Methods of Analysis by the U.S. Geological Survey 

National Water Quality Laboratory Comparison of a 

Nitric Acid In-Bottle Digestion Procedure to 

Other Whole-Water Digestion Procedures

By John R. Garbarino and Gerald L. Hoffman

U.S. GEOLOGICAL SURVEY 

Open-File Report 99-094

Denver, Colorado 

1999
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Charles G. Groat, Director

The use of brand, firm, and trade names in this report is for identification 

purposes only and does not constitute endorsement by the U.S. Government.

For additional information write to: Copies of this report can be purchased from:

U.S. Geological Survey U.S. Geological Survey

Chief, National Water Quality Laboratory Branch of Information Services

Box 25046, Mail Stop 407 Box 25286

Federal Center Federal Center

Denver, CO 80225-0046 Denver, CO 80225-0286
CONTENTS

Abstract............................................................................................................................... 1

Introduction........................................................................................................................ 1

Analytical method............................................................................................................... 2

1. Application.............................................................................................................. 2

2. Summary of method................................................................................................ 2

3. Interferences............................................................................................................ 2

4. Apparatus and materials.......................................................................................... 2

5. Reagents.................................................................................................................. 2

6. Nitric acid in-bottle digestion procedure ................................................................ 4

7. Calculations............................................................................................................. 5

8. Reporting results..................................................................................................... 5

Discussion of results........................................................................................................... 5

Conclusions ........................................................................................................................ 12

References cited.................................................................................................................. 17

Appendix............................................................................................................................. 18

FIGURES

1. Percentage yield as a function of hydrochloric acid in-bottle digestion, U.S. 

Environmental Protection Agency digestion, and nitric acid in-bottle 

digestion procedures for synthetic whole-water samples prepared using 

Buffalo River, Riverine, andEstuarine Sediments.................................................... 13

2-4. Graphs showing linear regression analysis of elemental percentage yield 

for the nitric acid in-bottle digestion in relation to the hydrochloric acid 

in-bottle digestion for synthetic whole-water samples made from National 

Institute of Standards and Technology standard reference material:

2. Buffalo River Sediment............................................................................................. 18

3. Riverine Sediment...................................................................................................... 19

4. Estuarine Sediment.................................................................................................... 19

TABLES

1. Methodologies used to determine whole-water recoverable elements in the

hydrochloric acid in-bottle digestate.......................................................................... 3

2-4. Elemental concentrations in various digestates of a synthetic whole-water 

sample made from National Institute of Standards and Technology standard 

reference material:

2. Buffalo River Sediment............................................................................................. 7

3. Riverine Sediment...................................................................................................... 8

4. Estuarine Sediment.................................................................................................... 9

CONTENTS
TABLES Continued

5-7. Percentage yield using various digestion procedures for synthetic 

whole-water samples made from National Institute of Standards 

and Technology standard reference material:

5. Buffalo River Sediment............................................................................................. 10

6. Riverine Sediment...................................................................................................... 11

7. Estuarine Sediment.................................................................................................... 12

8. Statistical analysis summary of elemental percentage yield for the nitric

acid in-bottle digestion in relation to the hydrochloric acid in-bottle digestion........ 17

9. Bias and variability for the subboiling evaporation technique .................................. 20

10. Bias and variability of subboiling evaporation of digestate from a synthetic 

whole-water sample made from National Institute of Standards and 

Technology Standard Reference Material 1646, Estuarine Sediment....................... 21

IV Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to Other Whole-Water Digestion Procedures
CONVERSION FACTORS AND ABBREVIATED WATER-QUALITY UNITS

Multiply To obtain

gram (g) 

liter (L)

microgram (jig)

milligram (mg)

milliliter (mL)

3.53 X 1(T2 

2.64 XKT1 

3.53 X 1(T8 

3.53 X 10-5 

2.64 X10"4

ounce, avoirdupois

gallon

ounce, avoirdupois

ounce, avoirdupois

gallon_______

Degree Celsius (°C) may be converted to degree Fahrenheit (°F) by using the following 

equation:

°F = 9/5 (°C) + 32.

Abbreviated water-quality units used in this report are as follows:

mg/g milligram per gram

ug/g microgram per gram

ug/L microgram per liter

Other abbreviations also used in this report:

ASTM American Society for Testing and Materials

DCP-AES direct current plasma-atomic emission spectrometry

F-AAS flame-atomic absorption spectrophotometry

GF-AAS graphite furnace-atomic absorption spectrophotometry

HC1 hydrochloric acid

HG-AAS hydride generation-atomic absorption spectrophotometry

HNOs nitric acid

ICP-AES inductively coupled plasma-atomic emission spectrometry, also known as

	inductively coupled plasma-optical emission spectrometry (ICP-OES) 

ICP-MS inductively coupled plasma-mass spectrometry 

MPV(s) most probable value(s) 

TV normality (acid equivalents per liter) 

NIST National Institute of Standards and Technology 

NWQL National Water Quality Laboratory 

SRM Standard Reference Material 

USEPA U.S. Environmental Protection Agency 

USGS U.S. Geological Survey 

< less than 

± plus or minus

Definitions:

MPV The most probable value (MPV) is equal to the median value for numerous 

interlaboratory analyses that use multiple analytical methods.

CONVERSION FACTORS AND ABBREVIATED WATER-QUALITY UNITS V
Whole-water recoverable. Pertains to the constituents in solution after a representative 

water-suspended-sediment sample is digested (usually using dilute acid solution). 

Complete dissolution of particulate matter often is not achieved by the digestion 

treatment, and thus the determination represents something less than the "total" 

amount (that is, less than 95 percent) of the constituent present in the dissolved and 

suspended phases of the sample. Equivalent digestion procedures would be required 

of all laboratories that perform such analyses to achieve comparability of analytical 

data, because different digestion procedures are likely to produce different analytical 

results.

VI Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to Other Whole-Water Digestion Procedures
Methods of Analysis by the U.S. Geological Survey 

National Water Quality Laboratory Comparison of a 

Nitric Acid In-Bottle Digestion Procedure to Other 

Whole-Water Digestion Procedures

By John R. Garbarino and Gerald L. Hoffman

ABSTRACT

A hydrochloric acid in-bottle digestion 

procedure is used to partially digest wholewater samples prior to determining 

recoverable elements by various analytical 

methods. The use of hydrochloric acid is 

problematic for some methods of analysis 

because of spectral interference. The inbottle digestion procedure has been 

modified to eliminate such interference by 

using nitric acid instead of hydrochloric acid 

in the digestion. Implications of this 

modification are evaluated by comparing 

results for a series of synthetic whole-water 

samples. Results are also compared with 

those obtained by using U.S. Environmental 

Protection Agency (1994) (USEPA) Method 

200.2 total-recoverable digestion procedure. 

Percentage yields that use the nitric acid inbottle digestion procedure are within 10 

percent of the hydrochloric acid in-bottle 

yields for 25 of the 26 elements determined 

in two of the three synthetic whole-water 

samples tested. Differences in percentage 

yields for the third synthetic whole-water 

sample were greater than 10 percent for 16 

of the 26 elements determined. The USEPA 

method was the most rigorous for 

solubilizing elements from particulate matter 

in all three synthetic whole-water samples. 

Nevertheless, the variability in the 

percentage yield by using the USEPA

digestion procedure was generally greater than 

the in-bottle digestion procedure, presumably 

because of the difficulty in controlling the 

digestion conditions accurately.

