Comparison of analytical approaches for the detection of oral testosterone undecanoate administration in men.

For antidoping laboratories, the determination of an illicit testosterone (T) administration in urine samples remains a difficult process as it requires the determination of the exogenous origin by carbon isotope ratios (CIRs) of testosterone and its metabolites. As a complement to the urinary analysis, targeting testosterone esters (e.g. testosterone undecanoate [TU]) in serum samples by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) could represent a simpler approach compared with isotope ratio mass spectrometry (IRMS). These two approaches both lead to the direct detection of the administration of exogenous T but with a difference in effort and complexity of the analysis. To compare the detection window obtained with the two strategies, serum and the corresponding urine samples collected from an administration study with oral TU were analysed. Results showed that, at all timepoints where the intact TU was detected in serum, the CIRs of urinary steroids were also not in agreement with an endogenous origin. IRMS analysis required more effort but resulted in slightly longer detection windows than the ester analysis. Finally, this comparison study showed that, in the presence of a suspicious urinary steroid profile, the LC-MS/MS steroid esters analysis in the corresponding serum samples can be very helpful. If steroid esters are not detected, the IRMS analysis can then be conducted on the urine sample afterwards. Overall, the combination of matrices might facilitate the detection of prohibited T administration in sports, especially for athletes with naturally low T/E ratios.

A comprehensive UHPLC-MS/MS method for the analysis of endogenous and exogenous steroids in serum for anti-doping purposes.

In the context of steroid analyses, the use of blood could represent a valuable complement to urine. While the blood steroid profile is currently being established to aid unveiling testosterone (T) doping, this matrix is also well suited for detection of exogenous anabolic steroids and steroid esters. In this study, a method to determine a simplified blood steroid profile in combination with the direct detection of exogenous anabolic steroids and steroid esters using just one serum aliquot was developed to obtain a comprehensive analytical workflow. Following the first chromatographic analysis of endogenous and exogenous steroids, samples were derivatised with Girard's reagent T (GT) to improve the ionisation of steroid esters and re-injected. The quantitative performance for T, androstenedione (A4) and 5α-dihydrotestosterone (DHT) was evaluated and the method was validated for qualitative analysis of exogenous analogues with estimated limits of detection (LOD) between 50 and 500 pg/ml. To demonstrate the applicability of the method, samples collected from a clinical study with an oral administration of testosterone undecanoate (TU) to 19 male volunteers were then analysed. The individual serum steroid profiles with the endogenous markers T, A4 and DHT were established as well as the concentrations of TU. TU was detected in all 19 volunteers up to 24 h, while DHT represented the most promising biomarker in endogenous steroid profile for the detection of oral TU administration. These results showed that the selected approach to combine exogenous and endogenous steroid analysis has the potential to strengthen T doping detection in the future.

Stability of drugs of abuse in synthetic oral fluid investigated using a simple "dilute and inject" method of analysis.

Human oral fluid is well established as a matrix for drug screening, particularly in the workplace. The need to synthesise synthetic oral fluid (SOF) has been recognised in order to overcome human oral fluid's composition variability. We have used SOF spiked with six common drugs of abuse or their primary metabolites: morphine, amfetamine, benzoylecgonine, cocaine, diazepam, and (-)-Δ9 -tetrahydrocannabinol (THC) in order to assess the suitability of this matrix for quality assurance purposes. For confirmation of a drug screening test, controls and spiked standards are normally required. All our analytes were detected by LC-MS/MS using a quick and easy "dilute and inject" sample preparation approach as opposed to relatively slower solid-phase extraction. The limit of detection (LOD) was 10 ng/ml for diazepam and THC and 5 ng/ml for morphine, amfetamine, benzoylecgonine and cocaine. Validation results showed good accuracy as well as inter- and intra-assay precision (CV [%] < 5). Our work highlighted the importance of adding Tween® 20 to the SOF and calibrants to reduce losses when handling THC. Furthermore, drug stability was tested at various temperatures (5°C, 20°C and 40°C), for a number of days or after freeze-thaw cycles. Recommendations regarding storage are provided, the spiked SOF being stable at 5°C for up to 1 week without significant drug concentration loss.

Ion mobility-high resolution mass spectrometry in doping control analysis. Part II: Comparison of acquisition modes with and without ion mobility.

