USGS-NWQL: I-1472-87: Metals in Water by ICP

Summary
Analytes
Revision
Data and Sites

Official Method Name

Metals, Atomic Emission Spectrometry, Inductively Coupled Plasma (ICP)

Current Revision

1987

Media

WATER

Instrumentation

Inductively Coupled Plasma - Atomic Emission Spectroscopy

Method Subcategory

Inorganic

Method Source

USGS-NWQL

Citation

Methods for the Determination of Inorganic Substances in Water and Fluvial Sediments, Techniques of Water-Resources Investigations of the United States Geological Survey, Book 5, Chapter A1 Edited by Marvin J. Fishman and Linda C. Friedman

Brief Method Summary

All metals are determined simultaneously on a single sample by a direct-reading emission spectrometric method using an inductively coupled argon plasma as an excitation source. Samples are pumped into a crossflow pneumatic nebulizer, and introduced into the plasma through a spray chamber and torch assembly. Each analysis is determined on the basis of the average of three replicate integrations, each of which is background corrected by a spectrum shifting technique except for lithium (670.7 nm) and sodium (589.0 nm). A series of five mixed-element standards and a blank are used for calibration. Detection limits vary by species; see the published method for detection limits for each species.

Scope and Application

This method is used only for the determination of dissolved metals in water samples that have a measured specific conductance of less than 2,000 uS/cm at 25 deg C. Samples containing analyte concentrations greater than the maximum concentration limit can be analyzed for calcium, magnesium, silica, and sodium if the sample is diluted and if, after dilution, the specific conductance is less than 2,000 uS/cm. Trace metals also can be determined after appropriate dilution in samples that have a measured specific conductance greater than 2,000 uS/cm; however, detection levels and sensitivity will change proportionally. This modified method was implemented in the National Water Quality Laboratory In August 1987.

Applicable Concentration Range

1 - 10000 (undiluted)

Interferences

Several interelement interference effects have been evaluated. Interelement correction factors are programmed into the Thermo Jarrell-Ash system software, and corrections are automatically applied internally to the data before they are printed. Samples containing high dissolved solids show a variety of unidentified interference effects. Therefore, analyses need to be limited to samples with a specific conductance of 2,000 uS/cm or less.

Quality Control Requirements

Method blanks, reagent spikes, surrogate spikes, certified reference material samples, continuing calibration verification standards, field blanks, field replicates, matrix spikes and matrix spike duplicates, quarterly control samples and Branch of Quality Assurance samples are analyzed. Data from these are compiled to continually monitor the QA/QC of the analysis. Each analyst must undergo technical and ethics training, perform an initial demonstration of capability, and annually demonstrate continuing capability on an analysis. Additional QA/QC practices may be added.

Sample Handling

Maximum Holding Time

180 days from sampling

Relative Cost

Less than $50

Sample Preparation Methods

This method has 20 analytes associated with it.

Analyte	Detection Level	Bias	Precision
Barium(7440-39-3) Ba Barium	1.000 ug/L	N/A	N/A
Beryllium(7440-41-7) Be Beryllium Glucinium	0.500 ug/L	N/A	N/A
Cadmium(7440-43-9) Cadmium Cd	1.000 ug/L	N/A	N/A
Calcium(7440-70-2) Ca Calcium	0.020 mg/L	N/A	N/A
Chromium(7440-47-3) Chromium Cr	5.000 ug/L	N/A	N/A
Cobalt(7440-48-4) Co Cobalt	3.000 ug/L	N/A	N/A
Copper(7440-50-8) Copper Copper (metallic) Cu	10.000 ug/L	N/A	N/A
Iron(7439-89-6) Fe Iron	3.000 ug/L	N/A	N/A
Lead(7439-92-1) Lead Lead and compounds (inorganic) Lead and lead compounds Pb	10.000 ug/L	N/A	N/A
Lithium(7439-93-2) Li Lithium	4.000 ug/L	N/A	N/A
Magnesium(7439-95-4) Magnesium Mg	0.010 mg/L	N/A	N/A
Manganese(7439-96-5) Manganese Mn	1.000 ug/L	N/A	N/A
Molybdenum(7439-98-7) Amperit 105.054 Amperit 106.2 EINECS 231-107-2 HSDB 5032 MChVL Metco 63 Mo Molybdenum Molybdenum, metallic TsM1	10.000 ug/L	N/A	N/A
Nickel(7440-02-0) Ni Nickel Nickel, soluble salts Raney Nickel (R)	10.000 ug/L	N/A	N/A
Silica(7631-86-9) Cab-O-Sil-St-2-0 Diatomaceous Earth SiO2 Silica Silicon dioxide Zeolex 7A	0.010 mg/L	N/A	N/A
Silver(7440-22-4) Ag Silver	1.000 ug/L	N/A	N/A
Sodium(7440-23-5) Na Natrium Sodium	0.200 mg/L	N/A	N/A
Strontium(7440-24-6) Sr Strontium	0.500 ug/L	N/A	N/A
Vanadium(7440-62-2) V Vanadium Vanadium (fume or dust)	6.000 ug/L	N/A	N/A
Zinc(7440-66-6) Zinc Zinc (fume or dust) Zinc and Compounds Zn	3.000 ug/L	N/A	N/A

