The determination of selenium by atom-trapping atomic absorption spectrometry

The application of atom-trapping atomic absorption spectrometry to the determination of selenium has been studied in detail. The optimum experimental parameters were established and the interference of major elements on the determination of selenium was studied using collection on a cold silica tube. The atom-trapping atomic absorption technique gives a detection limit of 0.03 ppm after 2-min collection on silica in an air—acetylene flame. This compares with ca. 1 ppm by the conventional absorption technique at the same 196.1-nm line. Methods to minimize interferences were examined, including the use of a double tube arrangement, an aluminium oxide-coated silica tube and ion-exchange separation. A combination of combustion in an oxygen flask and collection from an air—acetylene flame on the aluminium oxide-coated silica tube yielded satisfactory results in the analysis of four plant tissue samples.     

The determination of gallium by atomic absorption spectrometry in premixed inert gas(entrained air)-hydrogen flames

Gallium can be determined sensitively in premixed argon (entrained air)- and nitrogen (entrained air)-hydrogen flames at 287.4 nm ; sensitivity (for l% absorption) is 0.20–0.24 p.p.m. and calibration graphs are linear up to 10 p.p.m. Many elements and acids interfere, but the addition of magnesium (1000 p.p.m.) as chloride is very effective in eliminating these interferences. This finding was satisfactorily applied to the determination of gallium in some semi-conducting III–V compounds.     

Determination of gallium in biological materials by electrothermal atomic absorption spectrometry

In this determination of gallium, the condition of the graphite tubes influences the peak height. Common acids and salts seriously affect the results, but in the presence of EDTA, interferences of nitric and hydrochloric acids are suppressed completely, and interferences of phosphoric acid and some salts are suppressed partly. To compensate for the effects, a standard addition procedure is proposed, and is applied to healthy and tumor.bearing mice. A linear calibration is obtained for 0.12–12 ng Ga in 50-μl aliquots. The method is applied to tissues and body fluids with good recovery and precision.     

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%.     

The determination of sulphate in fertilizers by atomic absorption spectrometry

Methods are described for the determination of sulphate in superphosphate fertilizers. Barium sulphate precipitated from an acidified EDTA solution is filtered onto a membrane filter and redissolved in ammoniacal EDTA, and the barium equivalent to the sulphate is determined by atomic absorption spectrometry. Alternatively, after precipitation of calcium as oxalate during sample solution preparation, and by following a similar sulphate precipitation technique, excess of barium is determined in the filtrate. No interferences were encountered when a nitrous oxide—acetylene flame was used with a potassium ionization buffer.     

The determination of manganese in urine by atomic absorption spectrometry

Urine samples were digested with a mixture of nitric, sulfuric, and perchloric acids containing molybdate as catalyst. A two-point standard addition technique involved extracts of buffered, digested aliquots containing 10- and 20-p.p.b. manganese(II) in the aqueous phase. The extraction system was MIBK-cupferron. Of the substances tested only bismuth, antimony, and thallium interfered. From the same subject, five morning urine samples averaged 3.0 p.p.b. of manganese with a range of 2.0–4.2 p.p.b.; the average deviation was 0.6 p.p.b.     

The determination of tin by carbon filament atomic absorption spectrometry

The atomic absorption characteristics of tin on a carbon filament atom reservoir are described. The behaviour of tin in aqueous solution astin(II) chloride, in xylene as tin octoate and in oil solutions is studied. The interferenceeffects of a selected range of seven cations, added as chlorides in aqueous solution or as naphthenates in non-aqueous media, and of sulphate and phosphate were examined. In all cases, the signals were measured in the filament reservoir with a surrounding hydrogen diffusion flame. The 1% absorption sensitivity in the organic media at the 286.3-nm line was 10^-10 g and 9·10^-11 g in aqueous solution. In the latter medium, the corresponding sensitivity at 224.6 nm was 6.7·10^-11 g. The linear analytical range lay in the region 0 to 20 ng.     

Preconcentration of gallium by coprecipitation with synthetic zeolites prior to determination by electrothermal atomic absorption spectrometry.

Synthetic zeolites were dissolved in nitric acid, and the resulting solution used as a coprecipitant for the preconcentration of trace amounts of gallium in water samples prior to determination by electrothermal atomic absorption spectrometry (ETAAS). The gallium preconcentration conditions and the ETAAS measurement conditions were optimized. Gallium was quantitatively concentrated with the zeolites coprecipitate from pH 6.0 to 8.0. The coprecipitate was easily dissolved in nitric acid, and an aliquot of the resulting solution was introduced directly into a tungsten metal furnace. The atomic absorbance of gallium in the resulting solution was measured by ETAAS. An ashing temperature of 400 degrees C and an atomizing temperature of 2600 degrees C were selected. The calibration curve was linear up to 3.0 microg of gallium and passed through the origin. The detection limit (S/N > or = 3) for gallium was 0.08 microg/100 cm3. The relative standard deviation at 1.0 microg/100 cm3 was 3.0% (n = 5). The proposed method has been successfully applied to trace gallium analysis in environmental water samples.     

The determination of lead in petrol by atomic absorption spectrometry

The lead compounds are extracted into aqueous iodine monochloride, converted to lead nitrate by digestion with nitric acid, and determined by atomic absorption spectrometry against aqueous lead nitrate standards. The procedure is accurate, precise and rapid.     

