Direct assay of nonopioid analgesics and their metabolites in human urine by capillary electrophoresis and capillary electrophoresis-mass spectrometry

Polycaprolactone Composite Micro/Nanofibrous Material as an Alternative to Restricted Access Media for Direct Extraction and Separation of Non-Steroidal Anti-Inflammatory Drugs from Human Serum Using Column-Switching Chromatography

Application of the poly-ɛ-caprolactone composite sorbent consisting of the micro- and nanometer fibers for the on-line extraction of non-steroidal anti-inflammatory drugs from a biological matrix has been introduced. A 100 μL human serum sample spiked with ketoprofen, naproxen, sodium diclofenac, and indomethacin was directly injected in the extraction cartridge filled with the poly-ɛ-caprolactone composite sorbent. This cartridge was coupled with a chromatographic instrument via a six-port switching valve allowing the analyte extraction and separation within a single analytical run. The 1.5 min long extraction step isolated the analytes from the proteinaceous matrix was followed by their 13 min HPLC separation using Ascentis Express RP-Amide (100 × 4.6 mm, 5 µm) column. The recovery of all analytes from human serum tested at three concentration levels ranged from 70.1% to 118.7%. The matrix calibrations were carried out in the range 50 to 20,000 ng mL⁻¹ with correlation coefficients exceeding 0.996. The detection limit was 15 ng mL⁻¹, and the limit of quantification corresponded to 50 ng mL⁻¹. The developed method was validated and successfully applied for the sodium diclofenac determination in real patient serum. Our study confirmed the ability of the poly-ɛ-caprolactone composite sorbent to remove the proteins from the biological matrix, thus serving as an alternative to the application of restricted-access media.

Determination of ibuprofen and flurbiprofen in pharmaceuticals by capillary zone electrophoresis

Capillary zone electrophoresis with spectrophotometric detection was used for the determination of ibuprofen (IB) and flurbiprofen (FL) in pharmaceuticals. The separation was carried out in a fused silica capillary (60 cm x 100 microm i.d. effective length 45 cm) at 30 kV with UV detection at 232 nm. The optimized background electrolyte was 20mM N-(2-acetamido)-2-aminoethanesulfonic acid (ACES) with 20mM imidazole and 10mM alpha-cyclodextrin of pH 7.3. 2-Naphthoxyacetic acid was used as internal standard. A single analysis took less than 5 min. Rectilinear calibration ranges were 2-500 mg l(-1) for IB and 1-60 mg l(-1) for FL. The relative standard deviations (R.S.D.) values (n=6) were 1.53% for IB and 1.29% for FL (for 200 mg l(-1) IB and 10 mg l(-1) FL). This validated method has been successfully applied for the routine analysis of 10 commercially available pharmaceutical preparations (syrup, tablets, cream and gel).

Determination of paracetamol: historical evolution

Paracetamol is a common analgesic and antipyretic drug that is used for the relief of fever, headaches and other minor aches and pains. Their determination in pharmaceuticals is of paramount importance, since an overdose of paracetamol can cause fulminating hepatic necrosis and other toxic effects. Many analytical methodologies have been proposed for the determination of paracetamol. The aim of the present study is to evaluate the utility of different techniques for quantification of paracetamol content in pharmaceutical formulations and biological samples.

Simultaneous quantitation of etoricoxib, salicylic acid, valdecoxib, ketoprofen, nimesulide and celecoxib in plasma by high-performance liquid chromatography with UV detection

