Biomedical subjects

F T Delbeke

Publications and source records attributed to F T Delbeke.

At least 19 recordsLinked to original sources

PubMed2006

Detection of budesonide in human urine after inhalation by liquid chromatography-mass spectrometry.

Budesonide, a corticosteroid frequently used in the treatment of asthma, is most often administered via inhalation. Its use in sports is allowed when medically necessary. A fast, sensitive and accurate LC-MS method was developed and validated for the quantification of budesonide and its major metabolite 16alpha-hydroxyprednisolone in urine samples after inhalation of a metered dose (Pulmicort-Turbohaler 200). Sample preparation consists of an alkaline liquid-liquid extraction with ethyl acetate. Analysis was performed using liquid chromatography-tandem mass spectrometry with electrospray ionization (ESI). The method was linear in the range of 5-100 and 0.5-10ng/mL for 16alpha-hydroxyprednisolone and budesonide, respectively. The limits of quantification were 5ng/ml for 16alpha-hydroxyprednisolone and 0.5ng/mL for budesonide. The accuracy ranged from 2.2 to 3.5% for 16alpha-hydroxyprednisolone and from 0.8 to 16.4% for budesonide. After administration of 200microg of budesonide to five healthy volunteers budesonide could not be detected in any urine sample whereas 16alpha-hydroxyprednisolone was detectable up to 12h post-administration.

Administration, Inhalation↗

PubMed2006

Detection of hydroxyethylstarch (HES) in human urine by liquid chromatography-mass spectrometry.

The objective of this study was to establish the possibility of using liquid chromatography coupled to mass spectrometry for the detection of hydroxyethylstarch (a corn starch derived product) in urine as an alternative to the current time consuming GC-MS methods. Analyses were performed using an ion trap instrument after acidic hydrolysis. Ionization was carried out using atmospheric pressure chemical ionisation (APCI) operated in negative ionization mode and detection was performed using MS(2). The results indicate that the developed method can successfully be applied as a fast and reliable method for the detection and identification of hydroxyethylstarch.

Chromatography, High Pressure Liquid↗

PubMed2006

Distribution of caffeine levels in urine in different sports in relation to doping control before and after the removal of caffeine from the WADA doping list.

Caffeine concentrations were measured in the urine of 4633 athletes tested for doping control in the Ghent Doping Control Laboratory in 2004. Determination of these concentrations was done using an alkaline extraction with a mixture of dichloromethane and methanol (9 : 1; v/v) followed by high performance liquid chromatography and ultraviolet detection (HPLC-UV). The method was validated according to ISO 17 025 standards (International Organisation for Standardisation). Quantification was done by using a linear calibration curve in the range from 0 to 20 microg/ml. The limit of quantification (LOQ) was 0.10 microg/ml. Because the results were not normally distributed, transformation of the data was done to evaluate the difference in detected concentrations in several sports. This resulted in an overall average concentration of 1.12 +/- 2.68 microg/ml. Comparison of the most frequently tested sports in 2004 demonstrated that caffeine concentrations in samples originating from power lifters are significantly higher in comparison to urines taken in other sports. Also, a significant difference between caffeine concentrations found in cycling and concentrations found in other sports, including athletics and some ball sports, was observed. A comparison was made between results obtained in 2004 and results obtained before the removal of caffeine from the WADA (World Anti-Doping Agency) doping list indicating that average caffeine concentrations decreased after the withdrawal of caffeine from the list of prohibited substances. The overall percentage of positive samples between the two periods remained the same although the percentage of positive samples noticed in cycling increased after the removal of caffeine from the doping list.

Bicycling↗

PubMed2006

Quantitative LC-MS determination of strychnine in urine after ingestion of a Strychnos nux-vomica preparation and its consequences in doping control.

