Determination Of Arsenic In Foods Research Articles

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

ABSTRACTEnzymatic extraction methods were evaluated with classical extraction approaches for the determination of arsenic in food. The extraction efficiency for total arsenic was determined by analysing CRM materials DORM-3 fish protein, NIES 106 rice flour and GBW10015 spinach. These were compared with total arsenic concentration determined using microwave-assisted acid digestion and ICP-MS. The total arsenic concentrations in the CRM materials were in good agreement with the certified values. Enzymatic hydrolysis using trypsin has been successfully employed to extract arsenic species in DORM-3 and fish samples. Whilst this method of hydrolysing the proteins worked well for the fish samples, an alternative approach was required to facilitate the digestion of cellulose in plant materials. However, enzymatic extraction using cellulase was found to give unsatisfactory results for both the NIES and GBW10015 CRM materials. Dilute nitric acid (1% HNO3) was found to give a more efficient extraction for arsenic species in the same CRM materials and rice samples. The study was extended to evaluate a range of real samples. Total arsenic concentrations in 13 different types of fish tissue were determined following microwave-assisted acid digestion using nitric acid/hydrogen peroxide, followed by measurement using HPLC-ICP-MS for speciation analysis. The results obtained for fish were in the range of 3.53–98.80 µg g−1 As (dry weight). Similarly, the results of 17 rice samples were in the range of 0.054–0.823 µg g−1. This study demonstrates the importance of selecting an appropriate extraction technique for the quantitative measurement of arsenic species in food.

Determination of arsenic in food and dietary supplement standard reference materials by neutron activation analysis

Arsenic was measured in food and dietary supplement standard reference materials by neutron activation analysis for the purpose of assigning certified or reference As mass fractions and to assess material homogeneity. Instrumental neutron activation analysis was used to value assign As in candidate SRM 3532 Calcium Dietary Supplement and candidate SRM 3262 Hypericum perforatum (St. John’s Wort) Aerial Parts down to about 100 μg/kg. Values were also determined for two additional candidate St. John’s Wort SRMs with As mass fractions <100 μg/kg. The presence of significant amounts of 24Na and 82Br limited the reproducibility of the method below 100 μg/kg. For measurement of lower As mass fractions, a radiochemical neutron activation analysis method with extraction of As3+ into diethyl-dithiocarbamate in chloroform and detection limits down to 0.1 μg/kg. As was used to value-assign As mass fractions for SRM 3280 Multivitamin/Multielement Tablets and for candidate SRM 3233 Fortified Breakfast Cereal, and at <10 μg/kg in candidate SRM 1845a Whole Egg Powder.

Determination of arsenic in foods by flow injection on-line sorption pre-concentration with hydride generation atomic fluorescence spectrometry

A method was developed for the determination of total arsenic in foods using flow injection on-line sorption coupled with hydride generation atomic fluorescence spectrometry (HG-AFS) using a cigarette filter as the sorbent material. After reducing As(V) to As(III) by using L-cysteine, the determination of total arsenic was achieved through on-line formation and retention of the pyrrolidine dithiocarbamate arsenic complex (As(III)–PDC) on the cigarette filter, which was packed in the pre-concentration column and total arsenic was determined by HG-AFS. The analytes were eluted with 1.68 mol l−1 HCl from the sorbent material. With consumption of 22 ml of the sample solution, an enrichment factor of 25.6 was obtained at a sample throughput of 11.6 h−1. The detection limits (3 standard deviations) and the precision (relative standard deviation) in foods ranged from 2.5 to 9.9 ng g−1 and from 1.1 to 2.2%, respectively. The method was used to determine arsenic in carrot, mushroom, chicken tissue, cod fish, rice, common carp and shrimp.

Comparison of hydride generation and graphite furnace atomic absorption spectrometry for the determination of arsenic in food

Hydride generation (HG) and graphite furnace atomic absorption spectroscopy for determination of arsenic in various foodstuffs are compared. Two methods of sample pre-treatment, wet ashing and pressurized decomposition in an autoclave, are discussed in detail. It is shown that, for the determination of arsenic in foodstuffs, the HG technique is preferable. The relative standard deviation for arsenic determined by the HG technique does not exceed 15.4% for three parallel weighed samples with an arsenic content of 1.0 mg kg −1.

Critical review of the atomic spectrometric analysis of arsenic in foods

The literature on the determination of arsenic in foods by atomic spectroscopy involving hydride generation, platform furnace Zeeman and inductively coupled plasma has been critically reviewed. Hydride generation has been largely displaced as a powerful tool by platform furnace Zeeman, using the STPF (stabilized temperature platform furnace) concept for the control of interferences. Inductively coupled plasma with conventional pneumatic nebulization has been little used. An alternative is to employ hydride generation-ICP with extraction of the arsenic in an organic phase. This technique permits proper control of interferences together with an increase in sensitivity. Depending on the contents present in the foodstuff and the technique available, the sample can be solubilized by either wet or dry digestion.

Determination of Poisonous Metals by Atomic Absorption Spectrophotometry. IV. : Determination of Microamount of Arsenic with the Use of Absorption Tube

The determination of microamount of arsenic by atomic absorption spectrophotometry using absorption tube was described. Air-hydrogen flame, having low background absorption at 1937 and 1972 A for arsenic resonance lines, was able to be obtained by forcible exhaust of the flame gases from near the end of the absorption tube. Using this flame, operating conditions, sensitivity, interfering substances and determination of arsenic in foods were investigated. The calibration curves at two arsenic resonance lines were straight up to 1.0 μg/ml of arsenic, and the sensitivity (concentration giving 1% absorption in aqueous solution free from interfering substances) at 1937 and 1972 A were 0.02 and 0.03 μg/ml of arsenic, respectively. Sulfuric acid, glucose, sodium chloride and many other substances interfered remarkably the determination of arsenic, but only hydrochloric acid in the range of 0.01-1.0 N did not interfere. The determination of arsenic in foods could be facilitated by the extraction of arsenic with iodide-benzene system followed by re-extraction process from the organic phase. The results of analysis were in good agreement with those obtained by other methods.

Arsenic in Foods: Collaborative Comparison of the Arsine-Molybdenum Blue and the Silver Diethyldithiocarbamate Methods

Abstract A collaborative study was conducted on two arsenic methods: arsine-molybdenum blue procedure, and silver diethyldithiocarbamate procedure. Fourteen collaborators received six complete sets of the arsenic apparatus (including generator bottles, sulfide absorption tubes, special traps, and an aspirator assembly), two solutions of apple digests, one blank solution, recrystallized silver diethyldithiocarbamate, and directions for the procedure. A minimum of three runs for each procedure was requested; results were reported as ppm As2O3 present in the solution. The results warrant recommendation of both methods as official, first action and as alternative procedures for the determination of arsenic in foods.

The determination of arsenic in foods contaminated by war gases

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