A specific, accurate, precise and reproducible high performance liquid chromatography (HPLC) method was developed and validated for the simultaneous quantitation of etoricoxib, salicylic acid, valdecoxib, ketoprofen, nimesulide and celecoxib in human plasma. The method employed a simple liquid-liquid extraction of etoricoxib, salicylic acid, valdecoxib, ketoprofen, nimesulide and celecoxib and internal standard (IS, DRF-4367) from human plasma (500 microL) into acetonitirile. The organic layer was separated and evaporated under a gentle stream of nitrogen at 40 degrees C. The residue was reconstituted in the mobile phase and injected onto a Kromasil KR 100-5C18 column (4.6 x 250 mm, 5 microm). The chromatographic separation was achieved by gradient elution consisting of 0.05 M formic acid (pH 3)-acetonitrile-methanol-water at a flow rate of 1.0 mL/min. The eluate was monitored using an ultraviolet (UV) detector set at 235 nm. The ratio of peak area of each analyte to IS was used for quantification of plasma samples. Nominal retention times of etoricoxib, salicylic acid, valdecoxib, ketoprofen, nimesulide, IS and celecoxib were 15.63, 17.20, 21.66, 24.95, 26.27, 30.24 and 32.22 min, respectively. The standard curve for etoricoxib, salicylic acid, valdecoxib, ketoprofen and celecoxib was linear (r2 > 0.999) in the concentration range 0.1-50 microg/mL and for nimesulide (r2 > 0.999) in the concentration range 0.5-50 microg/mL. Absolute recovery was >83% from human plasma for all the analytes and IS. The lower limit of quantification (LLOQ) of nimesulide was 0.5 microg/mL and for etoricoxib, salicylic acid, valdecoxib, ketoprofen and celecoxib the LLOQ was 0.1 microg/mL. The inter- and intra-day precisions in the measurement of QC samples, 0.1, 0.3, 15.0 and 40.0 microg/mL (for all analytes except nimesulide), were in the range 2.29-9.37% relative standard deviation (RSD) and 0.69-10.28% RSD, respectively. For nimesulide the inter- and intra-day precisions in the measurement of quality control (QC) samples, 0.5, 1.5, 15.0 and 40.0 microg/mL, were in the range 3.21-7.37% RSD and 0.97-7.06% RSD, respectively. Accuracy in the measurement of QC samples for all analytes was in the range 91.03-106.38% of the nominal values. All analytes including IS were stable in the battery of stability studies, viz. bench top, autosampler and freeze-thaw cycles. Stability of all analytes was established for 21 days at -20 degrees C. The application of the assay in an oral pharmacokinetic study in rats co-administered with celecoxib and valdecoxib is described.

Importance of the counterion in optimization of a borate electrolyte system for analyses of anions in samples with complex matrices performed by capillary zone electrophoresis

Borate buffers are common background electrolytes for analyses of anions in capillary zone electrophoresis. Usually, sodium borate at a given pH is used and this specification seems to be sufficient for a successful analysis. In this paper, we show that free migration of OH(-) may deteriorate the analysis of a typical anionic analysis of clinical samples due to uncontrolled migration of OH(-) throughout the systems of analyzed zones and may damage the stacking of anionic analytes of interest. We have proven that the use of ammonium borate may remedy the situation where the presence of ammonium may selectively stop the free migration of OH(-) ions, slow down their effective mobility and bring their safe behavior resulting in reproducible stacking of clinically important anions. Results of real analyses of human serum samples confirmed the proposed method and proved that substitution of sodium for ammonium in borate buffers offers reliable analyses of clinical samples having chloride as the bulk component. The experimental results given in this paper are supported also by computer simulation, which can not only support the positive results but also show the dynamics of the separation that is otherwise hidden to any detection possibilities.

Simultaneous determination of paracetamol and chlorpheniramine maleate by micellar electrokinetic chromatography

A micellar electrokinetic chromatography (MEKC) method was established for determination of paracetamol (PARA) and chlorpheniramine maleate (CPM) in cold tablets. Separation of both drugs, as well as other seven cold remedy ingredients, was achieved in 25.5 min using a sodium dihydrogenphosphate-sodium tetraborate buffer (10 mM, pH 9.0) containing sodium dodecyl sulfate (SDS) (50 mM) and acetonitrile (26% v/v). The effective capillary length of 50 cm, the separating voltage of 15 kV and the temperature of 30 degrees C was optimized. Detection was by a diode array detector at 214 nm. Method linearity was excellent (r(2)>0.999) over the concentration tested (10-250 microg/ml) with good precision and accuracy. Recoveries were good (>99%) with limits of detection of 0.4 and 0.5 microg/ml and limits of quantitation of 2 (%R.S.D.=3.1%) and 4 (%R.S.D.=2.4%) microg/ml, for PARA and CPM, respectively. The developed method was applied to the determination of ingredients in cold tablets and was found to be simple, rapid and efficient.

Simultaneous determination of arylpropionic acidic non-steroidal anti-inflammatory drugs in pharmaceutical formulations and human plasma by HPLC with UV detection

A simple and sensitive high-performance liquid chromatography-UV detection method was developed for the simultaneous determination of non-steroidal anti-inflammatory drugs (NSAIDs) having an arylpropionic acid moiety in pharmaceutical formulations and human plasma. Isocratic separation was employed on ODS column (250 x 4.6 mm i.d., 5 microm) at ambient temperature. The mobile phase consisted of acetonitrile, phosphate buffer (pH 3.5; 50 mM), methanol and tetrahydrofuran. The NSAIDs in the eluent were monitored under a wavelength-programme to provide their maximum absorbance. Mefenamic acid was used as an internal standard. Drugs were found to be 96.8-101.9% of their label claim in pharmaceutical formulations. One hundred microliters of human plasma samples were pretreated with a simple liquid-liquid extraction using ethyl acetate. The detection limits of compounds studied at a signal-to-noise ratio of 3 were 11.5-75 ng/ml in human plasma samples. The proposed method is simple, selective and could be applicable for routine analysis of arylpropionic acidic NSAIDs in pharmaceutical as well as in human plasma samples.

