Atomic-fluorescence characteristics and analytical determination of manganese in an air-acetylene flame

The atomic-fluorescence characteristics of manganese atoms in a premixed nitrogen-shielded air-acetylene flame are described. Excitation is obtained at 280 nm from a microwave-excited electrodeless discharge tube. A detection limit of 0-001 ppm for the determination of manganese by atomic-fluorescence spectroscopy is obtained by measurement of the resonance fluorescence observed at this wavelength. In addition to several other weaker atomic-fluorescence signals observed from manganese atoms in the flame, weak resonance fluorescence at 258 and 260 nm from manganese ions stimulated by ion line-emission from the source has been recorded. Linear calibration graphs for atomic-fluorescence measurement at 280 nm are obtained over the range 0.0025-10 ppm of manganese in aqueous solution. Of 26 foreign anions and cations examined for interference at the 1000-fold weight excess level only four produced interference. Large amounts of Si, Th and V interfere by scattering of the incident radiation, while Mg causes depression of the atomic fluorescence by a chemical effect.     

Determination of manganese by atomicpluorescence spectroscopy using a carbon-filament atom-reservoir

The atomic-fluorescence characteristics of manganese heated on a carbon-filament atom-reservoir (CFAR) are described and compared with (a) the atomic-absorption behaviour of the element on the same filament apparatus, and (b) its fluorescence behaviour in a separated air-acetylene flame. By fluorescence at 279.5 nm, using 1-mul samples, manganese may be determined down to 0.6 pg (6 x 10(-4) ppm) by use of an electrodeless discharge lamp source (3 pg or 3 x 10(-3) ppm by absorption, and 20 ng or 1 x 10(-2) ppm by flame emission at 403 nm). The effects of fourteen representative cations and anions examined showed no interference at 10-fold and 100-fold levels and serious interference only from magnesium at the 1000-fold level, with ca. 10% suppression from Cr, V, Na and K. No fluorescence signals were observed at any wavelength other than 279.5 nm when the CFAR device was used.     

Use of a filter in atomic-fluorescence spectroscopy

A detecting system incorporating an interference filter is described for use in atomic-fluorescence spectroscopy analysis in the 200.0-300.0 nm spectral region. Results obtained by using this system are compared with those from a detecting system incorporating either a monochromator or a solar-blind photomultiplier. Improvements of approximately 700-fold and 10-fold respectively in the limits of detection for zinc and mercury result from replacing the monochromator with the filter, while results with the filter are similar to those from a solar-blind photomultiplier. Limits of detection of 10(-5) ppm for zinc and 2.5 x 10(-4) ppm for mercury, both in aqueous solutions aspirated into an air-town-gas flame, are an improvement on other published results for these elements, obtained by atomic-fluorescence flame spectroscopy.     

Studies in atomic-fluorescence spectroscopy-VII Fluorescence and analytical characteristics of arsenic, with a microwave excited electrodeless discharge tube as source

The construction of an electrodeless arsenic discharge tube and its use for atomic-fluorescence studies is described. Cool nitrogen-hydrogen and argon-hydrogen diffusion flames as well as normal premixed flames are considered as atom reservoirs and the atomic-fluorescence emission at 15 different wavelengths is evaluated. The diffusion flames give the largest emission signals at arsenic concentrations below 200 ppm, but show a premature curvature at higher concentrations because of the presence of an abnormally high density of arsenic atoms. Above 200 ppm of arsenic, the premixed air-acetylene flame is superior. The limit of detection at 1890 A is 0.2 ppm of arsenic in the nitrogen-hydrogen diffusion flame and 1.0 ppm in the airacetylene flame. A long path-length diffusion flame is also particularly useful in atomic-absorption measurements because it absorbs very little radiation in the far ultraviolet region and gives an abundance of arsenic atoms.     

Determination of zinc in copper by atomic-fluorescence flame spectroscopy

The application of atomic-fluorescence flame spectroscopy to the determination of trace quantities of zinc in copper is described. A limit of detection of 10(-5)% zinc in copper has been established. The scatter of primary radiation from within the flame determined the limit of detection, but it is suggested that scatter is not a serious limitation to the practical application of the technique.     

