The methods for arsenic speciation in hair currently available are scarce and highly time consuming, especially during sample preparation. This work presents alternative methods providing better recoveries and similar species distribution compared with established methods, but the extraction time is reduced from about 6 h to only a few minutes. First, several extraction media were studied and evaluated using ultrasound probe sonication. Either a solution of 0.5% performic acid or an enzymatic treatment (mixture of lipase and protease in aqueous media) was selected as the best treatment, which allowed us to reduce the extraction time to 5 or 10 min, respectively, achieving a slightly higher species recovery in the latter case. Second, a laboratorymade miniaturised device for pressurised liquid extraction is employed and compared with the previous methods. Initially, temperature, pressure and extraction time were optimised by applying chemometrics, in particular the use of a multivariate experimental design and analysis of variance. In order to improve the obtained results, additional variables such as type of solvent, particle size of dispersant medium and number of extraction cycles were further optimised. Optimum conditions were obtained using a mixture of 1% SDS and 5% isopropanol as extraction solvent at a temperature of 125 ºC and an applied pressure of 6 MPa for two cycles of 5 min each. The optimal particle size of dispersant was 35 micro-m. Total arsenic was determined by ICP-MS and the species present in hair were quantified by HPLC-ICP-MS. For method validation a Certified Reference Material (Human Hair GBW 07601) was used all throughout this study.
History
Publication title
Journal of Analytical Atomic Spectrometry
Volume
22
Pagination
131-139
ISSN
0267-9477
Publisher
Royal Soc Chemistry
Place of publication
Thomas Graham House, Science Park, Milton Rd, Cambridge, England, Cambs, Cb4 0Wf
Rights statement
Copyright 2007 The Royal Society of Chemistry
Repository Status
Restricted
Socio-economic Objectives
Public health (excl. specific population health) not elsewhere classified