INTRODUCTION

The U.S. Geological Survey (USGS) 

National Water Quality Laboratory (NWQL) 

has been using the hydrochloric acid (HC1) inbottle digestion procedure described by 

Hoffman and others (1996) since 1992. New 

analytical methods that expand the scope of 

elemental determinations, such as inductively 

coupled plasma-mass spectrometry (ICP-MS), 

have been developed that are adversely affected 

by the presence of HC1 in the in-bottle digestate.

Implementation of newer methods for the 

determination of elements in whole-water 

samples, therefore, requires modification of the 

in-bottle procedure. The proposed modification involves using nitric acid (HNOs) instead 

of HC1 for the in-bottle digestion. The bias and 

variability of such a modification were 

determined by digesting three synthetic wholewater samples by the HC1 and the HNOs inbottle procedures. Replicate samples were also 

digested using U.S. Environmental Protection 

Agency (1994) (USEPA) Method 200.2 as an 

additional comparison. Elements currently 

(1999) being determined in HC1 in-bottle

INTRODUCTION 1
digestate and their corresponding USGS 

analytical methods are listed in table 1.

The objectives of this report are as 

follows:

 To describe the HNOs in-bottle 

digestion procedure.

 To establish the bias and variability of 

the HNOs in-bottle digestion 

procedure.

 To discuss the advantages and

disadvantages of using the HNOs 

in-bottle digestion procedure.

The subject method was developed by 

the USGS for use at the NWQL. This 

method supplements other official USGS 

inorganic methods (Fishman and Friedman, 

1989; Fishman, 1993).

ANALYTICAL METHOD

Metals, Extraction Procedure, Acid 

Digestion, Whole-Water Recoverable, 

1-3487-98

1. Application

This method was developed to digest 

whole-water samples by using an HNOs inbottle procedure to determine the elements 

listed in table 1.

2. Summary of Method

Hoffhian and others (1996) have 

previously described an HC1 in-bottle 

digestion procedure. The HNOs in-bottle 

procedure requires minor modifications to 

the HC1 in-bottle procedure as outlined in 

section 6. After the preparatory procedure, 

the digestate can be analyzed by using any 

of the methods listed in table 1. Details of

these analytical methods can be obtained in 

Fishman (1993), Fishman and Friedman 

(1989), Garbarino and Struzeski (1998), and 

Jones and Garbarino (1999).

3. Interferences

There are no known interferences 

associated with procedures described in this 

report.

4. Apparatus and Materials

4.1 Clean bench, class-100.

4.2 Filter paper, Whatman No. 41 or 

equivalent.

4.3 Disposable filter funnels, Whatman 

No. 1920-1441 or equivalent.

4.4 Drying oven, mechanical convection 

heating, with controlled time and temperature 

accurate to ±1 percent.

4.5 Analytical balance, Mettler Model 

PM600 or equivalent capable of accurately 

weighing 0.01 g.

4.6 Sample bottles, made of polyethylene 

or polypropylene.

4.7 Filter-funnel racks, variable height 

adjustable, nonmetallic construction that 

tolerates dilute acid.

5. Reagents

5.1 Nitric acid (UNO3), concentrated 

(specific gravity 1.41), a grade verified to have 

elemental contaminant concentrations, after the 

prescribed dilution, that are less than the 

method detection limits for the method of 

analysis being used.

Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to Other Whole-Water Digestion Procedures
Table 1 . Methodologies used to determine whole-water recoverable elements in the 

hydrochloric acid in-bottle digestate

[Method, analytical methods are listed in the order of decreasing method detection limit; DCPAES, direct current plasma-atomic emission spectrometry; ICP-AES, inductively coupled 

plasma-atomic emission spectrometry; ICP-MS, inductively coupled plasma-mass spectrometry; 

HG-AAS, hydride generation-atomic absorption spectrophotometry; GF-AAS, graphite fumaceatomic absorption spectrophotometry; F-AAS, flame-atomic absorption spectrophotometry]

Element or 

constituent

Aluminum

Antimony

Arsenic

Barium

Beryllium

Boron

Cadmium

Calcium

Chromium

Cobalt

Copper

Iron

Lead

Lab 

codes

1283

2351

2372

80

2373

118

2162

234

2352

2374

236

2353

2375

1286

2354

131

2355

1555

2376

244

2356

246

1937

2377

149

2391

1557

2378

156

2358

1559

2379

189

2359

192

2360

1561

2380

Method

DCP-AES

ICP-AES

ICP-MS

HG-AAS

ICP-MS

HG-AAS

GF-AAS

F-AAS

ICP-AES

ICP-MS

F-AAS

ICP-AES

ICP-MS

DCP-AES

ICP-AES

F-AAS

ICP-AES

GF-AAS

ICP-MS

F-AAS

ICP-AES

F-AAS

GF-AAS

ICP-MS

F-AAS

ICP-AES

GF-AAS

ICP-MS

F-AAS

ICP-AES

GF-AAS

ICP-MS

F-AAS

ICP-AES

F-AAS

ICP-AES

GF-AAS

ICP-MS

Element or 

constituent

Lithium

Magnesium

Manganese

Molybdenum

Nickel

Potassium

Selenium

Silica (SiO2)

Silver

Sodium

Strontium

Thallium

Uranium

Vanadium

Zinc

Lab 

codes

277

2361

2381

261

2362

41

2363

2382

2364

1999

2383

198

2365

1563

2384

321

286

2163

2385

2366

2367

1553

2386

320

2368

290

2369

2387

2388

2389

2370

296

2371

2390

Method

F-AAS

ICP-AES

ICP-MS

F-AAS

ICP-AES

F-AAS

ICP-AES

ICP-MS

ICP-AES

GF-AAS

ICP-MS

F-AAS

ICP-AES

GF-AAS

ICP-MS

F-AAS

HG-AAS

GF-AAS

ICP-MS

ICP-AES

ICP-AES

GF-AAS

ICP-MS

F-AAS

ICP-AES

F-AAS

ICP-AES

ICP-MS

ICP-MS

ICP-MS

ICP-AES

F-AAS

ICP-AES

ICP-MS

ANALYTICAL METHODS 3
5.2 Water, ASTM Type I reagent 

water (American Society for Testing and 

Materials, 1995).

5.3 0.1N HNOs is prepared by adding 

6.4 mL of acceptable concentrated nitric 

acid to 500 mL of water and dilute to 1L 

with water.

6. Nitric Acid In-Bottle Digestion 

Procedure

Unfiltered, acidified (also known as 

raw acidified, RA) samples are digested by 

using the following procedure:

6.1 Weigh the sample bottle, cap, and 

contents to determine the gross weight.

6.2 Subtract the average weight of an 

identical size capped bottle to estimate the 

volume of the sample.

6.3 Add 1.6 mL of concentrated 

HNOs for every 50 mL (or about 3 percent 

by volume) of sample.

6.4 Recap the bottle and shake 

vigorously.

NOTE 1 : Prepare a reagent blank and a 

synthetic whole-water sample with each set 

of samples digested (see sections 6.1-6.4).

6.5 Place the capped sample bottles in 

a 65 °C oven and heat the samples for 8 

hours. Heating time includes the time 

required for the samples to reach oven 

temperature.

6.6 Preparation for filtering sample 

digestate

6.6.1 Open the sealed disposable 

filter funnels inside the clean bench and 

place in the filter-funnel rack.

6.6.2 Rinse each funnel by 

rapidly filling with 250 mL of 0.1 N 

HNOs; repeat rinsing with another 250 

mL of 0.17VHNO3 .

6.6.3 Similarly rinse each 

funnel three times with water. Allow 

the funnels to drain completely between 

each rinse.

