Improvements in the non-flame atomic fluorescence determination of mercury

A new non-flame atomic fluorescence system with a detection limit of 5 parts per trillion (p.p.t.) or 5 pg of mercury(II) has been developed. The relative precision is 5% or better above 50 p.p.t. Hg(II), and the dynamic range in terms of linearity is from 0–100 p.p.b. Hg(II). The system is useful for analysis of residual mercury levels in water at a rate of about thirty samples per h.     

The determination of mercury in soils and related materials by colc-vapour atomic absorption spectrometry

A method for the determination of mercury in soils and related materials, by the cold-vapour, reduction-aeration absorption technique, is described. The mercury in the reduced sample solution is partitioned, by agitation, between the liquid phase and a fixed volume of air which is then blown through an absorption cell for measurement. Three preparative methods were developed, two of which use acid digestion and wet oxidation and the other direct oxidation in an oxygenflask combustion technique. Comparative analysis of natural samples by the three methods was used to validate the techniques developed, since no authenticated reference samples were available. For 1-g samples, the analytical range was 0.01–0.5 p.p.m.     

Sub-picogram detection of lead by non-flame atomic fluorescence spectrometry with dye laser excitation

The frequency-doubled radiation of flashlamp-pumped dye laser has been compared with the radiation of an eleotrodeless discharge lamp (EDL) and a hollow cathode lamp (HCL) as excitation light sources in non-flame atomic fluorescence spectrometric (AFS) measurements. Detection limits and linear ranges of the analytical working curves have been studied. The aqueous Pb sample solutions used in this study were atomized in an electrically heated graphite rod. Direct line fluorescence at 405.8 nm has been observed. The limit of detection obtained with the laser as excitation source is about one order of magnitude lower than the detection limits obtained with the EDL and HCL. The absolute limit of detection of 0.2 pg is the lowest reported value to date attained in any atomic spectrometric method. The ultraviolet laser irradiance was found to be high enough to approach saturation conditions. As a result selfabsorption of the exciting laser beam is reduced and the linear range of the analytical working curve is extended to higher analyte concentrations.     

The determination of arsenic and selenium in coal by continuous flow hydride-generation atomic absorption spectrometry and atomic fluorescence spectrometry

Concentrated perchloric acid is used to digest coal for subsequent determination of arsenic and selenium by hydride-generation atomic absorption and fluorescence spectrometry. Arsenic and selenium are removed from potentially interfering metal ions by coprecipitation with lanthanum hydroxide. The detection limits, 58 and 36 ng g^?1 by atomic absorption and 25 and 10 ng g^?1 by atomic fluorescence, for arsenic and selenium in coal, respectively, are adequate for the normal levels of these metals.     

Trace determination of mercury in biological materials by flameless atomic absorption spectrometry

A new rapid wet-ashing procedure for biological material is described. The samples are boiled for 5–10 min in a mixture of nitric and hydrobromic acid under reflux. Mercury is then determined by the flameless cold-vapour, atomic absorption technique and complete release is shown to occur even when the fat present is not fully decomposed. The results are discussed with regard to the normal bromine and iodine content of marine samples. The enhancement obtained with bromine can easily be compensated by digesting the standards. Iodine, however, reduces the peak heights and the content of this element must be judged separately for samples other than fish, which can always be safely analysed without interference.     

The determination of gallium by atomic absorption spectrometry

The use of a nitrous oxide-acetylene flame for the determination of gallium by atomic absorption spectrometry was compared with the use of air-acetylene flames. The nitrous oxide method provided higher sensitivity and was much less sensitive to acid and base composition and to diverse added salts. Significant matrix and background effects, which occurred when gallium was determined in ore solutions with the air-acetylene flame, were eliminated with the nitrous oxideacetylene flame.     

原子吸收和原子荧光光谱分析

本文是《分析试验室》期刊定期评述中关于原子吸收光谱(AAS)及原子荧光光谱(AFS)分析的第11篇综述文章. 文中对2004年12月～2007年4月期间我国在AAS/AFS领域所取得的主要进展进行评述. 内容包括概述、仪器装置与数据处理、火焰原子吸收光谱法、电热原子吸收光谱法、化学蒸气发生技术以及原子荧光光谱法等. 收集文献670篇.     

Rapid separation on copper powder of total mercury in blood and determination of mercury by flameless atomic absorption spectrometry.

The determination of mercury in blood by flameless atomic absorption spectrometry (FAAS) has been described. Prior to its analysis, the sample was decomposed by combustion and separated on a copper powder micro-column. A special type of cell has been used which gives a better sensitivity compared with the types of cells described in the literature and the method of FAAS analysis has been improved. The sensitivity of 0.1 ng for 1% absorbance was observed and the standard deviation for six determinations at this level was found to be +/- 0.05 ng, for 95% probability.     

