Flow injection hydride generation electrothermal atomic absorption spectrometry with in-atomizer trapping for the determination of lead in calcium supplements

Lead hydride was generated from acid solution, containing potassium ferricyanide as an oxidizing agent, by the reaction with alkaline borohydride solution. The effects of reaction conditions (hydrochloric acid, ferricyanide and borohydride concentrations), and the lengths of reaction and stripping coils were studied. The effects of trapping temperature and argon flow rate were also investigated. Under the conditions giving the best peak area sensitivity, the detection limit (concentration giving a signal equal to three S.D. of the blank signal) was 0.12 mug l(-1) for a 1000 mul injection volume. The detection limit was improved to 0.03 mug l(-1) when the ferricyanide was purified by passage through a cation-exchange resin. Two calcium supplement materials were analyzed by the flow injection (FI)-hydride generation (HG)-electrothermal atomization atomic absorption spectrometry (ETAAS) method, giving values of 0.55 and 0.66 mug g(-1), in agreement with results obtained by previously validated methods. For a 500-mg sample the limits of detection and quantification were 0.006 and 0.02 mug g(-1), respectively.     

Sequential extraction--spectrofluorometric determination of lead and cadmium using cryptands.

A spectrofluorimetric method for the determination of ultratrace amounts of lead and cadmium is described based on the sequential extraction of the ternary ion-association complexes formed between the cation, a cryptand as the ligand and eosin as a counter ion. A linear working range from the detection limit (0.5 ng ml(-1) to 250 ng ml(-1) of lead and to 1 50 ng ml(-1) of cadmium was obtained. The relative standard deviation was 2-4%. The proposed method has been applied successfully to the determination of lead and cadmium in zinc metals and soft drinks.     

Rapid sample preparation and voltammetric determination of lead, cadmium and copper traces in calcium fluoride

An improved method is described for the voltammetric determination of Pb, Cd and Cu in calcium fluoride. A shortening of the time required has been achieved by omitting the removal of the fluoride ions and by measuring blank and sample signals in one and the same solution (before and after adding CaF₂). The results were in satisfactory agreement with those obtained by other methods.     

Comparison of dissolution procedures for the determination of cadmium and lead in plastics

Summary A microwave digestion procedure and an oxygen flask combustion procedure were developed for the determination of cadmium and lead in plastic materials. A comparison with conventional wet ashing shows acceptable agreement. Different types of plastics such as polyvinylchloride, polypropylene, polyethylene, polystyrene, polyamide, and polyethyleneterephthalate were investigated. The precision of microwave digestion was determined within a series and from day to day. The results obtained by flame atomic absorption spectrometry were verified by measurement with inverse voltammetry. Overall, microwave digestion as well as oxygen flask combustion are time saving and cost-effective dissolution procedures to supervise the legal cadmium limit in plastics.Abbreviations FAAS Flame atomic absorption spectrometry - GFAAS Graphite furnace atomic absorption spectometry - ICPMS Inductively coupled plasma mass spectrometry - PVC Polyvinylchloride - PP Polypropylene - PE Polyethylene - PS Polystyrene - PET Polyethyleneterephthalate - PA Polyamide 6.6 - PTFE-TFM Polytetrafluoroethylene-tetrafluoromethoxylate - HMDE Hanging mercury drop electrode - MS Mass spectrometry - OFC Oxygen flask combustion - MWD Microwave digestion - CWA Conventional wet ashing - DL Detection limit - QL Quantification limit     

In situ electrodeposition for the determination of lead and cadmium in sea water

Electrodeposition techniques for the direct determination of lead and cadmium in sea water at the natural pH and in the presence of dissolved oxygen are examined. Anodic stripping voltammetry, at either the hanging mercury drop electrode or glassy carbon thin film electrode, is suitable for the determination of labile lead and cadmium. The presence of dissolved oxygen increases the height of the lead wave with a shift to more negative potentials. A more versatile technique is in situ deposition of labile metals on a mercury-coated graphite tube electrode. The mercury film, deposited in the laboratory, is stable on the dried tubes which are used later for field electrodeposition. The deposited metals are determined by electrothermal atomic absorption spectrometry.     

能量色散型X射线荧光光谱法测定聚合物材料中镉和铅含量

提出了能量色散型X射线荧光光谱测定聚合物材料中镉和铅的测试分析方法及制样技巧。按照仪器分析条件测定同时含有镉和铅的6块不同浓度级别的标准物质来建立校准工作曲线,其线性范围分别在250ug·g-1、1100ug·g-1以内。镉和铅的方法检出限依次为4.7ug·g-1、4.1ug·g-1。该方法应用于测定欧洲标准物质ERM-EC680和ERM-EC681k,其镉和铅的实际测定值与标准物质证书的标称值相符,测定实际样品中的镉和铅的回收率介于90~110%。该方法测定标准物质和实际样品中镉和铅的精密度均小于10%。     

Direct atomic absorption determination of cadmium and lead in strongly interfering matrices by double vaporization with a two-step electrothermal atomizer

Thermal pretreatment of a sample using double vaporization in a two-step atomizer with a purged vaporizer makes possible the direct analysis of samples with strongly interfering matrices including solids. A porous-graphite capsule or a filter inserted into the vaporizer is used for solid sample analysis. The technique was used for the direct determination of Cd and Pb in human urine, potatoes, wheat, bovine liver, milk powder, grass–cereal mixtures, caprolactam, bituminous-shale and polyvinyl chloride plastic without chemical modification or any other sample pretreatment.     

