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Determination of Mercury in Aqueous 

and Geologic Materials by Continuous 

Flow–Cold Vapor–Atomic Fluorescence 

Spectrometry (CVAFS)

By Philip L. Hageman

Chapter 2

Section D, Geologic Analysis

Book 5, Laboratory Methods and Analysis

Techniques and Methods 5–D2

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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Suggested citation:

Hageman, P.L., 2007, Determination of mercury in aqueous and geologic materials by continuous flow−cold vapor−atomic 

fluorescence spectrometry (CVAFS): U.S. Geological Survey Techniques and Methods, book 5, chap. D2, 6 p.
iii

Contents

Contents..........................................................................................................................................................iii

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

Principle...........................................................................................................................................................1

Acknowledgments.........................................................................................................................................1

Interferences..................................................................................................................................................1

Scope...............................................................................................................................................................2

Apparatus........................................................................................................................................................2

Reagents..........................................................................................................................................................2

Safety Precautions ........................................................................................................................................4

Procedure for Digestion of Geologic Samples .........................................................................................4

Procedure for Aqueous Samples................................................................................................................4

Analytical Procedudure for Analysis of Samples for Mercury Using Continuous

Flow−Cold Vapor−Atomic Fluorescence Spectrometry (CVAFS).............................................5

Discussion of Results....................................................................................................................................5

Conclusion.......................................................................................................................................................6

References Cited............................................................................................................................................6

Figures

1. The Leeman HYDRA® cold vapor−atomic fluorescence spectrometry mercury

analyzer with added incandescent heat lamp.........................................................................3

2. Drilled aluminum heating block used for digestion of geologic matrices...........................3

Table

1. Analytical performance summary for determination of mercury by continuous 

flow−cold vapor−atomic fluorescence spectrometry ............................................................5
iv

Conversion Factors

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:

ng/g	 nanogram per gram

ng/L	 nanogram per liter

μg/g	 microgram per gram

μg/L	 microgram per liter

Multiply By To obtain

Length

centimeter (cm) 3.94 x 10-1 inch

millimeter (mm) 3.94 x 10-2 inch

micrometer (μm) 3.94 x 10-5 inch

Mass

gram (g) 3.53 x 10-2 ounce, avoirdupois

Volume

liter (L) 2.64 x 10-1 gallon

milliliter (mL) 2.64 x 10-4 gallon

microliter (μL) 2.64 x 10-7 inch

cubic centimeter (cm3) 0.06102 inch
v

The following abbreviations and symbols are used in this report:

ASTM	 	 American Society for Testing and Materials

CVAAS		 cold vapor−atomic absorption spectrometry

CVAFS	 	 cold vapor−atomic fluorescence spectrometry

DI	 	 deionized

M	 	 molarity (moles per liter)

MSDS	 	 materials safety data sheet

N	 	 normality (equivalents per liter)

NIST	 	 National Institute of Standards and Technology

NWQL	 	 National Water Quality Laboratory

ppb	 	 parts per billion

ppt	 	 parts per trillion

rpm	 	 revolutions per minute

SRM	 	 Standard Reference Material

USEPA	 	 U.S. Environmental Protection Agency

USGS	 	 U.S. Geological Survey

MΩ	 	 megohm

v/v	 	 volume per volume

w/v	 	 weight per volume

percent R	 percent recovery

>	 	 greater than

~	 	 about
Abstract

New methods for the determination of total mercury 

in geologic materials and dissolved mercury in aqueous 

samples have been developed that will replace the methods 

currently (2006) in use. The new methods eliminate the 

use of sodium dichromate (Na2Cr2O7 ·2H2O) as an oxidizer 

and preservative and significantly lower the detection limit 

for geologic and aqueous samples. The new methods also 

update instrumentation from the traditional use of cold 

vapor–atomic absorption spectrometry to cold vapor–atomic 

fluorescence spectrometry. At the same time, the new digestion procedures for geologic materials use the same size test 

