Lead and cadmium contamination of foods and feeds from selected areas of the Erfurt district. 4. Lead in vegetables grown in culture centers of the Erfurt region

For the purpose of determining the effect of heavy metal emissions of a great town on the lead and cadmium levels of vegetables that are of relevance to food supply, we analyzed 193 samples of vegetables from the important vegetable-growing centre of Erfurt during a 3-year period. With regard to the main wind direction and the infrastructure of the town, the samples were collected at four different areas under vegetable. Apart from a single exception, the lead and cadmium contents were inferior to the maximum tolerances provided by the regulation concerning the contents of foreign substances in foods, the metal contents of leaf vegetables being higher than those of brassicaceous plants. Vegetable samples from areas with heavier emission burdens showed somewhat higher metal contents. In contrast to this, the cadmium contents did not exhibit such differences. The highest lead and cadmium contents were found in spinach. To elucidate the effect of the washing and blanching techniques used in industrial processing, 23 spinach preserves were analyzed in addition; as expected, the heavy metal contents were reduced by these techniques. In summary, our investigations evidence that the main vegetables cauliflower, white cabbage, red cabbage, savoy cabbage, as well as lettuce and spinach (grown in the district of Erfurt) contribute but little to total food contamination if we consider the amounts consumed on an average.     

Determination of the levels of lead, cadmium, copper, zinc, and iron in selected foods

Vegetables from allotment gardens in the area of Kraków, from the trade (produced at a distance of about 25 km from Kraków), and from farms situated about 100 km from Kraków (control samples) were investigated by atom absorption spectroscopy. In the vegetables from the allotment gardens the levels of the determined elements were on an average several times higher (p less than 0.01) than that of the controls. In a few cases the maximum levels of some elements were near the admissible limit. Furthermore, Pb, Cd, Cu, Zn, and Fe were determined in pigs and cattle (muscle, kidney, liver). The average levels of Pb and Cd gave no reason for objection.     

阳极溶出伏安法同时测定高盐调味品中铅镉

采用湿法消解结合阳极溶出伏安法对沾水辣、酱油和鱼露等高盐调味品中铅镉的测定进行了方法研究。探索了仪器条件、电解质及其用量、高盐对铅镉的影响,并对酸类型及酸度的干扰、共存离子干扰进行了实验。铅、镉工作曲线的线性范围分别为2⁵0、1²0μg·L^-1,相关系数分别为0.9999和1.0000,仪器检出限为铅0.043μg·L^-1、镉0.029μg·L^-1,方法检出限为铅2.17μg·kg^-1、镉1.43μg·kg^-1。该方法测定实际样品中铅、镉含量的精密度分别为1.11%⁴.66%、0.69%⁵.34%,加标回收率分别为93.9%¹09.9%、94.7%¹07.5%。结果表明方法简便、灵敏,具有较好的选择性和可靠性。      

阳极溶出伏安法测定饮用水中镉、铅、铜、砷

目的建立阳极溶出伏安法快速测定饮用水中镉、铅、铜、砷含量的检测方法。方法采用微波消解处理水样,以玻碳电极为工作电极,Ag/AgCl电极为参比电极,铂电极为对电极测定其溶出电流,采用外标法定量。结果在浓度为0.1～10μg/L范围内, Cd、Pb、Cu、As线性关系良好,方法检出限为0.00004～0.001 mg/L,加标回收率在98.10%～100.35%间。实际样品测定精密度小于2%。结论该方法稳定、快速、灵敏度高、准确度好,是一种高效的检测痕量重金属离子的方法。     

线扫阳极溶出伏安法测食品包装品和食品容器中Pb、Cd

采用线扫阳极溶出伏安法同时测定食品包装品和食品容器中Pb、Cd,用4%HAc浸泡容器和包装品,在0.70mol/LHAc—0.05mol/LKNO3底液中测定Pb、Cd,Pb、Cd加标回收率为91.0%～109.0%、94.0%～108.3%,测定精密度RSD%分别为0.03%～5.56%、0.26%～4.82%,Pb、Cd的线性范围为:0.05～1.40mg/L。     

Determination of cadmium and lead in vegetables by stripping chronopotentiometry.

