High throughput on-line solid phase extraction/tandem mass spectrometric determination of paclitaxel in human serum

Development and qualification of an LC-MS/MS method for investigating the biological implications of micelle entrapped paclitaxel in cell culture and rats

Paclitaxel is a front-line antineoplastic drug used in chemotherapeutic modalities for treatment of various types of malignancies. However, its efficacy is limited by dose-related toxicities. In this study, we have explored two important biological aspects of entrapping paclitaxel in PEG₂₀₀₀ -DSPE micelles. First, we evaluated the impact of this micellar delivery system on P-glycoprotein (P-gp)-paclitaxel interaction, and we investigated differences in plasma pharmacokinetics of free and micelle-entrapped paclitaxel. For quantification of paclitaxel, an LC-MS/MS method was developed. Paclitaxel was extracted from samples using a simple one-step protein precipitation. Chromatographic conditions included a C₁₈ column with a mobile phase consisting of 0.1% formic acid in acetonitrile-water (60:40, v/v) pumped at 1 mL/min. The lower limit of quantitation in both plasma and cell lysate was 1.0 ng/mL. The quantitative linear range was 1-1000 ng/mL. In addition, P-gp efflux studies on free and micellar paclitaxel showed the proficiency of PEG₂₀₀₀ -DSPE micelles in evading P-gp-mediated efflux, thus increasing paclitaxel uptake. Furthermore, the micellar paclitaxel levels were maintained in the body for longer time as compared with taxol, which is desirable for increasing the efficacy of paclitaxel in cancer treatment.

Mass spectrometry in the pharmacokinetic studies of anticancer natural products

In the history of medicine, nature has represented the main source of medical products. Indeed, the therapeutic use of plants certainly goes back to the Sumerian and Hippocrates and nowadays nature still represents the major source for new drugs discovery. Moreover, in the cancer treatment, drugs are either natural compounds or have been developed from naturally occurring parent compounds firstly isolated from plants and microbes from terrestrial and marine environment. A critical element of an anticancer drug is represented by its severe toxicities and, after administration, the drug concentrations have to remain in an appropriate range to be effective. Anyway, the drug dosage defined during the clinical studies could be inappropriate for an individual patient due to differences in drug absorption, metabolism and excretion. For this reason, personalized medicine, based on therapeutic drug monitoring (TDM), represents one of most important challenges in cancer therapy. Mass spectrometry sensitivity, specificity and fastness lead to elect this technique as the Golden Standard for pharmacokinetics and drug metabolism studies therefore for TDM. This review focuses on the mass spectrometry-based methods developed for pharmacokinetic quantification in human plasma of anticancer drugs derived from natural sources and already used in clinical practice. Particular emphasis was placed both on the pre-analytical and analytical steps, such as: sample preparation procedures, sample size required by the analysis and the limit of quantification of drugs and metabolites to give some insights on the clinical practice applicability. © 2015 Wiley Periodicals, Inc. Mass Spec Rev. 36:213-251, 2017.

Quantification of taxanes in biological matrices: a review of bioanalytical assays and recommendations for development of new assays

Since the isolation of paclitaxel and its approval for the treatment of breast cancer, various taxanes and taxane formulations have been developed. To date, almost 100 bioanalytical assays have been published with the method development and optimization often extensively discussed by the authors. This Review presents an overview of assays published between January 1970 and September 2013 that described method development and validation of assays used to quantify taxanes in biological matrices such as plasma, urine, feces and tissue samples. For liquid chromatography assays, sample pretreatment, chromatographic separation and assay performance are compared. Since this Review discusses the limitations of previously developed liquid chromatography assays and gives recommendations for future assay development, it can be used as a reference for future development of liquid chromatography assays for the quantification of taxanes in various biological matrices to support preclinical and clinical studies.

Quantitative determination of Lx2-32c, a novel taxane derivative, in rat plasma by liquid chromatography-tandem mass spectrometry

A sensitive and reliable LC-MS/MS method for the determination of Lx2-32c, a novel taxane derived from cephalomannine, has been developed and validated. Plasma samples containing Lx2-32c and paclitaxel (internal standard) were prepared based on a simple protein precipitation by the addition of two volumes of acetonitrile. The analyte and internal standard were separated on a Zorbax SB-C18 column (3.5μm, 2.1mm×100mm) with the mobile phase of acetonitrile/water containing 0.1% formic acid (v/v) with gradient elution at a flow rate of 0.2ml/min. The detection was performed on a triple quadrupole tandem mass spectrometer equipped with atmospheric pressure chemical ionization (APCI) by multiple reactions monitoring (MRM) of the transitions at m/z 887.5→264.3 for Lx2-32c and 854.5→286.2 for IS. Linear detection responses were obtained for Lx2-32c ranging from 1 to 1000ng/ml. Inter- and intra-day precision (R.S.D.%) were all within 15% and the accuracy (R.E.%) was equal or lower than 8%. The lower limit of quantitation (LLOQ) was 1ng/ml and the average recovery was greater than 91.5%. The method was successfully applied to the pharmacokinetic study of Lx2-32c in rat plasma.