6.7 Sample digestate filtration

6.7.1 Place a clean, empty, 

acid-rinsed and labeled bottle under 

each funnel.

6.7.2 Vigorously shake the 

sample bottle containing digestate after 

it has been removed from the oven. Let 

stand for 30 minutes, and filter aliquots 

of the digestate by using the filter 

funnel.

6.7.3 Discard unfiltered 

digestate. Rinse the original sample 

bottle twice with water and dispose of 

the rinse into a suitable container 

clearly labeled as acid waste.

6.7.4 Transfer filtrate (see 

section 6.7.2) into its original sample 

bottle and seal with a new, clear cap.

6.7.5 Use aliquots of this 

filtered solution to determine wholewater recoverable elemental concentrations by the appropriate analytical 

methods.

NOTE 2: Filtration of 100 percent of 

the digestate volume is not required if 

the sample bottles are shaken 

vigorously after removal from the oven. 

At least 75 percent of the sample must 

be filtered to ensure sufficient volume 

for multiple analyses.

4 Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to Other Whole-Water Digestion Procedures
NOTE 3: If a filter becomes plugged 

during filtration, replace it with a rinsed 

filter funnel and continue the filtration.

7. Calculations

No calculations are required.

8. Reporting Results

Whole-water recoverable concentrations are reported in micrograms per liter to 

the number of significant figures outlined in 

the analytical method being used for 

quantitation.

DISCUSSION OF RESULTS

Currently (1999), selected USGS 

methods are used to analyze the HC1 inbottle digestate. However, new methods 

that expand the scope of elemental 

determinations that are adversely affected by 

the presence of HC1 in the in-bottle digestate 

have been developed. It is advantageous to 

have one in-bottle digestion procedure that 

is compatible with all the USGS methods 

used to determine the elements listed in 

table 1. Such a procedure is the HNOa inbottle digestion. Its digestate is entirely 

compatible with all whole-water recoverable 

methods because HNOs does not cause 

spectral interferences. The extraction 

efficiency of HNOa, however, is most likely 

different from that of HC1. All the digestion 

methods tested in this report are procedural 

and use different acids, acid concentrations, 

and methods of heating. For example, the 

USEPA procedure refluxes the digestate, 

whereas the in-bottle procedures do not.

The bias and variability associated 

with the HNOa in-bottle digestion procedure 

were determined by using results obtained 

for synthetic whole-water samples that were 

made from reference sediment. Synthetic

whole-water samples are used as 

benchmarks in this study, as in the 

study by Hoffman and others (1996), 

because they are based on readily 

available certified reference materials 

and because the mixtures can be 

accurately reproduced.

The synthetic whole-water 

samples were prepared by weighing 200 

to 600 mg of the National Institute of 

Standards and Technology (NIST) 

Standard Reference Material (SRM) 

2704 Buffalo River Sediment, 1645 

Riverine Sediment, or 1646 Estuarine 

Sediment into 200 to 500 mL of 0.1 N 

HNOs. Following preparation, the 

synthetic whole-water samples were 

shaken and allowed to stand at room 

temperature for about 3 days to simulate 

actual whole-water samples that are 

collected and acidified on-site. Four 

samples of each synthetic whole water 

were digested using the HC1 in-bottle 

procedure (Hoffman and others, 1996), 

the HNOa in-bottle procedure, and the 

USEPA procedure. Aluminum, 

antimony, arsenic, barium, beryllium, 

boron, cadmium, chromium, cobalt, 

copper, iron, lead, lithium, manganese, 

molybdenum, nickel, selenium, silver, 

strontium, thallium, uranium, vanadium, 

and zinc were determined in every 

synthetic whole-water digestate by 

ICP-MS. Calcium, iron, magnesium, 

silica (SiOz), and sodium were 

determined by inductively coupled 

plasma-atomic emission spectrometry 

(ICP-AES). Potassium was determined 

by using flame-atomic absorption 

spectrophotometry (F-AAS). Aliquots 

of each HC1 in-bottle and USEPA 

digestate were processed before ICPMS analysis to remove chloride by 

using the procedure described in the 

Appendix of this report.

DISCUSSION OF RESULTS 5
Elemental concentrations from ICPAES, ICP-MS, and F-AAS for all synthetic 

whole-water digestates are listed in tables 2 

through 4 with corresponding percentage 

yields listed in tables 5 through 7. 

Percentage yield was calculated from the 

concentration results by using equation 1.

Percentage yield = [(Q x VS)/(CR x WR)] x 100 (1)

where Cs is the elemental concentration (in 

micrograms per liter) in the digestate, Vs is 

the total volume (in liters) used to prepare 

the synthetic whole-water sample, CR is the 

elemental concentration in the reference 

sediment (in micrograms per gram), and WR 

is the weight of reference sediment (in 

grams) used to prepare the synthetic wholewater sample. Percentage yields listed in 

tables 5 through 7 are also plotted in 

figure 1. For some elements (for example, 

boron and silver), yields could not be 

calculated because elemental concentrations 

in the reference sediment were not reported. 

In these cases, the digestate concentrations 

can be used to compare different digest 

procedures.

Linear regression analysis and 

statistical tests were used to establish the 

bias and variability of the HNOs in-bottle 

procedure. All the mean percentage yields 

listed in tables 5 through 7, regardless of the 

element or method of analysis, were treated 

as a single data set for a given synthetic 

whole-water sample. Statistical results are 

listed in table 8 and the regression lines are 

shown in figures 2 through 4.

Because the yield data range over a 

wide percentage, the authors used linear 

regression analysis to calculate the slope, yintercept, and coefficient of determination 

(R2) for the equation describing the relation 

between percentage yield from the HNOs inbottle digestion to the HC1 in-bottle 

digestion. A slope coefficient of one and ayintercept of zero indicate exact correlation.

The corresponding p-values indicate the 

degree of confidence in each coefficient. 

For additional confirmation, the OneSample Sign Test or the Student f-Test, 

depending on whether the data set was 

normally distributed with equal variance, 

was used to test the null hypothesis. The 

null hypothesis tested whether the 

percentage yields for the HNOs in-bottle 

digestion are significantly different than 

the percentage yields for the HC1 inbottle digestion. The p-values were 

calculated for each synthetic wholewater sample to provide a level of 

confidence in accepting the null 

hypothesis. The larger the p-value the 

greater the confidence in accepting the 

null hypothesis. When the p-value 

exceeds 0.05, the null hypothesis is 

acceptable at the 95-percent confidence 

level.

Slope coefficients indicate that the 

HNOs in-bottle procedure provides 

percentage yields that are 5 to 20 percent 

lower than the HC1 in-bottle procedure, 

depending on the type of synthetic wholewater sample (see table 8). For every 

synthetic whole-water sample tested, most 

elemental results are highly correlated and 

within the 95-percent confidence limit (see 

figs. 2-4). The One-Sample Sign Test or 

the Student f-Test results shown in table 8 

indicate that there is a statistically 

significant difference (p-value less than 

0.05) between percentage yields, depending 

on the acid used for the in-bottle digestion.

