Arsenite oxidation and arsenate determination by the molybdene blue method

Based on the similarity in properties of arsenate and phosphate, the colorimetric method using the molybdene blue complex was tested in order to determine low As(V) concentration in waters. The influence of complex formation time, daylight, temperature and competitive anions (silicate and sulphate) upon complex formation was determined. Optimal complex formation was reached in 1 h at 20±1 °C and was slightly favoured when developed in daylight. The formation rate declined with decreasing reaction temperature and no influence of any of the competitive anions tested (at concentrations usually found in natural waters of granitic areas) was noted. The detection limit of this method was 20 μg As(V) l⁻¹. This simple, fast and sensitive arsenic determination method is suitable for field analysis, especially for waters containing low levels of phosphate and organic matter. Through arsenate determination, this colorimetric method allowed the arsenite oxidation efficiency of five common industrial oxidants to be compared. H₂O₂ and MnO_2(s) were not considered as effective oxidants as a high excess was necessary to ensure As(III) oxidation. NaOCl and KMnO₄ were promising oxidants as they allowed complete arsenite oxidation with a small excess for NaOCl or even less than the electron stoichiometric ratio in the case of KMnO₄. FeCl₃ was the most effective oxidant among the reagents tested here.     

碱性模式氢化物发生原子荧光光谱法测定铁矿石中砷

建立了碱性模式氢化物发生原子荧光光谱法测定铁矿石中砷的最佳仪器和实验条件。采用微波消解分解样品，在硫脲和L-半胱氨酸存在下将As（Ⅴ）还原为As（Ⅲ），以1mol／L KOH作为介质，以0．75mol／L H3PO4作为载流，原子荧光光谱法测定样品中的砷。方法检出限为0．35μg／L，RSD在2．0％。9．4％之间，加标回收率95％～103％。对标准样品进行分析验证，结果与标准值相符。应用于铁矿样品的测定，结果满意。     

Influence of some inorganic salts on the polarity of apolar polymer phases in capillary gas chromatography

Different stationary phases were prepared by mixing a series of inorganic salts with dimethylsiloxane polymer (SE-30) and then tested by capillary gas chromatography. It was demonstrated that the polarity (as evaluated by measurement of Rohrschneider constants) of the mixed stationary phases, which is inferior or equal to that of a medium-polar OV-25 phases, reached even lower values than SE-30 alone. The influence of NaF, NaCl, NaBr, AgNO₃, and other inorganic salts on the polarity of capillaries is reflected by a better resolution and shorter retention time of cis/trans isomers of fatty acid methyl esters (FAMES) as well as positional isomers of triglycerides.     

An Investigation on the Effect of Arsenic Poisoning on Humans,Agriculture, and Fisheries

The purpose of this investigation is to try and understand the degree of arsenic poisoning in the waste water from agricultural chemical factories which release effluents into the waterways in their vicinity. The method of determination is to use the water samples, soil, fish, clams, shell-fish, etc. found in the areas along the canals and aqueducts and those which lie upstream, midstream, and downstream and also the hair samples of people living in the contiguous areas, to check for the levels of arsenic in them by emission spectroscopy. From the analysis during a one year investigation, we find that the level of As in the water creatures of Chungkang Stream and Lu-Er-Men Stream is much higher than in the other water areas of Taiwan such as along beaches and the other rivers; the levels in the hair of the people who live nearby these water courses have a certain degree of correspondence with their eating habits and the quantity of food eaten; however, even those people who eat relatively little have almost 3% As, beyond the 2 mg/kg limit allowed for human beings. We are fully aware of the high level of food contamination on Taiwan, and this fact has been taken into consideration. The effect of As contamination in the soil on agricultural produce does not seem to have any apparent relationship. By the way, the influence of the monthly average rainfall on As contamination in the soil is not obvious.     

Size-based analysis of incinerator fly ash using gravitational SPLITT fractionation, sedimentation field-flow fractionation, and inductively coupled plasma-atomic emission spectroscopy

Fly ash has been regarded as hazardous because of its high adsorption of toxic organic and/or inorganic pollutants. Fly ash is also known to have broad distributions of different chemical and physical properties, such as size and density. In this study, fly ash emitted from a solid waste incinerator was pre-fractionated into six sub-populations by use of gravitational SPLITT fractionation (GSF). The GSF fractions were then analyzed by sedimentation field-flow fractionation (SdFFF) and ICP–AES. SdFFF analysis showed the fly ash has a broad size distribution ranging from a few nanometers up to about 50 µm. SdFFF results were confirmed by electron microscopy. Inductively coupled plasma–atomic emission spectroscopy (ICP–AES) analysis of the GSF fractions showed the fly-ash particles contain a variety of inorganic elements including Ca, Si, Mg, Fe, and Pb. The most abundant in fly ash was Ca, followed by Si then Mg. No correlations were found between trace element concentration and particle size.     