tubes, and the same aluminum heating block and hot plate 

as required by the current methods. New procedures for 

collecting and processing of aqueous samples use the same 

procedures that are currently (2006) in use except that the 

samples are now preserved with concentrated hydrochloric 

acid/bromine monochloride instead of sodium dichromate/

nitric acid. Both the “old” and new methods have the same 

analyst productivity rates. These similarities should permit 

easy migration to the new methods. Analysis of geologic and 

aqueous reference standards using the new methods show 

that these procedures provide mercury recoveries that are as 

good as or better than the previously used methods.

Principle

The digestion procedure for geologic materials is based 

on similar procedures that have been used for several years by 

the U.S. Environmental Protection Agency (USEPA) (2001).

 In order to determine the total mercury concentration 

in geologic materials, samples are digested using a hot plate 

and a mixture of concentrated nitric acid (HNO3) and concentrated hydrochloric acid (HCl) in a ratio of 0.5 / 2.0 mL, 

respectively. After digestion, all mercury in the sample is 

oxidized to Hg (II) using bromine monochloride (BrCl). The 

digestate is diluted to 14.75 mL with ASTM Type I reagent 

water and pre-reduced with hydroxylamine hydrochloride 

(NH2OH·HCl) prior to analysis.

The methods described herein for the preservation, 

processing, and analysis of aqueous samples for mercury 

are modifications to those used for several years by the U.S. 

Geologic Survey (USGS) National Water Quality Laboratory 

(NWQL) (Garbarino and Damrau, 2001) and procedures used 

by the U.S. Environmental Protection Agency (2002).

For determination of dissolved mercury in aqueous 

samples, samples must be filtered (0.45-μm capsule filter) and 

preserved at the time of collection with 0.5 mL mercury-free 

concentrated hydrochloric acid per 30 mL of sample. The sample must be collected and stored in acid-washed borosilicate 

glass bottles with fluoropolymer lined caps. Upon return to the 

laboratory, samples must be further preserved and oxidized by 

the addition of BrCl. This procedure preserves the samples for 

at least 5 months (Garbarino and Damrau, 2001).

For instrumental analysis of geologic and aqueous samples, 

Hg (II) is reduced to elemental mercury vapor (Hg0) by mixing 

the sample with stannous chloride (SnCl2) in a continuous flowcold vapor manifold. Elemental mercury vapor (Hg0

) is separated 

and purged from the solution with ultrapure argon, and mercury 

concentration is measured by atomic fluorescence spectrometry. Quality assurance is demonstrated through the analysis of 

blanks, replicates, and Standard Reference Materials (SRMs).

Acknowledgments

I would like to thank Sarah Stetson for help in developing 

these methods.

Interferences

Gold, silver, and iodide have been identified as interferences and have been shown to diminish the extraction 

efficiency and/or suppress the recovery of mercury from the 

sample when using these methods (Garbarino and Damrau, 

2001; U.S. Environmental Protection Agency, 2002). Geologic 

samples containing >10 μg/g or aqueous samples containing > 

100 μg/L of any of these constituents must be diluted prior to 

analysis to mitigate the potential interference.

Determination of Mercury in Aqueous and Geologic 

Materials by Continuous Flow–Cold Vapor–Atomic 

Fluorescence Spectrometry (CVAFS)

By Philip L. Hageman
Water vapor condensation in the fluorescence detector is 

a major interference if allowed to develop. To avoid this problem, the operator must periodically check for condensation 

during the course of analysis and make sure that fresh drying 

agent (soda lime) is maintained in the in-line drying cell of the 

instrument. An adjustable lamp with a 150-watt incandescent 

bulb can also be placed in front of the reaction cell (fig. 1) of 

the instrument. This lamp can be turned on during analysis to 

keep the tubing and reaction cell warm, which helps inhibit the 

formation of condensation.