Percentage yields for the Buffalo 

River Sediment synthetic whole-water 

sample indicated that the difference 

between the HC1 and HNO3 in-bottle 

procedures is less than 10 percent for all the 

elements except for selenium (fig. 1). All 

elemental percentage yields for the 

Estuarine Sediment synthetic whole-water 

samples are within 10 percent of the

6 Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to Other Whole-Water Digestion Procedures
Table 2. Elemental concentrations in various digestates of a synthetic whole-water sample 

made from National Institute of Standards and Technology Standard Reference Material 2704, 

Buffalo River Sediment

[Cert., certified concentration in units provided for each element. Concentrations in parentheses are 

uncertified; Digestate concentration is the elemental concentration recovered by the digestion relative to 

the weight of the sediment used to prepare the synthetic standard; HC1, hydrochloric acid (HC1) inbottle digestion with or without the HC1 removed by evaporation; HNO3 , nitric acid in-bottle digestion; 

USEPA, U.S. Environmental Protection Agency's digestion procedure with or without the HC1 removed 

by evaporation; f^g/g, micrograms per gram; mg/g, milligrams per gram; ±, plus or minus; the number 

following the ± is the standard deviation of four separate digestions; na, not available]

Element

Aluminum, mg/g

Antimony, (ig/g

Arsenic, (ig/g

Barium, (ig/g

Beryllium, (ig/g

Boron, ng/g

Cadmium, (ig/g

Calcium, mg/g

Chromium, (ig/g

Cobalt, ng/g

Copper, ng/g

Iron, mg/g

Lead, ^ig/g

Lithium, ng/g

Magnesium, mg/g

Manganese, (ig/g

Molybdenum, (ig/g

Nickel, ^ig/g

Potassium, mg/g

Selenium, (ig/g

Silica, SiO2, mg/g

Silver, ^ig/g

Sodium, mg/g

Strontium, (ig/g

Thallium, fxg/g

Uranium, (ig/g

Vanadium, (ig/g

Zinc, ng/g

Cert.

61.1

3.79

23.4

414

na

na

3.45

26

135

14.0

98.6

41.1

161

(50)

12.0

555

na

44.1

20.0

(1.1)

622

na

5.47

(130)

1.2

3.13

95

438

Digestate concentration

HCI

6.5510.09

1.9210.03

14.310.2

7913

0.5210.02

8.010.4

3.2010.03

22.610.6

63.810.7

10.710.1

7912

19.910.6

16411

15.910.2

7.210.2

40016

1.2510.08

28.710.6

1.410.1

0.810.1

2112

0.3510.03

0.2010.01

39.010.4

0.5710.01

0.4910.01

14.710.1

340110

HNO3

7.410.2

1.8810.04

13.410.1

8112

0.5210.03

6.710.4

3.1110.01

22.010.1

66.010.6

9.710.1

7711

18.710.2

14816

16.510.3

6.9010.01

39214

0.9010.07

26.410.4

1.4810.04

0.4410.08

20.710.5

0.3110.04

0.2010.01

35.510.7

0.5510.01

0.5010.02

13.810.4

29314

USEPA

12.410.6

1.310.2

18.510.7

91.210.5

0.6610.03

1615

3.4410.02

23.110.1

8212

12.010.4

9015

29.110.9

14618

25.810.8

8.410.1

490110

3.210.3

3411

1.910.2

0.810.1

3011

0.3510.02

0.3010.01

40.010.9

0.6010.02

0.6610.05

2111

390120

DISCUSSION OF RESULTS
Table 3. Elemental concentrations in various digestates of a synthetic whole-water 

sample made from National Institute of Standards and Technology Standard Reference 

Material 1645, Riverine Sediment

[Cert., certified concentration in units provided for each element. Concentrations in parentheses 

are uncertified; Digestate concentration is the elemental concentration recovered by the digestion 

relative to the weight of the sediment used to prepare the synthetic standard; HC1, hydrochloric 

acid (HC1) in-bottle digestion with or without the HC1 removed by evaporation; HNO3 , nitric acid 

in-bottle digestion; USEPA, U.S. Environmental Protection Agency's digestion procedure with 

or without the HC1 removed by evaporation; ug/g, micrograms per gram; mg/g, milligrams per 

gram; ±, plus or minus; the number following the ± is the standard deviation of four separate 

digestions; na, not available; nd, not detected]

Element

Aluminum, mg/g

Antimony, ug/g

Arsenic, ug/g

Barium, ug/g

Beryllium, ug/g

Boron, ug/g

Cadmium, ug/g

Calcium, mg/g

Chromium, mg/g

Cobalt, ug/g

Copper, ug/g

Iron, mg/g

Lead, ug/g

Lithium, ug/g

Magnesium, mg/g

Manganese, ug/g

Molybdenum, ug/g

Nickel, ug/g

Potassium, mg/g

Selenium, ug/g

Silica, SiO2, mg/g

Silver, ug/g

Sodium, mg/g

Strontium, ug/g

Thallium, ug/g

Uranium, ug/g

Vanadium, ug/g

Zinc, ug/g

Cert.

22.6

(51)

(66)

na

na

na

10.2

(29)

29.6

10.1

109

113

714

na

7.4

785

na

45.8

12.6

(1.5)

na

na

5.4

na

1.44

1.11

23.5

1.72

Digestate concentration

HCI

3.37±0.01

19.2±0.5

53±3

61.5±0.1

0.58±0.01

20.5±0.4

10.0+0.1

32.6±0.3

31.2±0.7

6.6±0.1

111±6

53.1±0.8

750±20

2.19±0.04

7.8±0.1

580±20

9.9±0.2

35.4±0.7

0.42±0.03

0.87±0.08

13.9±0.2

1.8±0.2

1.20±0.01

900±30

1.55±0.01

0.80±0.02

nd

1,640±40

HN03

2.77±0.01

13.3±0.5

36.6±0.9

48±1

0.43±0.01

15.0±0.2

7.73±0.03

26.0±0.5

25.5±0.1

4.80±0.05

86.1±0.3

38±9

64 1.1 ±0.4

1.61±0.01

6.1±0.2

420±3

6.6±0.1

26±2

0.34±0.01

0.37±0.03

11.0+0.1

1.4±0.3

1.00±0.01

727±1

1.18±0.03

0.65±0.01

nd

1,234+6

USEPA

4.0±0.3

17±1

45±1

56±2

0.53±0.02

16.3±0.9

8.79±0.05

27.6±0.4

27±1

5.7±0.1

94±3

64±4

650±10

2.6±0.2

6.5±0.1

540±20

10.4±0.8

30±1

0.58±0.05

0.46±0.04

15.1±0.3

1.41 ±0.09

1.10+0.01

710+30

1.13±0.01

0.77+0.02

nd

1,530±70

Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to Other Whole-Water Digestion Procedures
Table 4. Elemental concentrations in various digestates of a synthetic whole-water sample made 

from National Institute of Standards and Technology Standard Reference Material 1646, 

Estuarine Sediment

[Cert., certified concentration in units provided for each element. Concentrations in parentheses are 

uncertified; Digestate concentration is the elemental concentration recovered by the digestion relative to 

the weight of the sediment used to prepare the synthetic standard; HCI, hydrochloric acid (HCI) in-bottle 

digestion with or without the HCI removed by evaporation; HNO3 , nitric acid in-bottle digestion; USEPA, 

U.S. Environmental Protection Agency's digestion procedure with or without the HCI removed by 

evaporation; ug/g, micrograms per gram; mg/g, milligrams per gram; ±, plus or minus; the number 

following the ± is the standard deviation of four separate digestions; na, not available]

Element

Aluminum, mg/g

Antimony, ug/g

Arsenic, ug/g

Barium, ug/g

Beryllium, ug/g

Boron, ug/g

Cadmium, ug/g

Calcium, mg/g

Chromium, ug/g

Cobalt, ug/g

Copper, ug/g

Iron, mg/g

Lead, ug/g

Lithium, ug/g

Magnesium, mg/g

Manganese, ug/g

Molybdenum, ug/g

Nickel, ug/g

Potassium, mg/g

Selenium, ug/g

Silica, SiO2 , mg/g

Silver, ug/g

Sodium, mg/g

Strontium, ug/g

Thallium, ug/g

Uranium, ug/g

Vanadium, ug/g

Zinc, ug/g

Cert.