A method for the determination of cadmium and lead in vegetables by stripping chronopotentiometric analysis, after digestion of the sample with concentrated sulphuric acid and dry-ashing, is described. Metal ions were concentrated as their amalgams on a glassy carbon-working electrode previously coated with a thin mercury film and then stripped by a suitable oxidant. Potential and time data were digitally derived and E was plotted versus dt/dE(-1), thus increasing both the sensitivity of the method and the resolution of the analysis. Quantitative analysis was carried out by the method of standard addition; good linearity was obtained in the range of examined concentrations, as was shown by the determination coefficients, which were 0.998 (n = 4) for cadmium and 0.993 (n = 4) for lead. Recoveries of 85-100% for cadmium and of 84-97% for lead were obtained from a sample spiked at different levels. Accuracy was demonstrated by analysis of a matching reference sample of cabbage. The detection limits were 1.8 ng g(-1) of wet mass for cadmium and 5.1 ng g(-1) of wet mass for lead. The relative standard deviations (mean of nine determinations), evaluated on a real sample, were 6.7 and 6.2%, respectively. Results obtained on 10 different commercial samples of pepper (Capsicum annuum), and egg plant (Solanum melongena) were not significantly different from those obtained by graphite furnace atomic absorption spectrophotometry technique. The average content was in the range 3.1-18.6 ng g(-1) for cadmium and 38.2-64.3 ng g(-1) for lead.     

山东、河北及湖南产区芝麻中铅、镉、砷的 污染状况及评价

目的探究山东、河北、湖南3省芝麻中铅(Pb)、镉(Cd)、砷(As)的污染状况,为芝麻的安全生产提供科学依据。方法选取山东、河北、湖南3省的代表性种植区域的芝麻籽粒作为样品,测定其中的Pb、Cd、As含量,采用单项污染指数法和综合污染指数法对芝麻样品中的Pb、Cd、As进行污染评价。结果山东和湖南2省个别采样地块的芝麻样品中,Cd为中度污染和重度污染水平,河北省是综合污染指数最低的区域。各采样区域内芝麻中的Pb含量、山东和河北2省芝麻中的Cd、As含量均属中等变异程度;湖南省所产芝麻中的Cd、As含量均属强变异程度,且湖南省所产芝麻中的Cd超标率最高;各采样区域内,芝麻籽粒的Cd超标率高于Pb和As的超标率。结论在各采样区域内,Pb、Cd、As的单项污染指数和综合污染指数评价均为未受污染,Cd为综合污染的主要贡献因子,As的污染指数最低,Cd的污染指数最高。     

Determination of lead and cadmium content in sausages from Iran

The contents of lead and cadmium in five major brands of six types of cooked beef sausages consumed in Iran were determined by a graphite furnace atomic absorption spectrometer (GFAAS) after hydrogen peroxide/nitric acid digestion. The metal content in the samples, expressed in µg?kg^?1 wet weight, varied from 24.0 to 158.7 with an average of 53.5 for lead and from 2.2 to 13.5 with an average of 5.7 for cadmium. The highest lead and cadmium concentrations were obtained from a German sausage (158.7?µg?kg^?1; brand B) and hot dog (13.5?µg?kg^?1; brand D), respectively. The results indicate that the sausages from Iran have concentrations below the permitted levels for these heavy metals. The daily dietary intakes and the percentage contribution of the two considered metals to the provisional tolerable weekly intake (PTWI) were calculated for sausages.     

Quantification of lead and cadmium in poultry and bird game meat by square-wave anodic-stripping voltammetry

A square-wave anodic-stripping voltammetric method for the analysis of lead and cadmium in chicken muscle and liver was developed and validated, and the results of a monitoring study relative to chicken and pigeon meat are reported. The voltammetric method allows the analysis of lead and cadmium at the same time in samples after acid digestion. The use of perchloric acid for digestion and of acetate buffer in the supporting electrolyte are suitable to reduce matrix interferences and obtain limits of quantification which were below 10 ng g?1 for meat and liver samples. The regression between the analytical signal and the concentration of the target analytes in spiked samples and Certified Reference Materials proved to be linear within the 10-100 ng g?1 range for meat and within the 50-500 ng g?1 range for liver. The analytical method was verified using available Certified Reference Materials BCR-184 (cattle meat) and BCR-185R (cattle liver) as well as with spiked chicken samples. Precision (i.e. repeatability and intermediate precision) and accuracy (percentage recovery and bias) were of the order of 0.3-4.5% for both lead and cadmium The level of lead in muscle was in the range between 6.4 and 59.8 ng g?1 in chickens and between 7.9 and 63.6 ng g?1 in farmed pigeons, whereas it was between 8.0 and 84.4 ng g?1 in chicken liver. The cadmium concentration was 0.4-10.4 ng g?1 in chicken muscle, 10.4-90.6 ng g?1 in chicken liver and 2.2-8.0 ng g?1 in farmed pigeons.     

Determination of cadmium and lead in foods by graphite furnace atomic absorption spectrometry with Zeeman background correction: test with certified reference materials

Two methods for the determination of cadmium and lead based on graphite furnace atomic absorption spectrometry (GFAAS) with Zeeman background correction are described. The main difference between the methods is the method of sample destruction, bomb digestion versus dry ashing. The precision and accuracy of the methods has been tested by analysing 16 different reference materials, with cadmium concentrations varying from 2.9 micrograms/kg to 2.7 mg/kg and lead concentrations from 44 micrograms/kg to 13.5 mg/kg. The methods produced results which differ, with a few exceptions, less than 10% from the certified contents, with relative standard deviations of around 5%. The methods are not difficult to carry out, are not very laborious and without modifications are applicable to a large variety of products. The sample solutions obtained can also be used for the determination of other elements, e.g. Al, Cr, Cu, Hg, Mn, Ni and Zn. The detection limits, for test portions of 1 and 5 g (wet products) are 0.5-1 microgram/kg for cadmium and 5-20 micrograms/kg for lead.     

