First- and second-order multivariate calibration applied to biological samples: determination of anti-inflammatories in serum and urine

First- and second-order multivariate calibration of fluorescence data have been compared as regards the determination of anti-inflammatories and metabolites in the biological fluids serum and urine. The simultaneous resolution of naproxen-salicylic acid mixtures in serum and naproxen-salicylic acid-salicyluric acid mixtures in urine was accomplished and employed for a discussion of the relative advantages of the applied chemometric tools. The analysis of second-order fluorescence excitation-emission matrices was performed using iteratively reweighted generalized rank annihilation method (IRGRAM), parallel factor analysis (PARAFAC), and self-weighted alternating trilinear decomposition (SWATLD). The results were compared with first-order fluorescence emission data analyzed with partial least-squares regression (PLS). In all cases, the performance of the methods was improved through the formation of inclusion complexes of the analytes with beta-cyclodextrin. The concentration ranges in which the analytes could be determined were as follows: naproxen, 0-250 ng mL(-1) in serum and 0-200 ng mL(-1) in urine; salicylic acid, 0-500 ng mL(-1) in serum and 0-300 ng mL(-1) in urine, and salicyluric acid, 0-300 ng mL(-1) in urine.     

Pharmaceutical determination in surface and wastewaters using high-performance liquid chromatography-(electrospray)-mass spectrometry

A method was developed to determine 11 pharmaceutical compounds in water samples. The method uses SPE and HPLC coupled to MS (LC/MS) using ESI in both positive and negative modes. Three different sorbents were compared for the extraction of analytes from river and sewage treatment plant (STP) waters and OASIS HLB provided the best results. For the solid-phase extraction of 500 mL of river water samples, the recoveries were between 41 and 101% with the exception of acetaminophen, salicylic acid and naproxen. The LODs were between 3 and 5 ng/L for all the compounds, except naproxen which had an LOD of 15 ng/L. Acetaminophen, caffeine, carbamazepine, bezafibrate and ibuprofen were found in three of the tested river samples at ng/L levels and among them, the highest values were for caffeine and bezafibrate with 305 and 363 ng/L, respectively. For the influent and effluent water samples of the STP, volumes of 100 and 250 mL were used, respectively, to obtain acceptable recoveries. All the compounds showed recoveries between 33 and 91% for effluent samples and 33-72% for influent samples, with the exception of acetaminophen, salicylic acid and bezafibrate, which had lower recoveries. The method developed enabled pharmaceuticals in the influent and effluent sewage waters to be determined in five campaigns carried out between February 2004 and June 2005. Several pharmaceuticals were found in the influent samples: for instance, maximum concentrations of ibuprofen and caffeine were 6 and 40 microg/L, respectively.     

Simultaneous analysis of non‐steroidal anti‐inflammatory drugs using electrochemically controlled solid‐phase microextraction based on nanostructure molecularly imprinted polypyrrole film coupled to ion mobility spectrometry

A simple, rapid, and highly sensitive method for simultaneous analysis of anti‐inflammatory drugs (naproxen, ibuprofen, and mefenamic acid) in diluted human serum was developed using the electrochemically controlled solid‐phase microextraction coupled to ion mobility spectrometry. A conducting molecularly imprinted polymer film based on polypyrrole was synthesized for the selective uptake and release of drugs. The film was prepared by incorporation of a template molecule (naproxen) during the electropolymerization of pyrrole onto a platinum electrode using cyclic voltammetry method. The measured ion mobility spectrometry intensity was related to the concentration of analytes taken up into the films. The calibration graphs (naproxen, ibuprofen, and mefenamic acid) were linear in the range of 0.1–30 ng/mL and detection limits were 0.07–0.37 ng/mL and relative standard deviation was lower than 6%. On the basis of the results obtained in this work, the conducting molecularly imprinted polymer films as absorbent have been applied in the electrochemically controlled solid‐phase microextraction and ion mobility spectrometry system for the selective clean‐up and quantification of trace amounts of anti‐inflammatory drugs in human serum samples. Scanning electron microscopy has confirmed the nano‐structure morphology of the polypyrrole film.     