A simple, fast and sensitive method for the quantitative determination of strychnine residues in urine has been developed and validated. The method consists of a liquid-liquid extraction step with ethyl acetate at pH 9.2, followed by LC-MS/MS in positive atmospheric pressure chemical ionization (APCI)-mode. The method is linear in the range of 1-100 ng/mL and allows for the determination of strychnine at sub-toxicological concentrations. The accuracy of the method ranged from 1.3% to 4.4%. The method was used to determine the excretion profile of strychnine after the ingestion of an over-the-counter herbal preparation of Strychnos nux-vomica. Each volunteer ingested a dose equivalent to 380 micro g of strychnine. This dose is lower than the prescription dose but results in the detection of strychnine for over 24-h post administration. Maximum detected urinary concentrations ranged from 22.6 to 176 ng/mL. The results of this study show that the use of this type of preparation by athletes can lead to a positive doping case.

Doping in Sports↗

PubMed2006

Screening for anabolic steroids in doping analysis by liquid chromatography/electrospray ion trap mass spectrometry.

A fast and selective LC/MS/MS method for the screening of four anabolic steroids in human urine has been developed and validated. Liquid-liquid extraction with diethyl ether was applied after enzymatic hydrolysis. Analyses were performed on an ion trap mass spectrometer equipped with electrospray ionisation. MS/MS was applied for all compounds. The analytical run time was 11 min. The LOD for all compounds varied between 1 and 10 ng/mL. Left-over A samples, which were declared positive by GC/MS for the presence of 3'-hydroxystanozolol, were assessed using the described method.

Anabolic Agents↗

PubMed2006

Screening for amphetamine and amphetamine-type drugs in doping analysis by liquid chromatography/mass spectrometry.

A selective and sensitive method for the qualitative screening of urine samples for 27 amphetamine and amphetamine-type drugs in the field of doping analysis is described. The method consists of a liquid-liquid extraction with diethyl ether at pH 14 and analysis of the extracts with a LCQ-Deca mass spectrometer equipped with an atmospheric pressure chemical ionisation interface, operated in positive ionisation mode. The total run time was 15 min. All compounds were analysed in MS2 or MS3. The detection limit for all compounds was lower than 25 ng/mL except for chlorphentermine (detection limit: 250 ng/mL).

Amphetamine↗

PubMed2005

Quantitative analysis of androst-4-ene-3,6,17-trione and metabolites in human urine after the administration of a food supplement by liquid chromatography/ion trap-mass spectrometry.

6-OXO, a new nutritional supplement commercially available on the internet, is sold as an aromatase-inhibitor and contains androst-4-ene-3,6,17-trione as active ingredient. This anabolic steroid is a prohibited substance in sports. Androst-4-ene-3,6,17-trione is metabolised to androst-4-ene-6alpha-ol-3,17-dione and androst-4-ene-6alpha,17beta-diol-3-one. A fast, sensitive and accurate LC/MS method was developed and validated for the quantification of androst-4-ene-3,6,17-trione and its metabolites in urine. The method is capable of determining the stereochemical position of the hydroxy-group at C-6 of the metabolites and consists of a liquid-liquid extraction step with diethylether after enzymatic hydrolysis, followed by separation on a reversed phase column. Ionisation of the analytes is carried out using atmospheric pressure chemical ionisation. The limit of quantification of the method was 5 ng/mL for all compounds. The accuracy ranged from 14.8 to 1.3% for androst-4-ene-3,6,17-trione, 9.4 to 1.6% for androst-4-ene-6alpha-ol-3,17-dione and 4.1 to 3.2% for androst-4-ene-6alpha,17beta-diol-3-one in the range of 5-1000 ng/mL. Using this method androst-4-ene-6alpha-ol-3,17-dione was identified as a major urinary metabolite, whereas androst-4-ene-6alpha,17beta-diol-3-one as a minor metabolite. While the parent compound is predominantly excreted in conjugated form, both metabolites are solely excreted as conjugates.

Adult↗

PubMed2005

Detection of androst-4-ene-3,6,17-trione (6-OXO) and its metabolites in urine by gas chromatography-mass spectrometry in relation to doping analysis.

