Techniques and Methods 5-B1
Prepared by the USGS Office
of Water Quality
National Water Quality Laboratory
Determination
of Elements in Natural-Water,
Biota, Sediment, and Soil Samples Using Collision/Reaction Cell Inductively
Coupled
Plasma–Mass Spectrometry
By John R.
Garbarino, Leslie K. Kanagy, and
Mark E. Cree
Chapter 1 of Book 5,
Laboratory Analysis
Section B, Methods of the National Water Quality Laboratory
Abstract
A new analytical method for the
determination of elements in filtered aqueous matrices using inductively
coupled plasma–mass spectrometry (ICP–MS) has been implemented at
the U.S. Geological Survey National Water Quality Laboratory that uses
collision/reaction cell technology to reduce molecular ion
interferences. The updated method can
be used to determine elements in filtered natural-water and other filtered
aqueous matrices, including whole-water, biota, sediment, and soil digestates. Helium
or hydrogen is used as the collision or reaction gas, respectively, to
eliminate or substantially reduce interferences commonly resulting from
sample-matrix composition. Helium is used
for molecular ion interferences associated with the determination of As, Co,
Cr, Cu, K, Mg, Na, Ni, V, W and Zn, whereas hydrogen is used for Ca, Fe, Se,
and Si.
Other elements that are not affected by molecular ion interference
also can be determined simply by not introducing a collision/reaction gas
into the cell. Analysis time is
increased by about a factor of 2 over the previous method because of the
additional data acquisition time in the hydrogen and helium modes.
Method detection limits for As,
Ca, Co, Cr, Cu, Fe, K, Mg, Na, Ni, Se, Si (as SiO2), V, W, and Zn, all of which use
a collision/reaction gas, are 0.06 microgram per liter (µg/L) As, 0.04
milligram per liter (mg/L) Ca, 0.02 µg/L Co, 0.02 µg/L Cr, 0.04 µg/L Cu, 1
µg/L Fe, 0.007 mg/L K, 0.009 mg/L Mg, 0.09 mg/L Na, 0.05 µg/L Ni, 0.04 µg/L
Se, 0.03 mg/L SiO2, 0.05 µg/L V, 0.03 µg/L W, and 0.04 µg/L Zn. Most method detection limits are lower or
relatively unchanged compared to earlier methods except for Co, K, Mg, Ni,
SiO2, and Tl, which are less than a factor of 2 higher.
Percentage bias for samples spiked
at about one-third and two-thirds of the concentration of the highest
calibration standard ranged from –8.1 to 7.9 percent for reagent water,
–14 to 21 percent for surface water, and –16 to 16 percent for
ground water. The percentage bias for
reagent water spiked at trace-element concentrations of 0.5
to 3 µg/L averaged 4.4 percent with a range of –6 to 16 percent,
whereas the average percentage bias for Ca, K, Mg, Na, and SiO2 was 1.4 percent with a range of
–4 to 10 percent for spikes of 0.5 to 3 mg/L. Elemental results for aqueous standard
reference materials compared closely to the certified concentrations; all
elements were within 1.5 F-pseudosigma of the most
probable concentration. In addition,
results from 25 filtered natural-water samples and 25 unfiltered
natural-water digestates were compared with results
from previously used methods using linear regression analysis. Slopes from the regression analyses
averaged 0.98 and ranged from 0.87 to 1.29 for filtered natural-water
samples; for unfiltered natural-water digestates,
the average slope was 1.0 and ranged from 0.83 to 1.22. Tests showed that accurate measurements can
be made for samples having specific conductance less than 7,500 microsiemens per centimeter (µS/cm) without dilution;
earlier ICP–MS methods required dilution for samples with specific
conductance greater than 2,500 µS/cm.