Optimizing gas chromatographic-mass spectrometric analysis of selected pharmaceuticals and endocrine-disrupting substances in water using factorial experimental design

An analytical method based on gas chromatography-mass spectrometry (GC-MS) has been developed to simultaneously determine selected acidic and neutral pharmaceuticals and endocrine-disrupting substances in surface and tap water. Solid-phase extraction (SPE) with Oasis HLB cartridges is followed by derivatization of the target analytes in the eluted extract. Derivatization was systematically optimized by employing a factorial experimental design. More specifically a central composite design was applied to search for the optimal conditions of the derivatization process and it was demonstrated that N-methyl-N-tert-butyl-dimethysilyl-trifluoroacetamide (MTBSTFA) had a better overall performance compared to N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA). The influence of solvent ratios and elution volumes while using SPE were also studied using a factorial design. The method was developed successfully for most of the selected compounds [i.e. ibuprofen, salicylic acid, gemfibrozil, naproxen, triclosan, propranolol, diclofenac, carbamazepine, 4-octylphenol (OP), 4-nonylphenol (NP), nonylphenol-monoethoxylate (NP1EO), nonylphenoxyacetic acid (NP1EC), estrone (E1), and 17alpha-ethinyloestradiol (EE2)]. Relative recoveries for spiked river and tap water ranged from 47 to 130% and 60-109%, respectively. Typical limits of detection were less than 5 ng/L in tap water and less than 10 ng/L in river water. Twelve target compounds were detected in river and tap water samples using the developed method. This method is currently used in bench-scale drinking water treatment studies.     

Stereoselective determination of hydroxychloroquine and its metabolites in human urine by liquid-phase microextraction and CE

Liquid-phase microextraction based on polypropylene hollow fibers and CE were applied for the chiral determination of hydroxychloroquine (HCQ) and its metabolites (desethylchloroquine, DCQ; desethylhydroxychloroquine, DHCQ; bisdesethylchloroquine, BDCQ) in human urine. The analytes were extracted from 3 mL of urine spiked with the internal standard (metoprolol) and alkalinized with 250 muL of 2 M NaOH. The analytes were extracted into 1-octanol impregnated in the pores of the hollow fiber, and into an acid acceptor solution inside the hollow fiber. The electrophoretic separations were carried out in 100 mmol/L Tris buffer (pH adjusted to 9.0 with phosphoric acid) containing 1% w/v S-beta-CD and 30 mg/mL HP-beta-CD with a constant voltage of +18 kV. The method was linear over the concentration range of 10-1000 ng/mL for each HCQ stereoisomer and 21-333 ng/mL for each metabolite stereoisomer. Within-day and between-day assay precision and accuracy for the analytes were studied at three concentration levels for each stereoisomer and were lower than 15%. The developed method was applied for the determination of the cumulative urinary excretion of HCQ, DCQ, and DHCQ after oral administration of rac-HCQ to a health volunteer. The results obtained are in agreement with previous literature data.     

Simultaneous determination of naproxen, salicylic acid and acetylsalicylic acid by spectrofluorimetry using partial least-squares (PLS) multivariate calibration

Determination of naproxen, salicylic acid and acetylsalicylic acid has been carried out in mixtures of up to three components by recording emission fluorescence spectra between 300 and 520 nm with an excitation wavelength of 290 nm. The excitation-emission spectra of these compounds are strongly overlapped, which does not permit their direct determination without previous separation by conventional methodologies. Here, a method is proposed for the determination of these chemicals by the use of a full-spectrum multivariate calibration method, partial least-squares (PLS). The experimental calibration matrix was designed with 18 samples. The concentrations were varied between 0.1 and 1.0 mug ml(-1) for naproxen, 0.5 and 5.0 mug ml(-1) for salicylic acid and from 2.0 to 12.0 mug ml(-1) for acetylsalicylic acid. The cross-validation method was used to select the number of factors. To check the accuracy of the proposed method, the optimized model, obtained using PLS-1, was applied to the determination of these compounds in pharmaceuticals and human serum samples previously spiked with different amounts of each chemical.     

HPLC-DAD determination of plasma levels of the antipsychotic risperidone and its main metabolite for toxicological purposes

A new, rapid analytical method, based on liquid chromatography with diode array detection, has been developed and applied to the determination of risperidone and its main active metabolite 9-hydroxyrisperidone in human plasma. The chromatographic separation was obtained on a C8 (150 x 4.6 mm, 5 microm) column, using a mobile phase composed of acetonitrile (27%) and a pH 3.0 phosphate buffer (73%). A sample clean-up procedure was carried out by using C8 cartridges and eluting the analytes with methanol. The extraction yield was highly satisfactory for both analytes, with average absolute recovery values of about 95%. The experimental conditions permitted the quantitative determination of risperidone and 9-hydroxyrisperidone with high precision (RSD < 3.6%) and satisfactory sensitivity (LOQ = 4 ng mL(-1)). The method was applied to plasma samples from a patient who had tried to poison himself with 150 mg of risperidone, and was undergoing polypharmacy.     

