Simultaneous determination of antimony and boron in beverage and dairy products by flame atomic absorption spectrometry after separation and pre-concentration by cloud-point extraction

A new cloud-point extraction (CPE) method was developed for the pre-concentration and simultaneous determination of Sb(III) and B(III) by flame atomic absorption spectrometry (FAAS). The method was based on complexation of Sb(III) and B(III) with azomethine-H in the presence of cetylpyridinium chloride (CPC) as a signal-enhancing agent, and then extraction into the micellar phase of Triton X-114. Under optimised conditions, linear calibration was obtained for Sb(III) and B(III) in the concentration ranges of 0.5–180 and 2.5–600 μg l^?1 with LODs of 0.15 and 0.75 μg l^?1, respectively. Relative standard deviations (RSDs) (25 and 100 μg l^?1 of Sb(III) and B(III), n = 6) were in a range of 2.1–3.8% and 1.9–2.3%, respectively. Recoveries of spiked samples of Sb(III) and B(III) were in the range of 98–103% and 99–102%, respectively. Measured values for Sb and B in three standard reference materials were within the 95% confidence limit of the certified values. Also, the method was used for the speciation of inorganic antimony. Sb(III), Sb(V) and total Sb were measured in the presence of excess boron before and after pre-reduction with an acidic mixture of KI-ascorbic acid. The method was successfully applied to the simultaneous determination of total Sb and B in selected beverage and dairy products.     

Selective cloud point extraction for the determination of cadmium in food samples by flame atomic absorption spectrometry

A new cloud point extraction (CPE) procedure for preconcentration of cadmium prior to the determination by flame atomic absorption spectrometry (FAAS) was developed. The method is based on the fact that cadmium could form hydrophobic ion-associated complex in the presence of iodide and methyl green (MG), and the hydrophobic ion-associated complex could be extracted into surfactant-rich phase. The main factors affecting CPE procedure, such as pH, concentration of KI, MG and surfactant, equilibrium temperature and incubation time, sample volume were investigated. Potential interference from co-existing ions was largely eliminated as most of co-existing ions can not form extractable ion-associated complex with iodide and MG. Under the optimum conditions, the limit of detection (3σ) and limit of quantity (10σ) were 0.90 ng mL⁻¹ and 3.0 ng mL⁻¹ for cadmium, respectively, and relative standard deviation was 4.2% (c = 50 ng mL⁻¹, n = 7). The proposed method was successfully applied to determination of cadmium in the certified reference rice sample (GBW08510) and food samples with satisfactory results.     

UV-photolysis assisted digestion of food samples for the determination of selenium by electrothermal atomic absorption spectrometry (ETAAS)

An UV-oxidation procedure has been developed to completely digest biological/food samples for the determination of trace levels of selenium. A combined use of UV photolysis and hydrogen peroxide in the presence of an oxidant (HNO₃), results in the complete oxidation of the organic matter. This method is simpler and requires fewer reagents when compared with other sample pre-treatment procedures. The clear solution obtained was analysed for the selenium content by graphite furnace atomic absorption spectrometry. Unreduced palladium-nitrate modifier was used in all cases. However, in case of samples that are known to contain sulfur (like mushroom, Brazil nut, etc.), reduced palladium was used as modifier. The method was verified using three standard reference materials i.e., Whole egg powder-8415, Tuna fish-IAEA 350, Oyster tissue-1566a, and the results were in agreement at 95% confidence level. By using standards addition as calibration method, accurate results were obtained for the certified reference material, the precision for the CRM’s were in the range of 3.5–8%. The characteristic mass of selenium is assessed as 10 pg. The detection limits were in the range of 35–40 ng/g.     

原子吸收光谱法在食品分析中的应用

原子吸收光谱法在食品分析中得到了广泛应用,已成为定量分析检测微量元素和重金属的主要手段。     

石墨炉原子吸收法测定高盐食品中的微量铅

本文研究了吡咯烷二硫代甲酸铵—甲基异丁基甲酮(APDC—MIBK)体系络合萃取高盐食品中微量铅和原子吸收测定的方法。本方法能够将食品中的铅与食盐有效分离,重现性好且易于掌握,结果令人满意。本方法的相对标准偏差为2．8％,回收率为94％。104％,检出限为7．8ng／mL,本方法可用于酱油、蚝油等含盐量高的调味品中铅含量的测定。     

