High-performance liquid chromatographic determination of phenylephrine in human serum using column switching with fluorescence detection

Molecular Probes, Chemosensors, and Nanosensors for Optical Detection of Biorelevant Molecules and Ions in Aqueous Media and Biofluids

Synthetic molecular probes, chemosensors, and nanosensors used in combination with innovative assay protocols hold great potential for the development of robust, low-cost, and fast-responding sensors that are applicable in biofluids (urine, blood, and saliva). Particularly, the development of sensors for metabolites, neurotransmitters, drugs, and inorganic ions is highly desirable due to a lack of suitable biosensors. In addition, the monitoring and analysis of metabolic and signaling networks in cells and organisms by optical probes and chemosensors is becoming increasingly important in molecular biology and medicine. Thus, new perspectives for personalized diagnostics, theranostics, and biochemical/medical research will be unlocked when standing limitations of artificial binders and receptors are overcome. In this review, we survey synthetic sensing systems that have promising (future) application potential for the detection of small molecules, cations, and anions in aqueous media and biofluids. Special attention was given to sensing systems that provide a readily measurable optical signal through dynamic covalent chemistry, supramolecular host-guest interactions, or nanoparticles featuring plasmonic effects. This review shall also enable the reader to evaluate the current performance of molecular probes, chemosensors, and nanosensors in terms of sensitivity and selectivity with respect to practical requirement, and thereby inspiring new ideas for the development of further advanced systems.

Determination of Ibuprofen and Phenylephrine in Tablets by High-Performance Thin Layer Chromatography and in Plasma by High-Performance Liquid Chromatography with Diode Array Detection

Two chromatographic methods (high performance thin layer chromatography (HPTLC) and high performance liquid chromatography-diode array detector (HPLC-DAD)), were addressed for the analysis of a mixture consisted of phenylephrine hydrochloride and ibuprofen in two forms bulk and their combined dosage form. This binary mixture is considered to be a challenging one as the two drugs differ greatly in their chemical and physical properties. Not only this affects their simultaneous analysis, but also hinders their simultaneous extraction from biological fluids as plasma. That is the reason the literature lacks any report for the simultaneous extraction and analysis of these drugs from biological fluids. The concentration ranges of both drugs were 0.1-2.5 μg/spot and 0.1-100 μg/mL by HPTLC and HPLC, respectively. Not only was the HPLC-DAD method applied to the investigated drugs determination in pharmaceutical preparations, but also in spiked human plasma. Extensive study was conducted to optimize their simultaneous extraction from plasma as it was a crucial step for the in vivo analysis. The results obtained by proposed methods and a reference one were statistically comparable by analysis of variance test. No significant difference was recorded between the mean percent levels determined by the proposed methods and the reference one.

Direct detection of phenylephrine 3-O-sulfate in LS180 human intestinal cells using a novel hydrophilic interaction liquid chromatography (HILIC) assay

The efficacy of phenylephrine (PE) is controversial due to its extensive pre-systemic metabolism through sulfation to form phenylephrine-3-O-sulfate (PES). Hence quantitation of PES is important in order to study the metabolism of PE. There are no published methods available for direction detection of PES. We have developed and validated a hydrophilic interaction liquid chromatography (HILIC) method for the direct detection of PES and simultaneous detection of PE to study the enzyme kinetics and metabolism of PE to enable approaches to reduce the presystemic metabolism of PE. This is the first method which facilitates direct detection of PES and simultaneous detection of PE using a zwitterionic HILIC column with improved sensitivity in a single short run. The observed quantitative ranges of our method for PE and PES were 0.39-200μM and 0.0625-32μM (respectively) with a run time of 6.0min. The method was applied to the determination of PE and PES in LS180 human intestinal cell line, recombinant enzymes and human intestinal cytosol (HIC).

High-performance liquid chromatographic determination of phenylephrine and tropicamide in human aqueous humor

A high-performance liquid chromatographic method for the simultaneous determination of phenylephrine and tropicamide in human aqueous humor was developed. After centrifugation, an aliquot of the supernatant was injected onto the column and the eluent was monitored at 280 nm then 254 nm after 5 min. Separation was performed on a CN column with 0.01 M Pic B8 (octane sulfonic acid)-acetonitrile (65:35, v/v) as mobile phase. The standard curves were linear in the detection range. The precision of the method (expressed by relative standard deviation) and the accuracy (mean error in per cent) were <5% for both intra- and interassays.

High-performance liquid chromatographic determination of pholedrine in human serum using ion-pair extraction and amperometric detection

The method for the quantitation of pholedrine in human serum involves extraction of the sample with benzene utilizing an ion-pairing reagent, bis(2-ethylhexyl)phosphoric acid, and re-extraction into diluted phosphoric acid. Analysis is carried out on a ODS reversed-phase column with heptanesulfonate as the ion-pairing reagent. The procedure allows quantitation at the lower nanogram level and is useful for pharmacokinetic investigations.

High-performance liquid chromatographic determination of phenylephrine in human serum with coulometric detection

A high-performance liquid chromatographic method for the determination of phenylephrine (PE) in human serum using coulometric detection is described. PE and internal standard, orciprenaline, were extracted from serum by solid-phase extraction and separation achieved on a coupled column system consisting of two C18 cartridge columns (250 x 4.6 mm I.D. coupled to a shorter 50 x 4.6 mm I.D. column) using a mobile phase of methanol-50 mM phosphate buffer (pH 3.2; 10:90) at 36 degrees C. Dual electrode coulometric detection was used in the "oxidative screen" mode. Calibration curves were linear over the range 0.3-4 ng/ml with a limit of quantification (LOQ) of 0.35 ng/ml. The method has a greater degree of sensitivity, precision and accuracy compared to previously published methods for PE and is suitable for use in pharmacokinetic and bioequivalence studies in humans.