In the second part of this study, a systematic comparison was made between two ion fragmentation acquisition modes, namely data-independent acquisition (DIA) and DIA with ion mobility spectrometry (IMS) technology. These two approaches were applied to the analysis of 192 doping agents in urine. Group I included 102 compounds such as stimulants, diuretics, narcotics, and ß2-agonists, while Group II contained 90 compounds included steroids, glucocorticoids, and hormone and metabolic modulators. Important method parameters were examined and compared, including the fragmentation, sensitivity, and assignment capability with the minimum occurrence of false positive hits. The results differed between Group I and II in number of detected fragments when exploring the MS/MS spectra. In Group I only 13%, while in the Group II 64% of the substances had a higher number of fragments in DIA-IMS mode vs. DIA. In terms of sensitivity, the performance of the two modes with and without activated IMS dimension was identical for about 50% of the doping agents. The sensitivity was higher without IMS, i.e. in simple DIA mode, for 20-40% of remaining doping agents. Despite this sensitivity reduction with IMS, 82% of compounds from both Groups met the minimum required performance level (MRPL) criteria of the World Anti-Doping Agency (WADA) when the DIA-IMS mode was applied. Automated data processing is important in routine doping analysis. Therefore, processing methods were optimized and evaluated for the prevalence of false peak assignments by analysing the target substances at different concentrations in urine samples. Overall, a significantly higher number of misidentified compounds was observed in Group II, with an almost 2-fold higher number of misidentifications in DIA compared to DIA-IMS. This result highlights the benefit of the IMS dimension to reduce the rate of false positive in screening analysis. The optimized UHPLC-IM-HRMS method was finally applied to the analysis of urine samples from administration studies including nine doping agents from both Groups. However, to limit the number of interferences from the biological matrix, an emphasis is needed on the adequate settings of the data processing method.

Ion mobility-high resolution mass spectrometry in anti-doping analysis. Part I: Implementation of a screening method with the assessment of a library of substances prohibited in sports.

In this series of two papers, 192 doping agents belonging to the classes of stimulants, narcotics, cannabinoids, diuretics, ß2-agonists, ß-blockers, anabolic agents, and hormone and metabolic modulators were investigated, with the aim to assess the benefits and limitations of ion mobility spectrometry (IMS) in combination with ultra-high performance liquid chromatography (UHPLC) and high resolution mass spectrometry (HRMS) in anti-doping analysis. In this first part, a generic UHPLC-IM-HRMS method was successfully developed to analyze these 192 doping agents in standard solutions and urine samples, and an exhaustive database including retention times, TWCCSN2 values, and m/z ratios was constructed. Urine samples were analyzed using either a simple "dilute and shoot" procedure or a supported liquid-liquid extraction (SLE) procedure, depending on the physicochemical properties of the compounds and sensitivity criteria established by the World Anti-Doping Agency (WADA) as the minimum required performance levels (MRPL). Then, the precision of the generic UHPLC-IM-HRMS method was assessed as intraday, interday as well as interweek variation of UHPLC retention times and TWCCSN2 values, for which RSD the values were always lower than 2% in urine samples. The possibility to filter MS data using IMS dimension was also investigated, and in average, the application of IMS filtration provided low energy MS spectra with 86% less interfering peaks in both standard and urine samples. Therefore, the filtered MS spectra allowed for an easier interpretation and a lower risk of false positive result interpretations. Finally, IMS also offers additional selectivity to the UHPLC-HRMS enabling to separate isobaric and isomeric substances. Among the selected set of 192 doping agents, there were 30 pairs of isobaric or isomeric compounds, and only two pairs could not be resolved under the developed conditions. This illustrates the potential of adding ion mobility to UHPLC-HRMS in anti-doping analyses.

Artificial oral fluid characterisation: Potential for use as a reference matrix in drug testing.

Quality assurance schemes for drug-screening programmes require access to large quantities of biological matrices for reference or control samples. This presents problems when the availability of a matrix, such as oral fluid (OF) for screening or for confirmatory purposes, limits the collection of large volumes. In such cases, synthetic alternatives of OF may provide a solution. The preparation of an artificial (synthetic) oral fluid (AOF) was conducted by dissolving its components (salts, surfactant, antimicrobial agent and mucin) in water. We characterised the physical properties of AOF to determine its suitability as a matrix for quality assurance purposes. The evaluation of pH, specific gravity (SG), conductivity (mS cm-1 ), freezing point depression (°C), light-scattering and kinematic viscosity (mm2 s-1 ) showed AOF to be a stable, reliable matrix. Synthetic OF was prepared using components (mucin, surfactants and so on) obtained from different suppliers and a comparison was performed. Our results suggest that AOF is a feasible matrix for the preparation of quality assurance samples for confirmatory or drug screening programmes.

