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.     

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.     

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.     

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。     

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.     

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.

---

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.

     

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).     

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.     

江西赣南地区脐橙中镉、铬、铅的测定

应用电感耦合等离子体质谱法测定了江西赣南地区脐橙的根、枝、叶、皮及果实中镉、铬、铅等元素,采用微波消解,直接测定.其方法检出限低,准确度好.为进一步研究脐橙与镉、铬、铅关系,提供了很好的分析方法和信息.     

Exposure to cadmium from foods, estimated by analysis and calculation--comparison of the methods

Cadmium intake of 40 middle-aged Finnish men was determined both by calculation based on computer files and by analysis of duplicate portions. A significant difference was observed between intake estimates of the two methods. The average calculated cadmium intake was 15.8 micrograms/day compared to the 8.2 micrograms/day obtained by analysis. Factors causing the difference between the methods and affecting the comparability are: (i) expression of concentrations below the detection limit; (ii) the calculation is based on the analysis of foods being only washed and peeled whereas duplicate portions are normally processed; (iii) when duplicate portions are prepared using non-representative lots or brands of food, their cadmium content differs from average values used in calculation; (iv) the level of cadmium content in duplicate portion samples is very low affecting the accuracy of the results. The analytical level of cadmium during the analysis of duplicate portions was somewhat lower as compared to the analysis on which the food composition file and the calculation is based. It seems that the complicating factors identified in the present study potentially affect the reliability and comparability of studies of trace element intakes. Therefore one has to be careful when comparing intake estimates derived independently or by different methods.     

Determination of cadmium, chromium, lead and vanadium in six fish species from the Adriatic Sea

Concentrations of cadmium, chromium, lead and vanadium were determined in samples of six fish species collected along the coast of the Adriatic Sea. The concentrations of the elements studied were generally low, often below the detection limits of the analytical methods. The highest values (μg kg^-1 fresh weight) were observed, mainly in the central area of the Adriatic Sea, for anchovy (Cd 20.2, Cr 82.9, Pb 45.9, V 89.9), red mullet (Cd 3.1, Cr 31.0, Pb 36.0, V 79.1) and mackerel (Cd 7.7, Cr 28.0, Pb 11.4, V 43.5). The concentrations of cadmium and lead in all the species examined were below the maximum levels indicated by the European Community for these two elements in seafood, and also would lead to exposure levels lower than the provisional tolerable daily intakes suggested by the FAO/WHO for Cd (420 μg week^-1 for a 60-kg person) and Pb (1500 μg week^-1 for a 60-kg person). The concentration of chromium was lower than the recommended daily amount (50-200 μg day^-1 for a 60-kg person) indicated by the US National Research Council. An 11-34% contribution to the daily vanadium ingestion with fish was calculated for the population of the Adriatic coast.     

Determination of zinc,cadmium, lead and copper in wines by potentiometric stripping analysis

A method for determination of zinc, cadmium, lead and copper in wines by means of potentiometric stripping analysis (PSA) is described. Cadmium, lead and copper are determined directly, whereas the zinc determination is possible only after the wine samples decomposition. The results for five red and white Yugoslav wines are given. The contents of zinc, cadmium, lead and copper in analyzed samples were in the range of 0.16 — 0.79, 0.010 — 0.045, 0.13 — 0.27 and 0.10 —0.46 mg/l, respectively. The contents of the all analyzed metals were below the maximum ordered by the Yugoslav law.     

EDTA螯合树脂固相萃取装置预富集—ICP-OES测定食品添加剂中的铅和镉

选用EDTA螯合树脂固相萃取柱,ICP的蠕动泵过柱分离富集,电感耦合等离子体发射光谱法(ICP-OES)测定了盐类食品添加剂中的铅和镉。对铅和镉的富集与洗脱条件进行优化,消除了基体离子的干扰。结果表明,pH为7.3时,进样速度为5mL/min,以0.5mol/L硝酸溶液1mL/min洗脱,固相萃取同时富集铅和镉的效果最好。本方法铅和镉的检出限分别为0.030mg/kg和0.010mg/kg,富集倍数为10。本方法应用于几种食品添加剂的铅和镉的同时测定,样品加标回收率在86%⁹9%之间,RSD<6%(n=3)。