Absorption spectrophotometry.

A review is given of the development of spectrophotometers from the earliest models to the latest microprocessor instruments with photodiode detection systems.

Sulphur-containing metabolites of beta-bromostyrene formed by the marmoset, rabbit and rat.

1. The administration of beta-bromostyrene to the rat results in a fall in the level of hepatic glutathione. 2. Marmosets, rabbits and rats dosed with beta-bromostyrene excrete two mercapturic acids. One of these, N-acetyl-S-(2-hydroxy-2-phenyl-1-bromoethyl)-cysteine is readily converted into N-acetyl-S-(1-phenyl-2-bromo-2-ethenyl)-cysteine, the structure of which was established by mass spectrometry. 3. Mass spectrometric evidence suggests that the second mercapturic acid is N-acetyl-S-(1-hydroxy-2-phenylethyl)cysteine. 4. Mandelic acid was detected as a metabolite in all three species.

1-(3'-O-acyl)-beta-glucosyl-N-dihydroxypentatriacontadienoylsphingosine, a major component of the glucosylceramides of pig and human epidermis.

The least polar of four chromatographically distinct glucosylceramides in both pig and human epidermis, was identified from its infrared spectrum and degradation products as O-acylglucosylceramide. Permethylation studies indicated that the acyl group was attached predominantly (80%) to the C-3 of glucose in the pig and only to the C-3 glucose in the human O-acylglucosylceramide. Octadecadienoic acid was the major acid esterified to glucose in both pig and human O-acylglucosylceramides and sphingenine, sphinganine and heptadecasphinganine accounted for most of the long chain bases (87% in pig, 80% in human). Chromatographic and chemical-evidence suggested that a single, unknown unsaturated dihydroxy fatty acid with more than 30 carbon atoms was attached through the amide link to the sphingosines. This was confirmed by mass spectrometry. Precise mass measurements indicated that the acid had a relative molecular mass of 550.496115 (C35H66O4) and was a dihydroxy acid with two double bonds. Other mass spectrometric data suggested that the hydroxyl groups and double bonds were confined to the region between C-16 and C-20. The evidence indicated that the O-acylglucosylceramide in pig epidermis and, by the close similarity of its properties, probably that in human epidermis also was 1-(3'-O-acyl)-beta-glucosyl-N-dihydroxypentatriacontadienoylsphingosine.

Analytical mass spectrometry.

A review is made of the basic theory, instrumentation and application of mass spectrometry, with special reference to the development of the equipment and its impact on the scope of application.

Mass spectrometric analysis of carbon monoxide-nitrogen mixtures.

A method for the analysis of gas mixtures containing both carbon monoxide and nitrogen, by using a single-focussing mass spectrometer, is described. It involves measurement of the mass spectrum of a gas sample before and after conversion of the carbon monoxide present into carbon dioxide by means of the Schütze catalyst.

Direct determination of oxygen in organic materials-I A study of the carbon reduction method.

The results of an investigation into the nature of the carbon reduction process in the Unterzaucher method for the microdetermination of oxygen are reported and discussed. The reaction between carbon dioxide and carbon is discussed, and its relation to the specific surface area, which contrary to belief has been found not to contribute to the efficiency of the reaction. It is shown that carbon-oxygen complexes give rise to errors in the results, and that an intermediate, SiO(OH), formed on the inner surface of the silica pyrolysis tube might be a precursor to the formation of carbon monoxide as a source of blank error and of the apparent oxygen content of pure hydrocarbons.

Mass spectrometry of volatile mercury salts.

The integrated ion current method is applied to the determination of mug quantities of mercury(II) chloride. The mass spectra of both mercury(I) and (II) chlorides indicate that the analytical reagent grade chemicals contain traces of mercury(II) bromide and iodide.

A simple sensitive recording differential refractometer for column chromatography.

Light passes through a hollow prism containing the sample liquid and is then focussed on a position-sensitive photodiode. Movement of the image due to a change in the refractive index of the sample produces an electrical signal which is recorded directly on a potentiometer recorder.

Mass spectrometry of metal chelates-III Further studies on metal oxinates.

The mass spectra of the oxmates of gallium, dysprosium, beryllium, samarium, cadmium, neodymium, indium, bismuth, lanthanum, yttrium and gadolinium have been recorded. The results have been correlated with the structures proposed m the literature. The integrated ion current method has been applied to determine submicrogram quantities of some of these compounds. Oxinates insoluble in organic solvents or undergoing reaction on solution were precipitated directly in the evaporation probe. The factors which determine the suitability of metal chelates for the estimation of metals by this method are discussed together with the instrumental factors which determine the ultimate sensitivity.

The mass spectrometry of metal chelates--II. Oxinates of common metals.

The mass spectra of the oxinates of zinc, iron(III), manganese(II), nickel, cobalt, aluminium, copper and magnesium have been measured. Concentrations of several of these chelates have been related to the integrated ion currents recorded at a significant m/e value during evaporation of the sample in the source of an A.E.I. M.S.9 mass spectrometer. The structural significance of some of the mass spectra is discussed.