S.L. Bogdanski

Molecular emission cavity analysis—a new flame analytical technique : Part I. Description of the technique and the development of a method for the determination of sulphur

Abstract Analysis by molecular emission in cool flames is reviewed. A new analytical technique, utilizing such emissions, is described; the sample is deposited within a cavity at the end of a rod, and emission is stimulated within the cavity when placed in a hydrogen flame. The advantages of the technique are given, and the effects of many experimental parameters on the S2 emission from sulphur compounds are studied in detail. Methods for the determination of ng amounts of inorganic and organic sulphur compounds in μl samples are described. Other applications are briefly outlined.

Molecular emission cavity analysis—a new flame analytical technique: Part V. The determination of some sulphur anions

Abstract An investigation of the MECA behaviour of sulphate, sulphite, metabisulphite, peroxodisulphate, thiocyanate, thiosulphate and sulphide ions, has shown that ng amounts of these anions may be determined in samples of a few μl. Metal ion interferences in the determination of sulphate and sulphite are removed by addition of phosphoric acid.

Molecular emission cavity analysis: Part IX. The simultaneous determination of sulphur anions in admixture

Abstract Conditions for the rapid simultaneous determination of eleven binary and six ternary mixtures of sulphur anions at the p.p.m. level are described, based on the sequential appearance of their S2 emission peaks. The depressive effects of cations are removed by addition of phosphoric acid, pH 7.0 phosphate buffer or diammonium hydrogenphosphate as appropriate.

Molecular emission cavity analysis : Part X. The Separation and Simultaneous Determination of Arsenic and Antimony by Hydride Generation

Abstract Arsenic and antimony (both 0–50 p.p.m.) are determined simultaneously by conversion to their hydrides with sodium borohydride, followed by gas Chromatographic separation. and measurement of the eluted gases by molecular emission cavity analysis at 400 nm. Tin can also be determined simultaneously. All interferences are masked by EDTA. A more sensitive procedure for arsenic (0–2 p.p.m.) or antimony (0–4 p.p.m.) is also described, based on a cold trap collection technique.

A Preliminaty Study of Halide Determination by Molecular Emission Cavity Analysis (MECA)

Abstract A study of the determination of chloride, bromide and iodide by MECA, using the emissions of their indium salts, is described. Linear calibration graphs are obtained in each instance, with limits of detection of 0.5 ppm (2.5 ng) for chloride and bromide and 10 ppm (50 ng) for iodide. The effects of interferences are investigated, and a standard addition method is used for the rapid estimation of chloride in drinking waters.

Molecular emission cavity analysis: Part 17. Indirect determination of fluoride by volatilization of silicon tetrafluoride

Abstract Fluoride (10–300 μg) is determined by conversion to silicon tetrafluoride, and the volatile product is transported to a m.e.c.a. oxycavity, where the silicon is determined. The procedure is rapid and highly selective; only arsenic and boron interfere. It is applied to waters and toothpastes.

Molecular emission cavity analysis : Part XI. The determination of carbonyl compounds

Abstract Formaldehyde (2–750 μg), acetaldehyde (0.05–1.0 μg) and acetone (0.4–3.5 smg) can be determined in aqueous solution (⩽ 17.5 ml) by MECA. Sodium sulphite solution (5 ml, 500 p.p.m. S) and 1.5 ml of l M phosphoric acid are added and the delayed S2 emission from the sulphite addition compound in 5 ml of the solution is measured in a MECA cavity; a hydrogen-nitrogen flame is used. Mixtures of formaldehyde and acetone can be determined simultaneously on the basis of the resolved MECA peaks of their sulphite addition compounds, after evaporation of the excess of sulphite from the cavity.

Candoluminescence—a new flame technique for trace analysis—I: Development of a method for determination of bismuth

Early work on candoluminescence is reviewed and the phenomenon is investigated experimentally for the elements Bi, Mn, Sb and the lanthanides. It is demonstrated that it is feasible to determine bismuth (5-1000mug) by measuring its candoluminescent intensity at 399 nm, using a calcium hydroxide-calcium sulphate matrix and a hydrogen-helium-air flame.

Molecular emission cavity analysis: stimulation of metal halide emissions

Abstract Some metal halides (Mn, Co, Ni, Pb and possibly Fe) emit metal(I) halide spectra from the MECA cavity in hydrogen-nitrogen-air flames, in contrast to their behaviour in conventional aspiration flame systems. However, the emission intensity is too weak to provide sensitive analytical applications. Indium halides give intense emissions by either the MECA or aspiration method. Halogenated organic compounds give intense CH and C 2 emissions. Cadmium halides give only an intense atomic emission. Sensitive methods for halides, indium, cadmium and organic compounds are thus possible. Mercury (II) halides and metal fluorides give no measurable emission in the cavity method.

Determination of ammonium- and nitrate-nitrogen by molecular emission cavity analysis

Ammonium nitrogen is determined at parts per million to percentage levels by injecting the sample solution on to solid sodium hydroxide in a small vial. The ammonia generated is swept by nitrogen into a molecular emission cavity analysis (MECA) oxy-cavity and the intensity of the NO—O continuum is measured at 500 nm. The method is rapid, precise and free from interferences and has been applied successfully to the determination of ammonium ions in fertilisers, river waters and sewage samples. Nitrate ions can also be determined after reduction to ammonia by Devardas alloy.