We describe a procedure for measuring concentrations of cocaine in plasma by reversed-phase high-performance liquid chromatography, with ion-pairing. The procedure involves solvent extraction followed by back-extraction with dilute acid. The n-propyl ester of benzoylecgonine is used as an internal standard. An evaporation step is not required, and concentrations as low as 5 micrograms/L can be ...

Lipid extraction is an integral part of biodiesel production, as it facilitates the release of fatty acids from algal cells. To utilise thraustochytrids as a potential source for lipid production. We evaluated the extraction efficiency of various solvents and solvent combinations for lipid extraction from Schizochytrium sp. S31 and Thraustochytrium sp. AMCQS5-5. The maximum lipid extraction yie...

Chinese quince seed (CQS) is an underutilized oil source and a potential source of unsaturated fatty acids and α-tocopherol-rich oil. Subcritical fluid (SCF) extraction is executed at lower pressures and temperatures than the pressures and temperatures used in supercritical fluid extraction. However, no studies on the SCF extraction of CQS oil are reported. Therefore, the objective of this stud...

preparation of tretinoin-containing microspheres with the aim of reducing undesirable skin reactions towards trans retinoic acid (tra) and thus, improving patient compliance is of particular interest. these microspheres have to be smaller than 30 m m to avoid causing gritty feel when applying on the skin, and slow the release of drug to minimize its skin side effects. following preliminary eval...

abstract soil drying and rewetting (drw) cycles are considered as environmental stress that would affect the physical, chemical and biological properties of soil and nutrient cycles. the study of soil drying and rewetting effects on plant nutrition and soil fertility is very important and crucial specially their environmental effects. in this study, the effects of 1, 2, 3, 4 and 5 drying and re...

'Solids formed from coprocessing of 10% coal/90% resid were characterized by solvent extraction, elemental analyses, C'3/C'z isotope ratio, ESR, and GPC techniques. adsorbed petroleum-derived material (oil, resin, asphaltene). The THF insolubles in the product contained high oxygen, low vanadium and a higher level of polyaromatic radicals than the soluble fraction, indicating that these insolub...

a comparative study of ultrasound-assisted extraction (uae) and hydro-distillation was performed for fast extraction of estragole from tarragon (artemisia dracunculus l.) dried leaves. several influential parameters of the uae procedure in the extraction of estragole (type of solvent, extraction cycles, solvent to material ratio, irradiation time and particle size) were investigated and optimiz...

An analytical anion-exchange procedure has been developed for the rapid separation of acid-soluble nucleotides (the so-called "free" or tissue nucleotides). It permits assay at low pressures (275-415 kPa; 40-60 psi) in less than 1 h on 10-cm columns of Aminex resins (conventional styrene-type anion exchangers) with alkaline citrate solutions as the eluent. Separation variables have been investi...

The ability of a solute (inorganic or organic) to distribute itself between an aqueous solution and an immiscible organic solvent has long been applied to separation and purification of solutes either by extraction into the organic phase, leaving undesirable substances in the aqueous phase; or by extraction of the undesirable substances into the organic phase, leaving the desirable solute in th...