Comparison of extraction procedures for the determination of arsenic and other elements in lobster tissue by inductively coupled plasma mass spectrometry

Abstract

A variety of extraction procedures were evaluated for the extraction of arsenic and other analytes from lobster tissue samples using inductively coupled plasma mass spectrometry (ICP-MS) detection. Soxhlet, room temperature mixing, sonication, microwave assisted, supercritical carbon dioxide and subcritical water extractions were evaluated for a variety of solvent systems and optimum conditions determined using a partially defatted Lobster Hepatopancreas marine certified reference material, TORT-2 (National Research Council of Canada). The solubility trends and solvents into which the analytes extracted gave an indication as to the polar/non-polar nature of the compounds present. Analytes that prefer water are probably more polar or inorganic, while those preferring methanol solutions are less polar or organic in nature. Arsenic, cadmium, cobalt, molybdenum and selenium were probably all present in TORT-2 in both polar inorganic and non-polar organic forms. While TORT-2 may have contained similar amounts of selenium in both forms, the results suggested that more of the arsenic was present as less polar or more organic compounds, and cobalt existed mainly as more polar or inorganic species. Most of the extraction techniques suggested that, although there may be some less polar organic forms present, more of the cadmium was probably present as polar inorganic compounds. Additionally, most techniques indicated that molybdenum was possibly all less polar or more organic in nature. In general, microwave assisted extraction (MAE) yielded comparable or improved recoveries for all of the analytes monitored and usually required less solvent. Additionally, MAE proved to be the mildest, fastest, least complicated and most reproducible extraction technique evaluated. MAE at 75 degrees C for 2 min exposure time yielded quantitative recovery of arsenic from TORT-2. These conditions were evaluated for lobster tissue samples purchased from a local restaurant. Separate evaluation of the lobster meat and organs resulted in quantitative recoveries of arsenic from both tissue samples. The results indicated that the extraction efficiencies might have some dependence upon the extraction technique, extraction conditions, analyte, solvent, and sample matrix.

Evaluation of microwave and ultrasound extraction procedures for arsenic speciation in bivalve mollusks by liquid chromatography–inductively coupled plasma-mass spectrometry

“…By considering only MAE, such significantly better As recovery was obtained by using pure water or a 1:1 methanol-water solution. These results accord with those found by other authors [34][35][36][37][38]. However, the efficiency of As-species extraction may vary from one laboratory to another.…”

An evaluation of extraction techniques for arsenic in staple diets (fish and rice) utilising both classical and enzymatic extraction methods

“…Classical extraction methods using water (Wahlen et al, 2004), a mixture of water/methanol (Nam et al, 2010) or methanol/water followed by extraction of arsenic species from the residue with 2% nitric acid (Whaley-Martin et al, 2013) have been used to extract arsenic species from marine species with variable extraction efficiencies. Water was used to extract arsenobetaine (AsB), arsenocholine (AsC), As III , DMA, MMA, As V from lobster tissue and TORT-2 with a total extraction efficiency for arsenic of between 67.6 -81.3 % (Brisbin & Caruso, 2002). Li et al (2003) used methanol water to extract arsenical species in fish and shellfish with an extraction efficiency of between 61-91 %, while Gomez-Ariza el al 2000achieved extraction efficiencies 76-96 % for arsenic species in seafood using a methanol extraction and 91-95 % using a water-methanol extraction agent.…”

Non-chromatographic atomic spectrometric methods in speciation analysis: A review

“…MWAE provides a technique whereby intact organic and organometallic compounds can be selectively extracted. Methods for the speciation of As [107,108] and Se [109] using MWAE are proposed in the literature. Most of them involve the use of HG coupled with AAS or ICP-MS, show adequate sensitivity and are fast and simple.…”