Precision Descriptor Notes:	Single-operator precision for dissolved chromium samples is as follows: For Cr 11, 12, 18, 11 and 12 replicates were analyzed with mean recovery of 1.1, 10.9, 16.6, 19.7 and 24.6 ug/L and 1.2, 0.76, 1.0, 1.4 and 0.98 ug/L standard deviation with 109, 7, 6, 7 and 4 %-RSD, respectively. For Ni the values are: 12, 12, 9, 12 and 18 replicates with 10.6, 12.7, 19.8, 25.2 and 46.8 ug/L mean recoveries and 7.0, 4.1, 5.3, 3.3 and 4.2 ug/L standard deviation with 66, 32, 27, 13 and 9 %-RSD, respectively. For Ag the values are: 9, 12, 12 and 18 replicates with 0.37, 2.48, 3.87, 4.95 and 10.4 ug/L mean recoveries and 0.38, 0.52, 0.66, 1.5 and 1.8 ug/L standard deviation with 102, 21, 17, 30 and 17 %-RSD, respectively.
Detection Level Note:	The National Water Quality Laboratory (NWQL) has addressed the limitations of the USEPA Method Detection Limit (MDL) procedure outlined in 40 CFR 136, App. B. The NWQL recommends an alternative for determining MDL's and reporting limits. It's called the Long-Term Method Detection Limit (LT-MDL). The LT-MDL is designed to catch greater method variability because it requires a larger number of replicate spike samples - at least 24 per year, data be gathered over a longer period of time - 6 to 12 months, and incorporates more measurement variability inherent in routine sample analysis such as multiple instruments, operators, calibrations, blank contributions and sample preparation events. The LT-MDL is based upon key assumptions underlying the USEPA procedure. These are a normal frequency distribution, constant standard deviation, and best-case detection. LT-MDL's like MDL's are determined using spikes in a clean matrix. See USGS Open File Report 99-193 regarding the LT-MDL.

Precision Descriptor Notes:

Single-operator precision for dissolved chromium samples is as follows: For Cr 11, 12, 18, 11 and 12 replicates were analyzed with mean recovery of 1.1, 10.9, 16.6, 19.7 and 24.6 ug/L and 1.2, 0.76, 1.0, 1.4 and 0.98 ug/L standard deviation with 109, 7, 6, 7 and 4 %-RSD, respectively. For Ni the values are: 12, 12, 9, 12 and 18 replicates with 10.6, 12.7, 19.8, 25.2 and 46.8 ug/L mean recoveries and 7.0, 4.1, 5.3, 3.3 and 4.2 ug/L standard deviation with 66, 32, 27, 13 and 9 %-RSD, respectively. For Ag the values are: 9, 12, 12 and 18 replicates with 0.37, 2.48, 3.87, 4.95 and 10.4 ug/L mean recoveries and 0.38, 0.52, 0.66, 1.5 and 1.8 ug/L standard deviation with 102, 21, 17, 30 and 17 %-RSD, respectively.

Detection Level Note:

The National Water Quality Laboratory (NWQL) has addressed the limitations of the USEPA Method Detection Limit (MDL) procedure outlined in 40 CFR 136, App. B. The NWQL recommends an alternative for determining MDL's and reporting limits. It's called the Long-Term Method Detection Limit (LT-MDL). The LT-MDL is designed to catch greater method variability because it requires a larger number of replicate spike samples - at least 24 per year, data be gathered over a longer period of time - 6 to 12 months, and incorporates more measurement variability inherent in routine sample analysis such as multiple instruments, operators, calibrations, blank contributions and sample preparation events. The LT-MDL is based upon key assumptions underlying the USEPA procedure. These are a normal frequency distribution, constant standard deviation, and best-case detection. LT-MDL's like MDL's are determined using spikes in a clean matrix. See USGS Open File Report 99-193 regarding the LT-MDL.

Revision	PDF/Link
1987

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USGS-NWQL: I-1472-87: Metals in Water by ICP

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