Quantitative Determination of Selenium and Mercury, 

and an ICP-MS Semi-Quantitative Scan of Other 

Elements in Samples of Eagle Tissues Collected from 

the Pacific Northwest—Summer, 2011

Data Series 755

U.S. Department of the Interior

U.S. Geological Survey

Quantitative Determination of Selenium 

and Mercury, and an ICP-MS SemiQuantitative Scan of Other Elements in 

Samples of Eagle Tissues Collected from 

the Pacific Northwest—Summer, 2011

By Thomas May, Mike Walther, and William Brumbaugh

Data Series 755

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2013

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Suggested citation:

May, T.W., Walther, M.J., and Brumbaugh, W.G., 2013, Quantitative determination of selenium and mercury, and an ICPMS semi-quantitative scan of other elements in samples of eagle tissues collected from the Pacific Northwest—Summer 2011: U.S. Geological Survey Data Series 755, 3 p.
iii

Contents

Sample History ...............................................................................................................................................1

Methods...........................................................................................................................................................1

Non-Chemical Preparation .................................................................................................................1

Chemical Preparation ..........................................................................................................................1

Instrumental Analysis...........................................................................................................................1

Quality Control.......................................................................................................................................2

Results and Discussion.................................................................................................................................2

Quality Control................................................................................................................................................2

Calibration..............................................................................................................................................2

Control Materials ..................................................................................................................................2

Analytical and Method Precision.......................................................................................................3

Spikes......................................................................................................................................................3

Blank Equivalent Concentrations.......................................................................................................3

Instrument Detection, Method Detection, and Method Quantitation Limits...............................3

Reference Cited..............................................................................................................................................3

Sample History 

A group of 182 eagle tissue samples was received by the 

inorganic section of the Columbia Environmental Research 

Center (CERC) on August 18, 2011, consisting of liver [number (n)=26], kidney(n=25), brain (n=23), talon (n=25), feather 

(n=25), femur (n=25), humerus (n=25), and stomach contents 

(n=8). The samples originated from frozen eagle carcasses 

collected from the Pacific Northwest. The sample group was 

assigned Batch 1936 and CERC identifications 55117-55297, 

and Batch 2052 for 57302. This sample collection was part 

of a study to document the occurrence of metal and metalloid 

contaminants in tissues of eagle carcasses. These tissues were 

to be quantitatively analyzed for concentrations of selenium 

(Se) and mercury (Hg), and for other elements by semiquantitative scan (TotalQuantTM) with an inductively coupled 

plasma-mass spectrometer (ICP-MS).

Methods

Non-Chemical Preparation 

All eagle tissue samples were lyophilized with a Virtis 

GenesisTM 35EL lyophilizer, and percent moisture was 

determined as part of the lyophilization process. Following 

lyophilization, talon, humerus, femur, feather, and stomach 

content samples were further homogenized by freezing them 

in liquid nitrogen followed by cryogenic grinding using a 

Spex 6850 Freezer MillTM. After cryogenic grinding, samples 

once again were lyophilized to remove any residual moisture 

obtained during grinding. Cryogenically ground samples had 

the appearance of a fine dry powder. Dried liver, brain, and 

kidney samples were placed in a glass scintillation vial and 

ground to a coarse powder consistency with a glass rod. All 

dried and homogenized samples were stored in sealed glass 

vials in a desiccator until time of further processing.

Chemical Preparation

To prepare digestates of talon, femur, humerus, and 

feather eagle tissues suitable for semi-quantitative scan by 

ICP-MS, an aliquot part of each dried sample, ranging from 

approximately 0.2 to 0.25 grams (g), was heated with a mixture of nitric acid, hydrochloric acid, and hydrogen peroxide in a sealed TeflonTM medium pressure microwave oven 

