reagents 

5.1 Calcium standard solution, 1.00 mL= 

0.500 mg Ca: Suspend 1.250 g CaC03, dried at 

180 “C for 1 h before weighing, in demineralized 

water and dissolve cautiously with a minimum 

of dilute HCl. Dilute to 1,000 mL with demineralized water. 

5.2 Calcium working standards: Prepare 

at least six working standards containing 

either from 0.01 to 5.0 mg/L or from 1.0 to 

60 mg/L of calcium by diluting the calcium 

standard solution. To each working standard 

add 1.0 mL of LaCls solution for each 10 mL 

standard. Similarly, prepare a demineralized 

water blank. 

5.3 Lanthanum chloride solution, 87 g/L: 

Mix 29 g of LazO, with a few milliliters of 

demineralized water to form a slurry. Slowly 

add 250 mL concentrated HCl (sp gr 1.19) while 

stirring (reaction may be violent) to dissolve the 

La,O,. Dilute to 500 mL with demineralized 

water. 

6. Procedure 

6.1 Add 1.0 mL of LaCls solution per 10.0 

mL of sample solution. 

6.2 Aspirate the blank to set the automatic 

zero control. Use the automatic concentration 

control to set the concentrations of standards. 

Use at least six standards. Calibrate the instrument each time a set of samples is analzyed and 

check calibration at reasonable intervals. 

7. Calculations 

7.1 Determine the milligrams per liter of dissolved or total recoverable calcium in each sample from the digital display or printer while 

aspirating each sample. Dilute those samples 

containing calcium concentrations that exceed 

the working range of the method and multiply q \ 

by the proper dilution factors. 

7.2 To determine milligrams per liter of 

suspended recoverable calcium, subtract dissolved-calcium concentration from total-recoverable-calcium concentration. 

7.3 To determine milligrams per kilogram of 

calcium in bottom-material samples, first determine the milligrams per liter of calcium in each 

sample as in paragraph 7.1; then 

J 

mg/L CaX 

mL of original digest 

Ca (mg/kg)= 1000 

wt of sample (kg) 

8. Report 

8.1 Report calcium, dissolved (00915), totalrecoverable (none assigned), and suspendedrecoverable (81357), concentrations as follows: 

less than 1.0 mg/L, two decimals; 1.0 to 10 

mg/L, one decimal; 10 mg/L and above, two significant figures. 

8.2 Report calcium, recoverable-from-bottom-material (00917), concentrations as follows: 

less than 1,000 mg/kg, nearest 10 mglkg; 1,000 

mg/kg and above, two significant figures. 

a 
METHODS FOR DETERMINATION OF INORGANIC SUBSTANCES 139 

9. Precision 

9.1 Precision for dissolved calcium for 37 

samples within the range of 0.84 to 184 mg/L 

may be expressed as follows: 

s,= 0.087X - 0.249 

where 

S,= overall precision, milligrams per liter, 

and 

X= concentration of calcium, milligrams per 

liter. 

The correlation coefficient is 0.8632. 

9.2 Precision for dissolved calcium for five 

of the 37 samples expressed in terms of the percent relative standard deviation is as follows: 

Number of Mean Relative standard deviation 

laboratorles mW (percent) 

20 0.84 24 

14 10.7 6 

45 50.1 8 

110 

184 

9.3 Precision for dissolved calcium within 

the range of 0.05 to 5.0 mg/L in terms of the percent relative standard deviation by a single 

operator is as follows: 

Number of Mean Relative standard deviation 

replicates mm (percent) -_ 

I 

0.052 40.4 

1.02 5.9 

: 

1.85 10.3 

5.05 1.0 

9.4 It is estimated that the percent relative 

standard deviation for total recoverable and 

suspended recoverable calcium and for recoverable calcium from bottom material will be 

greater than that reported for dissolved 

calcium. 

