References of "Ceccato, Attilio"
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See detailSensitive determination of buprenorphine and its N-dealkylated metabolite norbuprenorphine in human plasma by liquid chromatography coupled to tandem mass spectrometry
Ceccato, Attilio ULg; Klinkenberg, R.; Hubert, Philippe ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2003), 32(4-5), 619-631

A highly sensitive method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the quantitative determination of buprenorphine and its active metabolite ... [more ▼]

A highly sensitive method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the quantitative determination of buprenorphine and its active metabolite norbuprenorphine in human plasma. Automated solid. phase extraction (SPE) on disposable extraction cartridges (DEC) is used to isolate the compounds from the biological matrix and to prepare a cleaner sample before injection and analysis in the LC-MS/MS system. After conditioning, the plasma sample (1.0 ml) is loaded on the DEC filled with octyl silica (C8) and washed with water. The analytes are, therefore, eluted by dispensing methanol containing 0.1% of acetic acid. The eluate is collected and evaporated to dryness. The residue is dissolved in mobile phase and an aliquot is injected in the LC-MS/ MS system. On-line LC-MS/MS system using atmospheric pressure chemical ionization (APCI) has been developed for the determination of buprenorphine and norbuprenorphine. The separation is obtained on a RP-18 stationary phase using a mobile phase consisting in a mixture of methanol and 50 mM ammonium acetate solution (50:50, v/v). Clonazepam is used as internal standard (IS). The MS/MS ion transitions monitored are m/z 468-->468, 414-->414 and 316-->270 for buprenorphine, norbuprenorphine and clonazepam, respectively. The method was validated regarding recovery, linearity, precision and accuracy. The limits of quantification (LOQs) were around 10 pg/ml for buprenorphine and 50 pg/ml for norbuprenorphine. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailAutomated determination of pirlindole enantiomers in plasma by on-line coupling of a pre-column packed with restricted access material to a chiral liquid chromatographic column
Chiap, Patrice ULg; Ceccato, Attilio ULg; Gora, R. et al

in Journal of Pharmaceutical & Biomedical Analysis (2002), 27(3-4), 447-455

A fully automated liquid chromatographic method has been developed for the determination of the enantiomers of pirlindole, an antidepressant drug, in human plasma. The method is based on the use of a pre ... [more ▼]

A fully automated liquid chromatographic method has been developed for the determination of the enantiomers of pirlindole, an antidepressant drug, in human plasma. The method is based on the use of a pre-column packed with restricted access material (RAM) (LiChrospher ADS RP-4) for sample clean-up coupled to a column containing a cellulose tris-(3,5-dimethylphenylcarbamate) based chiral stationary phase (Chiralcel OD-R) for the separation and quantitative analysis of pirlindole enantiomers. A 50-microl plasma volume was injected directly onto the pre-column using a mixture of phosphate buffer (pH 5.0) and methanol (97:3; v/v) as washing liquid. By rotation of a switching valve, the analytes were then eluted in the back-flush mode with the LC mobile phase. A complete separation of pirlindole enantiomers was obtained in 22 min on the Chiralcel OD-R column, using a mobile phase made of a mixture of phosphate buffer (pH 5.0) containing 50 mM sodium perchlorate and acetonitrile (65:35; v/v). The flow-rate was 0.6 ml/min and the analytes were detected fluorometrically using 295 and 340 nm as excitation and emission wavelengths, respectively. The method was then validated and was found to be linear in the 2.5-200 ng/ml range. The limit of detection was lower than 1 ng/ml. Repeatability and intermediate precision at a concentration of 50 ng/ml were about 1.5 and 3.5%, respectively. [less ▲]

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See detailDevelopment and Validation of an Automated Method for the Liquid Chromatographic Determination of Sotalol in Plasma Using Dialysis and Trace Enrichment on a Cation-Exchange Pre-Column as on-Line Sample Preparation
Chiap, Patrice ULg; Ceccato, Attilio ULg; Miralles Buraglia, B. et al

in Journal of Pharmaceutical & Biomedical Analysis (2001), 24(5-6), 801-14

A fully automated method for the determination of sotalol in human plasma was developed, involving dialysis through a cellulose acetate membrane, clean-up and enrichment of the dialysate on a strong ... [more ▼]

