We describe a liquid-chromatographic method for simultaneously determining norepinephrine, epinephrine, dopamine, and serotonin in 0.5 mL of human plasma. These analytes are purified on boric acid gel from Aldrich, separated on a reversed-phase C18 column, and detected electrochemically at +600 mV. Absolute recoveries of internal standards were 84% for 3,4-dihydroxybenzylamine and 57% for N-met...

This is a simple, rapid, sensitive method for routine quantification of the polyamine putrescine (1,4-diaminobutane) in cerebrospinal fluid. Sample preparation involves protein precipitation, acid hydrolysis for 18 h (if total putrescine is to be measured), pre-column derivatization with o-phthalaldehyde, and extraction into acetonitrile. The derivative is separated and quantified by "high-perf...

Surface Molecularly Imprinted Polymer (SMIP) for selective adsorption of di(2-ethylhexyl) phthalate(DEHP) was prepared on the surface of silica gel which was modified by aminopropyltriethoxysilane and acryloyl chloride in a two-step method. The prepared SMIP was used to prepare Molecularly Imprinted Solid-Phase Extraction (MISPE) column for selective extraction of DEHP from aqueous solution...

A novel, simple and economic reverse phase high performance liquid chromatography (RP-HPLC) Stability indicating method has been developed for the estimation of zolpidem tartrate in bulk and tablet dosage form with greater precision and accuracy. Separation was achieved on C18 column (250X4.6mm i.d.,5μm) in isocratic mode using methanol and acetonitrile in the ratio 50:50 (v/v) as mobile phase,...

Structurally new antioxidative metabolite was isolated from mycelial culture of mushroom Stereum hirsutum. Culture broth was subjected to Diaion HP-20 column chromatography, and 70% aqueous MeOH eluent was extracted with EtOAc. EtOAc extract was purified through silica gel and Sephadex LH-20 column chromatographies, and reversed phase C18 HPLC. Compound was revealed to be new dihydroxylated der...

A reverse-phase high-performance liquid chromatographic method is developed for the determination of astragaloside IV, a characteristic constituent in Radix Astragali. Samples are analyzed by means of a reverse-phase column (Zorbax Eclipse XDB C18) using acetonitrile and water under gradient conditions as the mobile phase for 30 min. An evaporative light-scattering detector is used and set at a...

We assay a 1-mL plasma sample containing angiotensin II (103 pg by radioimmunoassay) for the hormone by the following sequence of steps: add 125I-labeled val5-angiotensin II as an internal standard, extract on a C18 Sep Pak column, extract on an antibody affinity column, label the extract with an 125I Bolton-Hunter reagent, separate on a Bio Gel P2 column, and repetitively separate on a reverse...

In an estuary, a tidal bore may be generated at the leading edge of the flood tidal wave during the early flood tide under spring tide conditions into a narrow funnelled channel. For Froude numbers greater than 1.4–1.6, the leading edge of the bore is characterised by a breaking roller. The roller is characterised by a sudden increase in water depth, a highly turbulent flow with large-scale vor...

A method is described for estimating the cell concentration of bacterial suspensions by measurement of the column lengths of packed cells centrifuged into a capillary tube of fine bore. The total error, under the experimental conditions employed, checked by direct count, was >2 per cent for dense suspensions and about 5 per cent for light suspensions. The method is suitable for work requiring r...