Finally, great care must be taken when collecting samples 

(all matrices) for mercury analysis because contamination of 

either the sample or the sampling equipment is possible due to 

the ubiquitous nature of mercury in the environment.

Scope

For solid-phase samples, this method offers a low reporting limit of 5 ng/g mercury. Samples exceeding the working 

range of 5 to 500 ng/g mercury must be redigested, diluted, 

and reanalyzed. For all aqueous samples, this method offers 

a lower reporting limit of 5 ng/L. Samples exceeding the 

working range of 5 to 100 ng/L mercury must be diluted and 

reanalyzed. About 30 solid-phase samples can be analyzed per 

day with the digestion being the limiting factor. At least 40 

aqueous samples can be analyzed per day.

Note that for the analysis of solid-phase or routine aqueous 

samples, the new detection limits are considerably lower than the 

cold vapor–atomic absorption spectrometry methods previously 

used. The old detection limits were 20 ng/g for solid samples 

and 0.10 ng/g for routine aqueous samples (Brown and others, 

2002). Low-level mercury determinations in aqueous samples 

are currently (2006) being done using cold vapor–atomic 

fluorescence spectrometry and have a detection limit of 5 ng/L 

(Hageman, 2002). This means that for analysis of solid samples, 

the detection limit for the new procedure is four times lower than 

the method previously used, and for routine aqueous samples, 

the upper limit of the new procedure is equal to the lower detection limit of the old procedure. The lower detection limits will 

make it possible to determine mercury on a significantly higher 

percentage of the solid and aqueous samples submitted.

Apparatus

Vortex mixer

Leeman HYDRA® CVAFS Instrument with incandescent 

heating lamp (fig.1).

Standard laboratory hot plate (30 by 60 cm) that must be 

able to maintain a temperature of 90o C.

Drilled aluminum heating block (fig. 2) measuring 6.35 

cm thick by 19.05 cm wide by 31.75 cm long that can be 

placed directly on top of hot plate and hold 50 16- by 100-

mm disposable glass test tubes.

•

•

•

•

Reagents

Acids used for solids digestion are research grade. Acids 

used for aqueous analysis, and for making all reagents and 

calibration standards, are trace metal purified (distilled) and 

mercury free. All other chemicals used for these procedures are 

reagent grade unless specified. Deionized (DI) water is ASTM 

Type I reagent water (18-MΩ) and is referred to in this report 

as reagent DI water. It is important to use the same source of 

reagent DI water for all processes and procedures described 

herein, because the use of water that has not been certified to be 

mercury free can be a major source of mercury contamination.

Glassware used for this method, including volumetric 

flasks used for making stock and calibration standards, bottles 

or flasks used for storage of BrCl, and sampling bottles used 

for collection of aqueous samples, should be allowed to sit 

overnight filled with 10 percent mercury free hydrochloric 

acid, and then rinsed three times with reagent DI water. This 

procedure is referred to as “acid-washed” in this publication. 

To remain mercury free, all 16- by 100-mm test tubes used for 

these methods should be kept in an oven at 90° C until needed.

Note: All reagents must be prepared in a fume hood.

Argon gas: Ultrapure (99.998 percent), with in-line dryer to 

dehumidify gas before it reaches instrument.

0.2N Bromine monochloride (w/v): In an acid-washed borosilicate glass or fluoropolymer bottle containing an acid-washed 

magnetic stir bar, dissolve 3.78 g potassium bromide (KBr) 

in 350 mL concentrated hydrochloric acid (HCl, 12 M). Mix 

using a magnetic stirrer until totally dissolved. Slowly and 

carefully add 5.32 g potassium bromate (KBrO3) and continue 

stirring until dissolved.

Note: The addition of the KBrO3 results in a violent reaction with the evolution of free halogens.

2 percent HCl (v/v): Dilute 20 mL concentrated HCl (12 M) to 

1 L with reagent DI water.

10 percent HCl (v/v): Dilute 100 mL concentrated HCl (12 M) 

to 1 L with reagent DI water.