Determination of ketoprofen enantiomers in human serum by capillary zone electrophoresis: man pharmacokinetic studies after administration of rac-ketoprofen tablets

A rapid and stereospecific capillary zone electrophoresis (CZE) method to quantify ketoprofen (KTP) enantiomers was developed. The KTP enantiomers and (+)-S-naproxen [(+)-S-NPX] as an internal standard (IS) were extracted with methylene chloride from serum acidified. Recovery of both enantiomers was in the range of 85-91%. The enantiomers were determined using a background electrolyte (BGE), consisting of 0.05 M heptakis 2,3,6-tri-O-methyl-beta-cyclodextrin (TMbetaCD) in a phosphate-triethanolamine buffer, which filled a fused silica capillary of 75 micrometer i.d. The linear range of calibration curves was between 0.25 and 50 mg l(-1), with detection limit of 0.1 mg l(-1) (signal-to-noise baseline ratio (S/N) >4). Intra- and interday precision and accuracy of the calibration curves, expressed by the coefficient of variation (CV), did not exceed 15.0%. The validated method has been successfully applied for pharmacokinetic studies of KTP enantiomers from tablets with rac-KTP in man.

Rapid analysis of furosemide in human urine by capillary electrophoresis with laser-induced fluorescence and electrospray ionization-ion trap mass spectrometric detection

Furosemide, a drug that promotes urine excretion, is used in the pharmacotherapy of various diseases and is considered as a doping agent in sports. Using alkaline electrolytes, analysis of furosemide by dodecyl sulfate based micellar electrokinetic capillary chromatography (MECC) and capillary zone electrophoresis (CZE) with laser-induced fluorescence detection (LIF, analyte excitation with the 325 nm line of a HeCd laser) is described. Data produced by injection of plain or diluted patient urines are confirmed with those obtained via analysis of urinary solid-phase extracts. CZE-LIF and MECC-LIF are thereby shown to permit unambiguous recognition of furosemide in urines collected after ingestion of therapeutic doses of this drug. This is in contrast to solute detection via UV absorbance for which the extraction of furosemide is required. MECC based electropherograms are somewhat more complex compared to those obtained by CZE-LIF, this suggesting that the latter approach is more suitable for rapid screening of urines with direct sample injection and LIF detection. Alternatively, capillary electrophoresis with negative electrospray ionization-ion-trap tandem mass spectrometry (CE-MS2) is shown to permit the direct confirmation of furosemide in human urine. This approach is based upon the monitoring of the m/z 329.3-->4m/z 285.2 precursor-product ion transition. CZE-LIF and CE-MS2 with injection of plain or diluted urine represent simple, rapid and attractive urinary screening and confirmation assays for furosemide in patient urines.

A study of the conditions of the supercritical fluid extraction in the analysis of selected anti-inflammatory drugs in plasma

Supercritical fluid extraction (SFE) was employed to analyze selected anti-inflammatory drugs in plasma. Evaluation of selected drugs (ibuprofen, indomethacin, and flufenamic acid) was performed using the HPLC method on columns with the reverse phase C-18 and detection in the UV region of the spectrum. A study of the conditions of SFE carried out for 30 min at 50 degrees C investigated the magnitude of the pressure of carbon dioxide suitable for drug extraction, the selection of the collecting solvent, and the modification of CO2 with an organic solvent. The results of the study made it possible to determine the optimal procedure for SFE of ibuprofen, indomethacin, and flufenamic acid from plasma, which renders their HPLC quantification possible.

Advances ofcapillary electrophoresis in clinical and forensic analysis (1999-2000)

In this paper, capillary electrophoresis in clinical and forensic analysis is reviewed on the basis of the literature of 1999, 2000 and the first papers in 2001. An overview of progress relevant examples for each major field of application, namely (i) analysis of drug seizures, explosives residues, gunshot residues and inks, (ii) monitoring of drugs, endogenous small molecules and ions in biofluids and tissues, (iii) general screening for serum proteins and analysis of specific proteins (carbohydrate deficient transferrin, alpha1-antitrypsin, lipoproteins and hemoglobins) in biological fluids, and (iv) analysis of nucleic acids and oligonucleotides in biological samples, including oligonucleotide therapeutics, are presented.