(Perkin-Elmer MultiwaveTM). The cooled digestate liquid was 

transferred into a 125 milliliter (mL) polyethylene bottle with 

ultrapure water [greater than (>) 10 megohms per centimeter] 

to a final volume of 100 mL. Final acid matrix was 6 percent 

nitric acid and 1 percent hydrochloric acid. Similarly, aliquots 

of dried brain, kidney, and liver samples (approximately 

0.2 g) were heated with nitric acid in a CEM MARSExpressTM 

microwave oven, with a final acid matrix of 6 percent nitric 

acid and a 100 mL digestate volume. An additional tissue 

aliquot (approximately 0.5 g) of each dried tissue sample was 

subjected to a dry ashing procedure with a magnesium nitrate 

and nitric acid dry ashing procedure, followed by a hydrochloric acid reduction for the determination of Se. The dry ashing 

procedure consisted of three steps: boiling with nitric acid 

for solubilization and partial oxidation, 500 o

C ashing with 

magnesium nitrate to complete the oxidation and decompose 

remaining organic matter, and heating with HCl to dissolve 

the ash and reduce Se to the Se+4 oxidation state required for 

hydride generation. Following reduction, digestates were 

diluted to ~100 mL with deionized water, yielding a final acid 

matrix of 10% hydrochloric acid. 

For the determination of Hg in eagle tissue samples, there 

was no chemical preparation (digestion) because the dried 

sample was thermally decomposed during the analysis (see 

Instrument Analysis section below). 

Instrumental Analysis

To perform a scan of elements (excluding Se and Hg), 

samples were analyzed by ICP-MS using the semi-quantitative scan mode (TotalQuantTM). This scanning mode has a 

Quantitative Determination of Selenium and Mercury, and 

an ICP-MS Semi-Quantitative Scan of Other Elements 

in Samples of Eagle Tissues Collected from the Pacific 

Northwest—Summer, 2011

By Thomas May, Mike Walther, and William Brumbaugh 
2 Quantitative Determination of Selenium and Mercury, and an ICP-MS Semiquantitative Scan of Other Elements

manufacturer’s reported accuracy of +30 percent to 

+50 percent. All samples were diluted 10X by a CETAC 

ASD-500 autodiluter as part of the analytical sequence. 

Internal standards were scandium (10ppb), rhodium (10ppb), 

and thorium (10ppb), and the external standard consisted of an 

NIST traceable reference solution (Trace Metals in Drinking 

Water; High Purity Standards, Charleston, South Carolina) to 

which five elements (praseodymium, terbium, thulium, tantalum, and gold) were added for improved calibration in the rare 

earth region of the mass spectral range. 

Mercury was determined with a direct mercury analyzer. 

With this method, a dried eagle tissue sample (approximately 

10–80 mg) was combusted in a stream of oxygen. All Hg in 

the sample was volatilized and trapped by amalgamation on 

a gold substrate, and was thermally desorbed and quantified 

by atomic absorption spectrophotometry (U.S. Environmental 

Protection Agency, 2003). The entire sequence was conducted 

with a Milestone DMA-80TM analyzer equipped with an automated sample carousel.

The determination of Se in dry-ashed samples was 

accomplished by flow injection hydride generation atomic 

absorption spectroscopy. In this procedure, the digestate is 

mixed with a hydrochloric acid carrier solution and then 

reduced by sodium tetrahydridoborate that has been stabilized 

with sodium hydroxide. The resulting volatile hydrogen selenide is transferred with argon carrier gas into a heated quartz 

cell mounted on an atomic absorption spectrophotometer for 

decomposition and measurement. 

Quality Control

Samples were processed through the preparative and 

analytical flow scheme in eight analytical blocks or groups 

for the semi-quantitative scan, eight blocks for Hg, and eight 

additional blocks for preparation of samples for Se. Each 

block was identified by assigning a block initiation date (BID). 