Determination of lead and cadmium in food samples by the coprecipitation method

In this study, the coprecipitation method developed using a combination of 2-mercaptobenzothiazole (MBT) as a chelating reagent and copper as coprecipitate carrier was used for the determination of trace lead and cadmium in various food samples by graphite furnace atomic absorption spectrometry (GFAAS). The method was applied for the determination of Pb(II) and Cd(II) in salami, sausage, chicken, anchovy, spinach, cabbage, onion, dill, parsley, lettuce, tea and rice samples. The matrix modifiers were added as 50 μg NH₄H₂PO₄ + 3 μg Mg(NO₃)₂ for both Pb(II) and Cd(II). The signals were measured as peak area. The concentrations of Pb(II) and Cd(II) in the food samples were found to be in the range of 6.63 ng g⁻¹ (anchovy) −3.30 μg g⁻¹ (spinach) and 2.67 ng g⁻¹ (salami) −0.51 μg g⁻¹ (lettuce), respectively.     

Determination of lead and cadmium in wines by graphite furnace atomic absorption spectrometry.

The lead (Pb) and cadmium (Cd) content of various wines on the Korean market were determined by graphite furnace atomic absorption spectrometry using Zeeman background correction and peak area mode. All wine samples were microwave-digested in concentrated HNO(3). Ammonium dihydrogen phosphate and magnesium nitrate were used as matrix modifiers for both Pb and Cd analyses. The mean Pb content of the wines was about 29 microg l(-1) ranging from 5 to 87 microg l(-1). Also, the means of Cd were about 0.5 microg l(-1) ranging from < 0.1 to 3.0 microg l(-1). The mean recoveries of Pb and Cd were 92.8 and 101.3% and their analytical detection limits were 1.0 and 0.1 microg l(-1), respectively. Sixty brands of wine were classified into red and white, but no statistically significant difference in Pb and Cd content was observed.     

线扫阳极溶出伏安法测定茶汤中的Pb、Cu

采用线扫阳极溶出伏安法测定茶叶中的Pb、Cu含量 ,在 0 .3mol/L盐酸底液中 ,Pb、Cu的加标回收率P %分别为93.3%～ 1 0 6 .8%、93.9%～ 1 0 5 .4 % ,测定精密度RSD %分别为 0 .39%～ 2 .1 0 %、0 .33%～ 3.2 0 % ,Pb、Cu的线性范围为 0 .1 0～ 0 .70mg/L。     

微波消解石墨炉原子吸收法测定大米中铅镉

采用微波消解—石墨炉原子吸收法对大米中的铅、镉进行了测定,并与常规湿法消解方法进行了比较。利用国家标准物质杨树叶、甘蓝验证了方法的准确度与精密度。结果表明,采用微波消解法,方法准确度为95．0％～105%,精密度为2．8％～8．4%,该方法能够满足食品分析的要求。     

Simultaneous determination of ultra trace amounts of lead and cadmium in food samples by adsorptive stripping voltammetry

A selective and sensitive method for simultaneous determination of lead and cadmium by adsorptive differential pulse cathodic stripping voltammetry is presented. The method is based on adsorptive accumulation of the complexes of Pb (II) and Cd (II) ions with 2-mercaptobenzothiazole onto hanging mercury drop electrode (HMDE), followed by the reduction of the adsorbed species by differential pulse cathodic stripping voltammetry. Optimal conditions were obtained at pH 8.0, 2-mercaptobenzothiazole concentration of 1.0 × 10⁻⁴ M, the accumulation potential of −0.4 V (vs. Ag/AgCl), the accumulation time of 160 s, and the scan rate of 100 mV/s. Under optimised conditions, linear calibration curves were established for the concentration of Pb (II) and Cd (II) in the range of 0.5–70 and 0.2–30 ng/ml, respectively, with detection limit of 0.017 ng/ml for Pb (II) and 0.01 ng/ml for Cd (II). The procedure was successfully applied to the simultaneous determination of both ions in food samples (rice, soya and sugar).     

