农产品中重金属铅、砷、铬、镉的前处理及检测

介绍农产品中四种常见的重金属:Pb、As、Cr、Cd的检测方法,以及样品的前处理工艺。检测方法以分光光度法、电化学法、原子吸收法、原子荧光法四个大类来分别进行介绍。     

Assay of the antioxidant capacity of foods using an iron(II)-catalysed lipid peroxidation model for greater nutritional relevance

The formation of free radicals by the iron-catalysed Fenton reaction is a major cause of oxidative damage in the body. Here a common assay of antioxidant capacity, inhibition of the β-carotene-linoleic acid model of lipid peroxidation, has been modified by the addition of ferrous iron (final concentration 36 μmol/l), which makes the rate of oxidation of the lipids occur 25 times faster. Such an assay can simulate the oxidative damage to membrane lipids and low density lipoproteins occurring in the body in the presence of free iron. It thus may be nutritionally more relevant than traditional chemical assays of antioxidant capacity, as it measures pre-emptive antioxidant activity, i.e. activity which prevents free radicals being formed in the first place. Pre-empting their formation is likely to be more protective than scavenging of free radicals. The relative antioxidant activity of some food products found using this new assay was very different from that found using a radical-scavenging assay. Vitamin C, at 280 mg/l, was found to be 60 times better than blackcurrant puree in scavenging free radicals, but only one eighth as good as the blackcurrant puree in preventing iron-catalysed lipid peroxidation.     

鹰嘴豆油及对力竭运动大鼠心肌脂质过氧化的影响

采用响应面优化超声波辅助法提取鹰嘴豆油的工艺,并研究对力竭运动大鼠心肌脂质过氧化的影响.最佳工艺条件,液料比为13∶1 (mL/g)、超声功率为160 W提取温度为41 ℃,在此工艺条件下做3次平行实验,得出鹰嘴豆油提取率为69.72％.与预测值相近,表明该条件是可行的.同时大鼠力竭运动实验表明,大鼠灌胃鹰嘴豆油可以使...     

Comparison between acetic acid and landfill leachates for the leaching of Pb(II), Cd(II), As(V), and Cr(VI) from cementitious wastes

The Toxicity Characteristic Leaching Procedure (TCLP) has been widely used to characterize the suitability of solid wastes for disposal in landfills. However, the widespread application of this test for the assessment of wastes disposed in different landfill types is often questionable. This paper investigates the leaching profiles of cement-stabilized heavy metal ions, namely, Pb (II), Cd (II), As(V), and Cr(VI), using acetic acid and leachates from municipal and nonputrescible Australian landfill sites. The leaching profiles of Pb, Cd, As, and Cr using acetic acid were found to be similar to the nonputrescible landfill leachate and differed markedly from the municipal solid waste (MSW) leachate. The additional presence of high amounts of organic and inorganic compounds in the municipal landfill leachate influenced the leaching profiles of these metal ions as compared to the acetic acid and the nonputrescible systems. It is postulated that the organic compounds present in the municipal landfill leachate formed complexes with the Pb and Cd, increasing the mobility of these ions. Moreover, the organic compounds in the municipal landfill leachate induced a reducing environment in the leachate, causing the reduction of Cr(VI) to Cr(III). It was also found that the presence of carbonates in the municipal landfill leachate affected the stability of calcium arsenate, with the carbonate competing with arsenate for calcium at high pH, forcing arsenate into the solution.     

The effect of ginger on diabetic nephropathy,plasma antioxidant capacity and lipid peroxidation in rats

Oxidative stress is a major factor in the pathogenesis of diabetic complications. We studied the effects of ginger powder on nephropathy induced by diabetes, and measured changes in plasma antioxidant capacity and lipid peroxidation.     

