USGS-NWQL: I-2198-21: Four arsenic species (As(III), As(V), dimethylarsinate (DMA), and monomethylarsonate (MMA) in water by LC/ICP-MS/MS

Summary
Analytes
Revision
Data and Sites

Official Method Name

Determination of Four Arsenic Species in Environmental Water Samples by Liquid Chromatography with Inductively Coupled Plasma-Tandem Mass Spectrometry (LC/ICP-MS/MS)

Current Revision

USGS I-2198-21

Media

WATER

Instrumentation

Liquid Chromatography with Inductively Coupled Plasma-Tandem Mass Spectrometry

Method Subcategory

Organic+Inorganic

Method Source

USGS-NWQL

Citation

Stetson, S.J., Lawrence, C., Whitcomb, S., and Kanagy, C., 2021, Determination of four arsenic species in environmental water samples by liquid chromatography- inductively coupled plasma - tandem mass spectrometry: MethodsX, v. 8, p. 101183.

Brief Method Summary

This method optimizes liquid chromatography with an anion exchange column and a nitrate/phosphate mobile phase coupled with inductively coupled plasma - tandem mass spectrometry to analyze As(III), As(V), dimethylarsinate (DMA), and monomethylarsonate (MMA) in environmental water.

Scope and Application

This method covers the analysis of arsenic species As(III), As(V), dimethylarsinate (DMA), and monomethylarsonate (MMA) in surface water and groundwater samples.

Applicable Concentration Range

Tens of ng/L to 50 μg/L without dilution of the sample.

Interferences

(A) Interference on 75As+ from 40Ar35Cl+, 150Nd2+ and 150Sm2+ that also have m/z of 75. In the ICP-MS/MS analysis, mass 75 is isolated in quadrupole (Q)1 and then transmitted into a reaction cell where As is reacted with oxygen to form AsO+. AsO+ at mass 91 is then isolated in Q2 and transmitted to the detector. (B) The presence of significant concentrations of other organo-As species in surface water and groundwater samples. Spiking and dilution of samples with co-eluting peaks can help to confirm a peak as the analyte of interest and better resolve the peaks.

Quality Control Requirements

Single analyte primary stock standard solutions, Standard reference material (SRM) 3030 (MMA) and SRM 3031 (DMA) primary stock standards, Germanium solution, mixed intermediate calibration solution, mixed working standards, working calibration standards, intermediate calibration standards, continuing calibration verifications (CCVs), intermediate calibration verifications (ICVs), limit of quantitation standard (LOQ), blind blanks, carryover reagent-blanks, reagent spikes, field matrix spikes, laboratory duplicates, laboratory spike duplicates, and field duplicates.

Sample Handling

Samples are filtered in the field using a 0.45 μm filter into 10 mL opaque polyethylene bottles that contained 100 μL of 250 mM EDTA preservative to yield a final concentration of 2.5 mM EDTA in the sample. Bottles were filled to the shoulder with sample. All samples were stored at 4 °C ± 2 until analysis.

Maximum Holding Time

15 days (As species in surface water and groundwater, molar excess of EDTA, 4 ◦C, dark. Fe concentration < 1 mg/L)

Relative Cost

$201 to $400

Sample Preparation Methods

This method has 4 analytes associated with it.

Analyte	Detection Level	Bias	Precision	Spiking Level
As(III)(15502-74-6) Arsenic 3+ Arsenic III Arsenide As(III) As(III) arsenite ion arsenite(3-) trioxidoarsenate(3-)	0.030 ug/L	103% Rec	5.10 % RSD	0.50 ug/L
As(V)(15584-04-0) Arsenate (AsO43-) Arsenate ion Arsenic 5+ Arsenic V As(V) As(V)	0.050 ug/L	103% Rec	6.40 % RSD	0.50 ug/L
Dimethylarsenic Acid(75-60-5) Agent Blue Ansar 138 Arsan Arsine oxide, hydroxydimethyl-; Cacodylic acid DMA DMAA Dilic Dimethylarsenic Acid Phytar 138 Phytar 560 Rad-E-Cate 25 Silvisar 510 arsinic acid, dimethyl- cacodylic acid hydroxy-dimethylarsine oxide	0.030 ug/L	103% Rec	4.60 % RSD	0.50 ug/L
Methylarsonic Acid(124-58-3) Arsenic Acid, Methyl MAA MMAA Methylarsonic Acid monomethylarsonic acid	0.040 ug/L	104% Rec	5.10 % RSD	0.50 ug/L