Recent advances in pharmacokinetic applications of capillary electrophoresis

This article reviews recent capillary electrophoresis (CE)-based assays which were published for pharmacokinetic studies. Both the advantages and disadvantages of these CE-based assays are discussed based on their feasibility and the significance towards the better understanding of pharmacokinetics. In addition, as a future outlook, novel assays such as immunoaffinity CE and chip-based CE for analyzing drugs in biological fluids are summarized in view of their potential for pharmacokinetic applications.

The use of selective adsorbents in capillary electrophoresis-mass spectrometry for analyte preconcentration and microreactions: a powerful three-dimensional tool for multiple chemical and biological applications

Much attention has recently been directed to the development and application of online sample preconcentration and microreactions in capillary electrophoresis using selective adsorbents based on chemical or biological specificity. The basic principle involves two interacting chemical or biological systems with high selectivity and affinity for each other. These molecular interactions in nature usually involve noncovalent and reversible chemical processes. Properly bound to a solid support, an "affinity ligand" can selectively adsorb a "target analyte" found in a simple or complex mixture at a wide range of concentrations. As a result, the isolated analyte is enriched and highly purified. When this affinity technique, allowing noncovalent chemical interactions and biochemical reactions to occur, is coupled on-line to high-resolution capillary electrophoresis and mass spectrometry, a powerful tool of chemical and biological information is created. This paper describes the concept of biological recognition and affinity interaction on-line with high-resolution separation, the fabrication of an "analyte concentrator-microreactor", optimization conditions of adsorption and desorption, the coupling to mass spectrometry, and various applications of clinical and pharmaceutical interest.

Capillary zone electrophoresis of orotic acid in urine with on-line isotachophoresis sample pretreatment and diode array detection

Potentialities of capillary zone electrophoresis with on-line isotachophoresis sample pretreatment and diode array detection (ITP-CZE-DAD) to the separation, detection and identification of trace analytes present in biological matrices were investigated. Urine represented a multicomponent, variable and high ionic strength matrix while orotic acid was chosen as a model analyte of a practical clinical relevance in this investigation. Using the ITP-CZE combination in the column-coupling configuration of the separation system ITP provided an enhanced sample load capacity to the separation system (a 30 microl sample injection volume), concentrated the analyte and served as an on-line sample clean up technique. On the other hand, CZE performed a final separation of the analyte from matrix constituents present in the ITP pretreated sample and provided favorable conditions for its detection and identification by DAD. Using current correction and smoothing procedures analytically relevant DAD spectra of orotic acid could be obtained also in instances when this was injected in a model sample at a 2 x 10(-7) mol/l concentration (an estimated limit of determination of orotic acid at a 218 nm detection wavelength). ITP-CZE separations of urine samples (based on differences in acid-base properties and host-guest complexations of the analyte and matrix anionic constituents) led to significant sample clean ups. Consequently, DAD spectra of orotic acid matching its reference spectrum, could be acquired also in instances when the acid was present in urine matrices (loaded in 30 microl injection volumes of 20-fold diluted urine samples) at 4-6 x 10(-7) mol/l concentrations. Here, residual trace matrix interferents prevented a closer approach to the above value attainable for model samples. Although this work was focused only on one analyte and urine matrix it implies very promising potentialities of the ITP-CZE-DAD combination in the identification and quantitation of trace analytes present in biological matrices, in general.

Capillary electrophoresis-electrospray ionization ion trap mass spectrometry for analysis and confirmation testing of morphine and related compounds in urine

Using an aqueous background electrolyte containing 25 mM ammonium acetate and NH3 (pH 9), CE-tandem MS and CE-triple MS with atmospheric pressure electrospray ionization in the positive ion mode are shown to represent attractive approaches for analysis and confirmation testing of morphine (MOR) and related opioids in human urine. Injection of plain or diluted urine permits monitoring of solutes at concentrations above 2-5 microg/ml. For the recognition of lower concentrations, solute extraction and concentration is required. Liquid-liquid extraction at alkaline pH is shown to be suitable for analysis of free opioids only whereas solid-phase extraction using a mixed-mode polymer phase is demonstrated to permit analysis of both free and glucuronidated opioids. The former sample preparation approach, however, requires about half of the time only. Commencing with 2 ml of urine, reconstitution to provide a sample volume of 0.2 ml and hydrodynamic sample injection, detection limits for free opioids are shown to be on the 100-200 ng/ml drug level. Much improved (ppb) sensitivity is obtained by infusing the extract directly into the source of the MS system. However, solutes that produce equal fragments (such as the two glucuronides of MOR) can thereby not be distinguished. CE-tandem MS and CE-triple MS are demonstrated to be suitable to confirm the presence of MOR, MOR-3-glucuronide, 6-monoacetylmorphine, codeine, codeine-6-glucuronide, dihydrocodeine, methadone and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine in a toxicological quality control urine. The same is shown for selected metabolites of codeine and dihydrocodeine in urines collected after administration of pharmaceutical preparations.