Determination of lead and cadmium in milk with modern analytical methods

Summary Methods to determine lead and cadmium at the low g/kg-level in milk were investigated. Methods tested were differential-pulse anodic-stripping voltammetry (DPASV) and flameless atomic-absorption spectrophotometry (FAAS). Under the circumstances in which these methods were used, the analytical procedure based on DPASV was the most sensitive, with an estimated detection limit of about 0.2 g/l for lead and cadmium in liquid milk. The pretreatment of the milk samples before the DPASV-analysis included: freeze-drying, ashing in a muffle furnace at 550° C and finally dissolution of the ash in 0.1 M-hydrochloric acid. The recoveries of known amounts of lead and cadmium added to milk were 95 and 59%, respectively.A survey of the contents of lead and cadmium in the Swedish market milk was performed. This investigation showed that the average lead content in Swedish market milk was 2.0 g/l, with a standard deviation of 0.5 g/l. The cadmium content was below 0.2 g/l in all samples analyzed.

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Bestimmung von Blei und Cadmium in Milch mit modernen analytischen Methoden

Zusammenfassung Bestimmungsmethoden für Blei und Cadmium in Milch im Bereich von g/kg wurden untersucht. Die geprüften Methoden waren die differentiale Pulspolarographie (differential pulse anodic stripping voltammetry — DPASV) und die flammenlose Atomabsorptionsspektrophotometrie (FAAS). Unter den Bedingungen, bei denen diese Methoden angewandt wurden, war das DPASV-Verfahren mit einer ermittelten Erfassungsgrenze von etwa 0,2 g/l für Blei und Cadmium in Milch das empfindlichste. Die Vorbereitung der Milchproben für die DPASV-Analyse umfaßte: Gefriertrocknung, Veraschung im Muffelofen bei 550° C und anschlie ßende Auflösung der Asche in 0,1 m-Salzsüre. Die Wiederauffindbarkeit bekannter Zugaben von Blei und Cadmium zur Milch betrug 95 bzw. 59%.Eine Untersuchung des Blei- und Cadmiumgehaltes der Konsummilch in Schweden wurde durchgeführt. Diese wies einen mittleren Bleigehalt von 2,0 g/l bei einer Standardabweichung von 0,5 g/l auf. Der Cadmiumgehalt lag bei allen untersuchten Proben unter 0,2 g/l.

     

同位镀铋方波溶出伏安法检测蜂蜜中的痕量铅

目的 采用同位镀铋方波溶出伏安法检测蜂蜜中的痕量铅。 方法 采用铋膜电极替代传统的汞膜电极,并结合方波溶出伏安法和电极同位镀铋膜法,实现对蜂蜜中痕量铅的快速检测。结果 优化了底液, pH, 铋浓度, 沉积电位和沉积时间五项最佳实验条件参数。铅在铋膜电极上可得到灵敏的溶出峰, 其溶出电位为0.580 V。在优化的实验条件下, 该方法检测铅的线性范围为5~100 μg/L(r=0.9965), 检测限低达0.630 μg/L。实验结果与石墨炉原子吸收法结果相比无显著性差异。结论 该研究为蜂蜜等食品中铅的快速、高灵敏检测提供了新的手段。     

Contamination of dry foods with trimethyldiphenylmethanes by migration from recycled paper and board packaging

Contamination of foods with trimethyldiphenylmethanes is reported and the origin is shown to be migration from food packaging materials of which the use of recycled carbonless copy paper was found to be the major source. This chemical is one of the solvents used in the carbonless copy paper and its presence in food and the environment has not been previously identified. In this paper we have pursued previous studies on diisopropylnaphthalenes and hydrogenated terphenyls contamination from packaging and now report the identification of this new food contaminant and present evidence of its source. Solid foods such as egg pasta, barley coffee and rice were analysed by GC/MS and a mean concentration of 18 µg/kg of trimethyldiphenylmethanes was found. Extracts from carbonless copy paper were analysed by proton NMR to characterize the trimethyldiphenylmethanes. Since trimethyldiphenylmethanes are found in solid food together with diisopropylnaphthalenes, and considering their similar chemical character, they may follow the same migration pathway as one another.     

锑膜修饰电极差分脉冲溶出伏安法测定食品中痕量铅、镉

目的 考察并优化同位镀锑膜电极差分脉冲溶出伏安法测定铅、镉的条件.方法 采用差分脉冲溶出伏安法,以锑膜修饰金电极作为工作电极测定食品中痕量铅、镉离子.结果 铅、镉在锑膜电极上可得到灵敏的溶出峰,铅、镉的溶出电位分别为0.58 V(Epb)和0.81 V(Ecd).当电沉积时间为180 s时,铅、镉的检出限分别为1.95和2.10 μg/L,RSD分别为1.14％和0.95％,铅、镉溶出峰电流同0～100μg/L铅、镉离子呈良好的线性关系(r≥0.997).结论 利用本方法测定了食品样品中铅、镉的含量,并与石墨炉原子吸收分光光度法做了对比,结果令人满意,同时使用锑膜修饰电极可避免使用汞膜电极带来的环境污染.