5 percent stannous chloride solution (w/v): Dissolve 50.0 g 

stannous chloride (SnCl2· 2H2O) suitable for mercury analysis, in 50 mL concentrated HCl. Allow to stand for 20 to 30 

minutes until SnCl2 is totally dissolved. Dilute to 1 L with 

reagent DI water, cap, and shake. Allow the solution to clarify 

(1/2 hour) prior to use. When not in use, this reagent must be 

stored in the refrigerator (~5° C) until needed. If stored in this 

manner, reagent shelf life is at least 10 days.

15 percent hydroxylamine hydrochloride solution (w/v): Dissolve 15.0 g hydroxylamine hydrochloride (NH2

OH·HCl) in 

20 mL reagent DI water. After complete dissolution, bring to 

100 mL with reagent DI water.

Instrument calibration standards: For solids analysis, calibration 

standards with Hg concentrations of 0.05, 0.100, 0.500, 1.00, 

 Determination of Mercury in Aqueous and Geologic Materials by CVAFS
Figure 1. Leeman HYDRA® mercury analyzer with added incandescent heat lamp.

Figure 2. Drilled aluminum heating block used for digestion of geologic matrices.

Reagents 
and 5.00 μg/L are made from serial dilution of a 100-μg/L stock 

solution [stock made from dilution of National Institute of Standards and Technology (NIST) 3133] in the following manner: 

In acid-washed 100-mL volumetric flasks, 0.05, 0.10, 0.50, 1.0, 

and 5.0 mL of the stock solution is added to separate flasks containing 0.5 mL 0.2 N BrCl. All flasks are diluted with reagent 

DI water to final volume (100 mL), stoppered, and mixed.

For aqueous calibration standards, 5-, 10-, 50-, and 100-ng/L 

standards are prepared from serial dilution of a 1.0-μg/L stock 

solution (stock solution made from dilution of NIST 3133) as 

follows: In acid-washed 100-mL glass volumetric flasks, 0.5, 

1.0, 5.0, and 10.0 mL of the stock solution is added to separate 

flasks containing 0.5 mL 0.2 N BrCl. All flasks are diluted 

with reagent DI water to final volume (100 mL), stoppered, 

and mixed.

The blank solution for solid and aqueous analyses is made by 

adding 0.5 mL 0.2 N BrCl solution to an acid-washed 100-mL 

volumetric flask and diluting to volume with reagent DI water. 

Stock and calibration standards preserved with BrCl should be 

replaced every 3 months.

Safety Precautions

Observe normal laboratory safety procedures, including 

the use of protective eyewear, laboratory coat, and gloves. 

Perform all reagent mixing and chemical digestion activities 

in a chemical hood. See the Chemical Hygiene Plan (CHP) 

and Material Safety Data Sheet (MSDS) for further information concerning first-aid treatment and disposal procedures for 

chemical products used in this method. The atomic fluorescence spectrometer needs to be located under a vented exhaust 

hood so as to evacuate the acid gases and mercury vapors that 

are produced by the continuous flow–cold vapor system.

Procedure for Digestion of Geologic 

Samples

Weigh 0.100 g of sample into 16- by100-mm disposable borosilicate glass test tube.

Add 0.5 mL concentrated HNO3 (16 M) to test tube 

and mix with vortex to wet sample.

Add 2.0 mL concentrated HCl (12 M) (Add HCl in 

0.5-mL aliquots to carbonate rich samples.)

Vortex and let samples react overnight.

Vortex samples and place into a room temperature 

aluminum heating block.

Turn hot plate on and heat samples (uncovered) for 2 

hours at 90° C.

1.

2.

3.

4.

5.

6.

Remove samples from hot plate and cool to room 

temperature.

Add 30 μL 0.2 N BrCl to all samples and vortex.