Antioxidative effect of cactus pear fruit (<Emphasis Type="Italic">Opuntia ficus-indica</Emphasis>) extract on lipid peroxidation inhibition in oils and emulsion model systems

The lipid peroxidation inhibitory effects of cactus pear fruit (Opuntia ficus-indica) extracts (CPFE) on fish oil, fish oil-in-water emulsion and linoleic acid were studied using conjugated diene hydroperoxides (CDH), weight gaining, peroxide value (PV), and thiobabituric acid reactive substances (TBARS) assays. A modified DPPH assay was used in the characterization of CPFE antioxidants for their thermal stability. CPFE successfully controlled lipid peroxidation at different stages of the pathway in a dose-dependent manner. Inhibition of the lipid peroxidation in oils and emulsion was successfully improved by increasing the level of CPFE from 0.01 to 0.1%. CPFE controlled conjugated diene formation from lipid radicals, demonstrating lower conjugated diene hydroperoxide values than its control counterpart. Moreover, it controlled the addition of oxygen to conjugated dienes to form lipid peroxyl radicals, resulting in lower weight gain. It also recorded a lower PV than its control counterpart, indicating its inhibitory effect on peroxyl radical formation. Such multiple and integrated effects controlled the overall lipid peroxidation, resulting in lower TBARS values than the control. Characterization of the CPFE antioxidants proved that those antioxidants are heat-resistant, although the color of the CPFE pigments disappeared rapidly.     

Comparison of Cd(II), Cu(II), and Pb(II) biouptake by green algae in the presence of humic acid

The present study examines the role of humic acid, as a representative of dissolved organic matter, in Cd(II), Cu(II), and Pb(II) speciation and biouptake by green microalgae. Cellular and intracellular metal fractions were compared in the presence of citric and humic acids. The results demonstrated that Cd and Cu uptake in the presence of 10 mg L(-1) humic acid was consistent with that predicted from measured free metal concentrations, while Pb biouptake was higher. By comparing Cd, Cu, and Pb cellular concentrations in the absence and presence of humic acid, it was found that the influence of the increased negative algal surface charge, resulting from humic acid adsorption, on cellular metal was negligible. Moreover, the experimental results for all three metals were in good agreement with the ternary complex hypothesis. Given that metal has much higher affinity with algal sites than humic acid adsorbed to algae, the contribution of the ternary complex to metal bioavailability was negligible in the case of Cd (II) and Cu (II). In contrast, the ternary complex contributed to over 90% of total cellular metal for Pb(II), due to the comparable affinity of Pb to algal sites in comparison with humic acid adsorbed to algae. Therefore, the extension of the biotic ligand model by including the formation of the ternary complex between the metal, humic acid, and algal surface would help to avoid underestimation of Pb biouptake in the presence of humic substances by green algae Chlorella kesslerii.     

Chitosan, chitin-glucan and chitin effects on minerals (iron, lead, cadmium) and organic (ochratoxin A) contaminants in wines

Chitosan (F7), chitin (F2), chitin-glucan (F1) and chitin glucan hydrolysate (F5) of fungal origin were tested for removal of mineral (Fe or Pb and Cd) and organic (ochratoxin A: OTA) contaminants in wines. Red, white and sweet wines are spiked with either Fe (20 mg L⁻¹), or Pb (500 μg L⁻¹) and Cd (20 μg L⁻¹) or OTA (5 μg L⁻¹). The wines were then treated with F1, F2, F5 or F7 at doses of 0.1 g, 0.5 and 2 g L⁻¹. After 2 days, the levels of iron, copper, lead and cadmium were measured using a flame and graphite furnace atomic absorption spectrophotometer. Depending on the treatment red wines showed reductions of iron by 73–90%, cadmium by 29–57% and lead by 33–74%. The same treatments with white wine gave reductions for iron of 32–91%, cadmium fell by 11–23%, lead by 50–65%. In the case of sweet wines iron was reduced by 51–90%, cadmium by 17–25%, and lead by 38–84%. For wine enriched in OTA, treatments with F1, F2, F5, F7 were carried out at doses of 2 and 5 g L⁻¹. After 2 days, the levels of OTA in wines were analyzed by HPLC with fluorimetric detection. OTA was reduced by 56.7–83.4% in red wine, by 53.4–64.5% in white wine and 26.1–43.5% in sweet wine. These findings indicate that chitosan, chitin, chitin-glucan, or chitin glucan hydrolysate from fungal origin may be useful ancillaries for wine limpidity prevention by reducing levels of Fe, heavy metals (Pb, Cd) and mycotoxins (OTA) and thereby improving wine safety.     