Potential of capillary electrophoresis, tandem mass spectrometry and coupled capillary electrophoresis–tandem mass spectrometry as diagnostic tools

Urine and blood samples from patients with known metabolic disorders have been analyzed by CE, MS-MS and CE-MS-MS. For the identification of defects in acylcarnitine metabolism, blood spots on filter paper were analyzed using an MS-MS "neonatal screening" approach. Direct CE-MS-MS analysis was used for the analysis of urine samples from patients with different metabolic disorders, including galactosemia, neuroblastoma, Zellweger syndrome, propionic acidemia and alcaptonuria. The sensitivity of the CE-MS-MS method was increased by use of multiple reaction monitoring.

Recent advances in capillary electrophoresis/electrospray-mass spectrometry

In this review, the progress in hyphenation of capillary electrophoresis (CE) with electrospray ionization-mass spectrometry (ESI-MS) since the article of Banks (Banks, J. F., Electrophoresis 1997, 18, 2255-2266) is reported. In all capillary-based electromigration techniques, such as capillary gel electrophoresis (CGE), capillary isotachophoresis (CITP), capillary isoelectric focussing (CIEF), micellar electrokinetic chromatography (MEKC), affinity capillary electrophoresis (ACE), as well as in the hybrid techniques capillary electrochromatography (CEC), and pressurized capillary electrochromatography (pCEC) progress has been made in experimental setups, and for many groups of analytes, such as peptides, proteins, nucleotides, saccharides, drugs and their metabolites, CE/ESI-MS has been successfully applied. Electromigration is further miniaturized. New preconcentration methods allow the investigation of compounds, which are not sensitively detected with ESI-MS. Coordination ion spray (CIS) MS is another method for sensitivity enhancement by on-line formation of charged coordination compounds.

Determination of salicylate, gentisic acid and salicyluric acid in human urine by capillary electrophoresis with laser-induced fluorescence detection

Acetylsalicylic acid (Aspirin) is rapidly metabolized to salicylic acid (salicylate) and other compounds, including gentisic acid and salicyluric acid. Monitoring of salicylate and its metabolites is of toxicological, pharmacological and biomedical interest. Three capillary electrophoresis (CE) methods featuring alkaline aqueous buffers, laser-induced fluorescence (LIF) detection and no solute extraction or derivatization have been explored. A competitive binding, electrokinetic capillary-based immunoassay is developed that recognizes the presence of salicylate and gentisic acid in urine. Differentiation of the two compounds, however, is problematic. With appropriate ultraviolet excitation, many salicylate-related compounds are fluorescent so that CE with direct urine injection and LIF detection permits the determination of salicylate, gentisic acid and salicyluric acid. Using a HeCd laser with 325 nm produces interference-free monitoring of all three compounds. Using 257 nm excitation from a frequency doubled Ar ion laser, native fluorescence of an endogenous urinary compound that co-migrates with gentisic acid is observed. With wavelength-resolved fluorescence detection, however, the two substances are distinguished. Furthermore, this technique, with comparison to literature data, permits the putative assignment of several peaks to other salicylate metabolites, namely glucuronide conjugates of salicylate and salicyluric acid. All three CE-LIF techniques have been applied to toxicological patient urines and urines collected after ingestion of 500 mg acetylsalicylic acid. CE results compare favorably with those obtained by a commercial fluorescence polarization immunoassay and by a conventional photometric assay.

