China 
Africa 
Explore chapters and articles related to this topic
Pitfalls and Practical Solutions
Published in Joseph Chamberlain, The Analysis of Drugs in Biological Fluids, 2018
The chemical properties of extracting fluids can give rise to unwanted effects. These may be of two types: the chemical reactions of the solvent itself and the insiduous breakdown products they may contain. Some chemical properties may be fairly obvious, but just the same, they are often overlooked. Primary amines such as ethylamine will react with ketones and aldehydes to form Schiff’s bases, and conversely ketones used as extracting solvents, such as methylbutylketone, will react with drugs containing primary amines, in some instances the reaction may go unrecognized and the drug may be unknowingly (but still acceptably) assayed as the derivative. This phenomenon may often be at the root of puzzling chromatographic results when the nature of the extracting solvent is altered. This is well illustrated in Curry’s1391 procedure for chlorpromazine. Isoamyl alcohol used for extraction of chlorpromazine contains isovaleraldehyde as an impurity, which reacts spontaneously with primary amines such as didemethylchlorpromazine: this product then separates very efficiently from chlorpromazine and the monodesmethyl metabolite. In the absence of isovaleraldehyde, the separation of the two metabolites is very poor. As Curry put it: “We used bad isoamyl alcohol without knowing it.” Less obvious is the formation of hemiketals between ketones and alcohols, especially if traces of acids are present to catalyze the reaction.
Intake of New Zealand Blackcurrant Powder Affects Skin-Borne Volatile Organic Compounds in Middle-Aged and Older Adults
Published in Journal of Dietary Supplements, 2022
M. E. T. Willems, M. Todaka, M. Banic, M. D. Cook, Y. Sekine
Five skin VOCs (four with moderate and one with large effect size) showed a trend for change with intake of NZBC powder. Isovaleraldehyde, also known as 3-methylbutanal, has been shown in vitro that its formation is by interaction between human leucocyte antigen and skin microflora, and it suggested to contribute body odor (Savelev et al. 2008). Isovaleraldehyde was decreased by intake of NZBC powder. A trend for a decrease was also observed for hexanal. In general, hexanal is a product of lipid oxidation (Frankel 1980), and the skin VOC hexanal is the consequence of oxidation of human skin lipids. Hexanal is also taken as an oxidative stress marker in exhaled breath VOC in workers exposed to silica (Jalali et al. 2016). Therefore, it is possible that the intake of NZBC powder reduced lipid peroxidation of fatty acids in the sebaceous glands. 2-pentanone was reduced with intake of NZBC powder and just as benzaldehyde which is also a VOC released by muscle cells (Mochalski et al. 2014). The implications of a decrease in isovaleraldehyde, hexanal, and 2-pentanone by intake of NZBC powder are not clear. Two skin VOCs, heptanoic acid and γ-nonanolactone, showed a trend for an increase by intake of NZBC powder, with the implications also not clear.