The efficiencies of four types of strongly basic anion-exchange resins in the tetrahydroborate form for the generation of lead hydride, used in the determination of lead by quartz tube (QT) atomization AAS, were investigated. Amberlyst A-26 gave the highest peak-height and peak-area sensitivities. The effects of column dimensions, tetrahydroborate concentration, loading time, loading direction, carrier reagent flow rate, carrier gas flow rate, sample acidity, and stripping coil length were studied. Without the argon carrier gas, the sensitivity was improved almost five times, though the precision was dependent on carrier agent and waste flow rate. Three procedures for the purification of potassium hexacyanoferrate(III) were investigated; a batch procedure, based on plumbane generation, was found to be the most effective. The concentration of acid was critical. Interferences from coexisting cations and anions were investigated. Hydride forming elements and phosphate interfered, but less suppression than for conventional HG-AAS was observed for some species. The limit of detection (3s) in 3% K₃Fe(CN)₆ and 0.10 mol l⁻¹ HNO₃ was 0.25 μg l⁻¹, with a sampling frequency of 20–40 h⁻¹. The precision, expressed as RSD, was 6.4% and 3.5% (n = 5) at concentrations of 3.0 and 5.0 μg l⁻¹, respectively. The method was applied to the analysis of different types of biological matrices including natural waters, wine, human saliva and human urine. The detection limits (3s) were 0.20–0.85 μg l⁻¹ for natural waters and 3.1–5.2 μg l⁻¹ for the wine, human saliva and human urine. Recoveries for spiked samples were 86–110%. The results of the analyses of NIST standard reference materials, freeze-dried urine (SRM 2670), and apple leaves (SRM 1515) were in agreement with the certified values and the results for San Joaquin soil (SRM 2709) agreed with the leaching recovery values.

A large number of publications describe the determination of arsenic in “environmental” samples in the broadest sense, a substantial subset of which focus on plant-based foodstuffs. There is a considerable interest in the inorganic arsenic content of food, especially rice, as there is recent evidence that concentrations may be high enough to exceed acceptable risk thresholds. The methodology for the determination of arsenic in rice is critically evaluated and results (a) for a rice flour reference material (National Institute of Standards SRM 1568a, certified only for total arsenic) and (b) a recent proficiency test (run by the European Commission's Joint Research Centre Institute for Reference Materials and Measurement) are examined. Difficulties with this particular analysis may lie in the sample preparation stages, over which there is still disagreement with regard to species stability, though a simple, hot-water extraction may be sufficient. High performance liquid chromatography separations with plasma-source mass spectrometry detection are popular; however, chromatographic separations are often not adequately described, the enhancement effect of carbon-containing species is often overlooked, and the fate of chlorine-containing species, responsible for an isobaric overlap interference, often obscure. Compound-dependent responses, for which there is a plenty of evidence, are almost never acknowledged or discussed.

A procedure for the simultaneous determination of six selenium species and six arsenic species in human urine by ion-pair, reversed-phase liquid chromatography coupled to ICP-MS has been developed. Selenium species, trimethylselenonium ion (TMSe), selenocystine (SeCys), selenite (Se^IV), selenourea (SeUr), selenomethionine (SeMet), selenoethionine (SeEt), and arsenic species, arsenocholine (AsC), arsenobetaine (AsB), dimethylarsinic acid (DMA), methylarsonic acid (MMA), arsenite (As^III), arsenate (As^V) were separated on a C₈ reversed phase column by a mobile phase of 13.0 mmol l⁻¹ tetrabutylammonium hydroxide (ion-pair reagent) and 1.3% methanol at pH 5.7–5.8 (adjusted with malonic acid). The total analysis took less than 10 min with isocratic elution at a flow rate of 1.0 ml min⁻¹, and was free from chloride interference due to the complete separation of the analyte species from chloride. The detection limits, in synthetic urine for an injection volume of 50 μL, ranged between 0.1 and 0.4 μg l⁻¹ for the six arsenic species (except AsC) and between 0.7 and 2 μg l⁻¹ for the six selenium species (at m/z 78). The repeatability was less than 10% (RSD) for 1 μg l⁻¹ arsenic species and 5 μg l⁻¹ selenium species, except for AsC. Quantification was based on response factors in a synthetic urine matrix relative that of As^V in the mobile phase. The response factors for selenium species showed considerable compound dependence. Recoveries from spiked urine samples ranged from 81% to 103%, except for SeUr and SeEt, which were not recovered. The method was applied to the determination of arsenic and selenium species in urine, which only required filtering through a 0.45 μm membrane filter and dilution with mobile phase in order to measure arsenic and selenium urinary metabolites.