Reference 

Fishman, M. J., and Downs, S. C., 1966, Methods for 

analysis of selected metals in water by atomic absorption: U.S. Geological Survey Water-Supply Paper 

1540-C. p. C26-C28. 
Calcium, atomic absorption spectrometric, direct-EPA 

Parameter and Code: 

Calcium, total recoverable, l-3153-65 (mg/L as Ca): 00916 

1. Application 

1.1 This method may be used to analyze 

water-suspended sediment. Sample solutions 

containing from 0.1 to 60 mg/L of calcium may 

be analyzed without dilution; whereas, those 

containing more than 60 mg/L need to be 

diluted. 

1.2 For ambient water, analysis may be 

made on a measured portion of the acidified 

water-suspended sediment sample. 

1.3 For all other waters, including domestic 

and industrial effluent, the atomic absorption 

procedure must be preceded by a digestionsolubilization as specified below. In cases where 

the analyst is uncertain about the type of sample, the digestion-solubilization procedure must 

be used. 

2. Summary of method 

2.1 Calcium is determined by atomic absorption spectrometry (Fishman and Downs, 1966). 

Lanthanum chloride is added to mask interferences. 

2.2 Effluent samples must undergo a pre 

liminary nitric acid digestion followed by a 

hydrochloric acid solubilization. 

3. Interferences 

3.1 Phosphate, sulfate, and aluminum interfere but are masked by the addition of 

lanthanum. Silica reportedly also interferes. 

Because low calcium values result if the pH of 

the sample is above 7, standards are prepared 

in hydrochloric acid solution and samples are 

preserved in the field with use of nitric acid solution. Concentrations of magnesium greater than 

1,000 mg/L also cause low calcium values. 

3.2 Nitrate interferes, but in the presence of 

lanthanum chloride-hydrochloric acid solution, 

at least 2,000 mg/L can be tolerated. The addition of nitric acid to the sample as a preservative at the time of collection causes no problem 

in the following procedure. Samples should be 

evaporated just to dryness following nitric acid 

digestion to avoid any possible nitrate interference. 

4. Apparatus 

4.1 Atomic absorption spectrometer 

equipped with electronic digital readout and 

automatic zero and concentration controls. 

4.2 Refer to the manufacturer’s manual to 

optimize instrument for the following: 

Grating __-- ______-_ Visible 

Wavelength -------- 422.7 nm 

Source (hollow-cathode 

1-p) ____ -- ______ Calcium 

Oxidant ____ --_-__-- fi 

Fuel --___--- ____ -_- Acetylene 

Type of flame ------- Slightly reducing 

4.3 Different burners may be used according 

to manufacturers’ instructions. A nitrous oxid&acetylene flame provides 2 to 5 times greater 

sensitivity and freedom from chemical interferences; however, sodium or potassium chloride 

must be added to control ionization of calcium. 

5. Reagents 

5.1 Calcium standard solution, 1.00 mL= 

0.500 mg Ca: Suspend 1.250 g CaC03, dried at 

180 “C for 1 h before weighing, in demineralized 

water and dissolve cautiously with a minimum 

of dilute HCl. Dilute to 1,000 mL with demineralized water. 

5.2 Calcium working standards: Prepare a 

series of at least six working standards containing from 0.1 to 60 mg/L of calcium by dilution 

of calcium standard solution. To each working 

141 
142 TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS 

standard add 1.0 mL of LaCls solution for each 

10 mL of standard. 

5.3 Hydrochloric acid, 6M: Dilute 500 mL 

concentrated HCl (sp gr 1.19) to 1 L with 

demineralized water. 

5.4 Hydrochloric acid, 0.3M: Dilute 25 mL 

concentrated HCl (sp gr 1.19) to 1 L with demineralized water. 

5.5 Lanthanum chloride solution, 87 g/L: 

Mix 29 g La,Os with a few milliliters of demineralized water to form a slurry. Slowly add 250 

mL concentrated HCl (sp gr 1.19) while stirring 

(reaction may be violent) to-dissolve the LazO,. 

Dilute to 500 mL with demineralized water. 