Precision Descriptor Notes:	Method precision and bias were determined in ultrapure water, surface water, groundwater and a reference material. The 0.5 μg/L CCVs that were analyzed as routine QC throughout the method performance studies were included as ultrapure water samples in the precision and bias study along with the ultrapure water spike at 40 μg/L, and the surface water and groundwater spikes. Any spike data from the precision and bias study that were bracketed by QC that did not meet the QC acceptance criteria were omitted from the bias and variability analysis. Therefore, the number of replicates used varies. Mean recoveries of all As species in the LOQ, CCV, and ICV were determined over a seven-month period. Recovery of MMA was determined in NIST SRM 3030 and of DMA in NIST SRM 3031. An ultrapure water spike consisting of 40 μg/L of each As species was formulated in 2.5 mM EDTA using the same stock standards as used for preparing calibrators. Two surface water and two groundwater samples were prepared separately for the precision and bias studies. The concentration of As species in each sample was measured using the LC/ICP-MS/MS method described above. One surface water was spiked with all four As species to achieve approximate final concentrations of 0.3 μg/L of each As species and a second surface water was spiked with all four As species to achieve approximate final concentrations of 40 μg/L of each As species. One groundwater was spiked to achieve approximate final concentrations of 0.5 μg/L of each As species and a second groundwater was spiked to achieve approximate final concentrations of 40 μg/L of each As species. The exact concentration of each species in the final spiked solution are reported elsewhere. The spike concentrations were used to calculate percent recoveries of each species in the three matrices. Arsenic speciation concentrations in these spiked surface water and groundwater samples were determined during at least four separate analysis events over a three-month time period in order to characterize method bias and variability. Up to four replicates were measured in a single batch.
Detection Level Note:	The detection limit (DL) was determined using the Environmental Protection Agency spike and blank based procedures (USEPA, 2016, see method reference list). LOQ and blank measurements made over the course of seven months were used in the DL calculation procedure. The blank-based DL was lower than the spike-based DL (see supplemental material). Detection limits, reporting limits, and upper dilution limits are tabulated in the supplemental material. Data between the detection limit and reporting limit were reported as the measured value with a qualifier. Data below the detection limit were reported as less than the reporting limit (Williams and others, 2015, see method reference list).

Precision Descriptor Notes:

Method precision and bias were determined in ultrapure water, surface water, groundwater and a reference material. The 0.5 μg/L CCVs that were analyzed as routine QC throughout the method performance studies were included as ultrapure water samples in the precision and bias study along with the ultrapure water spike at 40 μg/L, and the surface water and groundwater spikes. Any spike data from the precision and bias study that were bracketed by QC that did not meet the QC acceptance criteria were omitted from the bias and variability analysis. Therefore, the number of replicates used varies. Mean recoveries of all As species in the LOQ, CCV, and ICV were determined over a seven-month period. Recovery of MMA was determined in NIST SRM 3030 and of DMA in NIST SRM 3031. An ultrapure water spike consisting of 40 μg/L of each As species was formulated in 2.5 mM EDTA using the same stock standards as used for preparing calibrators. Two surface water and two groundwater samples were prepared separately for the precision and bias studies. The concentration of As species in each sample was measured using the LC/ICP-MS/MS method described above. One surface water was spiked with all four As species to achieve approximate final concentrations of 0.3 μg/L of each As species and a second surface water was spiked with all four As species to achieve approximate final concentrations of 40 μg/L of each As species. One groundwater was spiked to achieve approximate final concentrations of 0.5 μg/L of each As species and a second groundwater was spiked to achieve approximate final concentrations of 40 μg/L of each As species. The exact concentration of each species in the final spiked solution are reported elsewhere. The spike concentrations were used to calculate percent recoveries of each species in the three matrices. Arsenic speciation concentrations in these spiked surface water and groundwater samples were determined during at least four separate analysis events over a three-month time period in order to characterize method bias and variability. Up to four replicates were measured in a single batch.

Detection Level Note:

The detection limit (DL) was determined using the Environmental Protection Agency spike and blank based procedures (USEPA, 2016, see method reference list). LOQ and blank measurements made over the course of seven months were used in the DL calculation procedure. The blank-based DL was lower than the spike-based DL (see supplemental material). Detection limits, reporting limits, and upper dilution limits are tabulated in the supplemental material. Data between the detection limit and reporting limit were reported as the measured value with a qualifier. Data below the detection limit were reported as less than the reporting limit (Williams and others, 2015, see method reference list).

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USGS I-2198-21

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USGS-NWQL: I-2198-21: Four arsenic species (As(III), As(V), dimethylarsinate (DMA), and monomethylarsonate (MMA) in water by LC/ICP-MS/MS

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