The determination of cadmium in environmental samples by slurry atomization graphite furnace atomic absorption spectrophotometry using platforms and matrix modification

The conditions which allow the accurate and precise determination of cadmium in environmental samples using direct solid introduction and electrothermal atomization atomic absorption spectrometry have been investigated. Cadmium was successfully determined in three certified reference materials (an aquatic plant, olive leaves, and mussels). Utilization of platform atomization and a 0.5% solution of ammonium phosphate as matrix modifier eliminated matrix interference effects. Excellent agreement was obtained with the certified values, with precision equivalent to that found by conventional acid digestion procedures.     

Stability of blood samples during blood-lead analysis by graphite furnace-atomic absorption spectrophotometry

Blood-Triton X-100 solutions are used routinely by a number of laboratories to determine the concentration of lead in blood by graphite furnace-atomic absorption spectrophotometry using autosamplers. Some controversy has arisen in the literature concerning whether blood-Triton X-100 solutions are sufficiently stable with respect to settling of blood cells and blood cell fragments to determine lead in blood using autosamplers. This study shows conclusively that blood-Triton X-100 solutions are stable for more than 3 hr. This is ample time to use an autosampler which contains a sample rack with a capacity of up to 50 samples.     

Fast determination of lead in lake sediment samples using electrothermal atomic absorption spectrometry with slurry samples introduction

An analytical method for the determination of glutamic acid by the sequential perturbation caused by different amounts of glutamic acid on the oscillating chemical system involving the Cu(II)-catalyzed oscillating reaction between hydrogen peroxide and sodium thiocyanate in an alkaline medium is proposed. The method relies on the linear relationship between the changes in the oscillation amplitude of the chemical system and the concentration of glutamic acid. The reaction is implemented in a continuous-flow stirred-tank reactor, and changes in the oscillation amplitude on each perturbation are proportional to the glutamic acid concentration. The use of the analyte pulse perturbation (APP) technique permits sequential determinations on the same oscillating system owing to the expeditiousness with which the steady state is regained after each perturbation. The dynamic range lies between 2.5x10(-6) and 3.2x10(-4) M of glutamic acid, with the regression coefficient is 0.9987. The precision is excellent (less than 0.68% as relative standard deviation (R.S.D.)). Some aspects of the potential mechanism of action of glutamic acid on the oscillating system are discussed.     

The determination of lead in copper-base alloys and steel by atomic absorption spectrophotometry

The principle of atomic absorption spectrophotometry has only recently been exploited as an analytical technique and details are given of the development of a procedure for determining lead in copper-base alloys and leaded steels. The recommended method is simple, rapid and provides results as accurate as those obtained by the more time-consuming alternative methods in current use.     

Rapid determination of lead and cadmium in sewage sludge samples using electrothermal atomic absorption spectrometry with slurry sample introduction

Lead and cadmium concentrations in sewage sludge samples are determined by suspending the ground samples in a solution containing 10% (v/v) concentrated hydrofluoric acid, 1% (v/v) concentrated nitric acid, 0.5% (m/v) dihydrogen ammonium phosphate and 0.1% (m/v) sodium hexametaphosphate. Aliquots of 20 microL of these suspensions (4 mg/mL) are diluted to 1000 microL with the same solution and then injected into the electrothermal atomizer. The drying stage is performed by programming a 400 degrees C temperature, a ramp time of 20 s and a hold time of 15 s on the power supply of the atomizer. No ashing step is used. Platform atomization is carried out at 1600 and 1800 degrees C for Pb and Cd, respectively. Calibration is performed using aqueous standards in the 5-75 and 0.2-5 microg/L Pb and Cd ranges, respectively. Results obtained for three certified reference materials and four samples demonstrate the reliability of the procedures described.     

Rapid determination of lead and cadmium in sewage sludge samples using electrothermal atomic absorption spectrometry with slurry sample introduction

Lead and cadmium concentrations in sewage sludge samples are determined by suspending the ground samples in a solution containing 10% (v/v) concentrated hydrofluoric acid, 1% (v/v) concentrated nitric acid, 0.5% (m/v) dihydrogen ammonium phosphate and 0.1% (m/v) sodium hexametaphosphate. Aliquots of 20 μL of these suspensions (4 mg/mL) are diluted to 1000 μL with the same solution and then injected into the electrothermal atomizer. The drying stage is performed by programming a 400?°C temperature, a ramp time of 20 s and a hold time of 15 s on the power supply of the atomizer. No ashing step is used. Platform atomization is carried out at 1600 and 1800?°C for Pb and Cd, respectively. Calibration is performed using aqueous standards in the 5–75 and 0.2– 5 μg/L Pb and Cd ranges, respectively. Results obtained for three certified reference materials and four samples demonstrate the reliability of the procedures described.     