SPE–MS analysis of absorption, distribution, metabolism and excretion assays: a tool to increase throughput and steamline workflow

In an effort to create faster and more efficient bioanalytical methods for drug development, many investigators have evaluated a variety of SPE–MS systems. Over the past 15 years online systems have evolved from run times of >1.5 min/sample to <10 s/sample. High-throughput SPE–MS methods for in vitro absorption, distribution, metabolism and excretion screening assays have been described by several laboratories and shown to produce results comparable to conventional LC–MS/MS systems. While quantitative analysis of small molecules in biological matrixes holds many challenges, for several applications SPE–MS methods have achieved comparable results to LC–MS/MS with the benefit of 10–30-times the throughput. Based on its distinct advantages of throughput and streamlined workflow efficiencies, SPE–MS is a useful tool for the analysis of many in vitro absorption, distribution, metabolism and excretion assays and in vivo bioanalytical studies. Further development of SPE–MS methods and analysis workflows has the potential to expand the capabilities of this technology for other challenging bioanalytical applications.

Simultaneous determination of paclitaxel and a new P-glycoprotein inhibitor HM-30181 in rat plasma by liquid chromatography with tandem mass spectrometry

An LC-MS/MS method for the simultaneous determination of a new P-glycoprotein inhibitor 4-oxo-4H-chromene-2-carboxylic acid [2-(2-(4-[2-(6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl)-ethyl]-phenyl)-2H-tetrazol-5-yl)-4,5-dimethoxy-phenyl]-amide (HM-30181) and a P-glycoprotein substrate paclitaxel in rat plasma was developed to simultaneously evaluate the pharmacokinetics of paclitaxel and HM-30181 in the rats. HM-30181, paclitaxel, HM-30059 (internal standard (I.S.) for HM-30181), and docetaxel (I.S. for paclitaxel) were extracted from rat plasma with methyl-tert-butyl ether and analyzed on an Atlantis C18 column (5 microm, 2.1 x 100 mm) with the mobile phase of ACN/10 mM ammonium formate (75:25 v/v). The analytes were detected using an ESI MS/MS in the multiple reaction monitoring (MRM) mode. The standard curves for HM-30181 and paclitaxel in plasma were linear (r > 0.999) over the concentration range of 2.0-500 ng/mL with a weighting of 1/concentration2. The method showed a satisfactory sensitivity (2 ng/mL using 50 microL plasma), precision (CV: < or = 6.6%), accuracy (relative error: -6.3 to 2.0%), and selectivity. This method was successfully applied to the pharmacokinetic study of HM-30181 and paclitaxel in rat plasma after oral-coadministration of paclitaxel and HM-30181 to male Sprague- Dawley rats.

Determination of paclitaxel in human plasma following the administration of Genaxol or Genetaxyl by liquid chromatography/tandem mass spectrometry

A sensitive and specific assay for paclitaxel in plasma has been developed to overcome limitations in previously published assays, using liquid chromatography with tandem mass spectrometric detection. Plasma samples (100 microL) were subjected to liquid-liquid extraction with 1-chlorobutane/acetonitrile (4:1, v/v), with [(2)H(5)]paclitaxel employed as the internal standard. Chromatography was carried out with a Waters SymmetryShield C8 column (50 x 2.1 mm, 3.5 microm). The total run time, including equilibration, was 8 min, using a gradient of acetonitrile and 10 mM ammonium formate, pH 4.0. The assay is accurate and precise over the range of 2-2500 ng/mL and has been successfully applied to study the clinical pharmacokinetics of two formulations of paclitaxel, Genaxol and Genetaxyl, given orally and intravenously.