Chromium determination in food by slurry sampling graphite furnace atomic absorption spectrometry using classical and permanent modifiers

A simple method, using permanent modifiers, has been developed for chromium (Cr) determination in food of plant origin by the slurry sampling graphite furnace atomic absorption spectrometry. In particular comparison of the action of Mg(NO₃)₂, iridium (Ir)/niobium (Nb) and iridium (Ir)/tungsten (W) was examined. Finally, for chromium determination in food, the mixture of 2 μg of Ir with 10 μg of Nb was used as permanent modifier. The analytical procedure was optimised carefully on the basis of the data from pyrolysis and atomisation temperature curves studies. The results obtained for four certified reference materials using external calibration with aqueous standards were in good agreement with the certified values. The precision and accuracy of Cr determination by the described method were also acceptable: the RSD were lower than 10% and recoveries for CRMs were in the range of 95-103%. The characteristic mass for chromium was determined to be 3.9 pg and the detection limit for the optimised procedure at the 0.75% (w/v) slurry concentration - 86.6 ng g⁻¹.     

Determination of arsenic in chicken feed by hydride generation atomic absorption spectrometry after pre-concentration with polyurethane foam

A pre-concentration procedure with solid-phase extraction was developed for the determination of arsenic (As) in chicken feed using hydride generation atomic absorption spectrometry (HG-AAS). The procedure was based on the sorption of As(III) ions as complexes with ammonium pyrrolidine dithiocarbamate onto a mini-column packed with polyurethane foam. After pre-concentration, the As was removed from the mini-column by acid solution, and the analyte content in the eluate was measured by HG-AAS. The following main experimental conditions were established: adjustment of the As solution pH with 0.05?mol?l^?1 HCl, 2.88?×?10^?3?mol?l^?1 complexing agent concentration and 6.0?mol?l^?1 eluting hydrochloric acid concentration. The proposed method produced an enrichment factor of 67, with 0.050 and 0.165?µg?g^?1 limits of detection and quantification, respectively. The procedure was applied to the determination of As content in two types of chicken feed using the proposed procedure and atomic absorption spectrometry with electrothermal atomisation (ETAAS). The t-test indicated that the results were not significantly different at a confidence level of 95%.     

Automatic determination of nickel in foods by flame atomic absorption spectrometry

A new sensitive and low cost flow injection method that combines acid extraction, preconcentration and flame atomic absorption spectrometric determination of nickel in food samples at μg/g levels is described. The dynamic acid extraction step was carried out by using a continuous ultrasound-assisted extraction system. The acid extract was preconcentrated on-line on a minicolumn packed with a chelating resin (Serdolit Che, with iminodiacetic groups) and nickel was eluted with diluted hydrochloric acid, being continuously monitored by flame atomic absorption spectrometry. An experimental design (Plackett-Burman 2⁶ × 3/16) is used to optimise the methodology proposed. The method allowed a total sampling frequency of 13–28 samples per hour. Good precision of the whole procedure (1.9–3.6% expressed as relative standard deviation) and a detection limit of 0.12 μg/g, for 60 mg of sample were achieved. The method was successfully applied to the determination of trace amounts of nickel in food samples.     

原子吸收光谱法测定辣椒及辣椒食品中的微量元素

应用火焰原子吸收光谱法对辣椒及辣椒食品中的Cu、Na、Fe、K、Sr、Mg、Ca、Mn、Zn等9种微量元素的含量进行测定分析。结果显示:Cu、Na、Fe、K、Sr、Mg、Ca、Mn、Zn的标准曲线相关系数为0.9999、0.9820、0.9997、0.9927、0.9982、0.9965、0.9991、1.0000和0.9985;辣椒及辣椒食品中均能检出这9种微量元素,其中辣椒籽中的Cu、Mg、Mn、Zn含量很高;制成辣椒食品后,Na含量大幅度增加,而相对于其他香辣酱,鲜食辣椒酱Na含量最低;辣椒制成辣椒食品后部分微量元素富集(如Cu、Na、Fe、Ca等)比鲜冻辣椒中微量元素含量高。      

A slurry sampling method for the determination of iron and zinc in baby food by flame atomic absorption spectrometry