3种食用油对大鼠脏器、生化指标及脂质过氧化的影响

通过研究花生油、菜籽油、大豆油对大鼠体重、脏器系数比、生化指标及脂质过氧化的影响,探讨这3种食用油对机体可能存在的危害,从而为居民合理摄取食用油提供理论依据。实验采用SD大鼠,按体重随机分为7组:对照组、花生油小剂量组(2.25g/kg)、花生油大剂量组(11.25g/kg)、菜籽油小剂量组(2.25g/kg)、菜籽油大剂量组(11.25g/kg)、大豆油小剂量组(2.25g/kg)、大豆油大剂量组(11.25g/kg)。灌胃3个月后测定各组大鼠的体重、主要脏器系数比、生化指标及脂质过氧化指标,并取部分肝脏冰冻切片,苏木精-伊红(HE)染色镜检。实验结果表明,与对照组相比花生油、菜籽油、大豆油大剂量组及大豆油小剂量组大鼠体重增加明显,菜籽油大剂量组肝体比升高明显、脾体比显著降低,花生油小剂量组睾丸体比升高,各组心体比无显著差异。与对照组比生化指标检测显示:菜籽油大剂量组超氧化物歧化酶(SOD)显著升高、谷草转氨酶(AST)显著降低;花生油小剂量组、大豆油大剂量组甘油三酯(TG)显著下降;菜籽油、大豆油小剂量组高密度脂蛋白胆固醇(HDL-C)显著升高。肝脏HE染色结果显示各组均无明显差异。实验结果:过量摄取3种食用油对体重和脏器有所影响,但无明显的毒副作用。     

Determination of Cd (II), Cu (II), and Pb (II) in Some Foods by FAAS after Preconcentration on Modified Silica Gels with Thiourea

Abstract: This study describes preconcentration method for determination of Cd (II), Cu (II), and Pb (II) in some food samples. Silica gel was modified with thiourea and characterized by IR and C, H, N, S elemental analysis. Modified silica gel was used as a solid phase extraction for determination of Cd (II), Cu (II) and Pb (II) in tuna fish, biscuit, black tea, rice, ka?ar cheese, honey, tomato paste, and margarine samples. The analytical conditions including eluent type, pH of sample solutions, flow rates of sample and eluent solutions, etc. were optimized. The influence of the matrix ions on the involvement of the Cd (II), Cu (II), and Pb (II) were also studied. GBW 07605 tea standard reference material was used for validation of method. The method was successfully applied for the determination of Cd (II), Cu (II), and Pb (II) ions in food samples. The detection limits were in the range of 0.81 μg/L, 0.38 μg/L, and 0.57 μg/L for cadmium, copper and lead, respectively. The relative standard deviations of the procedure were below 10%. The sorption capacities were found as 92 μmol/L Cd (II), 286 μmol/L Cu (II), and 121 μmol/L Pb (II).     

Application of a New Functionalized Nanoporous Silica for Simultaneous Trace Separation and Determination of Cd(II), Cu(II), Ni(II), and Pb(II) in Food and Agricultural Products

A novel sorbent for simultaneous separation of cadmium, copper, nickel, and lead was prepared by functionalizing SBA-15 nanoporous silica with dithizone. A solid-phase extraction method using the above sorbent was developed to separate and preconcentrate trace amounts of cadmium, copper, nickel, and lead ions from food and agricultural products by flame atomic absorption spectrometry measurements. The optimum experimental conditions such as pH; flow rates; type, concentration, and volume of the eluent; breakthrough volume; and effect of coexisting ions on the separation and determination of these heavy metals were evaluated. The extraction efficiencies for the mentioned heavy metals were greater than 97 %, and the limits of detection were 0.09, 0.16, 0.21, and 0.45 μg?L^?1 for cadmium, copper, nickel, and lead, respectively. The preconcentration factor for simultaneous analysis of the four heavy metals was found to be 100 approximately. The relative standard deviations of the method were <5 % for 10 separate column experiments for the determination of 5.0 μg of cadmium, copper, nickel, and lead ions. The adsorption capacity of the dithizone-SBA-15 was 189 mg?g^?1 for cadmium, 102 mg?g^?1 for copper, 91 mg?g^?1 for nickel, and 208 mg?g^?1 for lead.     