Measurement of paclitaxel and its metabolites in human plasma using liquid chromatography/ion trap mass spectrometry with a sonic spray ionization interface

A quantitative liquid chromatography/ion trap mass spectrometry method for the simultaneous determination of paclitaxel, 6alpha-hydroxypaclitaxel and p-3'-hydroxypaclitaxel in human plasma has been developed and validated. 6alpha-,p-3'-Dihydroxypaclitaxel was also quantified using paclitaxel as a reference and docetaxel as an internal standard. The substances were extracted from 0.500 mL plasma using solid-phase extraction. The elution was performed with acetonitrile and the samples were reconstituted in the mobile phase. Isocratic high-performance liquid chromatography analysis was performed by injecting 50 microL of reconstituted material onto a 100 x 3.00 mm C12 column with a methanol:1% trifluoroacetic acid/ammonium trifluoroacetate in H(2)O 70:30 mobile phase at 350 microL/min. The [M+H](+) ions generated in the sonic spray ionization interface were isolated and fragmented using two serial mass spectrometric methods: one for paclitaxel (transition 854 --> 569 & 551) and the dihydroxymetabolite (transition 886 --> 585 & 567) and one for the hydroxy metabolites (transition 870 --> 585 & 567; transition 870 --> 569 & 551) and docetaxel ([M+Na](+), transition 830 --> 550). Calibration curves were created ranging between 0.5 and 7500 ng/mL for paclitaxel, 0.5 and 750 ng/mL for 6alpha-hydroxypaclitaxel, and 0.5 and 400 ng/mL for p-3'-hydroxypaclitaxel. Adduct ion formation was noted and investigated during method development and controlled by mobile phase optimization. In conclusion, a sensitive method for simultaneous quantification of paclitaxel and its metabolites suitable for analysis in clinical studies was obtained.

Liquid chromatography-mass spectrometry for the quantitative bioanalysis of anticancer drugs

The monitoring of anticancer drugs in biological fluids and tissues is important during both pre-clinical and clinical development and often in routine clinical use. Traditionally, liquid chromatography (LC) in combination with ultraviolet (UV), fluorescence, or electrochemical detection is employed for this purpose. The successful hyphenation of LC and mass spectrometry (MS), however, has dramatically changed this. MS detection provides better sensitivity and selectivity than UV detection and, in addition, is applicable to a significantly larger group of compounds than fluorescence or electrochemical detection. Therefore, LC-MS has now become the method of first choice for the quantitative bioanalysis of many anticancer agents. There are still, however, a lot of new developments to be expected in this area, such as the introduction of more sensitive and robust mass spectrometers, high-throughput analyses, and further optimization of the coupled LC systems. Many articles have appeared in this field in recent years and are reviewed here. We conclude that LC-MS is an extremely powerful tool for the quantitative analysis of anticancer drugs in biological samples.

A simple and sensitive assay for the quantitative analysis of paclitaxel and metabolites in human plasma using liquid chromatography/tandem mass spectrometry

A sensitive and specific LC-MS/MS assay for the determination of paclitaxel and its 3'p- and 6-alpha-hydroxy metabolites is presented. A 200 microL plasma aliquot was spiked with a 13C6-labeled paclitaxel internal standard and extracted with 1.0 mL tert-butylmethylether. Dried extracts were reconstituted in 0.1 M ammonium acetate-acetonitrile (1:1, v/v) and 25 microL volumes were injected onto the HPLC system. Separation was performed on a 150 x 2.1 mm C18 column using an alkaline eluent (10 mm ammonium hydroxide-methanol, 30:70, v/v). Detection was performed by positive ion electrospray followed by tandem mass spectrometry. The assay quantifies a range for paclitaxel from 0.25 to 1000 ng/mL and metabolites from 0.25 to 100 ng/mL using 200 microL human plasma samples. Validation results demonstrate that paclitaxel and metabolite concentrations can be accurately and precisely quantified in human plasma. This assay is now used to support clinical pharmacologic studies with paclitaxel.

