B. Radziuk

Determination of alkyl lead compounds in air by gas chromatography and atomic absorption spectrometry

Abstract Alkyl lead compounds are condensed from a 70-l street air sample in a series of four traps at-72°C, separated by gas chromatography and determined by atomic absorption spectrometry with electrothermal atomization. Total atmospheric alkyl lead averaged 14 ng Pb m -3 . Vehicular exhaust fumes are an insignificant contributor to this total. Tetraethyllead, the only alkyl lead compound used in southern Ontario gasoline, is unstable in air. Besides decomposing, it reacts to give other alkyl lead compounds, which can be determined by the technique described. Evaporation of gasoline is almost exclusively the source of alkyl lead compounds in street air.

A study of atomic absorption and atomic fluorescence atomization systems as detectors in the gas chromatographic determination of lead

Abstract The suitability of various atomic absorption and atomic fluorescence atomizing systems connected to a gas chromatograph is compared for the determination of alkyl lead compounds. An electrothermally heated graphite tube gives the highest sensitivity but quartz tubes heated either in an air-acetylene flame or by electrical resistance wire provide adequate sensitivity for most applications. A “solvent peak” absorption thought earlier to be due to organic molecular absorption of radiation at the lead wavelength was shown to be due to deposition and remobilization of lead.

Atomic absorption spectroscopy as a detector for the gas chromatographic study of volatile selenium alkanes from Astragalus racemosus

Abstract A simple, inexpensive ( Astragalus of which two were readily shown to be the alkanes dimethyl selenide and dimethyl diselenide. Diethyl selenide was not detected.

Combined furnace—flame non-dispersive atomic fluorescence spectrometry for direct simultaneous multi-element analysis of air filters

Abstract Furnace volatilization followed by atomization in the flame of a non-dispersive atomic fluorescence spectrometer is used for the direct, simultaneous, multi-element determination of Zn, Cd, Pb and Fe on air filter papers. Standardization is done by using blank filter papers impregnated with standard metal solutions. The results agree well with those obtained by a standard atomic absorption procedure.

Simple, inexpensive, multi-element atomic absorption using a flame resonance spectrometer with a continuum source

Abstract This paper presents the design and performance of an atomic absorption spectrophotometer based on a continuum source and a flame resonance spectrometer. The continuum source used was an Eimac 150 W xenon arc lamp although fluctuations in this source were found to have a significant limitation on overall performance. Both air-acetylene and air-hydrogen flames were investigated for use as the resonance spectrometer and air-acetylene was preferred. Results are presented for Ag, Au, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni and Pb. This system can readily be used for rapid-sequential multi-element analysis by simply changing the solution aspirated into the spectrometer flame.

A universal microcomputer interface for the rapid acquisition of data from atomic absorption spectrometers

Abstract A universal data acquisition interface for atomic absorption spectrometers is described. A minimum of electronic circuitry is required. The software is designed for flexibility and simple operaion. Photomultiplier response is monitored directly so that separate plots of total absorbance, background absorbance and corrected atomic absorbance, as a function of time, can be produced for each measurement. Thus more information is provided than is normally available from the digital communications link of the most such instruments. Use of the system to interface an Apple II microcomputer with Perkin-Elmer 5000 and Zeeman 5000 instruments is described and examples of results are given.

Direct analysis of solids for trace elements by combined electrothermal furnace/quartz T-tube/flame atomic absorption spectrometry

Abstract The analysis of solid samples by a combined graphite-furnace/air-acetylene flame technique based on generally available atomic absorption instrumentation is described. Samples are injected into the furnace and atomized via a slotted T-tube in the flame. Non-specific absorption is greatly reduced compared to that obtained in graphite-furnace atomic absorption spectrometry (a.a.s.). Sensitivity is reduced by 10–200 times compared to the direct graphite-furnace method, so that large sample sizes (up to 0.2 g) can be used; this minimizes problems caused by sample inhomogeneity. The elements considered are cadmium, lead, copper, arsenic, cobalt, mercury, antimony and selenium. Volatile elements such as mercury and arsenic can be determined without the need for a char step. Simple calibration procedures are possible in some cases and the precision is usually better than 10%. Background reduction capabilities are compared with those of conventional graphite-furnace a.a.s., the isothermal-furnace and the hollow graphite T-tube techniques. Analytical capabilities and results are presented for the direct determination of trace elements in numerous biological and some geological samples.

A Zeeman-effect based scatter correction system for non-dispersive atomic fluorescence spectrometry

Abstract A Zeeman-effect based method of correcting for the scattering of source radiation in atomic fluorescence spectrometry (AFS) is described. The magnetic field is applied to the atomization cell in a direction transverse to the source and detected beams. Both polarized and field modulated Zeeman AFS are examined. Fluorescence signals corrected for scattering are derived from differences in the measured light intensities caused by changes in the incident light polarization and/or field intensity. Results are given for the determination of Cd in an Al matrix, and for Cd, Hg, and Zn in NBS fly ash, orchard leaves, and river sediment. The scatter corrected values obtained by this method are in agreement with certified values.

A Microcomputer-Controlled Simultaneous Multielement Nondispersive Atomic Fluorescence Spectrometer

An eight-channel multielement nondispersive AFS spectrometer based on the time division multiplex method and fitted with a Commodor PET 2001 microcomputer to control lamp firing and for data manipulation is described. The pulsed behavior of ten EDLs with respect to rf power, mode of pulsing, and step frequency is examined. This device is tested with the use of an air-acetylene flame atomizer. An in-depth examination of light scattering showed that such scattering depends on the particular analyte lamp, the angle of detection, and the sample matrix. Scatter correction in the analysis of NBS bovine liver, orchard leaves, fly ash, and river sediment was done with the use of a lamp of an element not present in the sample. Results are mixed, with good values being obtained for elements present in a sample matrix in which the analyte signal is appreciably greater than the scatter signal. Detection limits for ten elements in an air-acetylene flame are given for three different lamp duty cycles. The detection limits, generally, were comparable to those obtainable by ICP-AES, ICP-AFS, and flame AAS. Simultaneous multielemental analysis (up to eight elements) is possible with the proposed equipment.