References of "Crommen, Jacques"
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See detailAutomated determination of sulfadimidine in ovine plasma by solid phase extraction and HPLC
Hubert, Philippe ULg; Evrard, Brigitte ULg; Delattre, Luc ULg et al

in Journal de Pharmacie de Belgique (1992), 47

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See detailDetermination of Meprobamate in Pharmaceutical Dosage Forms Also Containing Carbromal by Liquid Chromatography and Indirect Photometric Detection
Bechet, I.; Ceccato, Attilio ULg; Hubert, Philippe ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (1992), 10(10-12, Oct-Dec), 995-9

In a pharmaceutical form also containing carbromal, meprobamate could not be quantified selectively by classical methods described in pharmacopoeias due to a significant interference from carbromal ... [more ▼]

In a pharmaceutical form also containing carbromal, meprobamate could not be quantified selectively by classical methods described in pharmacopoeias due to a significant interference from carbromal. Consequently, reversed-phase HPLC methods have been developed to separate the two active ingredients using indirect photometric detection to visualize and determine meprobamate which has very poor chromophoric properties. Different parameters influencing the sensitivity of the indirect response, such as the nature of the highly absorbing compound added to the mobile phase (the marker) as well as the methanol content and the pH of this phase, have been studied. Two chromatographic systems containing benzoic acid or cinnamic acid as the marker, have been optimized and validated. Good linearity and reproducibility have been obtained with both systems but the cinnamic acid method has the advantage that meprobamate and carbromal can be determined simultaneously at 273 nm. [less ▲]

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See detailAutomatic Determination of Diltiazem and Desacetyldiltiazem in Human Plasma Using Liquid-Solid Extraction on Disposable Cartridges Coupled to Hplc--Part II: Optimization of Liquid-Solid Extraction
Hubert, Philippe ULg; Chiap, Patrice ULg; Crommen, Jacques ULg

in Journal of Pharmaceutical & Biomedical Analysis (1991), 9(10-12), 883-887

An automatic liquid-solid extraction (LSE) procedure to be coupled to HPLC for the determination of diltiazem and desacetyldiltiazem in plasma has been developed. The LSE operations are performed on ... [more ▼]

An automatic liquid-solid extraction (LSE) procedure to be coupled to HPLC for the determination of diltiazem and desacetyldiltiazem in plasma has been developed. The LSE operations are performed on disposable extraction cartridges (DECs) by means of a sample processor equipped with a robotic arm holding a needle through which the different liquids are dispensed. The operating parameters of LSE have been optimized with respect to recovery, detectability and reproducibility by using, whenever possible, aqueous solutions of the analytes. Different kinds of DECs have been tested. For the compounds studied, DECs filled with 50 mg of cyanopropyl silica have been selected. The influence of the pH of the buffer used in the washing step has been studied, leading finally to the selection of the same phosphate buffer (pH 7.4) as in the HPLC mobile phase. The minimum volume of methanol which still gives a nearly complete elution of the analytes from the extraction cartridges has been determined. Under these conditions, a high sensitivity can be obtained without an evaporation step. Moreover, the volume of buffer to be added to the methanolic eluate before injection into the HPLC system has been optimized in such a way that a focusing effect is obtained at the top of the analytical column while the dilution of the extract is minimized. [less ▲]

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See detailAutomatic Determination of Diltiazem and Desacetyldiltiazem in Human Plasma Using Liquid-Solid Extraction on Disposable Cartridges Coupled to Hplc--Part I: Optimization of the Hplc System and Method Validation
Hubert, Philippe ULg; Chiap, Patrice ULg; Crommen, Jacques ULg

in Journal of Pharmaceutical & Biomedical Analysis (1991), 9(10-12), 877-882

A sensitive and automated method for the analysis of diltiazem and desacetyldiltiazem in plasma has been developed using liquid-solid extraction (LSE) on disposable extraction cartridges (DECs) in ... [more ▼]