Dilute all samples to 15 mL (0.6 cm below top of 

test tube) with reagent DI water.

In order to analyze samples at a later time, cap, 

shake, and store samples (samples processed in this 

manner can be stored for at least 1 month before 

being analyzed).

Prior to analysis, add 60 μL 15 percent NH2OH·HCl 

to each tube. Cap and shake samples. Let samples 

stand until the particulate matter has settled. This 

can also be achieved by centrifuging the samples at 

3,000 rpm for 10 minutes.

Remove cap and place samples into the instrument’s 

autosampler for analysis.

Any sample with mercury concentration exceeding the highest calibration standard (500 ng/g in 

sample) must be redigested, diluted, and reanalyzed. 

After the sample has been redigested and processed 

using the procedures described above, dilute the 

digestate by taking a 1.5-mL aliquot and adding it 

to a new 16- by 100-mm test tube containing 60 

μL NH2OH·HCl. Bring to volume (14.75 mL) with 

reagent DI water. Cap and shake the sample, and 

reanalyze using the procedures described above.

Procedure for Aqueous Samples

Aqueous samples are filtered into acid-washed borosilicate glass bottles using a 60-cm3

 (cubic centimeter) syringe 

and a 0.45-μm pore-size nitrocellulose filter. If filtration is 

difficult, a 0.70-μm glass fiber pre-filter can be used in conjunction with the 0.45-μm filter in a serial manner. Preserve 

the filtrate in the field or the laboratory by adding 0.5 mL 

concentrated, mercury free HCl (12 M) per 30 mL filtered 

sample. After preservation, store the bottles with caps that 

have fluoropolymer liners.

Upon arrival at the laboratory, add 60 μL 0.2 N BrCl 

to all samples. Following this, recap and shake all 

bottles. Samples preserved in this manner can be 

stored for up to 5 months.

Just prior to analysis, add 60 μL 15 percent 

NH2OH·HCl to all 16- by 100-mm test tubes that 

will go into the autosampler, and bring the test tubes 

to volume (14.75 mL) with sample. Cap, shake, and 

let samples stand 5 minutes.

Use aqueous calibration standards of 0, 5, 10, 50, 

and 100 ng/L Hg for analysis. Analyze samples 

7.

8.

9.

10.

11.

12.

13.

1.

2.

3.

 Determination of Mercury in Aqueous and Geologic Materials by CVAFS
using the same reagents and apparatus used for 

solids analysis.

Dilute and reanalyze any sample with mercury concentration exceeding the highest calibration standard 

(100 ng/L). To dilute the sample, take a 1.5-mL aliquot from the original sample and add it to a new 16- 

by 100-mm test tube containing 60 μL NH2OH·HCl. 

Bring to volume (14.75 mL) with reagent DI water. 

Cap, shake, and let stand for 5 minutes.

Analytical Procedure for Analysis of 

Samples for Mercury Using Continuous 

Flow−Cold Vapor−Atomic Fluorescence 

Spectrometry (CVAFS)

Mercury determination is fully automated using a 

Leeman HYDRA AF® CVAFS mercury analyzer (fig. 1). 

Prepared or digested samples are uncapped and loaded into 

4.

the instrument autosampler. The instrument is calibrated 

using matrix appropriate calibration standards, as explained 

in the previous section. For sample analysis, the instrument 

takes up a set volume of sample and mixes it with 5 percent 

SnCl2. This procedure results in any Hg (II) in the sample 

being reduced to Hg0. The solution is purged into the in-line 

phase separator of the instrument, and the liquid is separated from the mercury vapor. Ultrapure argon gas carries 

the vapor through a drying cell and introduces it into the 

fluorescence cell of the instrument. Mercury concentration 

is calculated by the instrument using the calibration curve 

and linear regression. Mercury concentration is reported in 

micrograms per kilogram for solids, and in nanograms per 

liter for aqueous samples.