Prediction of chromatographic retention time in high-resolution anti-doping screening data using artificial neural networks.

The computational generation of gradient retention time data for retrospective detection of suspected sports doping species in postanalysis human urine sample data is presented herein. Retention data for a selection of 86 compounds included in the London 2012 Olympic and Paralympic Games drug testing schedule were used to train, verify, and test a range of computational models for this purpose. Spiked urine samples were analyzed using solid phase extraction followed by ultrahigh-pressure gradient liquid chromatography coupled to electrospray ionization high-resolution mass spectrometry. Most analyte retention times varied ≤0.2 min over the relatively short runtime of 10 min. Predicted retention times were within 0.5 min of experimental values for 12 out of 15 blind test compounds (largest error: 0.97 min). Minimizing the variance in predictive ability across replicate networks of identical architecture is presented for the first time along with a quantitative discussion of the contribution of each selected molecular descriptor toward the overall predicted value. The performance of neural computing predictions for isobaric compound retention time is also discussed. This work presents the application of neural networks to the prediction of gradient retention time in archived high-resolution urine analysis sample data for the first time in the field of anti-doping.

Use of ultra-high pressure liquid chromatography coupled to high resolution mass spectrometry for fast screening in high throughput doping control.

We describe a sensitive, comprehensive and fast screening method based on liquid chromatography-high resolution mass spectrometry for the detection of a large number of analytes in sports samples. UHPLC coupled to high resolution mass spectrometry with polarity switching capability is applied for the rapid screening of a large number of analytes in human urine samples. Full scan data are acquired alternating both positive and negative ionisation. Collision-induced dissociation with positive ionisation is also performed to produce fragment ions to improve selectivity for some analytes. Data are reviewed as extracted ion chromatograms based on narrow mass/charge windows (±5ppm). A simple sample preparation method was developed, using direct enzymatic hydrolysis of glucuronide conjugates, followed by solid phase extraction with mixed mode ion-exchange cartridges. Within a 10min run time (including re-equilibration) the method presented allows for the analysis of a large number of analytes from most of the classes in the World Anti-Doping Agency (WADA) Prohibited List, including anabolic agents, ß2-agonists, hormone antagonists and modulators, diuretics, stimulants, narcotics, glucocorticoids and ß-blockers, and does so while meeting the WADA sensitivity requirements. The high throughput of the method and the fast sample pre-treatment reduces analysis cost and increases productivity. The method presented has been used for the analysis of over 5000 samples in about one month and proved to be reliable.

Comparison of reversed-phase and hydrophilic interaction liquid chromatography for the quantification of ephedrines using medium-resolution accurate mass spectrometry.

The separation and quantification of hydrophilic basic compounds continues to challenge reversed-phase chromatography. Ephedrines are an example where the optimal separation of their isomers and related substances is complicated due to both their hydrophilicity and basic nature. Here we study two potential ultra-high pressure liquid chromatography (UHPLC) methods and present the merits and limitations of a high pH reversed-phase and a hydrophilic interaction liquid chromatography (HILIC) approach for the separation and quantification of ephedrines for doping control analysis. The study compares a hybrid silica material used for the HILIC separations with a C18 reversed-phase material produced from the same hybrid silica. While both analytical approaches provide good retention and resolution, HILIC offers benefits in terms of peak shape, sample loading capacity and enhanced sensitivity with electrospray ionisation-mass spectrometry (ESI-MS). HILIC permits favourable kinetic performance owing to the low viscosity mobile phase and hence better mass transfer characteristics. Common problems associated with HILIC including retention shifts and undesirable peak shapes are investigated and overcome using a suitable re-equilibration time and injection solvent. Validation data show both approaches provide good linearity (r>0.995), accuracy (RPLC<7.5% error, HILIC<7.6% error) and precision (RPLC<7.0% RSD, HILIC<10.3% RSD) for all analytes. Matrix effects were shown to have a negligible effect on ionisation variability in each mode, with inter-day retention times also being repeatable (<0.17% RSD). HILIC gave increased sensitivity with ESI-MS, giving a 6-fold increase in signal over the RPLC approach. In this application, we demonstrate the use of UHPLC technology coupled with a hybrid quadrupole time-of-flight (QToF) mass analyser. This approach provides fast scanning medium-resolution accurate mass detection for reliable identification and quantification purposes.

A simple high pH liquid chromatography-tandem mass spectrometry method for basic compounds: application to ephedrines in doping control analysis.