Direct analysis of nitrocatechol-type glucuronides in urine by capillary electrophoresis-electrospray ionisation mass spectrometry and tandem mass spectrometry

Direct, quantitative capillary electrophoresis-electrospray ionisation mass spectrometric (CE-ESI-MS) and tandem mass spectrometric (CE-ESI-MS-MS) methods are described for the quantitation of 3-O-glucuronides of E- and Z-entacapone isomers (EEG and EZG) and tolcapone (TG) in urine. 3-O-Glucuronide of nitecapone was used as internal standard. Good separation of glucuronides was achieved with 20 mM ammonium acetate as separation solution at pH 6.84. Stacking was used to increase the sensitivity of the method by introducing samples in 5 mM ammonium acetate. CE-ESI-MS and CE-ESI-MS-MS methods are linear with correlation coefficients better than 0.9983 and 0.9982, and repeatable with relative standard deviations below 9 and 14%, respectively. The limit of detection (LOD) in CE-ESI-MS at signal-to-noise ratio 3 is 100 ng/ml for EEG and EZG and 250 ng/ml for TG. The CE-ESI-MS-MS method was the more sensitive; LOD was 7 ng/ml for all compounds, without any concentration of the sample.

Analysis of codeine, dihydrocodeine and their glucuronides in human urine by electrokinetic capillary immunoassays and capillary electrophoresis-ion trap mass spectrometry

Screening for and confirmation of illicit, abused and banned drugs in human urine is a timely topic in which capillary separation techniques play a key role. Capillary electrophoresis (CE) represents the newest technology employed in this field of analysis. Two rapid competitive binding, electrokinetic capillary-based immunoassays are shown to be capable of recognizing the presence, but not the identity, of urinary opioids, namely codeine (COD), codeine-6-glucuronide, dihydrocodeine (DHC), dihydrocodeine-6-glucuronide, morphine (MOR), morphine-3-glucuronide and ethylmorphine (EMOR). In these approaches, aliquots of urine and immunoreagents of a commercial, broadly cross-reacting fluorescence polarization immunoassay for opiates were combined and analyzed by capillary zone electrophoresis or micellar electrokinetic capillary chromatography with laser induced fluorescence detection. With the fluorescent tracer solution employed, the former method is shown to provide simple electropherograms which are characterized by an opioid concentration dependent magnitude of the free tracer peak. In presence of dodecyl sulfate micelles, however, two tracer peaks with equal opioid concentration sensitivity are monitored. These data suggest the presence of two fluorescent tracers which react competitively with the urinary opioids for the binding sites of the antibody. Assay sensitivities for COD and MOR are comparable (10 ng/ml), whereas those for DHC and EMOR are about four-fold lower. Furthermore, glucuronides are shown to react like the corresponding free opioids. Analysis of urines that were collected after administration of 7 mg COD and 25 mg DHC tested positively in both assay formats. The presence of the free and conjugated codeinoids in these urines and their identification was accomplished by capillary electrophoresis-ion trap mass spectrometry (CE-MS). This confirmatory assay is based upon solid-phase extraction using a mixed-mode polymer cartridge followed by CE hyphenated to the LCQ mass spectrometer with electrospray ionization in the positive ion mode. With this technology, MS2 is employed for proper identification of COD (m/z 300.4) and DHC (m/z 302.4) whereas MS3 provides unambiguous identification of the glucuronides of COD (m/z 476.5) and DHC (m/z 478.5) via their fragmentation to COD and DHC, respectively. MSn (n > or = 2) is shown to be capable of properly identifying the urinary codeinoids on the 100-200 ng/ml concentration level.

Hyphenated chromatographic methods for biomaterials

The improvement in hyphenated analytical techniques has significantly widened their applications to the analysis of biomaterials. In this article, we discuss recent advances in applications of hyphenated chromatographic techniques including capillary electrophoresis to the analyses of biological samples. As tools of separation, gas chromatography, high-performance liquid chromatography and capillary electrophoresis are considered with special emphasis on applications utilizing the hyphenation of these methods to mass spectrometry. Moreover, applications using other detection methods such as Fourier transform infrared spectroscopy hyphenated to gas chromatography and photodiode array detector combined with high-performance liquid chromatography or capillary electrophoresis are also discussed. Owing to their high sensitivity, luminescence-based detection systems such as laser-induced fluorescence and chemiluminescence are also included in this review.

Capillary electrophoresis-mass spectrometry, liquid chromatography-mass spectrometry and nanoelectrospray-mass spectrometry of praziquantel metabolites

Capillary electrophoresis-mass spectrometry (CE-MS) and liquid chromatography-mass spectrometry (LC-MS) coupling was used for the investigation of metabolites of the anthelmintic drug praziquantel. Human urine samples and microsomal incubation mixtures were investigated after preparation by solid-phase extraction. CE- and LC-MS coupling was performed using an electrospray ionization interface. An ion trap mass spectrometer equipped with a laboratory-made nanoelectrospray ion source was used for the investigation of the glucuronide conjugates by consecutive fragmentations. The nanoelectrospray interface offers the opportunity to perform complicated MSn spectrometric investigations. Different phase I metabolites of praziquantel and their glucuronidated and sulfated conjugates were detected.