Discussion of Results

As part of the validation process for the new methods, 

a series of reference standards and blanks were digested and 

analyzed using the described procedures. The results for 

analysis of the reference standards are listed in table 1.

Table 1. Analytical performance summary for determination of mercury by continuous flow–cold vapor−atomic fluorescence 

spectrometry (CVAFS)

[Mercury concentration for aqueous samples in nanograms per liter, solid-phase samples given in micrograms per kilogram; n, number of samples analyzed; s, 

standard deviation; pv, preferred value for the reference materials; Ref., Reference (footnote number); % RSD, percent relative standard deviation; %R, percent 

recovery; %R (new), percent recovery achieved using CVAFS and the new methods described in this paper; %R (old), percent recoveries achieved using 

CVAAS and the old dichromate method; ±, plus or minus; - -, not applicable]

Aqueous reference standard Type n Mean s pv Ref. %RSD %R

Hg 40 Water 9 62 - - 66(±2) -

2 - - 94

Hg 41 Water 9 46 - - 51(±7) -

2 - - 90

Geologic reference standard Type n Mean s pv Ref. %RSD %R (new) %R (old)

GXR-1 Jasperoid 9 4,100 117 3,900 -

1 2.8 105 103

GXR-2 Soil 9 2,900 148 2,900 -

1 5.1 99 107

GXR-3 Hot springs deposit 9 326 26 330 -

1 8.0 99 97

GXR-5 Soil 9 181 15 167 -

1 8.5 108 112

SGR-1 Shale 9 214 25 254 -

1 11.6 84 69

G-2 Granite 9 51 5.0 49 -

1 9.01 104 135

MESS 2 Marine sediment 9 79 9.3 92 -

4 11.8 86 - -

GDS 6 Steam sediment 9 47 10 45 -

3 21.4 104 - -

SRM 2709 Soil 9 1,500 37 1,400 -1 2.5 105 99

SRM 2711 Soil 9 6,200 180 6,250 -

1 2.9 100 94

Method blank results

Method blank n Mean s 3s 5s

Aqueous method 9 1.63 0.56 1.68 2.80

Geologic method 9 .071 .013 .039 .065

1

Brown, and others (2002).

2

U.S. Geological Survey (2006).

3

Govandaraju (1994).

4

Govandaraju (1989).

Discussion of Results   
Ten geologic reference standards were processed, digested, 

and analyzed using the methods described in this report. These 

standards represent a wide variety of geologic matrices. Percent 

recoveries for the six reference standards ranged from 84 to 108 

percent. Also listed in table 1 are the percent recoveries for the 

same reference materials that were digested and analyzed by the 

old procedures, which included the use of sodium dichromate 

(Brown and others, 2002). Two samples, MESS 2 and GSD 6, 

were not reported using the old procedure and thus no percent 

recoveries are listed for these materials.

Two aqueous reference standards were analyzed using the 

new procedures, and percent recoveries for the two samples 

were 94 and 90 percent, respectively. These reference samples 

were not preserved with dichromate so that no comparison can 

be made with the method that was previously used.

Overall, the new methods (geologic and aqueous) 

produce recoveries as good as, or better than, the dichromate 

methods that were previously used.

Blanks were digested and analyzed as part of the validation 

of the new procedures. Blanks for aqueous samples and solidphase samples were taken through all the procedures described 

herein and analyzed using CVAFS. Data for the blanks are listed 

in table 1. The value represented by three standard deviations 

is considered to be the lower limit of detection, and the value 

represented by five standard deviations is considered to be the 

lower limit of determination for the new methods.

Conclusion

New digestion and analytical methodology have been 

designed and tested for the determination of total mercury in 

geologic materials, and dissolved mercury in aqueous samples. 

These methods have been designed to replace the methods and 

procedures that are currently in use (2006) for these matrices. 

