W.P. Hayes

Pyrolysis—gas chromatography of histidine and 3-methylhistidine

Abstract Pyrolysis of histidine and 3-methylhistidine using a Curie-point analyser at 770°C yielded imidazole and 1-methylimidazole, respectively, which were identified by gas—liquid chromatography. The posibility of applying this reaction to the differentiation of vegetable and meat protein was examined.

Pyrolysis-gas chromatography of proline, hydroxyproline and related peptides

On pyrolysis using a Curie point analyser at 770 °C proline and hydroxyproline (cis- and trans-) yielded as their major products a previously unreported fragment, tentatively identified as 1-pyrroline, and pyrrole, respectively. A number of dipeptides and a tripeptide containing these heterocyclic amino acids were also examined. All the degradations were found to be dependent on the pH of the solution that was examined.

Elimination of nitrate interference in the trace détermination of sulphate as hydrogen sulphide

The microdetermination of sulphate by reduction to hydrogen sulphide, determined colorimetrically as Methylene Blue, is subject to interference from nitrate ion. This interference is eliminated by adding zinc acetate and igniting samples at 320 degrees for one hr.

Identification and determination of primary plasticisers in polyvinyl chloride calendered formulations

Abstract A method has been developed for the rapid identification and determination of single primary and certain mixed plasticisers in polyvinyl chloride sheetings. Direct injection of tetrahydrofuran solutions of sheet samples containing dibutyl phthalate as internal standard gave excellent quantitative results; individual analyses can be completed in less than 1 h.

The indirect spectrophotometric determination of sulphate with 2-aminoperimidine hydrochloride

SummaryA method is described for the indirect determination of sulphate after precipitation of 2-aminoperimidine sulphate. Beers law is obeyed over the range 0–30 ppm. Interferences have been investigated. The application of the method to rainwater is discussed.ZusammenfassungEin Verfahren zur indirekten Bestimmung von Sulfat nach Fällung als 2-Aminoperimidinsulfat wurde beschrieben. Zwischen null und 30 ppm ist das Beersche Gesetz erfüllt. In Betracht kommende Störungen wurden geprüft. Die Anwendung der Methode auf Regenwasser wurde erörtert.

Determination of perchlorate in samples of potassium chlorate. II

SummaryA method has been developed for the determination of small amounts of potassium perchlorate in admixture with potassium chlorate. The method involves preliminary decomposition of the potassium chlorate by boiling with concentrated hydrochloric acid, preparing a disc from the dried residue, and measuring its absorbance at 628 cm−1.ZusammenfassungEine Methode zur Bestimmung kleiner Mengen Kaliumperchlorat in Gegenwart von Kaliumchlorat wurde ausgearbeitet. Sie beruht auf der vorhergehenden Zersetzung des Chlorats durch Kochen mit konz. Salzsäure, Herstellung einer Scheibe aus dem Trockenrückstand und Messung ihrer Absorption bei 628 cm−1.