The metabolism and excretion of androst-4-ene-3,6,17-trione after administration of the 'nutritional' supplement 6-OXO was investigated by gas chromatography-mass spectrometry (GC-MS) in full-scan mode. The parent drug androst-4-ene-3,6,17-trione and androst-4-ene-6alpha,17beta-diol-3-one and androst-4-ene-6alpha-ol-3,17-dione were detected in the post-administration urine samples. Because androst-4-ene-3,6,17-trione is an anabolic steroid and an aromatase inhibitor, this substance is regarded as a doping agent. Hence, a selective and sensitive GC-MS method in selected ion monitoring mode for the detection of the TMS-enol-TMS-ether derivatives of these substances was developed and validated for doping control purposes. The limit of detection (LOD) of the investigated compounds ranged from 5 to 10 ng/mL. Using this method, the detection time for androst-4-ene-3,6,17-trione and androst-4-ene-6alpha,17beta-diol-3-one was 24 h, while androst-4-ene-6alpha-ol-3,17-dione could be detected up to 37 h after administration of the dose recommended by the manufacturer.

Adult↗

PubMed2005

Simultaneous determination of beta-blocking agents and diuretics in doping analysis by liquid chromatography/mass spectrometry with scan-to-scan polarity switching.

A previously described method for the screening of 18 diuretics and probenecid was substantially extended with 21 beta-blockers and 8 other diuretics allowing simultaneous determination of diuretics and beta-adrenergic blocking agents in human urine. Analysis was performed using an ion trap instrument with an electrospray ionisation (ESI) interface after liquid/liquid extraction with ethyl acetate. Full-scan MS and full-scan MS2 were applied in combination with scan-to-scan polarity switching. All compounds were separated in less than 22 min. The detection limits for the diuretics were between 5 and 100 ng/mL and for the beta-adrenergic blocking agents were between 5 and 500 ng/mL. The excretion of carvedilol was followed after intake of one tablet of Dimitone. Other doping agents including strychnine, norbuprenorphine and mesocarb hydroxysulfate could also be detected with this method.

Adrenergic beta-Antagonists↗

PubMed2005

Distribution of caffeine levels in urine in different sports in relation to doping control.

Caffeine concentrations were measured in the urines of 11 361 athletes tested for doping control in the Ghent doping control laboratory during the period 1993 - 2002. Determination of these concentrations was done using an alkaline extraction with a mixture of dichloromethane and methanol (9:1; v/v) followed by high performance liquid chromatography and ultraviolet detection (HPLC-UV). The method was validated according to ISO 17 025 standards (International Organisation for Standardisation). Quantification was done by using a calibration curve in the range from 0 to 20 microg/ml. The limit of quantification (LOQ) was 0.10 microg/ml. Most caffeine concentrations were far below 12 microg/ml. Because the results were not normally distributed, transformation of the data was done to evaluate the difference in detected concentrations in several sports. This resulted in an overall average concentration of 1.22 microg/ml +/- 2.45 microg/ml. Comparison of those sports with more than 200 samples being analysed demonstrated that caffeine concentrations in urine samples from bodybuilders are significantly higher in comparison to urines taken in the other sports. Also, a significant difference between caffeine concentrations found in cycling and concentrations found in other sports, including athletics and some ball sports, was observed.

Bicycling↗

PubMed2005

Validation of a GC-MS screening method for anabolizing agents in aqueous nutritional supplements.

A sensitive and selective method for the screening of anabolizing agents in aqueous nutritional supplements is described and validated. A total of 28 different anabolizing agents are screened for, including testosterone and prohormones, nandrolone and prohormones, stanozolol, and metandienone. The different analytes are extracted from the aqueous nutritional supplements by liquid-liquid extraction with a mixture of pentane and freshly distilled diethylether (1:1) after the supplements have been made alkaline with a NaHCO3-K2CO3 (2:1) buffer. The anabolizing agents are derivatized with a mixture of MSTFA-NH4I-ethanethiol (320:1:2) as routinely used for the screening of anabolic steroids extracted from urine. The derivatives are analyzed by gas chromatography (GC)-mass spectrometry (MS) in the selective ion monitoring mode. The limits of detection range from 1 to 10 ng/mL. One aqueous nutritional supplement (creatine serum) was analyzed with this screening method and was found to contain dehydroepiandrosterone (DHEA) at very low concentrations. The presence of DHEA could be confirmed with GC-MS-MS. Results of the application of this method and a similar method for solid nutritional supplements previously described are given.