A simple and sensitive assay for the quantitative analysis of paclitaxel in human and mouse plasma and brain tumor tissue using coupled liquid chromatography and tandem mass spectrometry

The development and validation of an assay for the determination of paclitaxel in human plasma, human brain tumor tissue, mouse plasma and mouse brain tumor tissue is described. Paclitaxel was extracted from the matrices using liquid-liquid extraction with tert-butyl methyl ether, followed by chromatographic analysis using an alkaline eluent. Positive ionization electrospray tandem mass spectrometry was performed for selective and sensitive detection. The method was validated according to the FDA guidelines on bioanalytical method validation. Validation results indicate that calibration standards in human plasma can be used to quantify paclitaxel in all tested matrices. In human samples, the validated range for paclitaxel was from 0.25-1000 ng ml(-1) using 200 microl plasma aliquots and from 5 to 5000 ng g(-1) using 50 microl tumor homogenate aliquots (0.2 g tissue ml(-1) control human plasma). In mice, the ranges were 1-1000 ng ml(-1) and 5-5000 ng g(-1) using 50 microl of mouse plasma and 50 microl of tumor homogenate aliquots (0.2 g tissue ml(-1) control human plasma), respectively. The method can be applied to studies generating only small sample volumes (e.g. mouse plasma and tumor tissue), but also to studies in human plasma requiring a lower limit of quantitation. The assay was applied successfully to several studies with both human and mouse samples.

Determination of paclitaxel in mouse plasma and brain tissue by liquid chromatography-mass spectrometry

Paclitaxel is an anticancer agent extracted from the bark of the yew tree and is widely used in chemotherapy for solid tumors, including non-small cell lung cancer and ovarian carcinoma. Most assays to measure paclitaxel in plasma require a large amount of sample (0.4-1 ml) to achieve the necessary sensitivity, and are not suitable when only small sample sizes are available. To circumvent this latter limitation, we developed a sensitive liquid chromatography-mass spectrometry (LC-MS) method for the determination of paclitaxel in plasma based on the use of small sample volumes (50 microl plasma). A solid phase extraction procedure was employed that enabled the eluent to be directly injected onto a reversed phase chromatographic HPLC system using positive electrospray ionization followed by mass spectrometric detection. The extraction recoveries of paclitaxel were 98 and 83% from plasma and brain tissues, respectively. The mobile phase consisted of 50% acetonitrile in 0.1% formic acid that was pumped at 0.2 ml/min to yield a retention time for paclitaxel of 6.2 and 5.4 min for cephalomannine, the internal standard. The method has been validated at paclitaxel plasma concentrations from 0.036 to 9.9 microg/ml, and from 0.054 to 1.96 microg/ml in brain homogenates. A sensitive and specific assay for paclitaxel has been developed that has the advantages of using small sample sizes, and a single extraction step without solvent evaporation.

Ultra-fast quantitative bioanalysis of a pharmaceutical compound using liquid chromatography-tandem mass spectrometry

This paper describes the ultra-fast determination of a pharmaceutical compound using TurboIonSpray LC-MS-MS on an API 4000 mass spectrometer. Sample preparation consisted of plasma protein precipitation, centrifugation and dilution of the supernatant. The use of small analytical column dimensions (2.1 mm x 10 mm) and high eluent flow rates (up to 2.2 ml/min) in isocratic mode led to a retention time of 9s. A sample-to-sample cycle time of only 10s was achieved by coupling two autosamplers. Partial separation of the drug and its main metabolite could be obtained. The d5-labeled drug used as internal standard compensated for matrix suppression effects. The assay was linear in the concentration range 1-1000 ng/ml, using standards prepared in human plasma. Inter-assay accuracy and precision were 98.5 and 6.2%, respectively. Mean intra-assay accuracy and precision calculated from quality control (QC) samples in human, rat and dog plasma at 3, 30 and 800 ng/ml were 100.8 and 3.8%, respectively. The ultra-fast LC-MS-MS method was successfully cross-validated against a commonly used column-switching LC-MS-MS assay with 2.3 min run time by analyzing real study samples.

Quantitative determination of paclitaxel in human plasma using semi-automated liquid-liquid extraction in conjunction with liquid chromatography/tandem mass spectrometry

This paper describes a high-throughput sample preparation procedure combined with LC-MS/MS analysis to measure paclitaxel in human plasma. Paclitaxel and an internal standard were extracted from plasma by a semi-automated robotic method using liquid-liquid extraction. Thereafter compounds were separated on a RP C18 column. Detection was by a PE Sciex API 3000 mass spectrometer equipped with a TurboIonSpray interface. The compounds were detected in positive ion mode using the mass transition m/z 854.6-->286.2 and m/z 831.6-->263.2 for paclitaxel and the internal standard, respectively. The limit of quantitation for paclitaxel was 1 ng/ml with an imprecision of 5.2% following extraction of 0.1 ml of plasma. Linearity was confirmed over the whole calibration range (1-1000 ng/ml) with correlation coefficients higher than 0.99 indicating good fits of the regression models. The inter and intra-day precision was better than 9.5% and the accuracy ranged from 90.3 to 104.4%. The assay was simple, fast, specific and exhibited excellent ruggedness.

