Determination of arsenic in seaweed kelp tablets by hydride generation: inductively coupled plasma atomic emission spectroscopy (ICP- AES)
Year: 2004
Type: dissertation
Abstract: A study was carried out for the determination of arsenic in commercial seaweed kelp tablets by developing and optimizing a hydride generation method.The effects of pH and different reaction media were investigated.A continuous hydride generator that generates arsine using sodium borohydride as a reductant was coupled to an inductively coupled plasma atomic emission spectrometer as a detection system.L-cysteine was used as a pre-reductant agent.L-cysteine enhances the As (Ill) signal at low acid concentration and fulfills other functions (such as reducing interferences).Interference studies were undertaken in different reaction media.The methodology developed has a detection limit (based on 3a) of 0.6 J-Lg/I for As (Ill) in 0.1 M HCI reaction media and a relative standard deviation of 4 %.By following the established method, arsenic levels were investigated in microwave -digested, dry -ashed and wet -digested commercial seaweed kelp tablets samples and the results were compared.The microwave assisted digestion procedure was found to give the highest arsenic concentrations (81.90 J-Lg/g for Tablet A; 93.69 J-Lg/g for Tablet B).The open beaker wet digestion procedure gave values of 22.71 J-Lg/g for Tablet A and 37.15 J-Lg/g for Tablet B and the dry ashing procedure gave 4.63 J-Lg/g for Tablet A and 5.95 J-Lg/g for Tablet B.The microwave procedure was found to be the preferred digestion procedure due to its efficiency, rapid, convenient and less prone to contamination.ix Xll LIST OF TABLES xiii 6.10 Experimental Results for Citrate Buffered Media for As(III)(in p,g/g) in Wet Digested Kelp Tablets . . . . . . . . . . . . . . . . . . . . . . . . . .103 6.11 Experimental Results for the Two Commercial Seaweed Kelp Tablets for Total As (in p,g/g) and Recoveries (%) in the Three Digestion Procedures 104 agent is necessary to reduce As(V) to As(III).In this investigation L-cysteine is used as a pre-reducing agent.It has the advantage of enhancing signal at low HC1 concentration, reducing interferences from some elements and more importantly almost the same optimum response under the same HC1 concentration can be obtained for As(III) and As(V).8In order to achieve the separation of arsenic species a detailed investigation of differ-PS
Author: Daniel Teclu
Language: English
Subfield: Analytical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2135569608