5.6 Nitric acid, concentrated (sp gr 1.41). 

6. Procedure 

6.1 Transfer the entire sample to a beaker. 

6.2 Rinse the sample bottle with 3 nil., concentrated HNO, for each 100 mL of sample and 

add to the beaker. Prepare a blank using 3 mL 

concentrated HNO, per 100 mL demineralized 

water. 

6.3 Evaporate samples and blank to dryness 

on a hotplate, making sure the samples do not 

boil. 

6.4 Cool and add an additional 3 mL concentrated HNO, to the beaker. Cover with a 

watchglass, return to the hotplate, and gently 

reflux the sample. 

6.5 Continue heating, adding additional acid 

as necessary, until the digestion is complete (indicated by a light-colored residue). Evaporate 

just to dryness. 

6.6 Add 6 mL 6M HCl solution per 100 mL 

of original sample and warm the beaker to dissolve the residue. 

6.7 Wash the watchglass and beaker with 

demineralized water and filter the sample 

(Whatman No. 41 or equivalent), rinsing the 

filter with hot, 0.3M HCl. Dilute to the original 

volume with demineralized water. 

6.8 Add 1.0 mL lanthanum chloride solution 

per 10.0 mL of sample. 

6.9 Aspirate the blank to set the automatic 

zero control. Use the automatic concentration 

control to set the concentrations of standards. 

Use at least six standards. Calibrate the instrument each time a set of samples is analyzed and 

check calibration at reasonable intervals. 

7. Calculations 

Determine the milligrams per liter of total 

recoverable calcium in each sample from the 

digital display or printer while aspirating each 

sample. Dilute those samples containing 

calcium concentrations that exceed the working 

range of the method and multiply by the proper 

dilution factors. 

8. Report 

Report calcium, total-recoverable (00916), 

concentrations as follows: less than 10 mg/L, 

one decimal; 10 mg/L and above, two significant 

figures. 

9. Precision 

It is estimated that the percent relative standard deviation for total recoverable calcium over 

the range of the method will be greater than 8 

percent. 

References 

Fishman, M. J., and Downs, S. C., 1966, Methods for 

analysis of selected metals in water by atomic absorp 

tion: U.S. Geological Survey Water-Supply Paper 

1540-C, p. C26-C28. 

U.S. Environmental Protection Agency, 1979, Methods for 

chemical analysis of water and wastes: Cincinnati, U.S. 

Environmental Protection Agency, p. 215.1-1. 
Calcium, atomic emission spectrometric, ICP 

Parameter and Code: 

Calcium, dissolved, l-1472-85 (mg/L as Ca): 00915 

2. Summary of method method utilizing an induction-coupled argon 

Calcium is determined simultaneously plasma as an excitation source. See method 

with several other constituents on a single sam- I-1472, metals, atomic emission spectrometric, 

ple by a direct-reading emission spectrometric ICP. 

143 
Calcium, total-in-sediment, atomic absorption spectrometric, direct 

Parameters and Codes: 

Calcium, total, l-5473-85 (mglkg as Ca): none assigned 

Calcium, total, l-5474-85 (mglkg as Ca): none assigned 

2. Summary of method 

2.1 A sediment sample is dried, ground, 

and homogenized. The sample is then treated 

and analyzed by one of the following techniques. 

2.1.1 The sample is fused with a mixture of 

lithium metaborate and lithium tetraborate in 

a graphite crucible in a muffle furnace at 

1000 “C. The resulting bead is dissolved in acidified, boiling, demineralized water, and calcium is 

determined by atomic absorption spectrometry. 

See method I-5473, metals, major, total in 

sediment, atomic absorption spectrometric, 

direct. 

2.1.2 The sample is digested with a combination of nitric, hydrofluoric, and perchloric acids 

in a Teflon beaker heated on a hotplate at 

200 “C. Calcium is determined on the resulting 

solution by atomic absorption spectrometry. 

See method I-5474, metals, major and minor, 

total-in-sediment, atomic absorption spectrometric, direct. 

145