Solvent systems for use with LC-MS often result in a compromise between chromatographic performance and mass spectrometric detection, exemplified here by a LC-MS/MS method development for the analysis of ephedrines in doping control. Ephedrines, frequently found in therapeutic and nutritional preparations, are among the most commonly administered doping agents in competitive sport. Improved separation of these hydrophilic, basic compounds, some of which are diastereoisomers, is achieved in reversed-phase LC by the use of a high pH mobile phase in order to suppress analyte ionisation, and thus alter their polarity, resulting in reduced peak tailing and enhanced retention. However, when coupled to an ESI-MS detector, this eluent composition generated a non-linear and poorly reproducible signal. APCI yielded greater stability and reproducibility and is here presented as an ion source for the analysis of basic compounds under conditions that suppress their ionisation. Errors as large as 49.3% were observed with ESI, compared with 15.4% generated using APCI, for pseudoephedrine over the calibration range (25-400 µg/mL) in urine with a simple dilution and injection of samples. These data highlight the importance of suitable MS conditions for stable performance, necessary for accurate quantification, without undue compromise to the LC separation.

Determination of topiramate in human plasma by capillary electrophoresis with indirect UV detection.

A rapid capillary zone electrophoresis method with indirect UV detection for the determination of topiramate in human plasma was developed and validated. The analyses were carried out with a background electrolyte composed of 10mM sulfamethoxazole as chromophore in phosphate buffer (25 mM, pH 12.0); gabapentin was selected as the internal standard. Application of a voltage of +15 kV led to an analysis time shorter than 5 min; indirect UV detection was operated at 256 nm. Isolation of topiramate from plasma was accomplished by a carefully implemented solid-phase extraction procedure on C18 cartridges. The method provided a linear response over the concentration range of 2-60 microg of topiramate per mL of plasma. The limit of detection (LOD) was 0.8 microg mL(-1) and the limit of quantitation (LOQ) was 2.0 microg mL(-1). Precision, expressed as relative standard deviation, was always lower than 7.3%, extraction yields were always greater than 92%. The results obtained analysing plasma samples from epileptic patients undergoing therapy with topiramate were satisfactory in terms of precision and selectivity.

Antipsychotic and antiepileptic drugs in bipolar disorder: the importance of therapeutic drug monitoring.

Bipolar disorder (BD) is a long-term illness with mood swings which are characterized by recurrent episodes of mania/hypomania and depression, with variable interpolations of relatively asymptomatic periods, called euthymic, in which, however, some psychopathological symptoms may persist. Although mood stabilizers, such as lithium, are the first-line treatment for the prevention of new BD episodes, combination therapy has become the standard of care for BD patients. Besides lithium, the use of a mood stabilizer along with an atypical antipsychotic is recommended in many patients. Recently, atypical antipsychotics (quetiapine, olanzapine, risperidone and aripiprazole) and antiepileptic agents (valproate, lamotrigine and oxcarbazepine) are increasingly used as mood stabilizers. To reduce side effects and optimize treatment it is important to perform accurate monitoring of drug blood levels in these patients, who are often treated with multiple drugs. Therapeutic drug monitoring (TDM) is in fact a powerful tool that, starting from clinical-chemical correlation data, allows to tailor-cut treatment to the specific needs of individual patients; hence the need to have reliable analytical methods available for the determination of plasma levels of drugs and their metabolites. Analyses of biological samples are mainly carried out using high-performance liquid chromatography (HPLC) coupled with different detectors, capillary electrophoresis and gas-chromatography. Various procedures are employed to remove biological interferences before analyzing the samples. This review focuses on currently available analytical TDM methods for atypical antipsychotics and antiepileptic agents used in the treatment of patients with bipolar disorder. Advantages and limitations of the various analytical methods will be reviewed and discussed, together with an evaluation of the role of TDM.

Determination of duloxetine in human plasma by capillary electrophoresis with laser-induced fluorescence detection.