A fully automated method for the determination of sotalol in human plasma was developed, involving dialysis through a cellulose acetate membrane, clean-up and enrichment of the dialysate on a strong cation-exchange pre-column and subsequent liquid chromatographic (LC) analysis with UV detection. All sample handling operations were carried out by means of an ASTED system. Before starting dialysis, the trace enrichment column (TEC) was conditioned. The plasma sample, to which the internal standard (atenolol) was automatically added, was then loaded in the donor channel and was kept static while the dialysis liquid, consisting of 0.017 M acetic acid, was passed through the acceptor channel in successive pulses. After each pulse, the dialysate was dispensed onto the TEC. When dialysis was discontinued, the analytes were eluted from the TEC by the LC mobile phase by rotation of a switching valve and transferred to the analytical column packed with octyl silica. The LC mobile phase was a mixture of methanol and pH 7.0 phosphate buffer containing 1-octanesulfonate at a concentration of 7.5 x 10(-4) M (19:81; v/v). The UV detection was performed at 230 nm. The influence of several parameters of the dialysis and trace enrichment processes on analyte recovery and method selectivity was investigated. The method was then validated. The mean absolute recovery for sotalol was about 60%. The limit of quantitation was 25 ng/ml and R.S.D. for repeatability and intermediate precision obtained at a concentration level of 50 ng/ml were 4.3 and 5.8%, respectively. [less ▲]

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See detailQuantitative Analysis of N-Acetylcysteine and Its Pharmacopeial Impurities in a Pharmaceutical Formulation by Liquid Chromatography-Uv Detection-Mass Spectrometry
Toussaint, B.; Pitti, C.; Streel, B. et al

in Journal of Chromatography. A (2000), 896(1-2), 191-9

A new method for the simultaneous determination of N-acetylcysteine and its pharmacopeial impurities, cysteine, cystine, N,N'-diacetylcystine and N,S-diacetylcysteine in an effervescent tablet has been ... [more ▼]

A new method for the simultaneous determination of N-acetylcysteine and its pharmacopeial impurities, cysteine, cystine, N,N'-diacetylcystine and N,S-diacetylcysteine in an effervescent tablet has been developed. The method is based on on-line LC-UV-MS using a pneumatically-assisted electrospray interface (ionspray). The stability of the thiol moieties of the analytes was ensured by the acidic pH of the LC mobile phase. Quantitation of N-acetylcysteine was performed with UV detection to avoid ion-source overloading effect due to its higher concentration, whereas the impurities could be easily separated and quantified in MS. The method was validated in terms of stability, linearity, precision and accuracy. [less ▲]

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See detailDetermination of the Enantiomers of 3-Tert.-Butylamino-1,2-Propanediol by High-Performance Liquid Chromatography Using Mass Spectrometric Detection
Toussaint, B.; Streel, B.; Ceccato, Attilio ULg et al

in Journal of Chromatography. A (2000), 896(1-2), 201-7

The chiral synthesis of beta-blockers such as (S)-timolol requires a sensitive analytical method for the enantioseparation of its intermediate, 3-tert.-butylamino-1,2-propanediol, in the ng/ml range. The ... [more ▼]

The chiral synthesis of beta-blockers such as (S)-timolol requires a sensitive analytical method for the enantioseparation of its intermediate, 3-tert.-butylamino-1,2-propanediol, in the ng/ml range. The method developed is based on on-line normal-phase LC-MS-MS using a chiral stationary phase and an atmospheric pressure chemical ionization (APCI) interface. The MS detection of 3-tert.-butylamino-1,2-propanediol was first optimized with a pneumatically-assisted electrospray interface (ionspray). The APCI interface was then selected for LC-MS-MS because of the incompatibility of electrospray with n-hexane. The method was validated for both enantiomers in the 25-500 ng/ml concentration range. [less ▲]

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See detailAutomated Liquid Chromatographic Determination of Atenolol in Plasma Using Dialysis and Trace Enrichment on a Cation-Exchange Precolumn for Sample Handling
Chiap, Patrice ULg; Buraglia, B. M.; Ceccato, Attilio ULg et al

in Journal of Chromatography. B : Biomedical Sciences and Applications (2000), 739(1), 205-17

