Titrimetric study of the reaction of chloramine-T with ammonia

A titrimetric study of the reaction between chloramine-T (CAT) and ammonia is described. The effects of the presence of bromide, the ratio of CAT to ammonia concentrations, the time for reaction and the pH of the reaction media are all significant in the quantitativeness of the reaction that occurs.     

Solution kinetics of the degradation of the chemiluminescent reagent bis(2,4-dinitrophenyl) oxalate in water/acetonitrile

Simultaenous ultraviolet absorbance measurements at 240 and 260 nm are used to quantify DNPO and its principle degradation product 2,4-dinitrophenol. The stability of DNPO was determined in various water acetonitrile mixtures (23±0.5°C). The decomposition follows (pseudo)- first-order kinetics in each system, and is third order in water concentration. An Arrhenius plot was used to obtain estimates for the activation energy, activation enthalphy, and activation entropy.     

Automation of pesticide residue analysis

Summary The routine analysis of pesticide residue levels in biological tissue by gas-liquid chromatography is greatly facilitated by the use of computers to reduce computation time. Modern systems can be readily adapted to small computers. The nature of gas chromatographic signals permits the insertion of digitizers between the gas chromatograph and the computer. The resulting system permits completely automatic retrieval of data; thus time is saved and operating efficiency of the analytical laboratory is increased.

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Die Automatisierung der Analyse von Pestizid-Rückständen

Zusammenfassung Die Routineanalyse des Gehalts an Pestizid-Rückständen in biologischem Gewebe durch Gas-Flüssig-Chromatographie wird durch den Einsatz von Computern zur Einsparung von Rechenzeit wesentlich erleichtert. Modeme Systeme können leicht an kleine Computer angepaßt werden. Die Art der gas-chromatographischen Signale gestattet die Einfügung von Digitalisierungs-Gliedern zwischen Gas-Chromatographen und Computer. Mit dem entstandenen System läßt sich die Datensuche vollständig automatisieren; auf diese Weise wird Zeit gespart, und die Leistungsfähigkeit des analytischen Labors wird erhöht.

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Automatisation de l'analyse des résidus de pesticides

Sommaire La determination de routine des teneurs en résidus de pesticides dans des tissues biologiques par chromatographie gaz-liquide est notablement facilitée par l'emploi d'ordinateurs; ceci réduit la durée du calcul. Des systèmes modernes sont faciles à adapter à de petits ordinateurs. La nature des signaux émis en chromatographie en phase gazeuse permet l'insertion de membres de digitalisation entre le chromatographe en phase gazeuse et l'ordinateur. Le système ainsi obtenu permet la recherche tout à fait automatique des données; ainsi on gagne du temps, et l'efficacité du laboratoire analytique est augmentée.

     

Structure in metastable peaks arising from reactions in which[C3H3]+ ions are produced

The metastable peak resulting from the fragmentation of [C₇H₇]²⁺? ions fram a variety of sources shows structure due to the presence of two reactions releasing different amounts of translational energy. The translational energy differences has been measured as 0.52 ± 0.04eV and is thought to be due to the formation of product ions of different structure via competing reactions from a single transition state. The possible structures of these ions are discussed, and it is proposed that the effect observed is due to the formation of [C₃H₃]⁺ ions in two forms, cyclopropenyl and proparg1. The metastable singly charged ions which also lead to product ions of formula [C₃H, ₃]⁺.     

A mass spectrometric study of the pyrolysis of gibberellic acid

The behaviour of gibberellic acid (GA₃) under electron impact and chemical ionization conditions has been examined. The tendency of GA₃ to undergo pyrolysis by the loss of the elements of water and carbon dioxide has been identified. Two methods of sample introduction can be used to minimize the occurrence of this pyrolysis. Accurate mass measurement allows the composition of the pyrolysis product to be determined and metastable techniques confirm the structure of this product to be epi-allogibberic acid rather than its isomer allogibberic acid. This result corrects a misconception in the literature and illustrates the advantage of metastable methods compared with accurate mass measurements, for the determination of small structural differences within a molecule.     

Decomposing the complete graph into cycles of many lengths

For all oddv 3 the complete graph onvK _v vertices can be decomposed intov – 2 edge disjoint cycles whose lengths are 3, 3, 4, 5,...,v – 1. Also, for all oddv 7,K _v can be decomposed intov – 3 edge disjoint cycles whose lengths are 3, 4,...,v – 4,v – 2,v – 1,v. Research supported by Australian Research Council grant A49130102