3. Soldin, S. J., and Hill, ,J. R., A rapid micromethod for measuring theophylline in serum by reversed-phase high-performance liquid chromatography. Clin. Biochem. 10, 74-77(1977). 4. Nelson, J. W., Cordry, A. L., Aron, C. C., and Baitell, R. A., Simplified micro-scale procedure for preparing samples for theophylline determination by liquid chromatography. Clin. Chem. 23, 124-126 (1977). 5. Pe...

losartan potassium, valsartan , telmisartan and irbesartan are angiotensin-ii-receptor antagonists (ara ii) group which used in treatment of hypertension alone or in combination with other drugs mainly hydrochlorothiazide. rp- hplc method was developed for the assay of three angiotensin-ii-receptor antagonists (ara-iis) in presence of hydrochlorothiazide. the method was performed by reversed ph...

Phenylalanine, tyrosine, and tryptophan are isolated and quantified by "high-pressure" liquid chromatography, with fluorescence detection. An isocratic mobile phase and reversed-phase column are used to provide rapid and reproducible measurement of these amino acids in as little as 1 to 2 microL of human plasma.

When the free cortisol in urine was analyzed by liquid chromatography after pretreatment with the usual organic extraction, interfering substances having chromatographic behavior similar to that of cortisol and the internal standard precluded accurate measurement. To remove these materials, we processed the organic extract by liquid chromatography with a normal-phase column for clean-up; the sp...

A method combining solid-phase extraction and reversed-phase high-performance liquid chromatography is described for the isolation of two key metabolites in the limonoid biosynthetic pathway critical to citrus quality. Potassium salts of limonoate A-ring lactone and nomilinoate A-ring lactone were isolated from young Chandler pummelo seedlings and characterized on the basis of proton and carbon...

The accurate prediction of protein stability is one of the most challenging goals in protein formulation and delivery. In this study, a gradient RP-HPLC method is described for the separation of human growth hormone (hGH) variants as deamidated and oxidized forms. The methodology employed a polymeric poly (styrene-co-divinylbenzene) column and a 1mL/min flow rate of a linear gradient of 0.1% v/...

The first oligonucleotide therapeutic was approved by the Food and Drug Administration in 1998, since then, 12 nucleic acids have been commercialised as medicines. To be approved, oligonucleotides need to identified characterised well its related impurities. Different methods exist, but most commonly used is ion-pairing reversed-phase liquid chromatography with tandem mass spectrometry. separat...

there is a great interest in developing rapid analytical methods and provide appropriate parametersfor quantitative analysis of compounds derived from refractory pollutants. such methods are important forroutine quality control analysis of an effluent before being discharged into the environment. therefore, a rapid methodology for identification and quantification of some aliphatic acids is pro...

The choice of analogue ion of the mobile phase additive is shown to significantly affect the analysis of quaternary ammonium compounds (QACs) in ion-pair reversed-phase high-performance liquid chromatography. A series of bromide-containing and dodecyl-sulfate-containing mobile phase additives are investigated using two QAC probe analytes. In all instances, the quaternary-ammonium-containing mob...