Lauren Jackson - Trace Metal Biogeochemistry

Marist College, Poughkeepsie, NY

Comparison of Analytical Methods for the Speciation and Quantification of
Arsenic in Environmental Samples

Various analytical methods were modified and evaluated to identify their advantages and disadvantages for speciation of the four most common arsenic compounds: arsenite (As III), arsenate (As V), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA).   Environmental samples analyzed were riverine water, estuarine water, and suspended particulate matter.  Using Cryogenic-Trapping Hydride Generation Atomic Absorption Spectroscopy (CT-HG-AAS) detection limits of 0.009 ppb for As III, 0.034 ppb for As V, 0.014 ppb for MMA, and 0.018 ppb for DMA were achieved.  An apparatus and methodology for High Performance Liquid Chromatography – Inductively Coupled Plasma – Mass Spectrometry (HPLC-ICP-MS) was created and optimized, respectively; detection limits of 0.076 ppb for As III, 0.074 ppb for As V, 0.072 ppb for MMA, and 0.057 ppb for DMA were achieved.  An apparatus and methodology for Hydride Generation – Cryogenic Trapping – ICP – MS (HG-CT-ICP-MS) was also created and optimized, respectively; detection limits of 0.447 part per trillion for As III, 0.752 ppt for As V, 0.507 ppt for MMA, and 0.137 ppt for DMA.  Analytical concerns such as time and ease of analysis, detection limits, and cost-efficiency were examined and compared across the three methods. 

This research project was presented as a poster at the 58th Pittsburgh Conference on Analytical Chemistry & Applied Spectroscopy in Chicago, Illinois.

Funding provided by the National Science Foundation – Research Experience for Undergraduates (REU)