Atomic-fluorescence spectroscopy of lead

The fluorescence spectrum of lead excited with a high-intensity hollow-cathode lamp has been investigated and the probable mechanism of fluorescence transitions is suggested. It is confirmed experimentally that the most intense fluorescence line at 405.78 nm is mostly due to direct-line fluorescence. The premixed air-hydrogen flame, the separated air-acetylene flame, and the oxy-hydrogen flame diluted with argon have been used, the last mentioned giving a detection limit of 0.02 ppm with the line at 405.78 nm.     

A flow cell optosensor for lead based on immobilized gallocynin in chitosan membrane

Gallocynin immobilized in chitosan membrane has been studied as a sensor element of an optical sensor for lead using a flowing system. By using this set up, lead in solution has been determined in the concentration range from 1.0x10(-1) to 1.0x10(3) ppm with a detection limit of 0.075 ppm. The standard deviation of the method for the repeatability of lead detection at a concentration of 100 ppm was found to be 2.10%. The response of the sensor was reproducible and can be regenerated by using acidified saturated KNO(3) solution. Interference from foreign ions was also studied at 1:1 mole ratio of Pb(II):foreign ions.     

火焰原子吸收光谱法测定粗锌中的铜

建立火焰原子吸收光谱法测定粗锌中的铜含量。采用硝酸–酒石酸溶解样品,并以其为测定溶液介质,检测波长为324.7 nm,以水为参比,采用空气–乙炔火焰以原子吸收光谱仪进行测定。在优化的实验条件下,铜的质量浓度在0.10~2.50μg/m L范围内与吸光度有良好线性关系,相关系数为0.999 7,方法检出限为0.01μg/m L。测定结果的相对标准偏差为1.0%~3.0%(n=11),样品加标回收率为97%~102%。该方法具有灵敏度高,干扰少,重现性好等优点,适用于铜含量在0.001%~0.50%之间的粗锌中铜的测定。     

Studies in atomic-fluorescence spectroscopy-VI The fluorescence characteristics and analytical determination of bismuth with an iodine electrodeless discharge tube as source

The atomic-fluorescence characteristics of bismuth atoms in cool nitrogen-hydrogen and argon-hydrogen diffusion flames burning in air are described. Excitation is obtained from the non-resonance iodine line at 2061.63 Å emitted by a microwave-excited electrodeless discharge tube operating at 2450 Mc/s. Fluorescence of the bismuth resonance line at 2061.70 Å is observed and also direct-line fluorescence at 2697 and 3025 A. In addition thirteen other much weaker lines were observed and two unidentified lines at 2880 and 2680 Å. The emissions at 2628 and 2938 Å appear to arise from “thermally assisted direct line fluorescence”. The most intense line at 3025 Å permits linear-dependence analytical atomic-fluorescence measurements to be made in the range 0.1–200 ppm with a detection limit of 0.05 ppm and with no problems of source scatter. No interference was observed from hundred-fold concentrations of fourteen ions. Matrix effects from aluminium and magnesium were overcome by raising the temperature of the cool diffusion flames. A bismuth microwave-excited electrodeless discharge tube was used as a source for atomic-absorption measurement in air-hydrogen and air-propane flames at 2231Å with a detection limit of 1 ppm and a linear-dependence analytical range of 10–100 ppm. With the iodine microwave-excited electrodeless discharge tube the detection limit for atomic absorption was 10 ppm at 2062 Å.     

Spectrophotometric determination of lead with 1-(2-pyridylazo)-2-naphthol and non-ionic surfactants Application to acetic acid extracts of ceramic enamels

The Pb-PAN system in the presence of non-ionic surfactants (polyoxyethylene nonylphenols) has been studied spectrophotometrically. The optimum conditions for Pb determination are pH 9 (Na(2)B(4)O(7)-HClO(4)), 5% surfactant and measurement at 555 nm. The system obeys the Lambert Beer law over the Pb concentration range 1.3-4.5 ppm; the molar absorptivity is 2.02 x 10(4) l.mole(-1).cm(-1) at 555 nm. The relative standard deviation is 0.9% and the limit of detection 0.12 ppm. Lead can be determined in acetic acid extracts of ceramic enamels by extraction with sodium diethyldithiocarbamate into carbon tetrachloride and stripping with 4M hydrochloric acid to remove interferent species. The results obtained are in agreement with those obtained by a standard AAS method.     