62.5

(0.4)

11.6

na

(1.5)

na

0.36

8.3

76

10.5

18

33.5

28.2

(49)

10.9

375

(2.0)

32

(14)

(0.6)

(663)

na

(20)

na

(0.5)

na

94

138

Digestate concentration

HCI

7.2±0.1

0.06±0.01

7.72±0.05

29.9±0.4

0.53±0.02

25.3±0.6

0.37±0.07

3.30±0.01

25.6±0.3

6.65±0.09

11.7±0.1

18.6±0.1

21.3±0.2

16.8±0.2

6.00±0.02

185±3

1.00±0.02

15.8±0.2

3.13±0.04

0.67±0.03

30±1

0.11 ±0.02

10.1±0.1

29.3±0.2

0.15±0.01

1.10±0.01

35.8±0.7

92.4±0.5

HN03

7.2±0.1

0.07±0.01

7.34±0.05

30.2±0.9

0.50±0.01

25.4±0.1

0.33±0.01

3.30±0.01

25.4±0.3

6.07±0.03

11.6±0.1

18.1±0.1

18.5±0.3

16.3±0.2

5.90±0.01

173±2

0.86±0.02

14.9±0.1

3.1±0.1

0.69±0.05

28.9±0.7

0.10±0.01

10.0±0.1

27.8±0.2

0.13±0.01

1.02±0.01

34.6±0.4

82.6±0.7

USEPA

14±1

0.03±0.01

8.13±0.09

40±1

0.72±0.02

29.8±0.9

0.34±0.01

3.7±0.1

31.4±0.6

6.92±0.08

13.3±0.2

22.6±0.4

16.3±0.2

24.4±0.9

7.1 ±0.1

216±2

1.14±0.03

18.8±0.3

3.9±0.1

0.60±0.03

35±5

0.12±0.01

10.6±0.1

29.5±0.6

0.13±0.01

1.09±0.02

37.9±0.6

98±1

DISCUSSION OF RESULTS 9
Table 5. Percentage yield for a synthetic whole-water sample made from National Institute of 

Standards and Technology Standard Reference Material 2704, Buffalo River Sediment, using 

various digestion procedures

[HC1, hydrochloric acid (HC1) in-bottle digestion with or without the HC1 removed by evaporation; 

USEPA, U.S. Environmental Protection Agency's digestion procedure with or without the HC1 

removed by evaporation; HNO3 , nitric acid in-bottle digestion; ±, plus or minus; the number following 

the + is the standard deviation of four separate digestions]

Element

Aluminum

Antimony

Arsenic

Barium

Cadmium

Calcium

Chromium

Cobalt

Copper

Iron

Lead

Lithium

Magnesium

Manganese

Nickel

Potassium

Selenium

Silica, SiO2

Sodium

Strontium

Thallium

Uranium

Vanadium

Zinc

Buffalo River Sediment, in percentage yield

HCI

10.7±0.2

50.7±0.8

61.2±0.9

19.2±0.8

92.7±0.9

87±2

47.3±0.5

76.5±0.8

80±2

48±1

102.2+0.9

31.9+0.4

60+2

72±1

65+1

6.8+0.7

80+10

3.4±0.3

4.1+0.4

30.0+0.3

47.2+0.4

15.8+0.2

15.5+0.1

76+2

HNO3

12.2+0.4

50+1

57.1+0.6

19.5+0.5

90.3+0.1

84.6+0.4

48.9+0.5

69.2+0.9

78±1

45.6+0.5

92+4

33.0+0.6

57.1+0.2

70.5+0.6

59.9+0.9

7.4+0.2

40+7

3.3±0.1

3.7+0.2

27.3+0.5

46+1

16.1+0.5

14.5+0.4

66.9+0.9

USEPA

20+1

35+4

79±3

22.0±0.1

99.7±0.5

89+1

61+1

86+3

92+5

71+2

91+5

52±2

69.9±0.9

88±2

78+3

9.7+0.8

70±10

4.8+0.2

6.1±0.2

30.8±0.7

50±2

21+2

22+1

89+4

HCI in-bottle yields. In contrast, the HNO3 

in-bottle yields for the Riverine Sediment 

synthetic whole-water samples are 11 to 30 

percent lower than for the HCI in-bottle 

results for 16 of the 26 elements determined. 

Such differences underscore the dependence 

of percentage yield on sediment 

composition.

For most elements, the USEPA 

digestion procedure provided higher 

percentage yields than both in-bottle 

procedures. The USEPA percentage yields, 

however, are also dependent on the 

composition of the whole-water matrix.

The higher yields primarily are related to 

differences in the digestion procedure. Samples 

are heated at 85°C until the solution is reduced 

by 80 percent. The remaining solution is 

covered and refluxed at the same temperature for 

30 minutes, diluted to volume, and analyzed. 

The increases in acid concentration and 

temperature during the reflux step enhance 

dissolution of refractory elements compared to 

the in-bottle digestion procedures.

The variability in both in-bottle digestion 

procedures was similar. Variability for the

in-bottle procedure ranged from 0.1 to 8

10 Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to Other Whole-Water Digestion Procedures
Table 6. Percentage yield for a synthetic whole-water sample made from National Institute of 

Standards and Technology Standard Reference Material 1645, Riverine Sediment, using various 

digestion procedures

[HC1, hydrochloric acid (HC1) in-bottle digestion with or without the HC1 removed by evaporation; 

USEPA, U.S. Environmental Protection Agency's digestion procedure with or without the HC1 removed 

by evaporation; HNO3, nitric acid in-bottle digestion; ±, plus or minus; nd, not detected, less than the 

method detection limit; the number following the ± is the standard deviation of four separate digestions]

Element

Aluminum

Antimony

Arsenic

Cadmium

Calcium

Chromium

Cobalt

Copper

Iron

Lead

Magnesium

Manganese

Nickel

Potassium

Selenium

Sodium

Thallium

Uranium

Vanadium

Zinc

HCI

15.0±0.1

38±1

81±2

99±1

112±1

103±3

65±1

101+4

47.0+0.7

104±2

106+1

73+2

75±3

3.4±0.2

54±6

23.0±0.2

108.2±0.7

72±1

nd

95±2

Riverine Sediment, in percentage yield

HN03

12.6+0.3

26.7+0.8

56+1

75.8+0.3

90+2

85±2

47.4+0.3

77+2

33.2+0.8

88+2

83+2

52+1

58+3

2.7±0.1

24±3

18.2±0.1

82+1

58.7+0.6

nd

71+1

USEPA

18+1

34+2

68+2

86+2

95.1+0.6

91+3

56±1

86±3

58+2

91+2

87.8+0.9

68±2

65+3

4.7+0.4

31+2

20.5+0.1

78.4±0.2

70+2

nd

89+4

percent for four replicate digestions of all 

three synthetic whole-water samples. By 

comparison, the variability in results with 

similar percentage yield is greater for 

selected elements when using the USEPA 

procedure. This increase in variability is 

caused by the difficulty in controlling 

digestate volumes and heating conditions 

during the refluxing step.

Elements that are most likely to be 

adsorbed to the particulate coatings, for 

example, cadmium, cobalt, copper, lead, 

manganese, and nickel, give higher 

percentage yields. Elements that 

predominately compose the sediment's 

mineral substrate, such as aluminum, iron,

potassium, silica, and sodium, give much lower 

percentage yields.