A slurry sampling method is proposed for the determination of iron and zinc in baby food by flame atomic absorption spectrometry without sample digestion prior to analysis. The effect of slurry concentration (the ratio of solid sample to total slurry volume), different acids at various concentrations as diluent and the addition of dispersant on accuracy and precision were investigated. The samples were dried at 105 °C overnight and ground using an agate mortar. To obtain quantitative recoveries, 500 mg of sample was slurried in 20 ml of 0.05% Triton X-114 containing 0.1 M HNO(3), homogenised using a high-performance overhead disperser at 15,000 rpm for 5 min and directly aspirated into the flame. The accuracy of the method was tested by determination of analytes in various certified reference materials. The limits of detection of the method (N = 10; 3σ) for iron and zinc were 5.5 and 3.4 μg g(-1), respectively, using a very dilute slurry of baby food, which gave a very low background signal. Finally, the proposed method was applied to the determination of iron and zinc in different baby food samples obtained from markets in Turkey. The range of iron and zinc content for the samples were 33-76 and 15-73 μg g(-1), respectively.     

微波消解-氢化物发生原子吸收光谱法测定酱油中总砷含量

采用微波消解-氢化物发生原子吸收光谱法测定酱油中总砷含量,并对样品前处理方式及测定的干扰情况进行分析讨论。方法的特征浓度为0.17μg/L,检出限为0.014μg/L,样品相对标准偏差为4.64%～9.92%,样品加标回收率为90.3%～96.5%。     

A slurry sampling method for the determination of iron and zinc in baby food by flame atomic absorption spectrometry

A slurry sampling method is proposed for the determination of iron and zinc in baby food by flame atomic absorption spectrometry without sample digestion prior to analysis. The effect of slurry concentration (the ratio of solid sample to total slurry volume), different acids at various concentrations as diluent and the addition of dispersant on accuracy and precision were investigated. The samples were dried at 105°C overnight and ground using an agate mortar. To obtain quantitative recoveries, 500?mg of sample was slurried in 20?ml of 0.05% Triton X-114 containing 0.1?M HNO₃, homogenised using a high-performance overhead disperser at 15,000?rpm for 5?min and directly aspirated into the flame. The accuracy of the method was tested by determination of analytes in various certified reference materials. The limits of detection of the method (N?=?10; 3σ) for iron and zinc were 5.5 and 3.4?µg?g^?1, respectively, using a very dilute slurry of baby food, which gave a very low background signal. Finally, the proposed method was applied to the determination of iron and zinc in different baby food samples obtained from markets in Turkey. The range of iron and zinc content for the samples were 33–76 and 15–73?µg?g^?1, respectively.     

火焰原子吸收法测啤酒中铜的改进

传统火焰原子吸收法测啤酒中的铜存在结果易受糖分和温度的影响的缺陷。通过预先消化,去除啤酒中的有机质,再测定啤酒中的铜,可以同时消除糖含量和温度的影响,提高测量的精确度。     

Direct determination of lead in human milk by electrothermal atomic absorption spectrometry

Infants are particularly sensitive to the toxic effects of lead. Since milk is their only or main food it is important to know the contribution of milk to lead intake. The purpose of this study was to develop a direct method for determining the lead content of human milk by electrothermal atomic absorption spectrometry when a deuterium lamp is the only background correction available. The optimum conditions for lead determination in breast milk: sample dilution in Triton ×-100, modifier (75 μg of palladium) and nitric acid contents (2%) and the graphite furnace program (mineralization: 1100°C; atomization: 2300°C) were selected. The analytical parameters are: linearity (20–300 ng ml⁻¹); detection limit (5.0 ng ml⁻¹); precision (intra-assay 11.7%) and recovery percentage (109.8±5.4%), and they show that the method is useful for determining lead in human milk.     

微波消解-石墨炉原子吸收光谱法测定花生中镉含量

本文研究了高脂肪高蛋白材料花生中镉含量测定方法。采用微波消解法处理花生样品,使用石墨炉原子吸收光谱法测定花生中镉含量。从广东、湖北和辽宁3省随机抽取收获的9个花生样品进行检测,镉含量范围为0．061～0．529mg／kg,RSD为1．22％-8．75％（n=6,c=0．859—7．409ng／mL）,该方法检出限为0．00019mg／kg,加标回收率为95．4％～100．1％,具有灵敏、快速、准确的特点,可用于高脂肪高蛋白样品中镉含量的测定。     

Evaluation of aluminium concentrations in samples of chocolate and beverages by electrothermal atomic absorption spectrometry