A fully automated method involving dialysis combined with trace enrichment was developed for the liquid chromatographic (LC) determination of atenolol, a hydrophilic beta-blocking agent, in human plasma ... [more ▼]

A fully automated method involving dialysis combined with trace enrichment was developed for the liquid chromatographic (LC) determination of atenolol, a hydrophilic beta-blocking agent, in human plasma. The plasma samples were dialysed on a cellulose acetate membrane and the dialysate was reconcentrated on a short trace enrichment column (TEC) packed with a strong cation-exchange material. All sample handling operations can be executed automatically by a sample processor (ASTED system). After TEC conditioning, the plasma sample, to which the internal standard (sotalol, another hydrophilic beta-blocker) was automatically added, was introduced in the donor channel and dialysed in the static/pulsed mode. The dialysis liquid consisted of 4.3 mM phosphoric acid. When the dialysis process was discontinued, the analytes were eluted from the TEC in the back-flush mode by the LC mobile phase and transferred to the analytical column, packed with octyl silica. The LC mobile phase consisted of phosphate buffer, pH 7.0-methanol (81:19; v/v) with 1-octanesulfonate. Atenolol and the internal standard were monitored photometrically at 225 nm. The different parameters influencing the dialysis and trace enrichment processes were optimised with respect to analyte recovery. The influence of two different kinds of cation-exchange material on analyte recovery and peak efficiency was also studied. The method was then validated in the concentration range 25-1000 ng/ml. The mean recovery for atenolol was 65% and the limit of quantitation was 25 ng/ml. [less ▲]

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See detailDetermination of N-acetylcysteine and its metabolites in plasma by LC-MS-MS
Toussaint, B.; Streel, B.; Ceccato, Attilio ULg et al

Poster (2000)

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See detailQuantitative analysis of N-acetylcysteine and its pharmacopeial impurities in a pharmaceutical formulation by LC-UV-MS
Toussaint, B.; Pitti, Ch.; Streel, B. et al

Poster (2000)

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See detailDetermination of 3-tert.butylamino-1,2-propanediol enantiomers by LC-MS-MS
Toussaint, B.; Streel, B.; Ceccato, Attilio ULg et al

Poster (2000)

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See detailAutomated Sample Preparation Techniques for the Determination of Drug Enantiomers in Biological Fluids Using Liquid Chromatography with Chiral Stationary Phases
Ceccato, Attilio ULg; Toussaint, B.; Chiap, Patrice ULg et al

in Enantiomer (1999), 4(3-4), 305-15

The determination of drug enantiomers has become of prime importance in the field of pharmaceutical and biomedical analysis. Liquid chromatography (LC) is one of the most frequently used techniques for ... [more ▼]

The determination of drug enantiomers has become of prime importance in the field of pharmaceutical and biomedical analysis. Liquid chromatography (LC) is one of the most frequently used techniques for achieving the separation and quantitation of the enantiomers of drug compounds. In the bioanalytical field, the integrated systems present an interesting alternative to time-consuming sample preparation techniques such as liquid-liquid extraction. Solid phase extraction (SPE) on disposable cartridges, dialysis or column switching are sample preparation techniques that can be fully automated and applied to enantioselective analysis in biological fluids. The selection of the most appropriate LC mode and chiral stationary phase for enantioseparations in bioanalysis is discussed and some aspects of these automated sample preparation procedures are compared, such as selectivity, detectability, elution of the analytes from the extraction sorbent, sample volume and analyte stability. [less ▲]

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See detailEnantiomeric Separation of Pirlindole by Liquid Chromatography Using Different Types of Chiral Stationary Phases
Ceccato, Attilio ULg; Hubert, Philippe ULg; De Tullio, Pascal ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (1998), 18(4-5), 605-14

The enantioseparation of pirlindole by liquid chromatography (LC) was investigated using three different chiral stationary phases (CSPs) containing either cellulose tris-(3,5-dimethylphenylcarbamate ... [more ▼]