An anomaly was also identified when 

comparing whole-water recoverable arsenic 

results from HG-AAS to those from ICP-MS. 

Arsenic results from HG-AAS were 20 to 50 

percent lower for all synthetic whole-water 

digestates reported here. In addition, arsenic 

results for USGS Standard Reference Water 

Sample WW-1, a synthetic whole-water 

standard, averaged 5±1 jug/L for four 

determinations as compared to the published 

most probable value of 20 jug/L (the ICP-MS 

yielded 18.13±0.09|ng/L). The HG-AAS 

concentrations are most likely lower because 

particulate material might settle out in the 

sample tube before sample introduction. This

DISCUSSION OF RESULTS 11
Table 7. Percentage yield for a synthetic whole-water sample made from National Institute of 

Standards and Technology Standard Reference Material 1646, Estuarine Sediment, using 

various digestion procedures

[HCI, hydrochloric acid (HCI) in-bottle digestion with or without the HCI removed by evaporation; 

USEPA, U.S. Environmental Protection Agency's digestion procedure with or without the HCI removed 

by evaporation; HNO3 , nitric acid in-bottle digestion; ±, plus or minus; the number following the ± is 

the standard deviation of four separate digestions]

Element

Aluminum

Antimony

Arsenic

Beryllium

Cadmium

Calcium

Chromium

Cobalt

Copper

Iron

Lead

Lithium

Magnesium

Manganese

Molybdenum

Nickel

Potassium

Selenium

Silica, SiO2

Sodium

Thallium

Vanadium

Zinc

Estuarine

HCI

11.5±0.2

15.8±0.7

66.6±0.5

35±2

100±20

39.8±0.1

33.7±0.4

63.3±0.8

64.9±0.4

55.7±0.2

75.5±0.6

34.3±0.4

55.0±0.2

49.3±0.8

49.9±0.9

49.510.5

22.3±0.3

112±5

4.6±0.2

50.5±0.2

29.4±0.4

38.1±0.7

66.9±0.4

Sediment, in percentage yield

HN03

11.6±0.2

16.9±0.7

63.3±0.4

33.6±0.6

92±3

39.4±0.3

33.5±0.4

57.8±0.3

64.5±0.7

54.1±0.4

66±1

33.4±0.5

53.7±0.4

46.1±0.5

43±1

46.7±0.2

22.3±0.4

114±8

4.4±0.1

50.2±0.3

26.1±0.3

36.8±0.5

59.8±0.5

USEPA

23±2

8±1

70.0±0.8

48±2

96±2

100±20

41.3±0.8

65.9±0.7

74±1

32±5

57.9±0.9

50±2

28±5

57.6±0.5

57±2

58.9±0.9

28.0±0.7

100±5

1.6±0.3

53.2±0.6

25.8±0.4

40.3±0.7

71.2±0.9

settling effect is worsened for the synthetic 

whole-water samples because they have 

sediment concentrations that are greater than 

those normally present in natural-water 

samples submitted to NWQL.

CONCLUSIONS

The advantages and disadvantage of 

using HNOs instead of HCI for the in-bottle 

digestion are summarized below.

Advantages of using the HNOs in-bottle 

digestion procedure:

 The digestate is compatible with all 

current (1999) USGS analytical 

methods used to determine 

aluminum, antimony, arsenic, 

barium, beryllium, boron, cadmium, 

calcium, chromium, cobalt, copper, 

iron, lead, lithium, magnesium, 

manganese, molybdenum, nickel, 

potassium, selenium, silica, silver, 

sodium, strontium, thallium, 

uranium, vanadium, and zinc.

 The variability of 0.1 to 8 percent is 

comparable to the HCI in-bottle 

digestion procedure.

12 Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to Other Whole-Water Digestion Procedures
1UU

90

80

3 70

p 60

r_J

0 50

£ 40

uS 30

CL

20

10

n

1 1 1

Aluminum

-

_

.

-

-

~y 1£

£

. « *

i i i

i i i

Antimony

E&

 i " " I S

BE

1 1 1

Arsenic

St ^r

-A- ~U-

^ rr_

1 1 1

Barium

-

-

_

.

-

-

-Q- -

i i i

BR RS ES BR RS ES BR RS ES BR RS ES

A *^ V

120

110

Q 100

J

3 90

HH

>< 80

o 70

< 60

H

^ 50

U 40

cu

20

10

0

i i i

- Beryllium

_

_

t

X

" 5

-

-

-

1 1 1 .

1 1 1

Cadmium

* * tS

^«- Ip-4_

x T

-L

i i i !

i i i

Calciun

*

>

=/£

^ TT

I

i-

(

_

i i i

Chromium -

_

I :

.

X

n

-

-y

B

it

* '

1 1 1

BR RS ES BR RS ES BR RS ES BR RS ES

SYNTHETIC WHOLE-WATER SAMPLE

EXPLANATION: Horizontal error bars equal standard deviation for four digestions. 

 HC1 X USEPA D HNO3

Figure 1. Percentage yield as a function of hydrochloric acid in-bottle digestion (HCI), U.S. 

Environmental Protection Agency digestion (USEPA), and nitric acid in-bottle digestion (HNO3) 

procedures for synthetic whole-water samples prepared using Buffalo River (BR), Riverine (RS), and 

Estuarine (ES) Sediments.

CONCLUSIONS 13
1ZU

110

100

Q 9°

W 80

^ 70

|«

S 5°

U 40

W 30 Cu

20

10

n

1 1 1

1 Cobalt

" * i

.

-

-

i i i

i i i

Copper

^ 

^F 

1

i ^

i TT

2 X

i i i

i i i

Iron

X

X g.

S 

0 X

i i i

i i i

Lead J

* i J

I s 

-

* J

re

^ :

-

-

M

BR RS ES BR RS ES BR RS ES BR RS ES

A JbU

110

100

Q 90

w 80

> 70

O 60 

H 50

^

tf 30

S 2 °

10 

0

1 1 1

1 Lithium

-

_ X "^7"

1 * *

-

1 1 1

1 1 1

Magnesiun

~^t

n

X

1 *

 1 

1 1 1

i Manganese

X

s |

1 1 1

Molybdenunj

-

-

-

X "

re J

-

-

-

BR RS ES BR RS ES BR RS ES BR RS ES

SYNTHETIC WHOLE-WATER SAMPLE

EXPLANATION: Horizontal error bars equal standard deviation of four digestions. 

 HC1 X USEPA D HNO3

Figure 1. Percentage yield as a function of hydrochloric acid in-bottle digestion (HCI), U.S. 

Environmental Protection Agency digestion (USEPA), and nitric acid in-bottle digestion (HNO3) 

procedures for synthetic whole-water samples prepared using Buffalo River (BR), Riverine (RS), and 

Estuarine (ES) Sediments Continued.

14 Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to Other Whole-Water Digestion Procedures
14U

130

120

110

Q100

w 90

> 80

g 70

Z 50

U 40

M 30

^ 20

10

0

m

I I I

'- Nickel

 ^p

~ n^ ' 1 ' \i/ 5- ^

r 4

_

_

-

-

-

i i i

i i i

Potassium

»

3i

w

i i i

i i i

Selenium

2vv

^h

!!

T.

h

X

n

i i i

i i i

Silica -

-

-

-

-

-

_

*

44C rri

* * -

III"

BR RS ES BR RS ES BR RS ES BR RS ES

M. *J V

120

110

100

Q

J 90

S 80

W 70

^ 60

CRCENT, W -UCft 000

M-l

PH 20

10 

0

i i i

Sodium

-

M

-

_

': * s

Strontium

i i i

i i i 

Thallium

^

5

1 1 1

Uranium -

-

-

-

t :

s -

X

BR RS ES BR RS ES BR RS ES BR RS ES

SYNTHETIC WHOLE-WATER SAMPLE

EXPLANATION: Horizontal error bars equal standard deviation of four digestions. 

