In this work, a validated stability-indicating ultra-high performance liquid chromatographic (UPLC) method has been developed for quantitative determination of related substances in Risperdal Consta. The chromatographic separation was achieved on a Waters BEH C18 column (2.1 × 100 mm, 1.7 μm) in an isocratic elution mode. The limit of quantification is 0.1 μg/mL, and the method is linear over t...

A simple and rapid method has been developed for routine compliance testing of lutein in pediatric formulas. Following a mild saponification procedure (70 °C for 10 min) demonstrated to be benign to lutein, lipophilic components were partitioned by a single extraction into hexane:diisopropyl ether (75:25 v/v) and concentrated in mobile phase. Baseline chromatographic separation of lutein and ze...

Metronidazole and its known metabolites in plasma can be rapidly separated by a "high-pressure" liquid-chromatographic method that can also be adapted for rapid determination of tinidazole. Samples deproteinized with trichloroacetic acid (50 g/L final concentration) undergo isocratic separation on a reversed-phase C18 column eluted with an 8/92 (by vol) mixture of acetonitrile/KH2PO4 (5 mmol/L,...

An isocratic high-performance liquid chromatographic method for the determination of testosterone (T) and epitestosterone (ET) in human urine using liquid-liquid or solid-phase extraction (SPE) is developed and validated. The optimum separation is achieved using a Hypersil C(18) column, water-acetonitrile (57:43, v/v) as the mobile phase and UV-absorbance detection at 245 nm. The recoveries obt...

The simultaneous determination of As(III), As(V), and DMA has been performed by ion chromatography (IC) coupled with inductively coupled plasma-mass spectrometry (ICP-MS). The separation of the three arsenic species was achieved by an anionic separator column (AS 7) with an isocratic elution system. The separated species were directly detected by ICP-MS as an element-selective detection method....

We described the first results of a quantitative ultra performance liquid chromatography-tandem mass spectrometry method for a novel antimicrobial peptide (phylloseptin, PSN-1). Chromatographic separation was accomplished on a Waters bridged ethyl hybrid (BEH) C18 (50 mm×2.1 mm, 1.7 μm) column with acetonitrile-water (25:75, v/v) as isocratic mobile phase. Mass spectrometry detection was perfor...

Two ion chromatographic methods have been proposed for the simultaneous determination of caffeine, theobromine and theophylline. The separations were based on isocratic elutions and the determinations on ultraviolet absorbance detections at 274 nm. The detection limits (signal-to-noise ratio 3:1) for the three compounds were all below sub-mg mlÿ1 level. The methods have been successfully applie...

New shell-type stationary phases are widely used in fast chromatographic measurements. These columns provide more efficient separation, when applied in a conventional high-performance liquid chromatography instrument, than columns with fully porous particles, and the volume overload of core-shell particles is 60% of the value obtained for fully porous particles. Additionally, to achieve adequat...

Alkylphenols can affect human health because they disrupt the endocrine system. In this study, an analytical method for determining trace amounts of 4-nonylphenol (NP) and 4-octylphenol (OP) in human blood samples was developed. Reversed-phase HPLC with multi-electrode electrochemical coulometric-array detection was used for the determination of NP and OP in plasma and serum samples prepared wi...

In this novel method for quantifying bethanidine in plasma, after a multi-step extraction of bethanidine and internal standard from 2.0 mL of plasma, the drugs are separated on a "microbore" C18 reversed-phase column and quantified by their ultraviolet absorbance at 210 nm. The isocratic chromatographic separation takes about 15 min with use of an ion-pairing regent in the mobile phase (acetate...