Contents
Abstract
Introduction
Purpose
and Scope
Analytical Method
Application
and Method Detection Limits
Interferences
Instrumentation
Sample
Collection, Preservation, Shipment, and Holding Times
Calibration
Standards and Other Solutions
Quantitation
Reporting
of Analytical Data
Laboratory
Quality Assurance/Quality Control
Results and Discussion of Method Validation Data
Summary and Conclusions
References Cited
Glossary
Appendix — Linear Regression Analyses of Elemental
Results
Figures
1. The effect of
increasing concentrations of chloride from two sources on the determination
of arsenic at mass-to-charge ratio 75
2. The effect of
increasing concentrations of chloride from two sources on the determination
of vanadium at mass-to-charge ratio 51
3. The effect of
increasing concentrations of dissolved organic carbon from two natural-water
sources on the determination of chromium at mass-to-charge ratio 52
4. The variability
in percentage recovery for selected elements extending the operational mass
range as a function of increasing specific conductance
5. Sample-flow
paths used with new collision/reaction cell inductively coupled
plasma–mass spectrometric methods
6. Linear
regression analysis of experimental concentrations for all elements in
biological standard reference material digestates
analyzed by collision/reaction cell inductively coupled plasma–mass
spectrometry in relation to the certified concentrations
Appendix Figures
A1. —
A58. Linear Regression Analyses of
Elemental Results
Tables
1. Codes
for elements in water, biota, and sediment and for arsenic species in water
samples determined by collision/reaction cell inductively coupled
plasma–mass spectrometry
2. Method
detection limits for elements and species determined using collision/reaction
cell inductively coupled plasma–mass spectrometry
3. Potential
molecular ion interferences for elements determined using collision/reaction
cell inductively coupled plasma–mass spectrometry
4. Effectiveness
of using a collision/reaction cell gas for the elimination of molecular ion
interferences
5. Typical
operating characteristics for collision/reaction cell inductively coupled
plasma–mass spectrometry
6. Long-term
bias and variability of results from aqueous standard reference materials
using collision/reaction cell inductively coupled plasma–mass
spectrometry
7. Long-term
bias and variability for the analysis of reagent water spiked with analyte
concentrations in the lower one-third of the normal calibration range using
collision/reaction cell inductively coupled plasma–mass spectrometry
8. Long-term
bias and variability for the analysis of reagent water spiked with analyte
concentrations at one-third and two-thirds of the normal calibration range
using collision/reaction cell inductively coupled plasma–mass
spectrometry
9. Long-term
bias and variability for the analysis of surface water spiked with analyte
concentrations at one-third and two-thirds of the normal calibration range
using collision/reaction cell inductively coupled plasma–mass
spectrometry
10. Long-term bias and variability for the analysis of ground water
spiked with analyte concentrations at one-third and two-thirds of the normal
calibration range using collision/reaction cell inductively coupled
plasma–mass spectrometry
11. Linear regression results for filtered natural-water samples
analyzed using collision/reaction cell inductively coupled plasma–mass
spectrometry and other spectrometric methods
12. Linear regression results for unfiltered natural-water digestates analyzed using collision/reaction cell
inductively coupled plasma–mass spectrometry and other spectrometric methods
13. Bias and variability of results for digested biological standard
reference materials analyzed by collision/reaction cell inductively coupled
plasma–mass spectrometry
This document is available
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The citation
for this report, in USGS format, is as follows:
Garbarino,
J.R., Kanagy, L.K., and Cree, M.E., 2006,
Determination of elements in natural-water, biota, sediment, and soil samples
using collision/reaction cell inductively coupled plasma–mass
spectrometry: U.S. Geological Survey
Techniques and Methods, book 5, sec. B, chap. 1, 88 p.
For more information about the
National Water Quality Laboratory, contact:
Laboratory Chief
U.S. Geological Survey
National Water Quality Laboratory (NWQL)
P.O. Box 25046, Denver Federal Center
Building 95, MS 407
Denver, CO 80225-0046
Or access the NWQL home page at:
http://wwwnwql.cr.usgs.gov/USGS
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