 HC1 X USEPA D HNO3

Figure 1. Percentage yield as a function of hydrochloric acid in-bottle digestion (HCI), U.S. 

Environmental Protection Agency digestion (USEPA), and nitric acid in-bottle digestion (HNO3 ) 

procedures for synthetic whole-water samples prepared using Buffalo River (BR), Riverine (RS), and 

Estuarine (ES) Sediments Continued.

CONCLUSIONS 15
± AV

100

90

Q 80 -J

H 70

W 60

o<< 50

H 

£ 40

U 30

W 20

10 

0

1 1 1

Vanadium

-

-

_

1 i

-

'_ X

-

i i i 

Zinc

T ?

V V

± ±

I

O X 

tt *

s

1 1 1

1 1 1

1 1 1

1 1 1

-

-

_

1 1 1

BR RS ES BR RS ES BR RS ES BR RS ES

SYNTHETIC WHOLE-WATER SAMPLE

EXPLANATION: Horizontal error bars equal standard deviation of four digestions.

HC1 X USEPA HNO

Figure 1. Percentage yield as a function of hydrochloric acid in-bottle digestion (HCI), U.S. 

Environmental Protection Agency digestion (USEPA), and nitric acid in-bottle digestion (HNO3) 

procedures for synthetic whole-water samples prepared using Buffalo River (BR), Riverine (RS), and 

Estuarine (ES) Sediments Continued.

 The procedure uses less chemical

reagents and, therefore, produces less 

chemical waste for some analytical 

methods.

 Interferences from chloride are reduced.

Disadvantage of using the HNOs in-bottle 

digestion procedure:

 Results from the synthetic whole-water 

samples indicate that the HNOs inbottle procedure might give 

negatively biased recoverable

concentrations relative to the HCI inbottle procedure. Recoverable 

concentrations are dependent on the 

composition of the particulate matter in 

the whole-water sample regardless of the 

digestion procedure used.

The three acid-digestion procedures tested 

do not completely solubilize all elements that 

were determined. If a total (100 percent) 

digestion is required for any element in a 

whole-water sample, then it can be argued that 

none of these methods will be satisfactory. 

However, if a recoverable elemental 

concentration (less than 100 percent) is

16 Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to Other Whole-Water Digestion Procedures
Table 8. Statistical analysis summary of elemental percentage yield for the nitric acid in-bottle 

digestion in relation to the hydrochloric acid in-bottle digestion

[BR, National Institute of Standards and Technology Standard Reference Material 2704, Buffalo River Sediment; RS, 

National Institute of Standards and Technology Standard Reference Material 1645, Riverine Sediment; ES, National 

Institute of Standards and Technology Standard Reference Material 1646, Estuarine Sediment; p-value, level of 

significance; R2, coefficient of determination; n, number of data points; <, less than]

Regression analysis

Slope y-intercept 

Coefficient p-value a___Coefficient p-value b R2 n

BR

RS

ES

0.88

0.81

0.95

O.0001

O.0001

O.0001

2.4

-3.9

0.1

0.4372

0.2011

0.9345

0.9296

0.9667

0.9875

24

19

23

Statistical tests 

Test

BR 

RS 

ES

One-Sample Sign Test 

Student /-Test 

One-Sample Sign Test

Statistic

1.75 

9.32 

1.30

p-value °

0.0227 

O.0001 

0.0009

n

24 

19

23

a The null hypothesis tested: slope is not equal to one.

b The null hypothesis tested: ^-intercept is equal to zero.

c The null hypothesis tested: the medians (or means for the Student /-Test) of the percentage yields for the nitric 

acid in-bottle digestion are not significantly different from the percentage yields for the hydrochloric acid in-bottle 

digestion.

acceptable for a whole-water sample, then 

the reproducibility of the digestion 

procedure should be the primary concern. 

Both the HC1 and HNO3 in-bottle digestion 

procedures give excellent reproducibility for 

all elements determined. Therefore, the 

simplicity of the digestion procedure should 

be the primary reason for the method 

selected. Newer methods that analyze the 

digestate from the HC1 in-bottle digestion 

procedure may require additional steps (for 

example, removal of HC1 and the 

reconstitution of the residue) to eliminate 

interferences. Such steps increase the 

analysis time and chances for contamination. 

The HNOs in-bottle digestion is the 

preferred method for routine use at the 

NWQL. Nevertheless, the original HC1 inbottle digestion procedure can be used if 

customers require this acid-digestion 

procedure.

REFERENCES CITED

American Society for Testing and Materials, 

1995, Annual book of ASTM 

standards, Section 11, Water (Dl 193, 

Standard specification for reagent 

water): Philadelphia, v. 11.01, 

p.122-124.

Fishman, M.J., ed., 1993, Methods of

analysis by the U.S. Geological Survey 

National Water Quality Laboratory 

Determination of inorganic and 

organic constituents in water and 

fluvial sediments: U.S. Geological 

Survey Open-File Report 93-125, 

217 p.

Fishman, M.J., and Friedman, L.C., eds., 

1989, Methods for determination of 

inorganic substances in water and 

fluvial sediments: U.S. Geological 

Survey Techniques of WaterResources Investigations, book 5, 

chap. Al, 545 p.

REFERENCES CITED 17
a fc

H O i 1 5

as H

o o

y 3

W o

U ffl

H *

140

120

100

80

60

40

a 20

BUFFALO RIVER SEDIMENT

 Linear fit

_ _ _ _ Upper 95% Confidence Limit 

...... Lower 95% Confidence

0 20 40 60 80 100 120 140

PERCENTAGE YIELD FOR HYDROCHLORIC 

ACID IN-BOTTLE DIGESTION

Figure 2. Linear regression analysis of elemental percentage yield for the nitric acid in-bottle digestion 

in relation to the hydrochloric acid in-bottle digestion for a synthetic whole-water sample made from 

Buffalo River Sediment.

Garbarino, J.R., and Struzeski, T.M., 1998, 

Methods of analysis by the U.S. 

Geological Survey National Water Quality 

Laboratory Determination of elements in 

whole-water digests using inductively 

coupled plasma-optical emission 

spectrometry and inductively coupled 

plasma-mass spectrometry: U.S. 

Geological Survey Open-File 

Report 98-165, 101 p.

Hoffman, G.L., Fishman, M.J., and

Garbarino, J.R., 1996, Methods of 

analysis by the U.S. Geological Survey 

National Water Quality Laboratory 

In-bottle acid-digestion of whole-water 

samples: U.S. Geological Survey 

Open-File Report 96-225, 28 p.

Jones, S.R., and Garbarino, J.R., 1999, 

Methods of analysis by the U.S. 

Geological Survey National Water 

Quality Laboratory Determination of

arsenic and selenium in water and 

sediment by graphite furnace-atomic 

absorption spectrometry: U.S. 

Geological Survey Open-File Report 

98-639, 39 p.

U.S. Environmental Protection Agency, 

1994, Methods for the determination 

of metals in environmental samples: 

EPA 200 Series, Supplement I, EPA600/R-94/111, Revision 2.8, May 

1994.

APPENDIX

The presence of chloride in the HC1 

in-bottle and the USEPA digestates 

interferes with the determination of ambient 

concentrations of arsenic and vanadium by 

ICP-MS and selenium by GF-AAS. 