Quantitative high-throughput analysis of drugs in biological matrices by mass spectrometry

To support pharmacokinetic and drug metabolism studies, LC-MS/MS plays more and more an essential role for the quantitation of drugs and their metabolites in biological matrices. With the new challenges encountered in drug discovery and drug development, new strategies are put in place to achieve high-throughput analysis, using serial and parallel approaches. To speed-up method development and validation, generic approaches with the direct injection of biological fluids is highly desirable. Column-switching, using various packing materials for the extraction columns, is widely applied. Improvement of mass spectrometers performance, and in particular triple quadrupoles, also strongly influences sample preparation strategies, which remain a key element in the bioanalytical process.

Ion suppression in the determination of clenbuterol in urine by solid-phase extraction atmospheric pressure chemical ionisation ion-trap mass spectrometry

Ion suppression effects were observed during the determination of clenbuterol in urine with solid-phase extraction/multiple-stage ion-trap mass spectrometry (SPE/MS(3)), despite the use of atmospheric pressure chemical ionisation. During SPE, a polymeric stationary phase (polydivinylbenzene) was applied. Post-cartridge infusion of analyte to the SPE eluate after the extraction of blank urine was performed to obtain a profile of the suppression. Single and multiple-stage MS were performed to provide insight in the suppressing compounds. The ion suppression was mainly ascribed to two m/z values, but still no identification of the compounds was achieved from the multiple-stage MS data. No ionisable and non-ionisable complexes and/or precipitation of clenbuterol with matrix compounds were observed. A concentration dependence of the percentage of suppression was observed. Up to 70% of the signal was suppressed upon post-cartridge infusion of 0.22 microg/mL (at 5 microL/min) clenbuterol into the eluate, and this decreased to about 4% at infusion of 22 microg/mL clenbuterol. Molecularly imprinted polymers were used to enhance the selectivity of the extraction. Although matrix components were still present after extraction, no interference of these compounds with the analyte was observed. However, the bleeding of the imprint from the polymer (brombuterol) caused significant ion suppression.

The investigation and the use of high flow column-switching LC/MS/MS as a high-throughput approach for direct plasma sample analysis of single and multiple components in pharmacokinetic studies

Recently direct plasma injection LC/MS/MS technique has been increasingly used in pharmaceutical research and development due to the demand for higher throughput of sample analyses. In this work, two on-line extraction methods including high flow LC/MS/MS and high flow column switching LC/MS/MS were investigated. The evaluations were conducted and focused on their performances with respect to peak responses, separation efficiency, and signal to-noise ratio in a multiple-component LC/MS/MS assay. Two HPLC pumps were used-with one for high flow delivery and one for gradient elution. A CTC autosampler was used to inject plasma samples. High flow LC was achieved by the use of 4 ml/min flow rate on a 1 x 50 mm Waters Oasis column. A 2 x 100 mm YMC column was coupled via a column-switching valve. The extracted analytes were analyzed in multiple-reaction-monitoring (MRM) mode using a triple quadrupole MS/MS. As a rapid and simple procedure, vortex-mixing plasma and internal standard directly in sample vials completed sample preparation. The high flow column switching method (two-column system) provided sharper peak shape than the conventional high flow method. This effect increased analyte signal-to-noise ratio and sensitivity. Narrower peak width resulted in much better separation efficiency, which was required for multiple compound (N-in-1) analysis. A 2 mm I.D. column resulted in better peak shape and resolution than using a smaller I.D. column. The selected method achieved acceptable recoveries for most of the compounds tested, and it was successfully applied to a 10-in-1 pharmacokinetic (PK) study. The results showed that the dynamic range, lower limit of quantitation, assay accuracy and precision were acceptable for all compounds. Rapid sample preparation eliminated labor intensive and time consuming processes and improved productivity. This high throughput on-line extraction high flow column switching method has been proven particularly useful for multiple component analysis in PK studies.

High-throughput high-performance liquid chromatography/mass spectrometry for modern drug discovery

High-throughput high-performance liquid chromatography/mass spectrometry can be used in the analysis of high-throughput organic synthesis products, bioanalytical target analysis for preclinical and clinical studies, and early absorption, distribution, metabolism and excretion (ADME) screening. New techniques are emerging, including system automation, faster analysis, programmed multiple extraction and analysis columns, multiple electrospray ionization channels, and automated 96-well sample preparation.