Radiochemical proton activation analysis for the determination of cadmium and lead in sediment reference materials

Proton activation analysis was used for the determination of cadmium and lead in three sediment reference materials. The method is based on the^111,112Cd(p, xn)¹¹¹ In and the^206,207,208Pb(p, xn)²⁰⁶Bi reactions.¹¹¹In and²⁰⁶Bi were chemically separated by anion exchange. The results obtained were taken into account for the certification of the materials and are in the excellent agreement with the certified values.     

Precise determination of cadmium and lead isotopic compositions in river sediments

A method for the accurate determination of Cd and Pb isotope compositions in sediment samples is presented. Separation of Cd and Pb was designed by using an anionic exchange chromatographic procedure. Measurements of Cd isotopic compositions were carried out by multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS), by using standard-sample bracketing technology for mass bias correction and Pb isotopic ratios were determined by thermal ionization mass spectrometry (TIMS). The factors that affect the accurate and precise Cd isotope compositions analysis, such as instrumental mass fractionation and isobaric interferences, were carefully evaluated and corrected. The Cd isotopic results were reported relative to an internal Cd solution and expressed as the δ^114/110Cd. Five Cd reference solutions and one Pb standard were repeatedly measured in order to assess the accuracy of the measurements. Uncertainties obtained were estimated to be lesser than 0.11‰ (2s) for the δ^114/110Cd value. Analytical uncertainties in 2s for Pb isotopic ratios were better than 0.5‰. The method has been successfully applied to the investigation of Cd and Pb isotope compositions in sediment samples collected from North River in south China.     

Anodic stripping voltammetric determination of lead and cadmium in soil extracts

Two single-step extraction procedures validated by BCR, extraction with 0.43 mol dm⁻³ acetic acid and 0.05 mol dm⁻³ EDTA, are used for assessing bioavailable species of Pb and Cd in soils. After an extensive study of interferences of humic substances and using standard additions procedures, the extractable contents of Pb and Cd have been determined by DPASV directly in soil extracts with a good reproducibility (RSD varied from 1.0 to 7.9 %). Pb(II) and Cd(II) were released from complex in EDTA extracts by pH adjustment to 1 with 1 mol dm⁻³ HCl. The results were compared with those obtained with atomic absorption spectrometry and indicated reasonable agreement of both methods. Exchangeable forms represented 0.2 to 3.3 % and 13.0 to 63.6 % of total content of Pb and Cd in soils, respectively. EDTA extraction released from soils 7.9 to 29.9 % and 33.5 to 59.6 % of total content of Pb and Cd, respectively.     

催化动力学光度法同时测定痕量铅和镉

在十六烷基三甲基溴化铵（CTAB）存在下，痕量的Pb(Ⅱ）和Cd(Ⅱ）在硼酸－氯化钾－氢氧化钠缓冲体系中，能同时催化过硫酸铵氧化焦锫酚红（PR）而发生褪色指示反应，通过研究该反应的最佳反应条件以及将多元线性回归（MIR）用于数据处理，建立了同时测定铅和镉的新方法，方法已用于废水及铜混中铅和镉的同时测定。     

A nanosized cadmium(II)-imprinted polymer for use in selective trace determination of cadmium in complex matrices

We describe a nanosized Cd(II)-imprinted polymer that was prepared from 4-vinyl pyridine (the functional monomer), ethyleneglycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the radical initiator), neocuproine (the ligand), and Cd(II) (the template ion) by precipitation polymerization in acetonitrile as the solvent. The imprinted polymer was characterized by X-ray diffraction, thermogravimetric analysis, differential thermal analysis, and scanning electron microscopy. The maximum adsorption capacity of the nanosized sorbent was calculated to be 64 mg g^?1. Cadmium(II) was then quantified by FAAS. The relative standard deviation and limit of detection are 4.2 % and 0.2 μg L^?1, respectively. The imprinted polymer displays improve selectivity for Cd(II) ions over a range of competing metal ions with the same charge and similar ionic radius. This nanosized sorbent is an efficient solid phase for selective extraction and preconcentration of Cd(II) in complex matrices. The method was successfully applied to the trace determination of Cd(II) in food and water samples.

