Determination of trace elements in biological materials using tetramethylammonium hydroxide for sample preparation

A method to prepare milk powder, bovine liver and bovine muscle samples for analysis by electrothermal atomic absorption spectrometry (ETAAS) is proposed. Samples are mixed with a small amount of tetramethylammonium hydroxide (TMAH) and a stable and homogeneous slurry is produced in ca. 2 h with heating at 60–70 °C. After such sample preparation and dilution with water, trace elements are determined in certified reference materials. Pyrolysis and atomisation temperatures are optimised for each element, and several modifiers are investigated. External calibration is used for every analyte. Limits of detection (LODs), precision and accuracy are reported for Cd, Pb, Ni, Cr, Cu and Ag and compared with those obtained after conventional acid digestion. The main advantages of the proposed method are the simplicity of sample preparation and the longer lifetime of the graphite tube.     

土壤重金属生物有效性的评价方法

土壤重金属污染已成为人们广泛关注的全球性的环境问题之一。重金属生物有效性已成为污染生态学研究的前沿。对国内外土壤重金属生物有效性评价方法的研究进展作了简要综述，并对今后的研究作了展望。     

Mechanisms of Photochemical Air Pollution

Selected aspects of the chemistry of photochemical air pollution is discussed and some important, unresolved problems dilineated. The reactive species considered include NO₂, O₃, O(³P), O(¹D), O₂(¹Δ_g), OH and HO₂. Both the kinetics and mechanicsms of the reactions constituting the major tropospheric sources and sinks of these species are treated where available. The application of this information in both computer and smog chamber simulations of photochemical smog is discussed.     

中药片仔癀,六味地黄丸中的微量铬,铅和镉石墨炉原子吸收法测定

本文采用ＧＦ－ＡＡＳ加平台技术，基体改进剂，测定了中药片仔癀，六味地黄丸中铬、铅和镉的含量，铬、铅和镉的线性范围分别为０－０．８ｎｇ／ｍＬ，０－５０ｎｇ／ｍＬ，０－５ｎｇ／ｍＬ，回收率分别为１０２－１０３％，９９－１０１％，９７．５－９８％，本方法简便快速、准确。     

Electrode Kinetics and Ternary Complex Formation of Cd2+‐Antibiotics‐Vitamin‐B5 System. A Polarographic Study

Cd²⁺ complexes with antibiotics viz. neomycin, chlortetracycline, oxytetracycline, tetracycline, penicillin‐V and penicillin‐G as primary ligands and vitamin‐B₅ as secondary ligand have been reported at pH = 7.30 ± 0.01 and μ = 1.0 M KNO₃ at 298 K by polarographic technique.¹ Cd²⁺ formed 1:1:1, 1:1:2, and 1:2:1 complexes with a stability constants trend of neomycin < chlortetracycline < oxytetracycline < tetracycline < penicillin‐V < penicillin‐G can be explained on the basis of the nature of ligands, bonding, and steric hindrance of these drugs. The nature of electrode processes were reversible and diffusion controlled. The values of stability constants showed that these drugs can be used to reduce the toxicity of Cd.     

Cloud point extraction of napropamide and thiabendazole from water and soil

The micellar extraction and enrichment of napropamide and thiabendazole using Genapol X 80 is described. Combined with their quantification by fluorescence, detection limits below 0.2 g/l with recovery rates of up to 95% were achieved. The recovery could be improved by lowering the extraction temperature and purificaton of the surfactants. This extraction method has been applied to the isolation and preconcentration of napropamide from standard soils. Experimental parameters affecting the recovery rates were examined.     

Decomposition of vegetables for determination of Zn,Cd, Pb and Cu by stripping voltammetry

A simple and accurate digestion method using nitric acid, perchloric acid and hydrogen peroxide has been developed for use in trace analysis for heavy metals in vegetables by differential pulse anodic stripping voltammetry. The recovery of the metals from the samples is lower if the hydrogen peroxide is omitted from the digestion mixture. Standard reference materials have been analysed satisfactorily by this method.     

Determination of mercury in soils and sediments by graphite furnace atomic absorption spectrometry with slurry sampling

A graphite furnace atomic absorption spectrometric procedure for the determination of mercury is presented, in which the samples are suspended in a solution containing hydrofluoric and nitric acids. Silver nitrate (4% m/v) and potassium permanganate (3%) are incorporated, in the order specified, and aliquots are directly introduced into the graphite furnace. A fast heating programme with no conventional pyrolysis step is used. The detection limit for mercury in a 125 mg ml⁻¹ suspension is 0.1 μg g⁻¹. Calibration is performed by using aqueous standards. The reliability of the procedure is proved by analysing certified reference materials.     

Semi-micro solvent extraction as a rapid and efficient preconcentration technique for the determination of n-alkanes in oil-contaiminated water and soil samples by capillary gas chromatography

Summary In this study, a rapid and efficient semi-micro extraction procedure is presented for the extraction of some higher n-alkanes from water and soil samples. In the case of water samples n-hexane was used as the organic phase in a phase volume ratio (volume of aqueous phase/volume of organic phase) higher than 285, while in the case of soil samples, extraction with n-hexane was carried out in the presence of an excess of 2 M NaCl solution. The extraction rate from soil samples is very high and is better than Soxhlet extraction, comparable with supercritical fluid extraction. High preconcentration factor in water samples allows the limits of detection to be in the ng.mL⁻¹ level with the use of gas chromatographic analysis. Flame ionization detector was used for monitoring the analytes. The obtained recoveries of all studied compounds from both water and soil samples are higher than 90%. This method was successfully used to determine some n-alkanes in municipal wastewater and contaminated soil.     

一维链状柔性羧酸镉配位聚合物[Cd(p-BDOA)·2H2O]n的合成、结构与性质研究(英)

A novel 1-D Cd(Ⅱ) coordination polymer, [Cd(p-BDOA)·2H₂O]_n(I) ( p-BDOA^2-=benzene-1,4-dioxyacetate dianion) has been synthesized and characterized by elemental analysis, IR, PL, TG and X-ray single crystal diffraction. The Crystal crystallizes in monoclinic system, the space group is C2/c, with the crystal cell parameters a=1.175 1(1) nm, b=0.551 0(1) nm, c=1.827 7(2) nm, β=96.14(2)°, and V=1.176 6(3) nm^3,, M_r=372.60, R=0.045 9, wR=0.127 9. The Cd(Ⅱ) ion has a trigonal prism coordination configuration that defined by four carboxyl O atoms from two different p-BDOA^2- ligands and two water molecules. Adjacent Cd(Ⅱ) ions are linked by carboxylate groups with the bidentate coordination mode, giving rise to a chain structure with the adjacent Cd…Cd distance of 1.526 3(5) nm. Furthermore, such chains are linked by hydrogen bonds to form supramolecular network. The results of PL and TG show that the complex exhibits intense fluorescent emissions and its chain skeleton is thermally stable up to 419 K. CCDC: 220443.