Occurrence of heavy metals (Hg, Cd, and Pb) and polychlorinated biphenyls in salted anchovies

The most popular brands of salted anchovies (Engraulis encrasicolus) from the Mediterranean Sea and Atlantic Ocean were purchased from several Italian supermarkets and grocery stores. Heavy metal (Hg, Cd, and Pb) and polychlorinated biphenyl (PCB) levels were determined and assessed by comparing the concentrations in these samples with the maximum permissible limits set by the European Union (Reg EC 629/2008 and Reg EC 1881/2006 [Off. J. Eur. Union L 173:3-9 and 364:5-24, respectively]). The Hg and Cd levels were higher than those of Pb in all samples examined. For Hg and Pb, the concentrations recorded in this study were below the authorized limits, while an appreciable percentage of samples from both locations (Mediterranean Sea, 35%, and Atlantic Ocean, 25%) showed Cd levels exceeding the threshold recommended for human consumption. Concerning PCBs, the results of principal component analysis showed that samples from the two different marine areas appeared to be discriminate, with Mediterranean anchovies more contaminated than the others, in spite of their lower lipid content. However, anchovy samples from both locations had dioxinlike-PCB levels (Mediterranean Sea, 0.011 pg World Health Organization toxic equivalency [WHO-TEQ] g(-1), wet weight, and Atlantic Ocean, 0.007 pg WHO-TEQ g(-1), wet weight) that were below the WHO-TEQ maximum concentration set by European regulation. The results of this study will help in generating data needed for the assessment of heavy metal and PCB intake from this food.     

ICP-MS测定饼干中的铅、砷、铬、镉、铜、锌、铁和锰

探讨了应用电感耦合等离子体质谱仪测定饼干中铅、砷、铬、镉、铜、锌、铁和锰8种重金属元素的方法。运用微波消解系统对样品进行消解,以铋、锗、钪和铟作为内标物,用ICP-MS对消解液进行检测,并采用国标方法对其结果进行验证。利用加标回收率试验和国家标准物质小麦(GBW 10052)检测试验考察了方法的准确性和可靠性。结果表明,该方法所测元素在标准溶液浓度范围内呈线性关系,相关系数均大于0.999,方法检出限在0.002~0.500 mg/kg之间,相对标准偏差均小于6.55%,本法与国标方法测量结果的相对偏差在3.73%~8.40%之间,加标回收率在88.0%~106%之间,标准物质的测定值与标准参考值符合要求。     

Toxic (Pb,Cd, Hg) and essential (Fe,Cu, Zn,Mn) metal content of liver tissue of some domestic and bush animals in Ghana

Accumulation of toxic metals in liver, a rich natural source of essential elements, can present health risks to regular consumers of liver. A total of 35 fresh liver samples of cow, sheep, goat, pig, grass-cutter (Thryonomys swinderianus), gaint rat (Cricetomys gambianus), red deer (Cervus elaphus), chicken and antelope (Antilocapra americana) were obtained from three different markets in Accra and Kumasi, Ghana. Samples were analyzed using atomic absorption spectrometry and an automatic mercury analyzer. Levels of iron in the grass-cutter and pig of 500.5–645.4 mg kg^?1 were the highest in the animal livers examined. Mn concentrations were highest in grass-cutter and rat liver, ranging 16.5–30.2 mg kg^?1. The safe Cu and Zn permissible limits of 20 and 50 mg kg^?1 were exceeded in 70 and 75% of the liver samples, respectively. Generally, for each animal group studied, at least 50% of the sample livers exceeded the Cd permissible limit of 0.5 mg kg^?1. The levels of Pb, which ranged 1.3–13.8 mg kg^?1, exceeded the proposed European Commission (EC) limit of 0.5 mg kg^?1. Care must be taken by regular consumers of the iron-rich animal livers of grass-cutter, pig and rat because they also had the highest levels of Pb (in grass-cutter and pig) and Cd (in grass-cutter, rat and pig). The liver samples analyzed for Hg had values far below the permissible limit of 0.5 mg kg^?1.     

