Profile analysis of mycolic acid ester patterns of Mycobacterium tuberculosis, Mycobacterium bovis, and Mycobacterium bovis bacillus Calmette-Gúerin (BCG) using high-performance liquid chromatography indicated that separation of BCG from M. tuberculosis and M. bovis by elution and relative retention times is possible. Mycolic acid patterns of BCG eluted from the column 0.5 min before M. tubercu...

The β-hydroxy/amino acid unit is a common structural feature of many bioactive marine cyanobacterial depsipeptides. In this study, the absolute stereochemistry of the β-hydroxy acid moieties in hantupeptins and trungapeptins were determined through their synthesis and HPLC analysis of the Mosher ester derivatives. Synthesis of two3-hydroxy-2-methyloctanoic acid (Hmoa) stereoisomers, (2S,3R)-Hmo...

Nine lab-scale continuous flow porous-pot bioreactors operating at various solids retention times and hydraulic retention times were conducted to simulate activated sludge (AS) systems and to evaluate the biodegradation kinetic models for the fate of 17α-ethinylestradiol (EE2), bisphenol-A (BPA), and triclosan (TCS) at the µg/L range. Mathematical models were applied to describe the degradation...

In this HPLC-diode-array detection method for toxicological drug screening, a mixed-mode solid-phase extraction procedure is optimized for isolation of a broad range of drugs from serum and urine. Basic, neutral, and weakly acidic drugs are uniformly recovered. The extract from the solid-phase cartridge is readily injected to a reversed-phase HPLC column for separation by gradient elution. Unkn...

Leiomyoma of the female urethra is a rare condition and there have been only 35-40 reported cases in literature. We report a 20-year-old woman who had referred with a painless mass in her vaginal vestibule, dysparonia dysuria and previouse history of urine retention for two times. After clinical examination, imaging studies (US, MRI) and cystoscopy a mass in urethra protruding to vagina and bla...

We report a procedure for determining nicotine and cotinine in plasma. Nicotine is extracted from 1 ml of plasma with diethyl ether, back extracted, and analyzed by gas-liquid chromatography with a nitrogen/phosphorus detector. Nicotine and its internal standard, modaline, had retention times of 1.9 and 2.9 min, respectively. Cotinine is then extracted from the same plasma with dichloromethane ...

Responses of American arborvitae (Thuja occidentalis), common yew (Taxus x media) and juniper (Juniperus communis) to enhanced UV-B irradiance were studied. Control plants were grown without UV treatment, but at identical PhaR and temperature regimes. Visual symptoms of the ultraviolet effect noted on Thuja shoots as brown/red discolouration were correlated with the accumulation of phenolic com...

Technological attempts have been made in the research and development of rate-controlled oral drug delivery systems to overcome physiological adversities, such as short gastric residence times (GRT) and unpredictable gastric emptying times (GET). Conventional oral dosage forms pose low bioavailability problems due to their rapid gastric transition from stomach, especially in case of drugs which...

Question: After mixing my mobile phase and using it over the course of several weeks, the retention times of my compounds gradually increase, ending up approximately 20–30% longer. Upon preparing a new mobile phase, the retention times almost immediately return to where they originally were. Then, the situation occurs again over the lifetime of the new mobile phase. This cannot be a pump proble...