Determination of (R)- and (S)-ketoprofen in human plasma by liquid chromatography/tandem mass spectrometry following automated solid-phase extraction in the 96-well format

A sensitive and selective method was developed for the determination of (R)-ketoprofen ((R)-kt) and (S)-ketoprofen ((S)-kt) in human plasma using chiral liquid chromatography/tandem mass spectrometry (LC/MS/MS). Plasma samples spiked with stable-isotope-labeled [(13)C(1), (2)H(3)]-(R and S)-ketoprofen, for use as the internal standards, were prepared for analysis using automated solid-phase extraction (SPE) in the 96-well microtiter format. The enantiomers were separated on an (R)-1-naphthylglycine and 3,5-dinitrobenzoic acid (Chirex 3005) 250x2.0 mm i.d. analytical column, equipped with a 30x2.0 mm i.d. guard column using isocratic mobile phase conditions. The (R)- and (S)-kt levels were quantifiable from 0.05 to 2500 ng ml(-1) by constructing two separate curves from calibration standards covering the same range. The first curve ranged from 0.05 to 100 and the second from 100 to 2500 ng ml(-1). A concentration of 0.05 ng ml(-1) of either enantiomer was easily detected using a 1 ml plasma sample volume. The average method accuracy, evaluated at four levels over an extended period, was better than +/-3% over the entire range. The precision for the same set of quality control samples ranged from 4.0 to 7.0 % RSD (n = 24). The method was applied to the evaluation of pharmacokinetic parameters in human plasma obtained from volunteers who received 25 mg of kt by peroral administration of Actron caplets or by topical administration of Oruvail gel.

Strategies to improve the sensitivity in capillary electrophoresis for the analysis of drugs in biological fluids

Capillary electrophoresis (CE) is a useful method to quantify drugs in biological fluids. However, especially for blood or plasma samples, the sensitivity is not sufficient to quantify drugs and their metabolites as they often need to be quantified in the lower microg/L range. To overcome this limitation and to increase the sensitivity, two strategies are applied: first, to increase the amount of analyte added to the capillary and, second, to increase the sensitivity on the detector site. To improve the sensitivity on the detector site, alternative detection techniques to UV detection, e.g., laser-induced fluorescence detection (LIF) or mass spectroscopy (MS), can be applied. However, LIF detection can only be used for fluorescent analytes and the current equipment for CE-MS coupling provides only small improvements in sensitivity compared to UV detection. The detection window for UV detection can be enhanced using capillaries with an extended light path (bubble cell) or Z-shaped capillaries. Sensitivity improvements up to a factor of 10 have been reported. Increasing the amount of analyte in the capillary can be done either by chromatographic or by electrokinetic methods. Chromatographic methods such as on-capillary membrane preconcentration have been used for several analytes. However, no validated application has been reported to date. In contrast, several validated examples can be found in which electrokinetic techniques like sample stacking have been applied to achieve limits of quantification in the lower microg/L range. In conclusion, to date, electrokinetic techniques such as field-amplified sample injection offer the most promising results in achieving a sufficient sensitivity to quantify drugs in biological fluids.

Confirmation testing of amphetamines and designer drugs in human urine by capillary electrophoresis-ion trap mass spectrometry

Monitoring of amphetamines and designer drugs in human urine is a timely topic in clinical toxicology, surveillance of drug substitution, forensic science, drug testing at the workplace, and doping control. Confirmation testing of urinary amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy) and 3,4-methylenedioxyamphetamine (MDA) by capillary electrophoresis (CE) combined with atmospheric pressure electrospray ionization and ion trap mass spectrometry (MS) is described. Using an aqueous pH 4.6 buffer composed of ammonium acetate/acetic acid, CE-MS and CE-MS2 provided data that permitted the unambiguous confirmation of these drugs in external quality control urines. Furthermore, other drugs of abuse present in alkaline urinary extracts, including methadone and morphine, could also be monitored. The data presented illustrate that the sensitivity achieved with the benchtop MS is comparable to that observed by CE with UV absorption detection. CE-MS2 is further shown to be capable of identifying comigrating compounds, including the comigration of amphetamine with nicotine.