Evaluation of several solid phase extraction liquid chromatography/tandem mass spectrometry on-line configurations for high-throughput analysis of acidic and basic drugs in rat plasma

Several configurations using 6- and 10-port switching valves were studied for high flow, on-line extraction of rat plasma coupled to an electrospray triple quadrupole mass spectrometer. Each plasma sample was diluted 1:1 with an aqueous internal standard solution. The sample was injected into a 2.1 x 20 mm cartridge column packed with 25 microm divinylbenzene/N-vinylpyrrolidone packing using 100% aqueous mobile phase at 4 mL/min. After sample loading and sample cleanup, the analytes were eluted from the extraction column with a 1.0-min gradient at 0.4 mL/min. The samples were either analyzed directly after elution from the extraction column or after additional separation using a short high performance liquid chromatography (HPLC) column. The different configurations were tested using an acidic drug (diflunisal) and a basic drug (clemastine) in rat plasma. On-line analysis was performed by injecting 200 microL of diluted plasma. The mass spectrometer was operated in the multiple reaction monitoring (MRM) mode. All calibration standards gave relative standard deviations (RSDs) below 5%. The total time per sample was 3 min.

On-line coupling of solid-phase extraction with mass spectrometry for the analysis of biological samples. II. Determination of clenbuterol in urine using multiple-stage mass spectrometry in an ion-trap mass spectrometer

Solid-phase extraction (SPE) was coupled to ion-trap mass spectrometry to determine clenbuterol in urine. For SPE a cartridge exchanger was used and, after extraction, the eluate was directly introduced into the mass spectrometer. For two types of cartridges, i.e. C18 and polydivinylbenzene (PDVB), the total SPE procedure (including injection of 1 mL urine, washing, and desorption) has been optimised. The total analysis, including SPE, elution, and detection, took 8.5 min with PDVB cartridges, while an analysis time of 11.5 min was obtained with C18 cartridges. A considerable amount of matrix was present after extraction of urine over C18 cartridges, resulting in significant ion suppression. With PDVB cartridges, the matrix was less prominent, and less ion suppression was observed. For single MS, a detection limit (LOD) of about 25 ng/mL was found with PDVB cartridges. With C18 cartridges an LOD of only about 50 ng/mL could be obtained. Applying tandem mass spectrometry (MS/MS) did not lead to an improved LOD due to an interfering compound. However, a considerable improvement in the LOD was obtained with MS3. The selectivity and sensitivity were increased by the combination of efficient fragmentation of clenbuterol and reduction of the noise. Detection limits of 2 and 0.5 ng/mL were obtained with C18 and PDVB cartridges, respectively. The ion suppression was 4 to 45% (concentration range: 250 to 1.0 ng/mL) after extraction of urine using PDVB cartridges, and up to 70% ion suppression was observed using C18 cartridges. With MS4, no further improvement in selectivity and sensitivity was achieved, due to inefficient fragmentation of clenbuterol and no further reduction of noise.

High-throughput approaches to the quantitative analysis of ketoconazole, a potent inhibitor of cytochrome P450 3A4, in human plasma

Ketoconazole, an imidazole-piperazine compound, is an orally active antimycotic agent. In addition, ketoconazole is a specific inhibitor of cytochrome P450 3A4. As about 60% of oxidized drugs are biotransformed by this isoform, the potential effect of a concomitant administration of ketoconazole on drug disposition may be of interest during drug development. The present paper describes three different approaches (methods A, B, and C) to attain high-throughput sample preparation and analysis in the quantification of ketoconazole in human plasma. Method A consisted of acetonitrile precipitation in a 96-well plate, transfer of the supernatant via a Tomtec Quadra 96 Model 320, and subsequent injection onto a 50 x 4.6 mm (i.d.) Develosil Combi-RP-5 column (packed with C30 bonded silica particles). Method B consisted of an identical sample preparation to method A with the exception that a Michrom Magic Bullet(trade mark) column, 2.0 --> 0.50 mm (i.d., tapered bore) x25 mm length, was used. Lastly, in method C, a turbulent-flow chromatography (TurboFlow LC/APCI-MS/MS) module was used for the direct analysis of ketoconazole in human plasma. A Sciex API 3000 was used in methods A and B, while a Micromass Quattro LC was employed in method C. Based on the values obtained for the calibrator (standard) and quality control samples, all three protocols yielded satisfactory accuracy, precision, and reduced manual sample preparation time.