![]() ![]() The resulting GC–MS data are used to compare samples visually and by means of MS-Percentage Weathering (MS–PW) plots and compound ratios. Gas chromatography-mass spectrometry (GC-MS) data of steranes, hopanes, n-alkanes, branched alkanes and compounds of two unknown compound series not related to the n-alkanes, have been selected for defining diagnostic ratios appropriate for paraffin. Gas chromatography-flame ionization detection (GC-FID) data have been used to compare paraffin profiles by using a novel weighted mean versus standard deviation graph, conventional GC-Percentage Weathering plots (GC-PW) plots and n-alkane ratios. The need to compare paraffin spill samples and cargo reference samples has led to the development and evaluation of a method for paraffin wax spill identification that conforms to the CEN method for oil spill identification. Paraffin wax spills from tanker discharges commonly impact shorelines. Leo Peschier, in Oil Spill Environmental Forensics Case Studies, 2018 Abstract ![]() The degree of branching has an important influence on the properties. A typical alkane paraffin wax’s chemical composition comprises hydrocarbons with the general formula C nH 2 n+2. ![]() Paraffin waxes are mixtures of saturated n- and iso-alkanes, naphthenes, and alkyl-substituted and naphthene-substituted aromatic compounds. These materials represent a significant fraction of crude oil and are refined by vacuum distillation. It is essentially a low-melting, ductile, microcrystalline wax.Īlthough many natural waxes contain esters, paraffin waxes are hydrocarbon derivatives, mixtures of alkane derivatives usually in a homologous series of chain lengths. However, in contrast to petroleum wax, petrolatum ( petroleum jelly), although solid at ordinary temperatures, does in fact contain both solid and liquid hydrocarbons. It is distinguished by its solid state at ordinary temperatures (25☌, 77☏) and low viscosity (35–45 SUS at 99☌, 210☏) when melted. Paraffin wax is a solid crystalline mixture of straight-chain (normal) hydrocarbons ranging from C 20 to C 30 and possibly higher, that is, CH 3 (CH 2) n CH 3 where n ≥ 18. Speight PhD, DSc, PhD, in Handbook of Industrial Hydrocarbon Processes (Second Edition), 2020 9.2 Composition It also allows a multitude of staining techniques to be employed and facilitates storage of the blocks and unstained mounted sections. The paraffin wax technique permits thin individual and serial sections to be cut with ease from the majority of tissues. The ante-medium is eventually replaced by molten paraffin wax and when sufficiently impregnated, the tissue is embedded in fresh wax which solidifies on cooling. For this reason, they are commonly referred to as ‘clearing agents’, but as this is a property not possessed by all of them, the term is incorrect. Many ante-media raise the refractive index of the tissue, imparting to it a transparent appearance. The alcohol-saturated tissue is then transferred to an ante-medium which is miscible with both the alcohol and the paraffin wax. The fixed tissue not being miscible with the wax, selected pieces are passed through baths of alcohol of ever-increasing concentration in order to remove all water. Paraffin wax is the most widely used embedding medium for preparing histological slides. SILVERTON F.I.M.L.S., L.I.Biol., in Introduction to Medical Laboratory Technology (Fifth Edition), 1976 PARAFFIN SECTIONS
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