Assessment of noise and heavy metals (Cr, Cu, Cd, Pb) in the ambience of the production line for recycling waste printed circuit boards

The crush-pneumatic separation-corona electrostatic separation production line provides a feasible method for industrialization of waste printed circuit boards (PCBs) recycling. To determine the potential environmental contamination in the automatic line workshop, noise and heavy metals (Cr, Cu, Cd, Pb) in the ambience of the production line have been evaluated in this paper. The mean noise level in the workshop has been reduced from 96.4 to 79.3 dB since the engineering noise control measures were employed. Noise whose frequency ranged from 500 to 1000 Hz is controlled effectively. The mass concentrations of TSP and PM(10) in the workshop are 282.6 and 202.0 μg/m(3), respectively. Pb (1.40 μg/m(3)) and Cu (1.22 μg/m(3)) are the most enriched metals in TSP samples followed by Cr (0.17 μg/m(3)) and Cd (0.028 μg/m(3)). The concentrations of Cu, Pb, Cr, and Cd in PM(10) are 0.88, 0.56, 0.12, and 0.88 μg/m(3), respectively. Among the four metals, Cr and Pb are released into the ambience of the automatic line more easily in the crush and separation process. Health risk assessment shows that noncancerous effects might be possible for Pb (HI = 1.45), and noncancerous effects are unlikely for Cr, Cu, and Cd. The carcinogenic risks for Cr and Cd are 3.29 × 10(-8) and 1.61 × 10(-9), respectively. It indicates that carcinogenic risks on workers are relatively light in the workshop. These findings suggest that this technology is advanced from the perspective of environmental protection in the waste PCBs recycling industry.     

ICP-MS analysis of a series of metals (Namely: Mg,Cr, Co,Ni, Fe,Cu, Zn,Sn, Cd and Pb) in black and green olive samples from Bursa,Turkey

Ninety-two black and green table olive samples from the Bursa, Turkey were analyzed. The olives were sampled from 56 brands, four processing methods and three packing types. The concentration of Mg, Cr, Co, Ni, Fe, Cu, Zn, Sn, Cd and Pb were measured by inductively coupled plasma mass spectrometry (ICP-MS). While the most concentrated element was Mg (125.11 ± 5.02), Co (0.09 ± 0.01) had the lowest concentration in tested olive samples. The levels of the ten metals studied are within safe limits. The data here obtained will be valuable in complementing available food composition data, and estimating dietary intakes of heavy metals in Turkey. The metals Mg, Fe, Zn, Sn and Pb presented significant differences (p < 0.05) in content between two types, hence processing method, brand and packing material must influence their content.     

A simplified method for the extraction of the metals Fe,Zn, Cu,Ni, Cd,Pb, Cr,Co and Mn from soils and sewage sludges

The method described for digestion of soil samples with aqua regia is simple, flexible and safe to operate with large sample throughout. At least nine metals can be determined in the resulting solutions with errors of <5%. The results compare favourably with those from reflux aqua regia and averaged 88% of the certified total values for reference soils and 88% of those for reference sewage sludges.     

Synthesis,characterisation and analytical application of Fe3O4@SiO2@polyaminoquinoline magnetic nanocomposite for the extraction and pre-concentration of Cd(II) and Pb(II) in food samples

This work describes a novel Fe₃O₄@SiO₂@polyaminoquinoline magnetic nanocomposite and its application in the pre-concentration of Cd(II) and Pb(II) ions. The parameters affecting the pre-concentration procedure were optimised by a Box–Behnken design through response surface methodology. Three variables (extraction time, magnetic sorbent amount and pH) were selected as the main factors affecting the sorption step, while four variables (type, volume and concentration of the eluent, and elution time) were selected as main factors in the optimisation study of the elution step. Following the sorption and elution of analytes, the ions were quantified by flame atomic absorption spectrometry (FASS). The limits of detection were 0.1 and 0.7 ng ml^?1 for Cd(II) and Pb(II) ions, respectively. All the relative standard deviations were less than 7.6%. The sorption capacities of this new sorbent were 57 mg g^?1 for Cd(II) and 73 mg g^?1 for Pb(II). Ultimately, this nanocomposite was successfully applied to the rapid extraction of trace quantities of these heavy metal ions from seafood and agricultural samples and satisfactory results were obtained.     