Samples of chocolate, cocoa, tea infusions, soft drinks and fruit juice have been examined by, electrothermal atomic absorption spectrometry (ETA-AAS) for the presence of aluminium (Al). Fruit juices and chocolate were analysed after an adequate sample preparation; the other products were evaluated directly. Sampling was performed in duplicate for 248 independent samples. The mean Al concentration in chocolate was 9.2 +/- 7.5 mg kg(-1), and individual values were correlated with the per cent of cocoa in samples (Y = 0.63 + 0.27X, r = 0.78, p < 0.0001). Al concentration in commercial tea infusions ranged from 0.9 to 3.3 mg l(-1) (mean = 1.80 +/- 65 mg l(-1), whereas in laboratory-prepared samples it was 2.7 +/- 0.93 mg l(-1). In soft drinks, the concentrations of Al were lower, ranging from 9.1 to 179 microg l(-1); the highest values were observed in samples of orange squash (mean = 114 +/- 56 microg l(-1)). Apricot juice showed the highest Al level (mean = 602 +/- 190 microg l(-1)), being statistically, different from that of pear (mean = 259 +/- 102 microg l(-1)), but not different from that of peach juice (mean = 486 +/- 269 microg kg(-1)). Toxicologically, the amount of Al deriving from the consumption of these products is far below the acceptable daily intake of 1 mg kg(-1) body weight indicated by the FAO/WHO, and it is a verv low percentage of the normal Al dietary intake.     

原子吸收法测定维他奶中铜不确定度的评定

根据国际“测量不确定度表示导则”的要求,通过对原子吸收光谱法(AAS)测定维他奶中铜含量过程的不确定度分析,对AAS测定结果的质量进行了定量表征。结果表明,样品中铜质量浓度为(0.88±0.11)mg/L,样品消化过程的不确定度因素对总体不确定度作用最大。     

Simultaneous kinetic-spectrophotometric determination of maltol and ethyl maltol in food samples by using chemometrics

A fast and accurate procedure has been researched and developed for the simultaneous determination of maltol and ethyl maltol, based on their reaction with iron(III) in the presence of o-phenanthroline in sulfuric acid medium. This reaction was the basis for an indirect kinetic spectrophotometric method, which followed the development of the pink ferroin product (λ_max = 524 nm). The kinetic data were collected in the 370–900 nm range over 0–30 s. The optimized method indicates that individual analytes followed Beer’s law in the concentration range of 4.0–76.0 mg L⁻¹ for both maltol and ethyl maltol. The LOD values of 1.6 mg L⁻¹ for maltol and 1.4 mg L⁻¹ for ethyl maltol agree well with those obtained by the alternative high performance liquid chromatography with ultraviolet detection (HPLC-UV). Three chemometrics methods, principal component regression (PCR), partial least squares (PLS) and principal component analysis–radial basis function–artificial neural networks (PC–RBF–ANN), were used to resolve the measured data with small kinetic differences between the two analytes as reflected by the development of the pink ferroin product. All three performed satisfactorily in the case of the synthetic verification samples, and in their application for the prediction of the analytes in several food products. The figures of merit for the analytes based on the multivariate models agreed well with those from the alternative HPLC-UV method involving the same samples.     

微波消解氢化物原子荧光法测定食品中的砷和汞

采用高压密闭微波消解氢化物原子荧光法对食品中砷、汞进行同时测定,并与传统的湿法消解进行比较。结果表明:该法具有操作简单、快速、干扰少、良好的过程可控性等优点。通过对大米、肉类罐头、矿泉水和水产品等样品的检测,发现砷、汞的检出限分别为0.030 6,0.005 2μg/L;相对标准偏差(RSD):砷为2.40%,Hg为1.39%;回收率:As为99.4%～101.2%,Hg为94.5%～106.5%;相关系数(r):As为0.999 7,Hg为0.999 6。结果良好,适用于多种食品中砷和汞的同时检测。     

甲基绿吸收光谱法同时测定饮料中的酒石黄和日落黄

研究建立了一种简便、快速、能同时测定饮料中共存着色剂——酒石黄和日落黄的吸收光谱新方法.在pH 9.43 Tris-HCl溶液中,甲基绿与酒石黄和日落黄发生显色反应,生成离子缔合物,在400～750 nm范围内,酒石黄体系在574 nm波长处产生1个能进行定量分析的特征负吸收峰,共存色素日落黄不干扰测定,酒石黄的质量浓...