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To deal the stubborn problem arising from oily matrix of cosmetics in the chromatography of parabens, an efficient, rapid, and economic sample preparation method is proposed involving separation of matrix material by extraction with 1 mL of isooctane/1-octanol (50:50, v/v) in the presence of 1 mL of 1 mol/L sodium hydroxide, and centrifugation. Then, parabens in the alkaline solution were preconcentrated, after acidification, by liquid–liquid–liquid microextraction using 200 µL of isooctane/1-octanol (50:50, v/v) as organic solvent and 5 µL of 0.1 mol/L of sodium hydroxide as the acceptor drop. Using the optimized procedure, the method provided a rectilinear graph for 0.01–8 mg/kg of parabens with correlation coefficient (r) in the range 0.9982–0.9990, limit of detection in the range 1.7–4.3 µg/kg, and enrichment factor in the range 79–118. Intra-day (and inter-day) RSD at 0.01 and 5 mg/kg spiked levels of parabens were found as 7.7% (9.2%) and 4.7% (5.6%), respectively. Average recovery of spiked amounts...

Summary Vicariance and dispersion both must be considered as possibilities for the fauna and flora of New Zealand and New Caledonia. Oligocene submersion, promoted by the geologists and several biologists, does not seem to have been total. Refuge stations must have existed in mountains and even in plains in some surrounding areas. From there the relicts must have radiated after the partial submersion. Certain “primitive” Chrysomelidae Eumolpinae (Bohumiljania spp.) are closely related to Patagonian genera. Their case is not unique among the terrestrial organisms of New Caledonia. How to explain the occurrence of Amborella in New Caledonia and of the tuataras in New Zealand, already very probably extinct elsewhere during the Paleogene?

Nitrite has been determined by reversed-phase high-performance liquid chromatography by its pre-column reaction with 2-aminobiphenyl to give a diazonium salt and with iodide to form 2-iodobiphenyl. Chromatographic analysis was done using a C18-column, a mobile phase of aceto-nitrile - 0.05M sulfuric acid, 60:40 (v/v), detection at 254 nm and using biphenyl as an internal standard. The pre-column derivatization required about 8 min and the chromatographic separation was complete in about 10 min. As low as 8 μg 1−1 of nitrite could be determined with a limit of detection of 2 μg 1−1 Application of the proposed method to river water and pharmaceutical tablets has been demonstrated.

Thallium (III) sulfate in dilute sulfuric acid quantitatively oxidizes isoniazid to nitrogen and 4-pyrldine carboxylic acid. The test material is reacted with a measured excess of the reagent, the residual amount being back-titrated with ascorbic acid using o-dianisidine or p-ethoxychrysoidine as indicator. 4-Aminosalicylic acid, thiacetazone, thiamine hydrochloride, lactose and a number of other excipients do not Interfere with the analysis.

Nitrite is determined by its reaction with a measured but excessive amount of pyridine-4-carboxylic acid hydrazide in acid medium (when the two substances react in a 1:1 molar ratio) and evaluation of the surplus hydrazide by titration with chloramine-T in the presence of acidified potassium bromide, the end-point being shown by the decolorization of the methyl red indicator. Nitrate, copper(II), mercury(II), etc. are found not to interfere, and the determination of nitrite in the presence of diazotized aromatic amines is demonstrated.