Low-Pressure Arsenic Speciation using the SC-DX chromFAST System with ICPMS Detection

Arsenic occurs in both organic and inorganic forms in the environment. Groundwater, for example, often contains inorganic species such as arsenite and arsenate from rock dissolution as well as organic species from agricultural and industrial runoff. Identifying which arsenic species are present in a sample can help determine the source of contamination.

Elemental Scientific's chromFAST arsenic speciation kit, coupled with the SC-DX FAST automated sampling system, is an economical and easy-to-use system that uses a peristaltic pump for low-pressure speciation, allowing researchers to detect a number of As species in a sample.

Instrumentation, Sample Introduction, and ICPMS Parameters

  • ESI chromFAST speciation kit (CF-KIT-As35) with the As anion exchange column (CF-As-01)
  • periSPEC software (ES-2999-4001)
  • Thermo Scientific ELEMENT2 ICPMS
  • Carrier flow rate: 170 µL/min
  • Sample Volume: 20 µL

Using an existing SC-DX FAST system, samples and standards are loaded into the sample loop via the PTFE vacuum pump. Once loaded, the valve switches and the peristaltic pump pushes the sample through the column for 7 seconds, introducing 20 µL of the sample into the column. The As species are separated on the column using a step gradient process and then nebulized using a low dead volume PFA-ST nebulizer.

Data Analysis
The collected data are analyzed with the ESI periSPEC Peak Area Finder software.This simple and relatively inexpensive software utilizes an Excel-based spreadsheet to integrate the chromatographic peak areas. The resulting data can then be used for calibration and determination of As species.

Spike Recovery Studies
Spike recoveries were measured by spiking 5 ppb each of DMA, As(III), MMA, and As(V) into a groundwater sample (Table 1). Spike recoveries ranged from 100% to 115%.

Table 1. Arsenic species spike recovery data from high mineral content groundwater sample (HMGW).
DUP = Duplicate; MS = Matrix Spike; MSD = Matrix Spike Duplicate.

Table 2.Arsenic speciation in high mineral content groundwater samples.

The chromFAST low-pressure anion exchange arsenic speciation kit (CF-KIT-As35) and SC-DX FAST system for ICPMS is an economical alternative to HPLC-ICPMS systems. The fully-automated and easy-to-use system produces quick separations, as fast as four minutes for inorganic As species. The flexible system can switch between multi-element ICPMS sample analysis to elemental speciation detection modes in minutes. The unique periSPEC peak finder software provides a straightforward method for data analysis. The robust anion exchange column can be used for multiple samples and efficiently separates As species in difficult matrices, providing a cost-effective solution for As speciation needs.

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The SC-2 DX FAST Low-Pressure Elemental Speciation System

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