Quality control included in each BID depended on the final 

instrumental approach. For digestion of eagle tissues for the 

ICP-MS scan, quality control included digestion blanks, reference solutions and materials, sample replicates, and sample 

spikes. Quality-control parameters for sample analysis by an 

ICP-MS scan included running the single calibration standard 

as a sample, a measurement of precision by repeated runs of a 

reference solution, the analysis of independent-source laboratory control samples, and within-run monitoring of changes in 

the internal standards. For samples analyzed by atomic absorption (Se), predigestion quality control included digestion 

blanks, replicates, spikes, and reference solutions and materials. Analytical quality control for Se included calibration verification solutions and analysis spikes. For direct analysis of Hg 

in tissue by thermal combustion, amalgamation, and atomic 

absorption spectroscopy (DMA-80), quality control included 

calibration verification solutions, reference tissues, replicates, 

method spikes, and blanks. All quality-control results were 

tabulated to provide an overview of quality assurance and to 

facilitate interpretation.

Results and Discussion 

Total recoverable concentrations of elements in eagle 

tissues, determined by ICP-MS semi-quantitative scan, are 

indicated in tables 1–8 in the Excel spreadsheet ds755_tables. 

For the various tissue matrices analyzed by an ICP-MS semiquantitative scan, some elemental concentrations were quite 

variable within a particular matrix; notable observations were 

as follows: Lead concentrations (μg/g dry weight) ranged from 

0.2 to 31 in femurs, 0.1 to 29 in humeri, 0.1 to 54 in talons, 

<0.05 to 120 in livers, <0.05 to 34 in kidneys, and 0.05 to 8 in 

brains; copper concentrations (μg/g dry weight) ranged from 

5 to 9 in feathers, 8 to 47 in livers, 7 to 43 in kidneys, and 7 

to 28 in brains; cadmium concentrations (μg/g dry weight) 

ranged from 0.1 to 10 in kidneys. In stomach contents, concentrations (μg/g dry weight)of vanadium ranged from 0.08 

to 5, chromium 2 to 34, manganese 1 to 57, copper 2 to 69, 

arsenic <0.05 to 6, rubidium 1 to 13, and barium <0.5 to 18. 

Measured concentrations of Se and Hg determined by 

quantitative atomic absorption techniques are indicated in 

tables 9–11 in the Excel spreadsheet ds755_tables. For selenium concentrations in eagle tissues (table 9), concentrations 

(μg/g dry weight) from highest to lowest based on the matrix 

mean were as follows: kidney, liver, feather, brain, stomach 

content, talon, femur, and humerus. For mercury (tables 10 

and 11) the highest to lowest concentrations were feather, 

liver, talon, brain, stomach content, femur, and humerus.

Note that the Se and Hg data in this report were produced 

using quantitative techniques, but all remaining data were produced usng a semi-quantitative technique. Because of greater 

imprecision and inaccuracy, any elemental values of concern 

found from the semi-quantitative scan require verification with 

a quantitative sample analysis.

Quality Control

Calibration

Periodic runs of a laboratory control solution served to 

monitor calibration throughout the semi-quantitative scan 

for fish tissue (tables 12–19 in the Excel spreadsheet ds755_

tables. In addition, separate calibration solutions also were 

analyzed at the beginning of each run, which exhibited recoveries ranging from 75% to 135% (tables 20–27 in the Excel 

spreadsheet ds755_tables. For Se and Hg, a calibration check 

solution was analyzed at the beginning and end of the analytical runs (table 28 in the Excel spreadsheet ds755_tables).

Control Materials

Results from the analysis of control materials are indicated in tables 29–41 in the Excel spreadsheet ds755_tables. 

Numerous tissue reference and research materials analyzed 
Reference Cited 3

by ICP-MS semi-quantitative scan (tables 29–37) exhibited 

recoveries mostly ranging from 80% to 120%. Poorer recoveries were evident for some materials, particularly those that 

contained low levels of Cr and Pb. Recoveries of elements 

from various reference and research materials, digested and 

analyzed in conjunction with the determination of Se by 

quantitative flow injection atomic absorption spectroscopy and 

determination of Hg by thermal combustion and amalgamation 

atomic absorption spectroscopy, are shown in tables 38–41. 

Recoveries were well within 80% to 120%.