Therefore, prior to comparing the results of 

the HC1 and HNO3 in-bottle digestion

18 Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to Other Whole-Water Digestion Procedures
a z

w

O Q

w 3 H H

w 

u

140

120

100

80

60

40

B 20

RIVERINE SEDIMENT

 Linear fit

_ _ _ _ Upper 95% Confidence Limit 

...... Lower 95% Confidence Limit

20 40 60 80 100 120 140

PERCENTAGE YIELD FOR HYDROCHLORIC 

ACID IN-BOTTLE DIGESTION

Figure 3. Linear regression analysis of elemental percentage yield for the nitric acid in-bottle digestion 

in relation to the hydrochloric acid in-bottle digestion for a synthetic whole-water sample made from 

Riverine Sediment.

UMM

H

^ W3

O g

^ S

o o

J td

w 

o

H

g =

tf <

w

e140

120

100

80

60

40

20

ESTUARINE SEDIMENT

 Linear fit

- - - - Upper 95% Confidence Limit 

...... Lower 95% Confidence Limit

20 40 60 80 100 120 140

PERCENTAGE YIELD FOR HYDROCHLORIC 

ACID IN-BOTTLE DIGESTION

Figure 4. Linear regression analysis of elemental percentage yield for the nitric acid in-bottle digestion in 

relation to the hydrochloric acid in-bottle digestion for a synthetic whole-water sample made from 

Estuarine Sediment.

APPENDIX 19
procedures, it was necessary to remove 

chloride from the HC1 in-bottle digestates. 

The method used is outlined here.

Subboiling Evaporation Procedure

The high concentration of HC1 in the 

HC1 in-bottle digestates is removed through 

volatilization by using subboiling 

evaporation at 85°C. At this temperature, 

the risk of losing temperature-sensitive 

elements is minimized. The bias and 

variability of subboiling evaporation was 

determined by using results from U.S. 

Geological Survey Standard Reference 

Water Sample T123, a multielement 

standard (see table 9), and a synthetic 

whole-water sample (see table 10). Four 

aliquots of each digestate were evaporated

on different days. Residues from the 

evaporation were dissolved in a calibrationblank solution before analysis by ICP-MS 

or ICP-AES. Results for T123 and the 

multielement standard show that every 

element is within one standard deviation of 

the most probable value, indicating there are 

no losses during the evaporation. Results 

for the multielement standard show that the 

variability of the evaporative procedure is no 

greater than 15 percent at about 5 u,g/L. In 

general, data in table 10 show that the 

elemental concentrations determined in the 

synthetic whole-water HC1 in-bottle 

digestate of the Estuarine Sediment were 

within the experimental error of 

corresponding results from the evaporated 

solutions.

Table 9. Bias and variability for the subboiling evaporation technique

[SRWS T123, U.S. Geological Survey Standard Reference Water Sample T123; MPV, most probable value from 

round-robin results using multiple analytical methods; THEO, theoretical mean and standard deviation of a 

multielement standard from four determinations on different days; EXP, experimental means after subboiling 

evaporation; na, not available; ±, plus or minus; the number following the ± in the EXP columns is the standard 

deviation of four aliquots evaporated and analyzed on different days]

Element

Aluminum

Antimony 

Arsenic

Barium

Beryllium 

Cadmium

Chromium

Cobalt

Copper 

Lead

Manganese 

Molybdenum 

Nickel

Silver

Strontium

Thallium

Uranium

Vanadium

Zinc

MPV

10±10

7±2 

20±2

7.6±0.9

8.1±0.8 

5.9±0.9

11±1

5.3±0.8

10±1 

10±2

14+1 

9±1 

4±1

1.4+0.6

49+3

na

na

4±1

6±4

SRWS T1 23

EXP

8.0±0.4

6.3+0.9 

19+2

7.1±0.5

7.5+0.6 

5.3±0.4

9.3±0.7

5.7±0.6

9.6±0.3

9.7±0.7

12.7±0.9 

9±1 

4.2±0.4

1.4±0.2

46±3

na

na

4.0±0.7

6.7±0.7

Multielement

THEO

5.5±0.1

6.17±0.02 

4.93±0.08

5.0±0.1

4.72+0.07 

4.9±0.5

4.94±0.02

5.23±0.07

4.8±0.2 

5.09±0.06

4.9±0.2 

5.53±0.09 

4.7±0.3

na

na

5.4+0.4

5.16±0.07

5.5±0.4

5.1±0.3

standard

EXP

6±1

5.9±0.4 

4.5±0.4

4.8±0.3

4.7±0.2 

4.9±0.5

4.8±0.4

5.5±0.7

4.7±0.5 

4.8±0.4

5.0±0.4 

5.0±0.5 

4.5±0.5

na

na

4.9±0.4

5.0±0.4

4.8±0.4

6.1±0.4

20 Comparison of a Nitric Acid In-Bottle Digestion Procedure 

to other Whole-Water Digestion Procedures
Table 10. Bias and variability of subboiling evaporation of digestate from a synthetic whole-water 

sample made from National Institute of Standards and Technology Standard Reference Material 1646, 

Estuarine Sediment

[ug/g, micrograms per gram; mg/g, milligrams per gram; HC1, hydrochloric acid (HC1) in-bottle digestate; -HC1, 

subboiling evaporation of HC1 in-bottle digestate; nd, not detected; ±, plus or minus; the number following the ± 

is the standard deviation of four aliquots evaporated and analyzed by inductively coupled plasma-atomic emission 

spectrometry on different days]

Element -

Aluminum, mg/g

Barium, ug/g

Beryllium, ug/g

Boron, ug/g

Cadmium, ug/g

Calcium, mg/g

Chromium, ug/g

Cobalt, ug/g

Copper, ug/g

Iron, mg/g

Lead, ug/g

Lithium, ug/g

Magnesium, mg/g

Manganese, ug/g

Molybdenum, ug/g

Nickel, ug/g

Silica, SiO2, mg/g

Silver, ug/g

Sodium, mg/g

Strontium, ug/g

Vanadium, ug/g

Zinc, ug/g

HCI

8.4±0.1

29.5±0.5

0.5±0.2

26±3

nd

3.30±0.01

26.1±0.5

84±4

12±1

18.7±0.1

nd

16±1

6.00±0.02

177.6±0.6

9±2

16±5

30±1

nd

10.10±0.05

26.8±0.1

28.2±0.6

92±6

Estuarine sediment

-HCI

8.18±0.07

28.0±0.3

0.2±0.2

27±3

nd

3.30±0.01

26±2

87±7

10.5±0.5

18.6±0.1

nd

16.4±0.4

6.00±0.03

178±1

11±7

20±10

23.1±0.8

nd

9.99±0.03

26.3±0.2

28.6±0.7

93±6

The entire evaporative procedure is 

conducted inside a laminar-flow clean 

bench. Details of the evaporative procedure 

are outlined as follows:

 Weigh a 25- to 50-g aliquot of in-bottle 

digestate (Hoffman and others, 1996) 

into a 50-mL Teflon centrifuge tube.

NOTE 4: Prepare a reagent blank and a 

standard reference material with each set of 

samples evaporated.

Place the centrifuge tube in a graphiteblock heater that is thermostatically 

heated to 85°C [see Hoffman and others 

(1996) for a description of the graphiteblock heater]. Heat to dryness (takes 

less than 8 hours for a set of 12 

samples); cool.

Reconstitute the sample residue to its 

original weight with the calibration 

blank solution specified in the analytical 

method being used for quantitation.

1 Printed on recycled paper ' H'.S. GOVERNMENT PRINTING OFFICE:1999-573-756/25006 APPENDIX 21