The enantioseparation of pirlindole by liquid chromatography (LC) was investigated using three different chiral stationary phases (CSPs) containing either cellulose tris-(3,5-dimethylphenylcarbamate) (Chiralcel OD-R), ovomucoid (OVM) or beta-cyclodextrin (beta-CD). The effects of the mobile phase pH on retention, enantioselectivity and resolution were studied. Methanol and acetonitrile were tested as organic modifiers while the influence of the addition to the mobile phase of sodium alkanesulfonates or sodium perchlorate was also investigated. Sodium perchlorate was only used on the Chiralcel OD-R column while sodium alkanesulfonates were tested as mobile phase additives on the three kinds of CSPs. The enantioseparation of pirlindole could be obtained on all CSPs tested, the best results with respect to chiral resolution being achieved on the Chiralcel OD-R and the OVM columns. The use of sodium octanesulfonate (NaOS) was found to improve the enantioseparation of pirlindole on the OVM column while enantioselectivity was considerably enhanced by addition of sodium perchlorate on the Chiralcel OD-R column. [less ▲]

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See detailSimultaneous Determination of Methylphenobarbital Enantiomers and Phenobarbital in Human Plasma by on-Line Coupling of an Achiral Precolumn to a Chiral Liquid Chromatographic Column
Ceccato, Attilio ULg; Boulanger, Bruno ULg; Chiap, Patrice ULg et al

in Journal of Chromatography. A (1998), 819(1-2), 143-53

A fully automated liquid chromatographic (LC) method for the simultaneous determination of methylphenobarbital enantiomers and phenobarbital in human plasma has been developed. The method is based on the ... [more ▼]

A fully automated liquid chromatographic (LC) method for the simultaneous determination of methylphenobarbital enantiomers and phenobarbital in human plasma has been developed. The method is based on the use of a precolumn packed with an internal-surface reversed-phase packing material (LiChrospher ADS) for sample clean-up coupled to LC analysis on a cellulose tris(4-methylbenzoate) based chiral stationary phase (Chiralcel OJ-R). A 100-microliter plasma sample was injected directly on the precolumn packed with LiChrospher RP-18 ADS using a mixture of pH 5.0 phosphate buffer-methanol (97:3, v/v) as washing liquid. The analytes were then eluted in the back-flush mode with the LC mobile phase. The enantiomeric separation of methylphenobarbital was achieved on Chiralcel OJ-R). The retention times were modelled using a D-optimal design with ten experimental points in order to optimise the LC mobile phase for the separation of phenobarbital from the enantiomers of mephobarbital. The factors selected were the acetonitrile content, the pH and the sodium perchlorate concentration in the mobile phase. A Derringer's desirability function was used to find an optimal and robust solution within the experimental domain. The mobile phase selected consisted of a mixture of pH 7.0 phosphate buffer-acetonitrile (60:40, v/v). The elution profiles of phenobarbital, methylphenobarbital and blank plasma samples on the precolumn and the time needed for analyte transfer from the precolumn to the analytical column were then determined. Finally, the method developed was validated. [less ▲]

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See detailSimultaneous Determination of Pirlindole Enantiomers and Dehydropirlindole by Chiral Liquid Chromatography
Ceccato, Attilio ULg; Hubert, Philippe ULg; De Tullio, Pascal ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (1998), 17(6-7), 1071-9

Liquid chromatography was employed for the determination of pirlindole enantiomers and its oxidation product dehydropirlindole (DHP). The direct separation of pirlindole enantiomers and DHP was achieved ... [more ▼]

Liquid chromatography was employed for the determination of pirlindole enantiomers and its oxidation product dehydropirlindole (DHP). The direct separation of pirlindole enantiomers and DHP was achieved on a cellulose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase (Chiralcel OD-R). Acetonitrile was used as the organic modifier and sodium perchlorate was used as an ionic additive in the mobile phase. The influence of acetonitrile and sodium perchlorate concentrations on enantioselectivity and achiral selectivity towards DHP was investigated in order to find suitable conditions for the determination of low amounts of each analyte. The mobile phase selected consisted of a mixture of acetonitrile and phosphate buffer (pH 5.0) containing sodium perchlorate (0.05 M) (35:65, v/v) and the UV detector was set at 220 nm. The method developed was validated and was found to be linear in the 0.1-5 microg ml(-1) range (r2 = 0.999 for the three compounds). Repeatability and the intermediate precision for the three analytes at a concentration of 0.1 microg ml(-1) were about 3 and 4%, respectively. This concentration corresponds to the quantification of 0.1% for the minor enantiomer. Actual determinations of enantiomeric purity for single enantiomers of pirlindole were performed. [less ▲]

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