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.     

A rapid method for the determination of mercury in air by flameless atomic absorption spectrometry.

A rapid method for the determination of total gaseous mercury in the atmosphere is described. A simple, inexpensive sampling device is used; the collection time for mercury levels above 5 ng m^?3 is less than 25 min; less than 10 min is then needed to determine the mercury by flameless atomic absorption. For subnanogram levels longer sampling periods are used, but air polluted with mercury can be monitored in a few minutes. Data obtained for different samples are presented.     

Indirect determination of submicrogram amounts of sulfide by flameless atomic absorption spectrometry of mercury

Summary A rapid and simple method to determineg and sub-g amounts of sulfide has been developed. It involves the addition of a known amount of mercury(II) to the sample solution, formation of stable HgS, and determination of the residual mercury(II) in the solution by flameless atomic absorption spectrometry. The proposed method allows sulfide to be determined down to 0.2 ppb with a relative standard deviation of less than 2%.

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Zusammenfassung Ein schnelles und einfaches Verfahren zur Bestimmung von Mikrogramm und Submikrogrammengen Sulfid wurde ausgearbeitet. Es beruht auf der Zugabe einer bekannten Menge Hg(II) zur Probelösung, der Bildung von beständigem HgS und der Bestimmung des restlichen Hg(II) durch flammenlose Atomarabsorptionsspektrometrie. Die vorgeschlagene Methode erlaubt die Bestimmung von mindestens 0,2 ppb Sulfid mit einer relativen Standardabweichung von weniger als 2%.

     

The determination of traces of mercury in solid fuels by high-temperature combustion and cold-vapour atomic absorption spectrometry

A high-temperature combustion technique is described for the determination of mercury in coal, coal products including ash, and other samples of environmental interest. The liberated mercury is absorbed in an acidified potassium permanganate solution and determined by cold-vapour atomic absorption spectrometry. The vapour generation assemblage is constructed of standard ground-joint glassware, and is designed to produce non-transient signals suitable for either analog or digital recording devices. Accuracy and precision for 1-g coal samples is 0.02 μg g^-1.     

Simultaneous determination of arsenic, selenium, tin and mercury by non-dispersive atomic fluorescence spectrometry

A procedure is described for simultaneous determination of arsenic, selenium, tin and mercury in aqueous solution by non-dispersive atomic-fluorescence spectrometry. Radiofrequency-excited EDLs, 100% modulated in the kHz region, were used for atom excitation. Sodium tetrahydroborate was used as reductant and a hydrogen-argon miniflame as atomizer. In the optimized procedure, which uses 1 ml of sample, the limits of detection (three times the standard deviation of the blank) were 0.04, 0.08, 0.1 and 0.1 ng ml for arsenic, selenium, tin and mercury respectively. The linear dynamic range was greater than three decades for all analytes and the precision was better than 7% (typically 3%) for concentrations 1 ng ml . Results for mutual interference effects are reported. Copper, nickel, lead and cobalt interfered only with selenium (5 ng ml ), when present in at least 200-fold weight ratio to it. Using 5 ml of sample improved the limits of detection for selenium and arsenic (0.01 and 0.02 ng ml respectively), but at the expense of greater interference. Recovery from spiked natural water samples was better than 95% at the ng ml level, except for selenium in sea-water, when the recovery was only 85%. Determination of the four elements, including standard-addition and background measurements, requires about 10 min.     

The determination of mercury in air samples by flameless atomic absorption

A method is described for the determination of mercury in air by furnace atomic absorption. The porous graphite cups used ordinarily fail to adsorb mercury vapors from the air. When these same porous graphite cups are plated on the inner surface with a thin layer of gold the retention of mercury from an air sample passed through the cup is shown to be quantitative. The sensitivity of the analytical system is 3 × 10^?10 g which is equivalent to 0.6 $\text{μg}\text{m}{}^3$ for a 500 cm³ air sample. Relative S.D. is 11.2%. The method described should also prove useful for other types of flameless devices.     

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.     

Sensitive determination of gaseous mercury in air by cold vapour atomic fluorescence spectrometry after amalgamation

A method was developed for the determination of mercury in air, using preconcentration by amalgamation on gold absorbers followed by measurement by atomic fluorescence spectrometry (AFS). The system has a detection limit of ca. 2.0 pg and the precision is in the range 5–10% (relative standard deviation). The accuracy was confirmed by comparison with cold vapour atomic absorption spectrometry. The method was applied to the determination of gaseous mercury in both indoor and outdoor air. As a result of the sensitivity small sample volumes can be analysed and only short sampling times are required. The method is thus suitable for continuous monitoring of mercury and for the fast and reliable determination of gaseous mercury in the atmosphere, even at background levels.     

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.     

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.