Determination of lead in fish samples by slurry sampling electrothermal atomic absorption spectrometry

Ultrasonic slurry sampling electrothermal atomic absorption spectrometry (USS-ETAAS) was been applied to the determination of lead in several fish samples. The influences of instrument operating conditions and slurry preparation on the signal were examined. Palladium and ammonium nitrate were used as the modifier to improve the signal. Since the sensitivity to lead in various fish slurries and aqueous solutions was different, the standard additions method was used for the determination of lead in these fish samples. The method was applied to the determination of lead in dogfish muscle reference material (DORM-2) and a swordfish muscle sample purchased from the local market. The analysis results agreed with the reference value. The accuracy was better than 6%. The precision between sample replicates was better than 16% with the USS-ETAAS method. The detection limit of lead estimated from standard additions curve was about 0.053-0.058 microgram g-1 in different samples.     

Use of aqueous slurry sampling for the determination of lead in human hair samples by electrothermal atomic absorption spectrometry

A method for the determination of lead in human hair slurries by electrothermal atomic absorption spectrometry was optimized. Particle size reduction was achieved with a vibrational mill ball equipped with zirconia cups, 20 min being sufficient grinding time to achieve an adequate particle diameter (<1 mum). The use of different thickening agents, namely glycerol, Triton X-100 and Viscalex HV30, was studied and glycerol was found to be the best. The use of Pd and Mg(NO(3))(2) at optimum concentrations of 20 and 25 mg l(-1) respectively was found to be satisfactory for stabilizing lead at 1100 degrees C. A limit of detection of 0.21 mg kg(-1) was obtained. The limit of detection can be reduced to 0.05 mg kg(-1) without loss of analytical performance by increasing four-fold the amount of hair sample. Accuracy was studied by analysis of a CRM 397 human hair reference material with a certified lead content of 33.0 +/- 1.2 mg Pb kg(-1). The standard addition method was used for the determination of lead in hair samples from healthy people, the levels being between 2.3 and 35.5 mg kg(-1).     

Zeeman effect electrothermal atomic absorption spectrophotometry with matrix modification for the determination of arsenic in urine

Arsenic was determined in urine by electrothermal atomic absorption spectrophotometry using Zeeman Effect background correction and after matrix modification with 5% nickel nitrate. Mean recovery of urine samples spiked with 100 micrograms . L-1 dimethylarsinic acid was 97.9 micrograms . L-1. Within-run CV was 2.4%, between-run CV was 7.3% and the detection limit was determined to be 10.0 micrograms . L-1. The method can be used for the rapid screening of urine samples for elevated arsenic levels.     

On-line solid-phase extraction using alizarin violet functionalized silica gel for determination of trace lead in environmental samples and wastewater by sequential injection spectrophotometry

Trace of Pb(Ⅱ) has been on-line separated and enriched from environmental samples and wastewater by using the self-made alizarin violet functionalized silica gel micro-column coupling with a sequential injection sampling technology. The determination is based on the color reaction of Pb(Ⅱ) with iodide and crystal violet to form an ionic association complex in the presence of polyvinyl alcohol and hydrochloric acid. The use of the microcolumn can prevent the interference of most familiar metal ions, and ther...     

消解方法对原子吸收分光光度法测定藜麦中铅含量的影响

采用原子吸收分光光度法测定藜麦中的痕量铅,研究了五种不同的前处理方式对藜麦中铅含量测定的影响。五种方法的加标回收率为95.4%~104.8%,分析标准物质的结果与推荐值一致,比较得出微波消解法具有操作简单、消解彻底、稳定性高和污染低等优点,在藜麦中铅含量的测定中具有很大的应用前景。     

Graphite furnace-atomic absorption spectrophotometric determination of palladium in soil

A new and sensitive procedure for the graphite furnace-atomic absorption spectrophotometric (GF-AAS) determination of Pd in soil at nanogram level is described. The method is based on prior separation and enrichment of the metal as Pd(II)-SnCl₃ ^–-N-butylacetamide (BAA) complex into 1-pentanol (PN) by solvent extraction method. The value of the molar absorptivity of the complex in three solvents, i.e. ethyl acetate, 1-pentanol, chloroform, lie in the range of (0.70–2.75) × 10⁴ L mol^–1 cm^–1 at λ_max 360–440 nm. The metal could be enriched into organic solvent, i.e. PN, up to 10-folds. The sensitivity (A = 0.0044) of the method in the term of the peak height was 0.5 ng Pd/mL of the aqueous solution at an enrichment factor (EF) of 5. Optimization of analytical variables during enrichment and GF-AAS determination of the metal are discussed. The method has been applied for the analysis of Pd to soil samples derived from roads and highways in Germany.     

