Heat stabilization of blood spot samples for determination of metabolically unstable drug compounds.

BACKGROUND: Sample stability is critical for accurate analysis of drug compounds in biosamples. The use of additives to eradicate the enzymatic activity causing loss of these analytes has its limitations. RESULTS: A novel technique for sample stabilization by rapid, high-temperature heating was used. The stability of six commercial drugs in blood and blood spots was investigated under various conditions with or without heat stabilization at 95°C. Oseltamivir, cefotaxime and ribavirin were successfully stabilized by heating whereas significant losses were seen in unheated samples. Amodiaquine was stable with and without heating. Artemether and dihydroartemisinin were found to be very heat sensitive and began to decompose even at 60°C. CONCLUSION: Heat stabilization is a viable technique to maintain analytes in blood spot samples, without the use of chemical additives, by stopping the enzymatic activity that causes sample degradation

LIQUID-CHROMATOGRAPHIC CHIRAL SEPARATIONS OF THE N-6-(ENDO-2-NORBORNYL)-9-METHYLADENINE ENANTIOMERS

Attempts to separate the enantiomers of the novel adenosine antagonist N-0861, the racemic mixture of N-6-(endo-2-norbornyl)-9-methyladenine, by high-performance liquid chromatography are described. Owing to the very low efficiency and the lack of selectivity of the alpha-AGP column, the direct separation method did not give satisfactory results. The indirect separation method involved derivatization of N-0861 with (+)-1-(9-fluorenyl)ethylchloroformate. The method is easy to perform and aqueous solutions can be used. The calibration graphs showed that the reaction is linear. A resolution between the formed diastereoisomers of 1.13 within 30 min was obtained on a C-8 column with an acetonitrile-water eluent. The identities of the reaction products were checked by LC-MS

Heat stabilization of blood spot samples for determination of metabolically unstable drug compounds.

BACKGROUND: Sample stability is critical for accurate analysis of drug compounds in biosamples. The use of additives to eradicate the enzymatic activity causing loss of these analytes has its limitations. RESULTS: A novel technique for sample stabilization by rapid, high-temperature heating was used. The stability of six commercial drugs in blood and blood spots was investigated under various conditions with or without heat stabilization at 95°C. Oseltamivir, cefotaxime and ribavirin were successfully stabilized by heating whereas significant losses were seen in unheated samples. Amodiaquine was stable with and without heating. Artemether and dihydroartemisinin were found to be very heat sensitive and began to decompose even at 60°C. CONCLUSION: Heat stabilization is a viable technique to maintain analytes in blood spot samples, without the use of chemical additives, by stopping the enzymatic activity that causes sample degradation

Antarctic winter mercury and ozone depletion events over sea ice

International audienceDuring atmospheric mercury and ozone depletion events in the springtime in polar regions gaseous elemental mercury and ozone undergo rapid declines. Mercury is quickly transformed into oxidation products, which are subsequently removed by deposition. Here we show that such events also occur during Antarctic winter over sea ice areas, leading to additional deposition of mercury. Over four months in the Weddell Sea we measured gaseous elemental, oxidized, and particulate-bound mercury, as well as ozone in the troposphere and total and elemental mercury concentrations in snow, demonstrating a series of depletion and deposition events between July and September.The winter depletions in July were characterized by stronger correlations between mercury and ozone and larger formation of particulate-bound mercury in air compared to later spring events. It appears that light at large solar zenith angles is sufficient to initiate the photolytic formation of halogen radicals. We also propose a dark mechanism that could explain observed events in air masses coming from dark regions. Br2 that could be the main actor in dark conditions was possibly formed in high concentrations in the marine boundary layer in the dark. These high concentrations may also have caused the formation of high concentrations of CHBr3 and CH2I2 in the top layers of the Antarctic sea ice observed during winter.These new findings show that the extent of depletion events is larger than previously believed and that winter depletions result in additional deposition of mercury that could be transferred to marine and terrestrial ecosystems