The levels of heavy metals (Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Hg) in fish from onshore and offshore waters of the German Bight

Zusammenfassung Mit dem Ziele, unsere Kenntnisse über den gegenwärtigen Grad der Schwermetallspeicherung in Fischen zu erweitern, wurde der Gehalt an den metallischen Spurenelementen Mangan, Eisen, Kobalt, Nickel, Kupfer, Zink, Cadmium, Blei und Quecksilber in bestimmten Fischarten (Kabeljau und Scholle) aus küstennahen und küstenfernen Fanggebieten der Deutschen Bucht bestimmt. Als Meßverfahren wurde die Atom-Absorptions-Spektrophotometrie eingesetzt: Bei der Bestimmung der Elemente Mn, Fe, Cu und Zn wurde die herkömmliche Flammentechnik (Laminarbrenner, Luft-Acetylen-Flamme) verwendet. Die flammenlose Atom-Absorptions-Spektrophotometrie unter Verwendung der Graphitrohrküvette diente der Bestimmung von Cd, Pb, Co und Ni. Der Gehalt an Gesamt-Quecksilber wurde mit der sogenannten Kaltdampf-Methode ermittelt. Zur Vermeidung von Fehlinterpretationen der Meßwerte von Kobalt und Nickel, die sich insbesondere bei diesen Elementen als Folge von Matrixeffekten ergeben, wurde eine spezielle Aufarbeitungstechnik entwickelt, die auf einer selektiven Abtrennung und Anreicherung durch Chelataustauscher-Chromatographie über Chelex 100 beruht.Die ermittelten analytischen Daten werden in einem Diagramm mit doppelt logarithmischem Maßstab dargestellt. Auf der Abscisse ist der Gehalt (Mittelwert von Mehrfachbestimmungen) aufgetragen, auf der Ordinate die zugehörige Reproduzierbarkeit (als Variationskoeffizient) des jeweiligen Meßverfahrens. Allen untersuchten Elementen lassen sich gut umrissene Gehaltsbereiche zuordnen.Das Spektrum der Gehalte an den Übergangsmetallen Mangan, Eisen, Kobalt, Nickel, Kupfer und Zink zeigt bei einem Vergleich von Fischen gleicher Art, aber verschiedener Herkunft nur geringe Unterschiede. Ebenso entsprechen einander die Gehalte, welche an Hand der Untersuchungen verschiedener Fischarten (Kabeljau, Scholle) gleicher Herkunft gewonnen wurden. Die ermittelten Werte für Cadmium, Blei und Quecksilber lassen erkennen, daß Schollen, die sich in der unmittelbaren Küstenzone aufhalten, erhöhte Gehalte aufweisen.

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The levels of heavy metals (Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Hg) in fish from onshore and offshore waters of the German Bight

Summary With the intention of increasing our knowledge about the actual degree of heavy metal accumulation in fish, the contents of the elements manganese, iron, cobalt, nickel, copper, zinc, cadmium, lead and mercury in certain fish species (cod and plaice) from onshore and offshore waters of the German Bight have been determined. The measurements have been performed by atomic absorption spectrophotometry: Flame AAS was used as investigating procedure for the determination of Mn, Fe, Cu and Zn. A non-flame atomization system with a heated graphite tube was used for the determination of Cd, Pb, Co, and Ni. The concentration of total Hg was estimated according to the so-called cold vapour atomic absorption method. In order to avoid errors in interpretation of measured values of Co and Ni, which occured as a result of matrix effects, a special technique has been developed. This based upon an selective separation and enrichment by chelate exchanger chromatography (Chelex 100).The analytical data obtained are plotted in a diagram with log.-log. scale. The content is shown on thex-axis, and the corresponding relative reproducibility (variation coefficient) of the method used is shown on the y-axis. For all elements investigated certain levels have been found out.From an examination of the results it appeared that there were comparatively small differences in the prevailing concentrations of transition metals Mn, Fe, Co, Ni, Cu, and Zn between samples of the same species from different areas. Likewise, the levels estimated for plaice did not differ from those estimated for cod. There is some evidence of elevated levels of Cd, Pb, and Hg in plaice from areas along the coastline.