Determination of cadmium by atomic-fluorescence and atomic-absorption spectrophotometry

The adaptation of a conventional atomic-absorption/flameemission spectrophotometer to the measurement of atomic-fluorescence in an air-acetylene flame is described. The determination of cadmium on the same instrument by both atomic-fluorescence and absorption shows that, even with a rather simple and inefficient means of exciting and measuring fluorescence, results can be obtained which indicate that the fluorescence technique is considerably more sensitive than atomic-absorbance and is equally free from inter-element interference.     

Non-dispersive atomic-fluorescence spectrometry of trace amounts of bismuth by introduction of its gaseous hydride into a premixed argon (entrained air)-hydrogen flame

A method has been developed for the determination of bismuth by generation of its gaseous hydride and introduction of the hydride into a premixed argon (entrained air)-hydrogen flame, the atomic-fluorescence lines from which are all detected by use of a non-dispersive system. The detection limit is 5 pg/ml, or 0.1 ng of bismuth, but the reagent blank found in a 20-ml sample volume was approximately 2 ng of bismuth. Analytical working curves obtained by measuring peak-heights and integrated peak-areas of the signals are linear over a range of about four orders of magnitude from the detection limit. Perchloric, phosphoric and sulphuric acids up to 2.0M concentration give no interference, but nitric acid gives slight depression of the signal. The presence of silver, gold, nickel, palladium, platinum, selenium and tellurium in 1000-fold ratio to bismuth causes pronounced depression of the signal, whereas mercury and tin slightly enhance the atomic-fluorescence signal. The method has been applied to the determination of bismuth in aluminium-base alloys and sulphide ores with use of the standard additions method. The results are in good agreement with those obtained by flame atomic-absorption spectrometry and optical emission spectrometry with an inductively coupled plasma.     

Spectrophotometric determination of selenium(IV) with 5,5-dimethyl-1,3-cyclohexanedione

5,5-Dimethyl-1,3-cyclohexanedione (dimedone) reacts in acid aqueous solution with selenium(IV) to give a benzoxaselenol which has an absorption maximum at 313 nm with a molar absorptivity of 4.00 x 10(3) l.mole(-1).cm(-1). The compound is extractable into chloroform, to give a solution with an absorption maximum at 300 nm with a molar absorptivity of 3.77 x 10(3) l.mole(-1).cm(-1). The calibration graph is linear up to 30 ppm selenium, with a detection limit of 0.1 ppm in the final solutions. Of the various other ions tested, only iron(III) interferes at all concentrations but the addition of 1000 ppm fluoride will mask 50 ppm Fe(3+). The method has good reproducibility, with a relative standard deviation of 1.0% for pure solutions. The method has been applied to the analysis of fire-refined copper.     

Non-dispersive atomic-fluorescence spectrometric determination of lead by the hydride-generation technique

Non-dispersive atomic-fluorescence spectrometry combined with hydride-generation has been developed for lead determination. A radiofrequency-excited electrodeless discharge lamp was used as light-source and a small argon-hydrogen flame as atomizer. The detection limit was 0.06ng/ml and the linear calibration graph was linear up 300ng/ml, with a precision of 5-6% over the dynamic range. Interference studies and optimization of the experimental parameters are reported. Severe suppression of the lead signal was observed in presence of Cu, Se or Te. An empirical equation was obtained for predicting the effect of copper on the lead signal at various concentration ratios. The strong effect of complexing agents such as EDTA was removed by addition of zinc salts.     

Indirect method for the determination of aluminium by atomic-absorption spectrometry using an air-acetylene flame

The enhancement of the atomic-absorption signals of iron, cobalt, nickel and chromium in a fuel-rich air-acetylene flame by small amounts of aluminium makes possible the indirect determination of aluminium in the concentration range 0.01-10 ppm. The optimization of working conditions and the occurrence of interferences are reported.     

