A comparative study of chemical modifiers in the determination of total arsenic in marine food by tungsten coil electrothermal atomic absorption spectrometry

Determination of As, Cd, Cu, Hg and Pb in biological samples by modern electrothermal atomic absorption spectrometry

“…However, if inadequate equipment is used to conduct the acid digestion, unacceptable losses of analytes such as As and Hg may arise by volatilization. The widespread use of microwave assisted acid digestion with elevated pressure and temperature control has alleviated these problems [2,4,[7][8][9][10][12][13][14]17,20,[27][28][29]32,[35][36][37][38]41,43,[45][46][47][48][50][51][52][53][54][55][56][57][59][60][61][62][64][65][66]69,[71][72][73]76] and enabled the use of large sample masses (1-2 g) without the danger of vessel rupture and with a minimal chance for contamination. Microwave assisted processes are particularly important when the determination of As and Hg is targeted as complete mineralization of the sample can be achieved at low temperature preventing losses of these elements.…”

“…Moreover, attention must be paid to sources of contamination arising from use of concentrated acids and from containers used for the digestion process. Additionally, attention must be paid to the microwave assisted temperature and pressure program in order to achieve complete mineralization of all organoforms of the analytes as, for example, organoarsenicals can then be lost during the pyrolysis stage of the thermal program of atomizer [76]. When ultra pure acids and use of appropriate microwave digestion apparatus utilizing optimized programs, digestion using HNO 3 alone or with other acids provides the most comprehensive treatment compared to slurry sampling or simple leaching [10,31,53,54] if the aim is to determine the total analyte concentration.…”

“…As a consequence, lower detection limits have been successfully achieved. As recent examples, As has been successfully determined directly in acid digests, slurries or liquid-solid leachates [9,11,25,45,48,49,55,[59][60][61]64,70,73,76,97,102,154,163,176,177] and in biological fluids [45] with or without use of a modifier [75]. For direct liquid sampling, detection limits between 0.24 and 10 µg L − 1 were achieved.…”

“…The use of modifiers is especially pertinent to prevent volatilization of As during the pyrolysis stage. In most cases, modifiers such as Pd [59,177], Rh [76], (NH 4 ) 2 HPO 4 [70], Ir+Mg [104] and Pd/Mg(NO 3 ) 2 [9,25,48,52,61,69,70,73,97,132] have been applied. Pd + MgNO 3 is most commonly used and was proven to decrease interferences produced by phosphates [52] as well as allowing better thermal stability of As to yield the best results for digested marine tissues [25].…”

“…The citric acid evolved active gases and carbon during decomposition, facilitating creation of a favorable reduction atmosphere for the formation of a Rh-As alloy or intermetallic compounds which stabilized arsenic at high temperature [55,176]. A furnace coated with W [76] or Ir + Rh [55,97] has also been used as a modifier with good results for As in animal, plant and moss tissues.…”