Screening test of silver nanoparticles in biological samples by graphite furnace-atomic absorption spectrometry

A simple, rapid and inexpensive screening test is presented to determine the presence of silver (Ag) nanoparticles in biological samples. The method is based on graphite furnace-atomic absorption spectrometry (Zeeman background correction) where an increase in the atomization temperature is observed with an increase in the particle size of Ag. The method is able to determine the presence of Ag ions from the presence of nano-Ag of 20, 60 and 80?nm, but the methodology was less apt to resolve nanoparticles between 20 and 60?nm. The proposed methodology was capable of determining the presence of dissolved Ag(+) from 20?nm in prepared mixtures, and in the liver of rainbow trout exposed to either dissolved or 20-nm nano-Ag.     

Graphite furnace-atomic absorption spectrophotometric determination of palladium in soil

A new and sensitive procedure for the graphite furnace-atomic absorption spectrophotometric (GF-AAS) determination of Pd in soil at nanogram level is described. The method is based on prior separation and enrichment of the metal as Pd(II)-SnCl3- -N-butylacetamide (BAA) complex into 1-pentanol (PN) by solvent extraction method. The value of the molar absorptivity of the complex in three solvents, i.e. ethyl acetate, 1-pentanol, chloroform, lie in the range of (0.70-2.75) x 10(4) L mol(-1) cm(-1) at lambda(max) 360-440 nm. The metal could be enriched into organic solvent, i.e. PN, up to 10-folds. The sensitivity (A = 0.0044) of the method in the term of the peak height was 0.5 ng Pd/mL of the aqueous solution at an enrichment factor (EF) of 5. Optimization of analytical variables during enrichment and GF-AAS determination of the metal are discussed. The method has been applied for the analysis of Pd to soil samples derived from roads and highways in Germany.     

The determination of gold by atomic absorption spectrophotometry

Gold can be isolated from most other elements other than the platinum metals by the extraction of iron(II) 1,10-phenanthroline tetrabromoaurate in chloroform. After isolation gold can be determined in the organic solvent by atomic absorption spectroscopy or colorimetrically by decomposition of the complex and determination of the iron by bathophenanthroline.     

The determination of selenium by atomic absorption spectrophotometry

The problems involved in the determination of selenium by atomic absorption spectrophotometry are discussed. A practical method is described for which the sensitivity is approximately 1 p.p.m. Such concentrations can be determined in organic samples, but with mineral samples the preliminary treatment renders the procedure unsuitable for concentrations lower than 50 p.p.m. in a sulphide ore.     

Determination of cadmium in biological and environmental samples by slurry electrothermal atomic absorption spectrometry

The retention of cadmium by the bacteria Escherichia coli and Pseudomonas putida was optimized in order to develop a rapid and selective preconcentration method for cadmium from biological and environmental samples prior to determination by electrothermal atomic absorption spectrometry. Living and lyophilized cells for both bacteria were used, but the method using dead cells shows better analytical capabilities. Cadmium from aqueous solutions is easily retained on the outer membrane of both bacteria in the pH range 4-10, although the selected working pHs for E. coli and P. putida were 5 and 9, respectively. Cadmium retained by the bacteria was dispersed in 3.5 M nitric acid and the slurry was introduced directly into the graphite tube. The best sensitivity and detection limit were obtained for E. coli (0.03 ng ml(-1) and 0.04 ng ml(-1) respectively, in the absence of any chemical modifier). A strong spectral interference from nickel chloride was found and methods to overcome it were developed. The proposed extraction procedure was tested by the determination of cadmium in different standard biological and environmental samples.     

Determination of lead in biological samples by use of slurry sampling electrothermal atomic absorption spectrometry

Slurry-sampling electrothermal atomic absorption spectrometry has been applied to the determination of lead in several biological samples (fish and marine algae). The slurries were prepared both by magnetic shaking and microwave-heating and the effect of instrument operating conditions and slurry preparation conditions on the signal were examined. In addition, results from slurry sampling were compared with those obtained by microwave-assisted acid digestion of the same samples and no significant differences were found between them when the analysis of variance (ANOVA) was applied. The between-batch precision of the slurry techniques employed was similar to that for the microwave-assisted digestion procedure; values were always below 6.7%, except for the Dicentrarchus labrax sample for which the value obtained was 9.5% when using slurry magnetic shaking and 7.6% when using the slurry microwave heating. The accuracy of the slurry methodology employed was also evaluated by analysis of two biological reference materials (NIST-1577b and IAEA-V10); percentage recoveries obtained were between 95.6 and 98.5% of the values certified for lead.