Determination of NH(3) in pyrolysis gases by ammonia selective electrode

The suitability of ion-selective electrode for the determination of ammonia in pyrolysis gases of fossil fuels was studied. The ammonia was absorbed into acidic solution and two kinds of determination methods were carried out. The ammonia was either measured directly from the acid solution, or ammonia was first released into the gas phase and then determined (air gap method) by the ammonia selective electrode. The electrode functioned well in both cases, but the linear calibration range was rather narrow, slightly more than one tenfold. The quantitative detection limit in the water phase was 5 x 10(-6)M (0.085 ppm) NH(3) and in gas phase operation solutions above 5 x 10(-4)M (8.5 ppm) NH(3) it was possible to measure quantitatively. The applications were carried out with Finnish energy peat samples and a coal sample.     

Determination of dysprosium by resonance light scattering technique in the presence of BPMPHD

Dysprosium has been determined by resonance light scattering (RLS) method in the presence of 1,6-bi(1'-phenyl-3'-methyl-5'-pyrazolone-4'-)hexanedione (BPMPHD) at pH 5.5. The Dy-BPMPHD system has three characteristic peaks at 358, 399 and 450 nm, especially the peak at 358 nm, which is proportional to the concentration of Dy(3+) in the range of 1.0 x 10(-10)-1.0 x 10(-5) mol l(-1). The detection limit (S/N=2) is 5.6 x 10(-12) mol l(-1). Synthetic samples are determined satisfactorily. A new sensitive method for detection of dysprosium has been proposed.     

The atomic absorption spectroscopy of selenium

Selenium can be determined in aqueous solution by atomic absorption spectroscopy at 1960, 2040,2063 or 2075 Å; the sensitivities for these lines with a Techtron 10-cm air-acetylene burner are in the ratio of 1:9:60:93. When a Beckman tripleburner (air-hydrogen) and a triple-pass optical system are used, the most sensitive1960 Å line provides a sensitivity of 0.5 p.p.m. and a detection limit of 1.0 p.p.m. The performence in air-hydrogen and air-acetylene flames is described,and optimum experimental conditions determined.With the Se 1960 Å line and a Techtron 10-cm air-acetylene burner, selenium extracted into methyl isobutyl ketone as its diethyldithiocarbamate complex gives a sensitivity of 0.30 p.p.m.,which is a 2.4-fold increase over that found in aqueous solution.     

Flame and flameless atomic-absorption determination of tellurium in geological materials

The sample is digested with a solution of hydrobromic acid and bromine and the excess of bromine is expelled. After dilution of the solution to approximately 3 M in hydrobromic acid, ascorbic acid is added to reduce iron(III) before extraction of tellurium into methyl isobutyl ketone (MIBK). An oxidizing air-acetylene flame is used to determine tellurium in the 0.1–20 ppm range. For samples containing 4–200 ppb of tellurium, a carbon-rod atomizer is used after the MIBK extract has been washed with 0.5 M hydrobromic acid to remove the residual iron. The flame procedure is useful for rapid preliminary monitoring, and the flameless procedure can determine tellurium at very low concentrations.     

Miniaturization of batch- and flow-type chemiluminescence detectors in capillary electrophoresis

Glass and PTFE tubes as detection cells were put in small light-tight boxes to achieve miniaturization of batch-and flow-type chemiluminescence detectors for capillary electrophoresis. These light-tight boxes which included a detection cell and a photosensor module were successfully designed. In the batch-type detector using a glass tube as a detection cell, the influences of a repeated injection of sample and a reagent volume of the detection cell on chemiluminescence intensity were examined in detail. By using 3.8 mm I.D. glass tube including 400 microl chemiluminescence reagent solution, the chemiluminescence peaks were reproducibly observed for the repeated injection experiment up to the eight injection with each run time of 3.0 min. Dansyl-Trp was determined over the range 3 x 10(-8)-1 x 10(-5) M with the detection limit of 0.43 fmol (S/N=3). In the flow-type detector using a PTFE tube as a detection cell, both ends of the PTFE tube were connected to three-way joints; a chemiluminescence reagent solution was delivered into the cell and a capillary was inserted through one of the joints while an electrode was inserted through the other one. Dansyl-Trp was determined over the range 1 x 10(-7)-1 x 10(-5) M with the detection limit of 1.3 fmol (S/N=3). By using the compact flow-type detector, a mixture of dansyl-amino acids was separated and detected in micellar electrokinetic chromatography mode.