This study indicates that the new methods offer significant 

improvements over the procedures currently in use. The new 

methods eliminate the use of sodium dichromate as an oxidant 

and preservative, replacing it with concentrated hydrochloric 

acid and bromine monochloride. Eliminating the dichromate 

will result in a substantial cost savings because it will not have 

to be collected, stored, and disposed of as hazardous waste. 

The use of hydrochloric acid is also safer, less restrictive, and 

less expensive to ship to or from the field.

The new methods offer lower detection limits for solids 

and aqueous samples and update the instrumentation used for 

analysis. These improvements are achieved by replacing the 

traditional use of cold vapor–atomic absorption spectrometry 

(CVAAS) with cold vapor–atomic fluorescence spectrometry 

(CVAFS) for geologic and all aqueous samples, thus eliminating the two-tier system of analysis for aqueous samples, which 

previously required analysis by CVAAS and CVAFS.

The new methods will result in an increase in laboratory 

capacity and promote efficiency of the operator/analyst because 

a higher percentage of the submitted samples will be quantified for mercury. Benefit and production increases also will be 

seen by the submitter/investigator due to the generation of more 

geochemical data and increased sampling efficiency.

Finally, the new digestion procedures for geologic 

materials have been designed to use the same size test tubes, 

aluminum heating block, and hot plate as the current methods 

(2006) require. For aqueous samples, the new method for 

collection and processing require the use of the same collection procedures and equipment as have been used traditionally except that the samples are preserved with concentrated 

hydrochloric acid instead of sodium dichromate. Ultimately, 

for geologic and aqueous samples, these similarities will allow 

for relatively simple changeover to the new methods, and once 

implemented, the new methods will enhance, simplify, and 

provide substantial cost savings over the old methods.

References Cited

Brown, Zoe Ann, O’Leary, R.M., Hageman, P.L., and Crock, 

J.G., 2002, Mercury in water, geologic, and plant materials 

by continuous flow–cold vapor–atomic absorption spectrometry, in Taggart, J.E., Jr., Analytical methods for chemical analysis of geologic and other materials: U.S. Geological Survey Open-File Report 02-0223, Chapter M.

Garbarino, J.R., and Damrau, D.L., 2001, Methods of analysis 

by the U.S. Geological Survey National Water Quality Laboratory—Determination of organic plus inorganic mercury in 

filtered and unfiltered natural water with cold vapor–atomic 

fluorescence spectrometry: U.S. Geological Survey Water 

Resources Investigations Report 01-4132, 16 p.

Govandaraju, K., ed., 1989, 1989 Compilation of working 

values and sample description of 272 geostandards: Geostandards Newsletter, v. 13, Special Issue, 67 p.

Govandaraju, K., ed., 1994, 1994 Compilation of working values and sample descriptions for 383 geostandards: Geostandards Newsletter, v. 18, Special Issue, 158 p.

Hageman, P.L., 2002, Mercury in water samples by flow 

injection–cold vapor–atomic fluorescence spectrometry, in

Taggart, J.E., Jr., Analytical methods for chemical analysis 

of geologic and other materials: U.S. Geological Survey 

Open-File Report 02-0223, Chapter N.

U.S. Environmental Protection Agency, 2001, Appendix to 

Method 1631: Total mercury in tissue, sludge, sediment, 

and soil by acid digestion and BrCl oxidation: EPA 821-R01-013, 2001, 13 p.

U.S. Environmental Protection Agency, 2002, Method 1631, 

Revision E: Mercury in water by oxidation, purge, and trap, 

and cold vapor−atomic fluorescence spectrometry: EPA 

821-R-02-019, 2002, 38 p.

U.S. Geological Survey, 2006, Standard reference samples, 

Office of Water Quality, Branch of Quality Systems, Standard Reference Sample Project, accessed January 24, 2007, 

at URL http://qadata.cr.usgs.gov/srs_study/reports/index.php

 Determination of Mercury in Aqueous and Geologic Materials by CVAFS
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