Anabolic Agents↗

PubMed2004

Validation of a GC-MS screening method for anabolizing agents in solid nutritional supplements.

A sensitive and selective method for the screening of 28 different compounds including testosterone and prohormones, nandrolone and prohormones, stanozolol and metandienone in solid nutritional supplements is described and validated. The different substances are extracted from the solid nutritional supplements by liquid-liquid extraction with a mixture of pentane and freshly distilled diethylether (9/1) after dissolving the supplement in NaOH (1 N). The anabolizing agents are derivatized with a mixture of MSTFA/NH(4)I/ethanethiol (320/1/2), routinely used for the derivatization of anabolic steroids extracted from urine. The TMS-derivatives are analysed by GC-MS in the SIM mode. The limits of detection were in the range from 2 to 40 ng/g. One supplement was analysed with this method and was found to contain several forbidden substances according to IOC doping regulations. All detected compounds, except dihydrotestosterone, could be confirmed with GC-MS(2), proving that the proposed method is suitable for the screening of anabolizing agents in solid nutritional supplements.

Anabolic Agents↗

PubMed2003

Detection and disposition of tolmetin in the horse.

Non-steroidal anti-inflammatory drugs (NSAIDs) are prohibited by the International Federation of Horse Racing Authorities but are commonly used in veterinary practice. Plasma and urinary concentrations of the NSAID tolmetin were determined by a high-performance liquid chromatographic procedure with UV detection following oral administration of a dose of 1 g to six fasted untrained standard bred mares. With a limit of quantitation (LOQ) of 0.05 microg/ml tolmetin was present in plasma for 9-12 h post-administration. Maximum concentrations of 2.1+/-0.89 microg/ml were found after 0.7+/-0.25 h. The elimination half-life was 2+/-1.25 h. Plasma protein binding at concentrations of 0.25 and 2.5 microg/ml was 92+/-4.9 and 84+/-4.2%, respectively. As early as 1 h after dosage, tolmetin could be detected in unhydrolysed urine and remained detectable up to 48 h (LOQ=0.5 microg/ml). The maximum concentrations occurred 1.8+/-0.4 h after administration. The percentage of the dose excreted as unchanged tolmetin within 12 h was 58+/-7.9%. Neither conjugates nor metabolites could be detected under the experimental conditions studied. For confirmatory analysis in doping control, an LC-MS method was developed. Analysis was performed on an ion trap LC-MS system equipped with an ESI probe in positive MS(2) mode.

Administration, Oral↗

PubMed2003

Urinary concentrations of morphine after the administration of herbal teas containing Papaveris fructus in relation to doping analysis.

A quantitative method for the analysis of morphine in human urine in the concentration range between 0.25 and 2 microg/ml is described and validated. Morphine was determined after enzymatic hydrolysis of the urine. After liquid-liquid extraction with dichloromethane-methanol (9:1) at pH 9.5, morphine was derivatized with N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA) and analyzed with GC-MS (full scan). The limit of quantification of the method was 0.25 microg/ml. Two Papaveris fructus containing herbal teas were administered to five male volunteers and urine samples were taken quantitatively during the first 12 h after the administration. The morphine concentration in the tea was 10.4 and 31.5 microg/ml, respectively. Morphine was detected in the urine of all volunteers by 1 h after drinking the tea. Maximum morphine concentrations, 4.3 and 7.4 microg/ml, respectively, were obtained 4-6 h after administration. Doping positive urine samples were delivered for 1-9 h.

Adult↗

PubMed2003

Validation of a screening method for corticosteroids in doping analysis by liquid chromatography/tandem mass spectrometry.