A method based on capillary electrophoresis has been developed for the analysis of the novel antidepressant drug duloxetine in human plasma. The method makes use of laser-induced fluorescence detection after derivatisation of the analyte with 5-(4,6-dichlorotriazinyl)aminofluorescein at pH 11. A single step liquid/liquid extraction procedure with a mixture of hexane/2-propanol allows the sample clean-up with extraction yields always >or=84% and interference removal. The electrophoretic separation is achieved using uncoated fused silica capillaries (60.0 cm effective length, 75.0 cm total length, 50 microm internal diameter) and a background electrolyte composed of borate buffer (40 mM, pH 10.3), tetrabutylammonium bromide (10 mM), and acetone (10%, v/v). The applied voltage is 20 kV; the samples are injected by pressure (50 mbar x 8 s). The method has been fully validated in terms of linearity range (2.5-150 ng mL(-1)), LOD and LOQ (1.0 and 2.5 ng mL(-1), respectively), precision (R.S.D.<6.7%) and accuracy (recovery >78%). Application to samples obtained from patients under treatment with duloxetine gave good results. The method represents the first application of capillary electrophoresis to the analysis of duloxetine in human plasma.

Novel mucoadhesive nasal inserts based on chitosan/hyaluronate polyelectrolyte complexes for peptide and protein delivery.

OBJECTIVES: The purpose of this study was the preparation and characterisation of mucoadhesive nasal inserts based on chitosan/hyaluronate polyelectrolyte complexes prepared at various pHs and at different molar ratios. METHODS: A suspension of chitosan/hyaluronate complexes with or without the model drugs (vancomycin or insulin) was lyophilised into small inserts. Complexation yield, FT-IR spectra and thermogravimetric analysis were used to study the degree of interactive strength between polyions. In-vitro swelling, mucoadhesion and release tests were performed in order to investigate delivery of vancomycin and insulin in the nasal cavity. KEY FINDINGS: The results indicated that the selection of complex preparative conditions allows modulation of insert swelling and mucoadhesion ability. Nasal inserts containing vancomycin or insulin had showed completely different drug release behaviour. CONCLUSIONS: Chitosan/hyaluronate polyelectrolyte complexes can be used for the formulation of mucoadhesive nasal inserts for the delivery of peptide and protein drugs.

Determination of insulin in innovative formulations by means of LC coupled to fluorescence detection.

A fast and simple method based on LC with fluorescence detection has been developed for the determination of insulin in innovative formulations consisting of microparticles and inserts for oral and nasal drug administration, respectively. A reverse-phase C8 column and a mobile phase composed of pH 3.7, 40 mM sodium sulphate solution and acetonitrile (24%, v/v) were employed. Using isocratic elution at 1.0 mL/min flow, analysis is completed within 7 min. Three different kinds of spray-dried microparticles were analysed, consisting of an insulin loaded core composed of chitosan salts (chitosan succinate, chitosan adipate or chitosan suberate) coated with stearic acid. Nasal inserts consisted of chitosan/hyaluronate polyelectrolyte complexes which were loaded with insulin and freeze-dried. Insulin was extracted from both the oral and nasal formulations using pH 7.4 phosphate buffer. The employment of fluorescence detection (lambda(exc) = 276 nm, lambda(em) = 306 nm) granted high selectivity, with no interference from the matrix. Full method validation was performed with good results in terms of linearity (insulin concentration range 0.10-30.0 microg/mL), LOD (0.03 microg/mL) and LOQ (0.10 microg/mL), precision (R.S.D.%<3.6) and accuracy (recovery percentage>90.0%). Insulin content in innovative formulations, expressed as percentage w/w, resulted to be between 0.90 and 0.97 for oral innovative formulations, while an average value of 342 microg of insulin was found in a single nasal insert, in good agreement with preparative protocols.

Analysis of the anti-Parkinson drug pramipexole in human urine by capillary electrophoresis with laser-induced fluorescence detection.

A sensitive method based on capillary electrophoresis with laser-induced fluorescence detection has been developed for the analysis of the non-ergoline dopamine agonist pramipexole in human urine. Separation was carried out in uncoated fused silica capillaries (75microm internal diameter, 75.0 and 60.0cm total and effective length, respectively), with a background electrolyte composed of borate buffer (50mM, pH 10.3), tetrabutylammonium bromide (30mM), and acetone (15%, v/v). Applying a 20kV voltage, the electrophoretic run is completed within 12min. A sample pre-treatment procedure based on liquid/liquid extraction with ethyl acetate, followed by derivatisation of pramipexole with fluorescein isothiocyanate at pH 9, allows the complete removal of biological interferences, with extraction yields always higher than 94.5%. Method validation gave good linearity (r(2)=0.9992) in the 25.0-1000ngmL(-1) range; limit of detection and limit of quantitation were 10.0 and 25.0ngmL(-1), respectively; precision was 90.0. The method was applied to the analysis of urine samples from patients undergoing therapy with pramipexole.

Chitosan salts coated with stearic acid as colon-specific delivery systems for vancomycin.