The indirect determination of organic compounds by atomic absorption spectrometry

The feasibility of determining indirectly certain organic compounds by precipitation of insoluble silver compounds and determining the excess silver(I) by atomic absorption spectrometry (AAS) has been demonstrated. The determination of other compounds, such as alkylated barbiturates and mercaptans by similar methodology should be possible. Although direct AAS methods are preferable to indirect methods, the insolubility of many silver salts, the inherent sensitivity of the AAS method for silver, and the speed and convenience of AAS methodology suggests that under certain conditions, an indirect AAS method may be appropriate and the method of choice.     

Indirect determination of perchlorate by atomic absorption spectrometry

A liquid-liquid extraction and determination of perchlorate by atomic absorption spectrometry is described. The method involves extraction of perchlorate with the Schiffs base complex [Co(BPTC)₂]⁺, where BPTC = 2-benzoyl pyridine thiosemicarbazone, in methyl isobutyl ketone in acidic medium and subsequent analysis of cobalt in flame AAS, hence indirectly for perchlorate. The extraction efficiency is 98%. The calibration graph was found to be linear for 1.0–11.4 g ClO ₄ ^– per ml of solvent, and the limit of detection is 30 ng ml^–1. The present method is free from interference of large number of foreign ions. The method has been applied for determination of perchlorate in human blood serum samples spiked with perchlorate, urine and commercial potassium chlorate sample.     

Indirect determination of pilocarpine by atomic absorption spectrometry

Atomic absorption spectroscopic (AAS) method for microdetermination of pilocarpine alkaloid has been developed. The procedure is based upon the measurement of mercuric content of pilocarpine complex. The experimental conditions as well as the molar ratio were thoroughly studied. The percentage recovery of pilocarpine was found to be (99.15 ± 0.79). The proposed method was applied on pharmaceutical formulations and the results were satisfactory and in good agreement with that given by the official one.     

Indirect determination of vanadium by atomic absorption spectrometry

An indirect method for the determination of vanadium as vanadate by atomic absorption spectrometry is described. In neutral medium, vanadate forms a stable ion-association complex with copper (II) and biguanide, which is extractable into butanol with an efficiency higher than 99%. The copper content in the extract (and hence indirectly VO^?₃) is determined by aspirating it directly into an acetylene flame. The calibration graph is linear up to 3.4 μg ml^?1 of VO^?₃. The limit of detection is 16 ng ml^?1. Only chromium interferes.     

The determination of zinc in blood plasma by atomic absorption spectrometry

Atomic absorption spectrometry has been used in the analysis of plasma zinc because of its sensitivity and simplicity. Dilution techniques reduce the viscosity of plasma and facilitate direct analysis, but viscosity differences can produce deviations in aspiration rates between sample and standard, and so cause errors. A direct (1 + 4) dilution of plasma with deionized water is suggested. Working zinc standards are prepared in 5% glycerol to approximate the viscosity characteristics and aspiration rates of the diluted plasma samples. The analytical curves for diluted plasma samples and 5% glycerol working standards proved identical. Plasma zinc concentrations are accurately calculated from a daily working curve. The accuracy of the method exceeds 99% and recovery of added inorganic zinc to a pooled plasma averages 99.8%. The precision is primarily limited by baseline drift. A confidence interval of ± 2 μg/100 ml was achieved by means of six contiguous 10s-integration readings. The method is free of nebulizer clogging and matrix interferences and is not subject to significant day-to-day variations. Because the method is accurate, sensitive, reliable and specific, it should be useful in the clinical laboratory.     

The determination of gold in vegetation by electrothermal atomic absorption spectrometry

A method is described for determining nanogram quantities of gold in vegetation. The sample is digested with fuming nitric acid. After addition of hydrochloric acid, the gold is extracted into 1 ml of 4-methylpentan-2-one; the organic layer is back-extracted with distilled water to remove iron interference, and gold in the organic layer is determined by electrothermal (graphite furnace) atomic absorption spectrometry. Limits of detection depend on the volume of organic phase used but can be as low as 0.2 ng g^?1 for an original sample weight of 1 g.     

Indirect flow-injection determination of methadone by atomic absorption spectrometry

A simple continuous redox flow system coupled on-line with an atomic absorption spectrometer for the determination of methadone at the ng ml^?1 level is described. It is based on the reduction of the keto group of the analyte in a camium or zinc microcolumn and determination of the metal ions formed. The drug can be determined in the range 5–50 ng ml^?1 with a relative standard deviation between 1.8 and 2.5% at a sampling frequency of 150 h^?1. The selectivity of the method allows the analyte to be determined in the presence of other drugs.     

间接原子吸收法测定乳酸环丙沙星

研究了在弱酸性介质中，乳酸环丙沙星与雷氏盐定量生成缔合物的反应条件，以及通过原子吸收法测定沉淀中Cr的含量而间接测定乳酸环丙沙星含量的分析方法。线性范围在5－40mg/L，相对标准偏差为2．5％，回收率在98％－101％之间。     

The determination of titanium in iron and steel by atomic absorption spectrometry

A method has been developed for the determination of titanium by atomic absorption spectrometry in a wide range of iron and steels containing <1% aluminium. Interferences are overcome by the addition of aluminium to sample and standard solutions. The accuracy and reproducibility of the method have been established at the 0.05,0.15 and 0.50% levels with British Chemical Standard samples. The procedure is time-saving, particularly as aluminium may be determined on the same initial 2% ($\text{w}\text{v}$) sample solution.