Biomedical subjects

Ian D Wilson

Publications and source records attributed to Ian D Wilson.

44 records · Page 3Linked to original sources

PubMed2003

Comparison of normal and reversed-phase solid phase extraction methods for extraction of beta-blockers from plasma using molecularly imprinted polymers.

A molecularly imprinted polymer (MIP) prepared using propranolol as template, methacrylic acid (MA) and ethylene glycol dimethacrylate (EGDMA) was used to develop SPE methods in "reversed-" and normal phase mode for an analogue of propranolol (M47070) with another analogue (M45655) used as an internal standard. The compounds were also extracted in reversed-phase mode onto a non-imprinted polymer. It was necessary to employ a protein precipitation step ahead of MIP-SPE in order to facilitate downstream analysis. High extraction efficiencies and linear calibration ranges were achieved using both reversed-phase (RP) and normal phase (NP) MIP-based methods. Extraction efficiencies were lower on the non-imprinted polymer indicating stronger retention by the MIP. This stronger retention was attributed to selective imprint-based binding by the MIP that was not available for the non-imprinted polymer. Although clean extracts were obtained in both RP and NP modes, low level interference from template-related impurities or degradation products compromised detection of M47070 at low concentrations for the MIP-based methods. This interference made accuracy of the MIP-based methods poorer at low concentrations. The reversed-phase method showed marginally better accuracy and precision than the normal phase method.

Adrenergic beta-Antagonists↗

PubMed2003

Metabonomic analysis of mouse urine by liquid-chromatography-time of flight mass spectrometry (LC-TOFMS): detection of strain, diurnal and gender differences.

The application of HPLC-MS combined with principal components analysis (PCA) to the metabonomic analysis of mouse urine is demonstrated. Urine samples from three strains of mouse were analysed by gradient HPLC-MS combined with positive and negative electrospray time-of-flight mass spectrometry. Analysis of the resulting data using PCA enabled the samples to be discriminated between on the basis of gender, strain and diurnal variation. These preliminary results suggest that HPLC-MS-based approaches may have a useful role in metabonomic analysis that complements existing approaches.

Animals↗

PubMed2002

Reversed-phase HPLC of polymer additives with multiple on-line spectroscopic analysis (UV, IR, (1)H NMR and MS).

The reversed-phase chromatography of a number of polymer additives has been undertaken with on-line characterisation via a combination of diode array UV, (1)H NMR, IR spectroscopy and mass spectrometry. This combination of spectrometers enabled the on-flow collection of full UV, (1)H NMR, IR and mass spectra for a range of common polymer additives in amounts ranging from ca. 230 to 900 micro g on-column. The practical difficulties associated with multiple hyphenation and potential future developments are discussed.

Butylated Hydroxytoluene↗

PubMed2002

Flow injection analysis with multiple on-line spectroscopic analysis (UV, IR, 1H-NMR and MS).

Studies on the capabilities of flow injection analysis (FIA) combined with on-line characterisation of model compounds via a combination of diode array UV, 1H-NMR, FT-IR spectroscopy and mass spectrometry are described. Using this combination of spectrometers enabled the on-flow collection of UV, 1H-NMR, IR and MS for a range of model compounds. Samples were introduced into the system as solutions in deuterium oxide in concentrations ranging from 1.4 to 8.4 mg ml(-1). A sample volume of 100 microl was used for FIA at a flow rate of 1 ml min(-1). From these studies a practical working quantity of ca. 140 microg/sample of analyte was determined which provided characteristic spectra.

4-Aminobenzoic Acid↗

PubMed2002

HPLC analysis of ecdysteroids in plant extracts using superheated deuterium oxide with multiple on-line spectroscopic analysis (UV, IR, 1H NMR, and MS).

HPLC, using superheated D20 as the mobile phase, combined with on-line characterization via a combination of diode array UV, 1H NMR, FT-IR spectroscopy, and mass spectrometry has been used for the analysis of a standard of 20-hydroxyecdysone- and ecdysteroid-containing plant extracts. This combination of spectrometers enabled the on-flow collection of UV, 1H NMR, IR, and mass spectra not only for pure 20-hydroxyecdysone (100-400 microg on column) but also the major ecdysteroids present in crude extracts of Silene otites, Silene nutans, and Silene frivaldiskyana. The ecdysteroids unequivocally identified in these extracts included 20-hydroxyecdysone, polypodine B, and integristerone A.

Animals↗

PubMed2002

Quantitation in gradient high performance liquid chromatography/inductively coupled mass spectrometry investigated using diclofenac and chlorpromazine.

The use of directly coupled high performance liquid chromatography/inductively coupled plasma mass spectroscopy (HPLC/ICPMS) employing chlorine ((35)Cl/(37)Cl) detection has been investigated with respect to the detection and quantitation of the drugs diclofenac and chlorpromazine. By integration of peak areas in the 'chloratogram' (the chlorine specific HPLC chromatogram), a calibration curve was constructed, from which the concentrations could be determined. Chlorine detected HPLC/ICPMS is quantitative over a wide range of concentrations of pharmaceutical relevance for metabolite detection and the results reproducible (standard deviation +/- 0.43%) over multiple injections. Application of gradient chromatography and variation in the bulk mobile phase physicochemical properties has little effect on the ICPMS detection response for these compounds. This work indicates that the use of HPLC/ICPMS is likely to be quantitatively reliable for metabolism studies for a range of chlorinated xenobiotics.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMedDate not supplied

Superheated water chromatography-nuclear magnetic resonance spectroscopy of kava lactones.

Three kava lactone constituents of Piper methysticum, namely, kawain, methysticin and desmethoxyyangonin, have been separated and identified by reversed-phase HPLC using superheated deuterium oxide as the mobile phase and on-line 1H-NMR detection. The method avoids the use of organic solvents in the mobile phase and hence interferences in the NMR analysis are minimised.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

High resolution "ultra performance" liquid chromatography coupled to oa-TOF mass spectrometry as a tool for differential metabolic pathway profiling in functional genomic studies.

The combination of a new 1.7 mum reversed-phase packing material, and a chromatographic system, operating at ca. 12,000 psi, (so-called ultra performance liquid chromatography, UPLC) has enabled dramatic increases in chromatographic performance to be obtained for complex mixture separation. This increase in performance is manifested in improved peak resolution, together with increased speed and sensitivity. Here, we show that UPLC offers significant advantages over conventional reversed-phase HPLC amounting to a more than doubling of peak capacity, an almost 10-fold increase in speed and a 3- to 5-fold increase in sensitivity compared to that generated with a conventional 3.5 microm stationary phase. The first functional genomic application of UPLC-MS technology is illustrated here with respect to multivariate metabolic profiling of urines from males and females of two groups of phenotypically normal mouse strains (C57BL19J and Alpk:ApfCD) and a "nude mouse" strain. We have also compared this technology to conventional HPLC-MS under similar analytical conditions and show improved phenotypic classification capability of UPLC-MS analysis together with increased ability to probe differential pathway activities between strains as a result of improved analytical sensitivity and resolution.

Animals↗