电磁感应在线消化-原子荧光光谱法测定茶水中的砷

利用电磁感应加热原理,研制了在线消化还原、氢化物发生原子荧光法分析装置,实现了茶水中As量的在线测定.对各种实验参数和干扰情况进行了研究.方法的检出限为0.063 μg/L;样品分析精密度(RSD)为2.5%(n=11).     

Arsenic Speciation in Urine and Blood Reference Materials

Acute and chronic exposure to arsenic is a growing problem in the industrialized world. Arsenic is a potent carcinogen and toxin in humans. In the body, arsenic is metabolized to produce several species, including inorganic forms, such as trivalent (As^III) and pentavalent (As^V), and the methylated metabolites such as monomethylarsonic acid, (MMA^V), and dimethylarsinic acid (DMA^V), in addition to arsenobetaine (AsB) which is ingested and excreted from the body in the same form. Each of these species has been reported to possess a specific but different degree of toxicity. Thus, not only is the measurement of total As required, but also quantification of the individual metabolites is necessary to evaluate the toxicity and risk assessment of this element. There are a large number of reference materials that are used to validate methodology for the analysis of As in blood and urine, but they are limited to total As concentrations. In this study, the speciation of five arsenic metabolites is reported in blood and urine from commercial available control materials certified for total arsenic levels. The separation was performed with an anion exchange column using inductively coupled plasma mass spectrometry as a detector. Baseline separation was achieved for As^III, As^V, MMA^V, DMA^V, and AsB, allowing us to quantify all five species. Excellent agreement between the total arsenic levels and the sum of the speciated As levels was obtained.     

Ion chromatographic separation of car☐ylic acids prediction of retention data

The retention behavior of biologically relevant monovalent (formic, acetic, propionic, lactic and pyruvic) and divalent (oxalic, malonic, succinic, fumaric, maleic and tartaric acids) car☐ylic acids together with inorganic analytes (chloride and sulphate) has been studied. The separation was performed on a latex-based strong anion-exchange resin using carbonate buffer systems in suppressed IC. The retention behaviour of analytes was investigated at different pH values and [HCO₃⁻]+[CO₃²⁻] concentrations. A theoretical model, involving ion-exchange equilibria of sample and eluent anions, was derived and applied to the chromatographic data obtained. Chromatographic ion exchange selectivity values were determined and retention data were calculated for the anions using different carbonate eluent conditions. The average of errors between the predicted and the measured retention volumes of the analytes studied does not exceed 4.0%. The study effectively characteristics the behaviour of different analytes under elution conditions of practical importance.     

Speciation analysis of inorganic arsenic by microchip capillary electrophoresis coupled with hydride generation atomic fluorescence spectrometry

A novel method for speciation analysis of inorganic arsenic was developed by on-line hyphenating microchip capillary electrophoresis (chip-CE) with hydride generation atomic fluorescence spectrometry (HG-AFS). Baseline separation of As(III) and As(V) was achieved within 54 s by the chip-CE in a 90 mm long channel at 2500 V using a mixture of 25 mmol l(-1) H3BO3 and 0.4 mmol l(-1) CTAB (pH 8.9) as electrolyte buffer. The precisions (RSD, n=5) ranged from 1.9 to 1.4% for migration time, 2.1 to 2.7% for peak area, and 1.8 to 2.3% for peak height for the two arsenic species at 3.0 mg l(-1) (as As) level. The detection limits (3sigma) for As(III) and As(V) based on peak height measurement were 76 and 112 microg l(-1) (as As), respectively. The recoveries of the spikes (1 mg l(-1) (as As) of As(III) and As(V)) in four locally collected water samples ranged from 93.7 to 106%.     

ICP—AES法测定玩具材料中痕量砷,硒,锑

用电感耦合等离子体原子发射光谱法（ＩＣＰ－ＡＥＳ０测定了玩具材料中的痕量砷，硒和锑。方法简便快速，回收率为９７．５％－１０２．７％，相对标准偏差小于３％。