Determination of aluminium and chromium in serum by atomic absorption spectrometry

Summary The optimal conditions for the determination of aluminium and chromium in blood serum are proposed. Several sample pretreatment procedures for the purpose are compared. The best results are obtained by sample dilution with nitric acid (0.1 mol/l) and addition of Mg(NO₃)₂ as modifier with a magnesium concentration of 0.2 mg/ml. This procedure has been used for studying the intestinal intake of aluminium by patients after oral administration of aluminium compounds.     

Determination of trace metals in sodium by electro-thermal atomic absorption spectrometry

Graphite-furnace atomic absorption spectrometry is used to analyze sodium metal after conversion to sodium nitrate. Chromium, Ni, Co, Cd and Pb have detection limits in sodium of 0.18, 0.48, 0.11, 0.02 and 0.48 μg g^-1; these are similar to the concentrations in nuclear-grade sodium, except for lead, which is below the detection limit. The behaviour of sodium nitrate, chloride and sulphate as matrices is compared.     

Determination of lithium in human serum by electrothermal atomic absorption spectrometry

An efficient method was developed for the determination of nanogram levels of lithium in biological samples. Serum samples from human subjects from southeastern Spain, treated or not treated with lithium carbonate, were analyzed by electrothermal atomic absorption spectrometry. The samples were previously treated with a matrix modifier consisting of 0.1% Triton X-100 and injected through a graphite tube with L'vov platform. The Li concentrations measured by the procedure described for the 3 certified reference samples used were not significantly different (p > 0.05) than certified levels. Sample recoveries and variability during several days, with coefficients of variation from 4.00 to 14.8%, demonstrated the reliability and accuracy of this technique. Mean Li concentration determined in the serum of individuals with psychiatric disorders treated with Li (n = 117, 5.077 +/- 1.795 microg Li/mL) was significantly higher (p < 0.001) than that in individuals not treated with Li (n = 24, 1.902 +/- 2.054 ng Li/mL).     

Determination of chromium in human milk and urine by graphite-furnace atomic absorption spectrometry

Low-temperature ashing and dry ashing at 500°C are compared for the analysis of urine and human milk. Dry ashing gives superior accuracy. The importance of contamination control, background correction and temperature control are stressed. Both urine and human milk contain about 1 ng Cr ml^-1.     

Determination of chromium in sea water by atomic absorption spectrometry

A method for the determination of chromium in sea water is described which requires minimal sample preparation. The chromium from filtered samples is oxidized with permanganate, extracted with ammonium pyrrolidine dithiocarbamate into MIBK, and analyzed by atomic absorption spectrometry in a fuel-rich air-acetylene flame. Non-filterable solids are extracted with 12 M hydrochloric acid and analyzed. Detection limits for the methods are 0.05 μg 1^-1 in the soluble phase and 0.06 μg 1^-1 in the particulate phase.     

Determination of chromium in gallium arsenide by electrothermal atomic absorption spectrometry

The sample is decomposed with 50% (v/v) aqua regia and the diluted solution is injected into the graphite furnace. The temperature program developed minimizes non-specific background signals, so that correction is not required. For a 100-mg sample, the 3σ detection limit is 70 ng Cr g^?1. The relative standard deviation of the overall procedure is 5–7%.     

Direct determination of chromium in human urine by electrothermal atomic absorption spectrometry

A rapid, accurate and direct method for urinary chromium determinations by graphite-furnace atomic absorption spectrometry is described. Few reagents are used and very little sample preparation and manipulation are required, greatly reducing the incidence of sample contamination. The method of standard additions is used to compensate for changes in sensitivity as the furnace tube ages, and for the widely different matrices encountered in urine samples. Furnace parameters must be carefully controlled. The detection limit is in the order of 0.03 ng Cr ml^-1. Agreement with independent methods is evaluated.     

石墨炉原子吸收光谱法测定蚕蛹中Cr、Se量

建立了石墨炉原子吸收光谱法测定蚕蛹中Cr、Se的方法,为蚕蛹新资源食品的开发及明确其营养价值提供科学数据。利用石墨炉原子吸收光谱法,偏振塞曼效应扣除背景,石墨炉程序升温方式进行Cr、Se的原子化,检测峰值吸收。加入硝酸镍、吐温X-100为基体改进剂,在体积分数0.5%HNO3介质中对桑蚕蛹中Cr、Se进行测定。方法的精密度:4.0%(Cr),3.1%(Se)。加标回收率:96.8%~105.3%(Cr),92.1%~108.8%(Se)。Cr、Se的线性范围和检出限分别为:0~10μg/L(Cr),0~40μg/L(Se);LOD=1.22μg/L(Cr),1.86μg/L(Se)。建立的分析方法适用于蚕蛹中Cr、Se的测定。     