Analytical and Method Precision

Analytical precision for the semi-quantitative scan 

on digestates of eagle tissue samples was estimated by 

repeated runs of a reference solution, which exhibited percent 

relative standard deviation (%RSD) values of ≤20 percent 

(tables 12–19). Internal standards differed by ≤31 percent from 

the beginning to the end of the analytical runs (table 42 in the 

Excel spreadsheet ds755_tables, except for Sc in femur and 

humerus matrices, which exhibited more change exacerbated 

by high Ca content. Instrumental precision for Se and Hg, 

determined by repeated analysis of a standard throughout the 

runs, was <4 percent RSD (table 43 in the Excel spreadsheet 

ds755_tables. A duplicate analysis of digestates from each 

matrix produced relative percent differences (RPDs) of <2 percent (table 44 in the Excel spreadsheet ds755_tables. Method 

precision for eagle tissues was determined by triplicate 

digestion and analysis of a sample (tables 45–53 in the Excel 

spreadsheet ds755_tables). Triplicate digestion and analysis 

of eagle tissue samples analyzed by ICP-MS semi-quantitative 

scan (tables 45–52) exhibited percent RSDs generally ≤30 percent for most elements in most matrices. Replicate digestion 

and analysis of samples for Hg and Se determination produced 

percent RSDs ≤13 percent (table 53). 

Spikes

Recoveries of elements spiked into eagle tissue samples 

prepared for the semi-quantitative scan are presented in tables 

54–61 in the Excel spreadsheet ds755_tables. Recoveries 

ranged from 80 percent to 130 percent for most elements, 

with the exception of higher recoveries for Be (132 percent 

to 160 percent), and one case of a low recovery for V

(71 percent). Samples of eagle tissue spiked with Hg and Se 

exhibited recoveries ranging from 88 percent to 113 percent 

(tables 62 and 63 in the Excel spreadsheet ds755_tables. 

Recoveries of Se in analysis (post-digestion) spikes ranged 

from 97 percent to 110 percent (table 64 in the Excel spreadsheet ds755_tables. 

Blank Equivalent Concentrations

Blank equivalent concentrations (BEC) were computed 

for digestion blanks analyzed with each set of eagle tissue 

samples (tables 65–72 in the Excel spreadsheet ds755_tables. 

For most elements determined by ICP-MS semi-quantitative 

scan, BECs generally were below the reporting limits of the 

semi-quantitative scan (“less than” values of 0.04, 0.05, 0.4, 

or 0.5 μg/g dry weight). For those eagle tissues that were 

subjected to cryogenic grinding, quartz chips were ground and 

digested to simulate elements that might be picked up from 

grinding a hard material (tables 73 and 74 in the Excel spreadsheet ds755_tables. Mean BECs for Se and Hg are indicated 

in tables 75 and 76 in the Excel spreadsheet ds755_tables; all 

BECS were below their respective method detection limits 

except for one case of Se (eagle talon; 0.006 μg/g dry weight; 

table 75). 

Instrument Detection, Method Detection, and 

Method Quantitation Limits

Instrument detection limits for Se determined by flow 

injection hydride generation atomic absorption spectroscopy 

and Hg by thermal combustion/amalgamation atomic absorption spectroscopy are indicated in table 77 (Excel spreadsheet 

ds755_tables), whereas method detection and quantitation limits are indicated in table 78 (Excel spreadsheet ds755_tables). 

Overall, quality-control results were acceptable based on 

specifications established by CERC.

Reference Cited

U.S. Environmental Protection Agency, 2003. Test Methods: 

SW-846 Manual, Draft Update IVA, 7000 Series, Method 

7473, “Mercury in Solids and Solutions by Thermal 

Decomposition, Amalgamation, and Atomic Absorption 

Spectrophotometry”, 17 pages, February 5, 2013, at http://

www.epa.gov/sam/pdfs/EPA-7473.pdf.
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For more information concerning this publication, contact:

Director, USGS Columbia Environmental Research Center

4200 New Haven Road

Columbia, MO 65201

(573) 875–5399

Or visit the Columbia Environmental Research Center Web site at:

http://www.cerc.usgs.gov/

Thomas May and others—Quantitative Determination of Selenium and Mercury, and an ICP-MS Semi-Quantitative Scan of Other Elements—Data Series 755