A selective and sensitive method for the screening of nine corticosteroids in human urine has been validated. Analyses were performed using an ion trap instrument equipped with an electrospray ionisation (ESI) interface. All corticosteroids were separated in less than 20 min after liquid/liquid extraction with diethyl ether. The limit of detection for all substances was 4 ng/mL or lower. The method was applied to detect betamethasone after the intramuscular injection of Diprophos. Betamethasone could be detected for up to 12 days after administration. Validation of the chromatographic separation and mass spectrometric identification of mixtures of betamethasone and dexamethasone are also presented.

Adrenal Cortex Hormones↗

PubMed2003

The prevalence of doping in Flanders in comparison to the prevalence of doping in international sports.

For many years, doping has been considered a major problem in sports. Recent doping cases have shocked the general public and press reports have further generated the idea that a great number of athletes are doped. In this study statistical data provided by the International Olympic Committee (1996 - 2000) to IOC accredited laboratories and results from the Flemish anti-doping program (1993 - 2000) are discussed. During these periods, the average percentage positive samples in the IOC accredited laboratories and in Flanders were 1.8 % and 4.1 %, respectively. The percentage of positive samples was significantly higher for in-competition than for out-of-competition samples. During the period 1993 - 2000, doping was detected in all sports in Flanders, for which a representative number of samples (n > 50) was tested except mini-soccer, where no positive doping samples were found. The use of doping among male athletes is significantly higher than for female athletes. Bodybuilding and power lifting had the highest incidence of positive cases in Flanders. The distribution of detected drugs among the different groups of prohibited substances shows a significant increase in the number of samples containing cannabis over the last years. The occurrence of cannabis in all sports and the high frequency of detection in Flanders, indicate that cannabis is predominantly misused as a "social" drug rather than for doping purposes. In Flanders, multiple prohibited substances were detected in 41 % of all positive cases. At least 27.6 % out of those were due to co-administration of drugs.

Belgium↗

PubMed2003

Quantitation of 11 -nor-delta9-tetrahydrocannabinol-9-carboxylic acid with GC-MS in urine collected for doping analysis.

An accurate, reproducible, and validated gas chromatography-mass spectrometry (GC-MS) method for the quantitation of 11 -nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH), the major metabolite of delta9-tetrahydrocannabinol, in urine is described. Extraction was performed with n-hexane/ethyl acetate. Deuterated THC-COOH was used as the internal standard. The GC-MS analysis was done by selected ion monitoring. No interferences were detected in 20 blank urine samples of different origin. The calibration curve was found to be linear over the range of 10-100 ng/mL. The calculated limits of detection and quantitation were 1.0 ng/mL and 1.7 ng/mL, respectively. Results of positive findings for cannabis use in doping control in Flanders and Portugal in the period of 1997-2000 are commented.

Dronabinol↗

PubMed2002

Detection of inhaled clenbuterol in horse urine by GC/MS2.

Clenbuterol, a beta-adrenergic agonist, is used in the treatment of recurrent airway obstruction in horses. It is prohibited by horse racing authorities, because of its stimulating and growth-promoting properties. However, information on detection times of clenbuterol after administration by nebulization is lacking. In this study, a fast, sensitive quantitative GC-MS(2) method for the detection of clenbuterol in urine was developed. Alkaline liquid-liquid extraction was followed by derivatization to a cyclic methyl boronate derivative and analysis on a Finnigan MAT GCQ instrument. Method validation showed good linearity in the range 0.1-2.0 ng/mL, excellent repeatability and specificity. The limit of quantitative detection of the method was 0.1 ng/ml. Different instrumental parameters of the ion trap mass spectrometer were changed to increase the number of diagnostic ions for the cyclic methyl boronate derivative of clenbuterol. The influence of these changes and their applicability within the requirements and the criteria for mass spectrometry set by the responsible regulatory bodies are discussed. Clenbuterol was administered via nebulization to five standardbred mares (0.4 micro g/kg body weight). Analysis of the urine samples resulted in the detection of clenbuterol, as early as 2 h post administration and for up to 36 h post treatment. Generally, maximum urinary concentrations of 1.2 ng/mL were reached after -6-9 h.

Administration, Inhalation↗