碱消解-火焰原子吸收光谱法测定土壤中六价铬

建立了碱消解-火焰原子吸收光谱法测定土壤中六价铬的方法.讨论了pH值对六价铬测定的影响.干扰实验的结果表明同等含量的三价铬对六价铬测定无干扰.实验对比了无背景校正、氘灯背景校正、塞曼背景校正三种工作方式,分别对低、中、高三个水平土壤六价铬标准物质进行了测定,结果表明,低含量的土壤样品用塞曼背景校正方式测定的结果更准确,...     

Determination of selenium in human tissues by atomic absorption spectrometry

A simple method is described for the determination of selenium in human tissues without the use of perchloric acid. Digestion with nitric and sulphuric acids is followed by hydride generation and atomic absorption spectrometry. Results for NBS bovine liver and IAEA horse kidney reference materials were in good agreement with assigned concentrations, as was also achieved with the perchloric acid digestion. Recovery of added selenium was >90%, and the relative standard deviation was 5.5% for within-batch and 6.9% for between-batch analyses. The values of selenium in heart tissue were 0.9–1.3 μg g^?1 dry weight.     

Determination of total chromium traces in tannery effluents by electrothermal atomic absorption spectrometry, flame atomic absorption spectrometry and UV-visible spectrophotometric methods

Three different analytical methods comprising colorimetric method with 1,5-diphenyl-carbazide, electrothermal atomic absorption spectrometry (ET AAS) and flame atomic absorption spectrometry were utilized in a study to determine traces of chromium (Cr) in synthetic tannery effluent from laboratory scale treatment process variations. All the results obtained using the three different methods showed good agreement and met the requirement of Brazilian regulation for total Cr for effluent discharges (<0.5 mg l(-1)). However, ET AAS has been the proposed method because it was faster, less laborious, needed smaller volume of sample and presented lower limit of quantification (LOQ=2.2 mug l(-1)).     

Determination of traces of chromium in cocaine and heroin by flameless atomic absorption spectrometry

A method for the determination of total chromium in cocaine and heroin by flameless atomic absorption spectrometry is presented. Cocaine samples were dissolved in 2 ml of HNO(3) 35.0% (v/v) and diluted to 10 ml with ultrapure water; heroin samples were dissolved in ultrapure water, adding 0.4 ml of HNO(3) 35.0% (v/v) to dissolve inert species, and also diluted to 10 ml. Mg(NO(3))(2) and HNO(3), as chemical modifiers, were compared in terms of sensitivity, precision and accuracy, a lower detection limit being obtained for the use of Mg(NO(3))(2), 5.77 mug kg(-1) (7.23 mukg(-1) for HNO(3)). Within-batch precision was found to be 6.19% and 1.48% for drug solution spiked with 0 and 10 mug l(-1) of Cr(3+), respectively, when using Mg(NO(3))(2), and 7.45 and 1.19% for the same respective concentration levels when using HNO(3). Similar results on analytical recovery were obtained for both Mg(NO(3))(2) and HNO(3). Mg(NO(3))(2) was selected as the more adequate of the two chemical modifiers. A study of the introduction of a cooling-down step of 50 degrees C was carried out and compared in terms of sensitivity to the programme without a cooling-down step, but no advantage was observed. Studies on the variation in precision and analytical recovery with the amount of sample, and interferent effects of different species on chromium determination were developed. Finally, chromium concentrations obtained in cocaine samples varied between 0.02 and 0.14 mg kg(-1), the levels in the heroin samples being in the 0.05-0.59 mg kg(-1) range.     

Determination of serum selenium by hydride generation flame atomic absorption spectrometry

Serum is rapidly digested with a mixture of nitric and perchloric acids at a temperature of 180 +/- 10 degrees C, and hydrochloric acid is used to reduce selenium(VI) to selenium(IV). Selenium is determined by hydride generation flame atomic absorption spectrometry. The results show that this method has the advantages of being sensitive, accurate, rapid and simple. After the serum is digested and diluted, 4.0 ml is taken for the determination. The characteristic concentration, detection limit, variation coefficient, recovery rate and linear range are 2.93 mug 1(-1), 1.55 mug l(-1), 1.6-5.0%, 97.3-99.2% and 0.0-320.0 mug l(-1) respectively. Serum at 4 degrees C and in frozen state can be preserved for at least 7 and 14 days, respectively.     