Chromatographic screening techniques in systematic toxicological analysis

A review of techniques used to screen biological specimens for the presence of drugs was conducted with particular reference to systematic toxicological analysis. Extraction systems of both the liquid-liquid and solid-phase type show little apparent difference in their relative ability to extract a range of drugs according to their physio-chemical properties, although mixed-phase SPE extraction is a preferred technique for GC-based applications, and liquid-liquid were preferred for HPLC-based applications. No one chromatographic system has been shown to be capable of detecting a full range of common drugs of abuse, and common ethical drugs, hence two or more assays are required for laboratories wishing to cover a reasonably comprehensive range of drugs of toxicological significance. While immunoassays are invariably used to screen for drugs of abuse, chromatographic systems relying on derivatization and capable of extracting both acidic and basic drugs would be capable of screening a limited range of targeted drugs. Drugs most difficult to detect in systematic toxicological analysis include LSD, psilocin, THC and its metabolites, fentanyl and its designer derivatives, some potent opiates, potent benzodiazepines and some potent neuroleptics, many of the newer anti-convulsants, alkaloids colchicine, amantins, aflatoxins, antineoplastics, coumarin-based anti-coagulants, and a number of cardiovascular drugs. The widespread use of LC-MS and LC-MS-MS for specific drug detection and the emergence of capillary electrophoresis linked to MS and MS-MS provide an exciting possibility for the future to increase the range of drugs detected in any one chromatographic screening system.

Systematic toxicological analysis procedures for acidic drugs and/or metabolites relevant to clinical and forensic toxicology and/or doping control

This paper reviews systematic toxicological analysis (STA) procedures for acidic drugs and/or metabolites relevant to clinical and forensic toxicology or doping control using gas chromatography, gas chromatography-mass spectrometry, liquid chromatography, thin-layer chromatography and capillary electrophoresis. Papers from 1992 to 1998 have been taken into consideration. Screening procedures in biosamples (whole blood, plasma, serum, urine, vitreous humor, brain, liver or hair) of humans or animals (horse, or rat) are included for the following drug classes: angiotensin-converting enzyme (ACE) inhibitors and angiotensin II (AT-II) blockers, anticoagulants of the 4-hydroxy coumarin type, barbiturates, dihydropyridine calcium channel blockers (calcium antagonists), diuretics, hypoglycemic sulfonylureas and non-steroidal anti-inflammatory drugs (NSAIDs). Methods for confirmation of preliminary results obtained by screening procedures using immunoassay or chromatographic techniques are also included. Furthermore, procedures for the simultaneous detection of several drug classes are reviewed. The toxicological question to be answered and the consequences for the choice of an adequate method, the sample preparation and the chromatography itself are discussed. The basic information about the biosample assayed, work-up, separation column, mobile phase or separation buffer, detection mode and validation data of each procedure is summarized in 16 tables. They are arranged according to the drug class and the analytical method. Examples of typical applications are presented. Finally, STA procedures are reviewed and described allowing simultaneous screening for different (acidic) drug classes.

Identification, quantitation, and characterization of biomolecules by capillary electrophoretic analysis of binding interactions

The high resolving power of capillary electrophoresis combined with the specificity of binding interactions may be used with advantage to characterize the structure-function relationship of biomolecules, to quantitate specific analytes in complex sample matrices, and to determine the purity of pharmaceutical and other molecules. We here review recent and innovative methodologies and applications of high resolution affinity electrophoresis within the fields of binding constant determination, structure-activity studies, quantitative microassays, analysis of drug purity and protein conformation, and immobilized affinity ligands. Despite the virtues of these approaches with respect to applicability, resolving power, speed, and low sample consumption, problems remain with respect to analyte identification and low concentration limits of detection. The ongoing development of new detector technologies for capillary electrophoresis such as mass spectrometry, and possibly nuclear magnetic resonance and other spectroscopic methods, is therefore very promising for the continued increased use of affinity capillary electrophoresis.

Capillary electrophoresis in clinical and forensic analysis: recent advances and breakthrough to routine applications

This paper is a comprehensive review article on capillary electrophoresis (CE) in clinical and forensic analysis. It is based upon the literature of 1997 and 1998, presents CE examples in major fields of application, and provides an overview of the key achievements encountered, including those associated with the analysis of drugs, serum proteins, hemoglobin variants, and nucleic acids. For CE in clinical and forensic analysis, the past two years witnessed a breakthrough to routine applications. As most coauthors of this review are associated with diagnostic or forensic laboratories now using CE on a routine basis, this review also contains data from routine applications in drug, protein, and DNA analysis. With the first-hand experience of providing analytical service under stringent quality control conditions, aspects of quality assurance, assay specifications for clinical and forensic CE and the pros and cons of this maturing, cost-and pollution-controlled age technology are also discussed.