A sensitive and automated method for the analysis of diltiazem and desacetyldiltiazem in plasma has been developed using liquid-solid extraction (LSE) on disposable extraction cartridges (DECs) in combination with HPLC. After isolation from plasma, the analytes are separated on a highly deactivated octyl silica column with a mobile phase of methanol-0.05 M phosphate buffer (pH 7.4) (62:38, v/v). The analytes are monitored photometrically at 238 nm. The complete preparation of the plasma sample as well as the injection of the final extract on to the analytical column are performed automatically by means of a sample processor equipped with a robotic arm to which is attached a needle dispensing the different liquids. The internal standard solution is first added to the plasma sample. The DEC is then conditioned successively with methanol and phosphate buffer (pH 7.4). A 1.0-ml volume of sample containing the internal standard solution is applied on an extraction cartridge filled with cyanopropyl silica (50 mg). After the DEC has been washed with the same buffer, the analytes are eluted with 0.16 ml of methanol. A 0.14-ml volume of buffer is then passed through the DEC and 0.25 ml of the final extract is injected onto the HPLC column. The absolute recoveries of the drugs are about 90% and the limit of detection for diltiazem is 0.8 ng ml-1. Relative standard deviations of 2.6% (within-day) and 3.7% (between-day) have been obtained for this compound at a plasma concentration of 50 ng ml-1. [less ▲]

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See detailIndirect photometric detection of amino acids in capillary zone electrophoresis
Bechet, Isabelle; Hubert, Philippe ULg; Crommen, Jacques ULg

in Journal de Pharmacie de Belgique (1991), 46

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See detailPercutaneous administration of indomethacin in rheumatoid arthritis, evaluation of two topical preparations
Reginster, Jean-Yves ULg; Crommen, Jacques ULg; Renson, M et al

in Current Therapeutic Research (1990), 47(3), 548-553

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See detailA Fully Automated High-Performance Liquid Chromatographic Method for the Determination of Indomethacin in Plasma
Hubert, Philippe ULg; Renson, M.; Crommen, Jacques ULg

in Journal of Pharmaceutical & Biomedical Analysis (1989), 7(12), 1819-27

A fully automated method is described, which enables the determination of indomethacin in plasma by reversed-phase HPLC following on-line sample enrichment and clean-up on a short pre-column. The plasma ... [more ▼]

A fully automated method is described, which enables the determination of indomethacin in plasma by reversed-phase HPLC following on-line sample enrichment and clean-up on a short pre-column. The plasma sample is introduced directly into the column switching system. The pre-column, filled with a pellicular bonded phase, is first washed with phosphate buffer, pH 7.4. The compounds retained on the pre-column are then eluted in the fore-flush mode and separated on an octadecylsilica column with a methanolic phosphate buffer (pH 7.4) mobile phase. Indomethacin is determined spectrophotometrically at 254 or 260 nm. The effect of changes in the pH and flow rate of the washing eluent are studied. Under the conditions selected, memory effects can be avoided, the absolute recovery of the drug is 70% and the limit of detection 10 ng ml-1 for a 100 microliter injection of plasma. At a concentration of 100 ng ml-1, the relative standard deviations (RSD) are 1.7% (within-day) and 3.5% (between-day), respectively. [less ▲]

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See detailIndirect Uv Detection of Hydrophilic Ionized Compounds in Reversed-Phase Liquid Chromatography by Use of a Uv-Absorbing Ion of the Same Charge
Crommen, Jacques ULg; Herné, Patrick ULg

in Journal of Pharmaceutical & Biomedical Analysis (1984), 2(2), 241-53

Ion-pair reversed-phase liquid chromatographic systems have been developed that allow the detection and quantitation of low amounts of hydrophilic ionized substances, which otherwise display little or no ... [more ▼]

Ion-pair reversed-phase liquid chromatographic systems have been developed that allow the detection and quantitation of low amounts of hydrophilic ionized substances, which otherwise display little or no capability for optical detection. The mobile phase contains a UV-absorbing ion of the same charge and hydrophobic character as the samples, most often together with a hydrophobic counter-ion to give the samples suitable retention; the stationary phase consists of octadecylsilica. Chromatograms featuring two system peaks are usually obtained, and these give rise to some deviations from the usual response pattern. In the present work the influence on retention and detection sensitivity of the non-absorbing counter-ion, the UV-absorbing ion and the uncharged organic modifier have been studied systematically. Principles for optimizing the detector response by changing the mobile phase composition have been deduced. Examples of applications of the indirect detection technique to the analysis of hydrophilic compounds of pharmaceutical and biological interest, such as amino acids, water-soluble vitamins and piperazine, are presented. [less ▲]

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See detailDetermination of thiamine and thiamine phosphates in excitable tissues as thiochrome derivatives by reversed phase high-performance liquid chromatography on octadecyl-silica.
Bontemps, José; Philippe, P.; Bettendorff, Lucien ULg et al

in Journal of Chromatography. B : Biomedical Applications (1984), 307

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