High-sensitivity determination of lead and cadmium based on the Nafion-graphene composite film

Graphene nanosheets, dispersed in Nafion (Nafion-G) solution, were used in combination with in situ plated bismuth film electrode for fabricating the enhanced electrochemical sensing platform to determine the lead (Pb²⁺) and cadmium (Cd²⁺) by differential pulse anodic stripping voltammetry (DPASV). The electrochemical properties of the composite film modified glassy carbon electrode were investigated. It is found that the prepared Nafion-G composite film not only exhibited improved sensitivity for the metal ion detections, but also alleviated the interferences due to the synergistic effect of graphene nanosheets and Nafion. The linear calibration curves ranged from 0.5 μg L⁻¹ to 50 μg L⁻¹ for Pb²⁺ and 1.5 μg L⁻¹ to 30 μg L⁻¹ for Cd²⁺, respectively. The detection limits (S/N = 3) were estimated to be around 0.02 μg L⁻¹ for Pb²⁺ and Cd²⁺. The practical application of the proposed method was verified in the water sample determination.     

Recognizing and overcoming analytical error in the use of ICP-MS for the determination of cadmium in breakfast cereal and dietary supplements

The potential effect of spectral interference on the accurate measurement of the cadmium (Cd) mass fraction in fortified breakfast cereal and a variety of dietary supplement materials using inductively coupled plasma quadrupole mass spectrometry was studied. The materials were two new standard reference materials (SRMs)—SRM 3233 Fortified Breakfast Cereal and SRM 3532 Calcium Dietary Supplement—as well as several existing materials—SRM 3258 Bitter Orange Fruit, SRM 3259 Bitter Orange Extract, SRM 3260 Bitter Orange-containing Solid Oral Dosage Form, and SRM 3280 Multivitamin/Multielement Tablets. Samples were prepared for analysis using the method of isotope dilution and measured using various operating and sample introduction configurations including standard mode, collision cell with kinetic energy discrimination mode, and standard mode with sample introduction via a desolvating nebulizer system. Three isotope pairs, ¹¹²Cd/¹¹¹Cd, ¹¹³Cd/¹¹¹Cd, and ¹¹⁴Cd/¹¹¹Cd, were measured. Cadmium mass fraction results for the unseparated samples of each material, measured using the three instrument configurations and isotope pairs, were compared to the results obtained after the matrix was removed via chemical separation using anion exchange chromatography. In four of the six materials studied, measurements using the standard mode with sample introduction via the desolvating nebulizer gave results for the unseparated samples quantified with the ¹¹²Cd/¹¹¹Cd isotope pair that showed a positive bias relative to the matrix-separated samples, which indicated a persistent inference at m/z?112 with this configuration. Use of the standard mode, without the desolvating nebulizer, also gave results that showed a positive bias for the unseparated samples quantified with the ¹¹²Cd/¹¹¹Cd isotope pair in three of the materials studied. Collision cell/kinetic energy discrimination mode, however, was very effective for reducing spectral interference for Cd in all of the materials and isotope pairs studied, except in the multivitamin/multielement matrix (SRM 3280) where the large corrections for known isobaric interferences or unidentified interferences compromised the accuracy. For SRM 3280, matrix separation provided the best method to achieve accurate measurement of Cd.     

Polarographic determination of uranium and lead in the presence of each other

Summary The microanalysis of solutions of dioxouranium- (VI) has been investigated employing differential pulse polarography. These studies show that uranium and lead can be determined accurately and economically in the presence of each other. The lead current peak occurs at –0.325 V, the uranium peak at – 0.200 V. Quantitative determinations are possible in the presence of Bi, Zn, Co and Fe.

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Polarographische Bestimmung von Uran und Blei nebeneinander

     

An assessment of contemporary atomic spectroscopic techniques for the determination of lead in blood and urine matrices

The preparation and validation of a number of clinical reference materials for the determination of lead in blood and urine is described. Four candidate blood lead reference materials (Lots, 047–050), and four candidate urine lead reference materials (Lots, 034, 035, 037 and 038), containing physiologically-bound lead at clinically relevant concentrations, were circulated to up to 21 selected laboratories specializing in this analysis. Results from two interlaboratory studies were used to establish certified values and uncertainty estimates for these reference materials. These data also provided an assessment of current laboratory techniques for the measurement of lead in blood and urine. For the blood lead measurements, four laboratories used electrothermal atomization AAS, three used anodic stripping voltammetry and one used both ETAAS and ICP-MS. For the urine lead measurements, 11 laboratories used ETAAS (most with Zeeman background correction) and 10 used ICP-MS. Certified blood lead concentrations, ±S.D., ranged from 5.9±0.4 μg/dl (0.28±0.02 μmol/l) to 76.0±2.2 μg/dl (3.67±0.11 μmol/l) and urine lead concentrations ranged from 98±5 μg/l (0.47±0.02 μmol/l) to 641±36 μg/l (3.09±0.17 μmol/l). The highest concentration blood lead material was subjected to multiple analyses using ETAAS over an extended time period. The data indicate that more stringent internal quality control practices are necessary to improve long-term precision. While the certification of blood lead materials was accomplished in a manner consistent with established practices, the urine lead materials proved more troublesome, particularly at concentrations above 600 μg/l (2.90 μmol/l).     

Voltammetric determination of lead,cadmium and copper traces in ammonium fluoride

A rapid and precise voltammetric method for the determination of traces of Pb, Cd and Cu in NH(4)F has been developed based on the capability of boric acid to mask fluoride ions and on the measurement of the analyte signals of the blank and the sample in the same solution.