Site-specific controlled release systems have been extensively investigated during the last decade. The aim of this study was to describe a pH-dependent drug release system based on chitosan salts for vancomycin hydrochloride delivery. Chitosan salts with succinic acid, adipic acid, and suberic acid were prepared by spray-drying and were coated with stearic acid by the same technique. This study characterized the carriers in terms of morphology, size, swelling, mucoadhesive properties, and drug loading and focused on the in vitro, influence of chitosan salts on the release behavior of vancomycin hydrochloride from the uncoated and coated systems at pH levels of 2.0, 5.5, and 7.6.

Comparison of analytical methods for the quality control of a new formulation containing soy extract and melatonin.

Three analytical methods have been developed and compared for the quality control of a new formulation (Soymen GN(R) capsules) containing soy extract and melatonin for the treatment of menopausal symptoms. The first method is based on MEKC with diode-array detection, using a mixture of basic carbonate buffer (95%) and methanol (5%), containing 55 mM SDS, as the BGE. The second method is an HPLC method with UV detection at 260 nm. The third method is an HPLC method coupled to amperometric detection which is carried out at an oxidation potential of +0.8 V. In both HPLC systems, the chromatographic separation is obtained on an RP C18 column using a mixture of ACN and an acidic phosphate buffer (25:75 v/v) as the mobile phase. A feasible pretreatment procedure with a methanol/water mixture has been implemented to achieve the quantitative extraction of the main soy isoflavones and of melatonin from the capsules. The results obtained with the three methods are in good agreement with each other and satisfactory in terms of linearity (r(2) >0.9996), precision (RSD <5.4%) and accuracy (recovery >97%). Thus, each of the three analytical methods seems to be suitable for the simultaneous analysis of the main soy isoflavones and melatonin in the new commercial formulation.

Analysis of the recent antipsychotic aripiprazole in human plasma by capillary electrophoresis and high-performance liquid chromatography with diode array detection.

Two methods, based on the use of capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC), respectively, were developed for the analysis of the atypical antipsychotic aripiprazole in plasma of schizophrenic patients for therapeutic drug monitoring purposes. Good analytical performances were obtained with the CE method, using uncoated fused silica capillaries and a background electrolyte composed of 50mM phosphate buffer at pH 2.5. With 20 kV voltage, aripiprazole was detectable at 214 nm within 5 min. The second analytical method, based on HPLC with diode array detection, employed a C8 reversed-phase column and a mixture of a 12.5mM phosphate buffer, pH 3.5, containing triethylamine and acetonitrile as the mobile phase. Aripiprazole was detected at 254 nm and a complete chromatographic run lasted about 10 min. For both analytical methods loxapine was used as the internal standard and the same plasma sample pre-treatment by means of solid-phase extraction on cyano cartridges was carried out, with extraction yield values always higher than 91.3%. Linear responses for aripiprazole were obtained between 70 and 700 ng mL(-1) and precision assays (expressed as relative standard deviation values) were lower than 7.0%. After validation, both methods were successfully applied to human plasma samples drawn from schizophrenic patients undergoing therapy with Abilify tablets. Accuracy was satisfactory, with recovery value higher than 91.0%.

Determination of plasma and urine levels of Delta9-tetrahydrocannabinol and its main metabolite by liquid chromatography after solid-phase extraction.

Delta9-Tetrahydrocannabinol is the most widespread drug of abuse in the world and it is also currently available as the active principle of formulations for the treatment of chronic pain. Its main metabolite, 11-nor-Delta9-tetrahydrocannabinol-9-carboxylic acid, is the most important marker of Delta9-tetrahydrocannabinol consumption. An original liquid chromatographic method has been developed for the determination of these two analytes in human plasma and urine. Separation was obtained on a C8 column using a mobile phase with 35% phosphate buffer at pH 2.7 and 65% acetonitrile. The UV detector was set at 220 nm and indomethacin was used as the internal standard. Sample pre-treatment was carried out by solid-phase extraction with C8 cartridges; urine samples were subjected to basic hydrolysis before extraction. Both extraction yields (>91%) and precision values were highly satisfactory. The method was successfully applied to biological samples collected from Cannabis users. Accuracy and selectivity results were satisfactory. This is the first HPLC-UV method developed for the simultaneous quantification of Delta9-tetrahydrocannabinol and 11-nor-Delta9-tetrahydrocannabinol-9-carboxylic acid in both plasma and urine for the monitoring of either therapeutic or recreational use.