Determination of total chromium in fresh water by atomic absorption spectrometry following flotation preconcentration

A flotation method is proposed for the quantitative preconcentration and determination of total chromium by electrothermal atomic absorption spectrometry in fresh water samples, without previous reduction or oxidation of the chromium ion state. Hydrated iron(III) oxide and iron(III) tetramethylenedithiocarbamate were used as precipitating collectors. The detection limit of the method is 0.01 g/L.     

Determination of manganese in serum and urine by electrothermal atomic absorption spectrometry

Manganese is determined in serum and urine by graphite-furnace atomic absorption spectrometry after dilution (1 + 1) with distilled water. Simple aqueous standards are used for calibration. Background absorption from the matrix is decreased by attention to the heating programme, sample dilution and gas flow-rate during atomisation. Remaining background absorption is removed by a deuterium-arc background correction system. To obtain accurate results, great care is needed in collecting samples to avoid contamination. Blood is collected through a plastic cannula, because stainless steel needles introduce considerable contamination. The mean normal concentration of manganese in serum was found to be 0.58 μg l^?1 (it- = 9) which is in agreement with other literature values. For urine, the mean normal concentration found was 0.7 μg l^?1 (it- = 16). Patients on total parenteral nutrition with manganese supplements show elevated serum and urine manganese concentrations.     

Determination of strontium in human tooth enamel by atomic absorption spectrometry

Interferences in the atomic absorption of strontium by calcium and phosphate at the levels found in human tooth enamel were investigated for both air-acetylene and nitrous oxide-acetylene flames. In air-acetylene flames, the interferences can be reduced by the addition of lanthanum(III); but perchloric acid, used for sample dissolution, causes a significant reduction in the calcium-phosphate interference, so that a standard addition method can be applied, without the need for any chemical separations. An average recovery of 98.6% for added amounts of strontium to enamel showed the proposed method to be reliable.     

Determination of molybdenum, chromium and aluminium in human urine by electrothermal atomic absorption spectrometry using fast-programme methodology

Rapid and direct procedures for the determination of molybdenum, chromium and aluminium in human urine samples are developed. Fast-programme methodology is used to simplify the heating cycles. Hydrogen peroxide, nitric acid and Triton X-100 are added to the urine samples which are directly introduced into the furnace. For molybdenum, two successive injection steps are required due to the low level of this element in the samples analyzed. Calibration is carried out using aqueous standards for aluminium and the standard additions method for both molybdenum and chromium. The reliability of the procedures is checked by analyzing two certified reference materials.     

Determination of aluminium and chromium in slurried baby food samples by electrothermal atomic absorption spectrometry

Electrothermal atomic absorption spectrometry was used to determine aluminium and chromium in different types of baby foods. Samples without previous treatment were introduced into the atomizer as suspensions, which were prepared in a medium containing 0.1% (w/v) Triton X-100 (for chromium) or 10% (v/v) ethanol (for aluminium), 5% (v/v) concentrated hydrogen peroxide, and 0.5% (v/v) concentrated nitric acid. The slurries were homogenized with a potter and introduced directly into the furnace. The presence of nitric acid allowed a substantial amount of analyte to be extracted to the liquid phase. No matrix effect was observed and aqueous standard solutions were used for calibration. The detection limits were 4 and 50 pg for chromium and aluminium, respectively; characteristic masses were 3.8 pg for chromium and 18 pg for aluminium. Reliability of the procedures was checked by statistically comparing the results with those obtained with a previous microwave oven mineralization stage and by analyis of several certified reference materials. Values for the aluminium content ranged between 0.4 and 3.0 microg/g, and for chromium between 0.003 and 0.06 microg/g.     

Determination of aluminium in blood plasma or serum by electrothermal atomic absorption spectrometry

A carbon-furnace atomic absorption method is used to determine aluminium in blood serum or plasma, diluted (1 + 2) with purified water prior to injection (20 μl) into the furnace. Procedures are described to reduce contamination during sample collection, storage and preparation of samples. A study of the interferences of inorganic ions shows that the temperature programme developed minimises these, allowing the use of aqueous standards for calibration. Ashing at 1400°C, prior to atomisation, also removes non-specific background effects, and optical correction is not required. A sample throughput of 50 duplicate analyses per day is possible and the precision (between batch) at 24 μg Al l^-1 was 11.2% (n = 10) and at 340 μg Al l^-1 was 6.3% (n = 18). Down to 4 μg Al l^-1 can be determined. Reference values for a healthy population were 4.1–20 μg Al l^-1 (mean 10.2).