Vacuum Sublimation of Polynuclear Aromatic Hydrocarbons Separated by Thin-layer Chromatography for Detection with Shpol’skii Low Temperature Fluorescence
A method for the vacuum sublimation of polynuclear aromatic hydrocarbons (PAHs) from thin-layer chromatographic plates is described. Low-temperature fluorescence spectroscope, utilizing the Shpol'skii effect, is used for the detection and identification of benzo[a]pyrene, pyrene and benzo[ghi]perylene in samples from different sources. The recoveries of these PAHs were optimized by varying the time and temperature of sublimation.
Sulfur-containing derivatives of Hexachlorobenzene (HCB) – metabolites in the rat
Convulsive properties of Lindane, Lindane metabolites, and the Lindane isomer a-Hexachlorocyclohexane: Effects on the convulsive threshold for Pentylenetetrazol and the brain content of g-Aminobutyric acid (GABA) in the mouse
Synthesis of methylthio- and methylsulfonyl-polychlorobiphenyls via nucleophilic aromatic substitution of certain types of polychlorobiphenyls
Synthesis of [14C]Biphenyl and of some chlorinated [14C]Biphenyls containing 4-chloro-, 2,4-dichloro- and 2,3,6-trichlorophenyl nuclei from the corresponding labelled anilines
Synthesis of methanesulfonyl derivatives of 2,2-Bis(4-chlorophenyl)-1,1-dichloroethylene (p,p’-DDE), present in seal from the Baltic
The determination of penicillins by titrations with mercury(II) solution
A simple technique, involving two titrations with mercury(II) solutions, is described for the determination of penicillins and their degradation products. The first titration, at pH 4–5 on an untreated penicillin solution, gives the amount of degradation products; the second titration, on a hydrolysed solution at the same pH, gives the sum of the degradation products and penicillin degraded during the hydrolysis. Enzymic hydrolysis is superior to alkaline hydrolysis for penicillinase-sensitive penicillins. Enzyme-resistant penicillins should be hydrolysed with alkali at optimum conditions, e.g. for cloxacillin at pH 13.5 for 5 min. A standard deviation of less than 0.5 % was obtained for the penicillins investigated. The method is absolute; calibration with standard penicillin is not necessary.