Simultaneous determination of dipyridamole and salicylic acid in human plasma by high performance liquid chromatography-mass spectrometry

A sensitive, rapid and simple high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) method for simultaneous determination of dipyridamole and salicylic acid in human plasma has been developed and validated. After the addition of diazepam and rosiglitazone as internal standard (IS), plasma samples were prepared by liquid-liquid extraction followed by an isocratic elution with methanol:2 mM ammonium acetate buffer (pH 4.25; 70/30, v/v) on a Shimadzu VP-ODS C(18) column (5 microm, 150 x 2.0 mm I.D.). Detection was performed on a quadrupole mass spectrometer with ESI interface operating in the positive-ion mode for dipyridamole and negative-ion mode for salicylic acid. Calibration curves were linear (r(2) > 0.99) over the concentration range 10-2500 ng/mL for dipyridamole and 30-4000 ng/mL for salicylic acid with acceptable accuracy and precision, respectively. The intra- and inter-batch precisions were less than 15% of the relative standard deviation. The limits of detection of dipyridamole and salicylic acid were 1 and 15 ng/mL, respectively. The validated HPLC-ESI-MS method was successfully applied to a preliminary pharmacokinetic study of fixed-dose combination of sustained-release dipyridamole/aspirin in Chinese healthy male volunteers.     

Simultaneous determination of salicylic acid and salicylamide in biological fluids

A new methodology for the simultaneous determination of salicylic acid and salicylamide in biological fluids is proposed. The strong overlapping of the fluorescence spectra of both analytes makes impossible the conventional fluorimetric determination. For that reason, the use of fluorescence decay curves to resolve mixtures of analytes is proposed; this is a novel technique that provides the benefits in selectivity and sensitivity of the fluorescence decay curves. In order to assess the goodness of the proposed method, a prediction set of synthetic samples were analyzed obtaining recuperation percentages between 98.2 and 104.6%. Finally, a study of the detection limits was done using a new criterion resulting in values for the detection limits of 8.2 and 11.6 μg L(-1) for salicylic acid and salicylamide respectively. The validity of the method was tested in human serum and human urine spiked with aliquots of the analytes. Recoveries obtained were 96.2 and 94.5% for salicylic acid and salicylamide respectively.     

Capillary electrophoresis determination of nonsteroidal anti‐inflammatory drugs in wastewater using hollow fiber liquid‐phase microextraction

The presence of pharmaceuticals in the environment due to growing worldwide consumption has become an important problem that requires analytical solutions. This paper describes a CE determination for several nonsteroidal anti‐inflammatory drugs (ibuprofen, naproxen, ketoprofen, diclofenac, ketorolac, aceclofenac and salicylic acid) in environmental waters using hollow fiber membrane liquid‐phase microextraction. The extraction was carried out using a polypropylene membrane supporting dihexyl ether and the electrophoretic separation was performed in acetate buffer (30 mM, pH 4) using ACN as the organic modifier. Detection limits between 0.25 and 0.86 ng/mL were obtained, respectively. The method could be applied to the direct determination of the seven anti‐inflammatories in wastewaters, and five of them have been determined or detected in different urban wastewaters.     

Simultaneous determination of harpagoside and cinnamic acid in rat plasma by liquid chromatography electrospray ionization mass spectrometry and its application to pharmacokinetic studies

A simple and sensitive method was developed for the simultaneous quantification of harpagoside and cinnamic acid in rat plasma using high-performance liquid chromatography system coupled to a negative ion electrospray mass spectrometric analysis. The plasma sample preparation was a simple deproteinization by the addition of two volumes of acetonitrile. The analytes were separated on an Intersil C8-3 column (2.1 mm i.d.x250 mm, 5 microm) with acetonitrile-5 mm ammonium formate aqueous solution (60:40, v/v) as mobile phase at a flow-rate of 0.2 mL/min. Detection was performed on a quadrupole mass spectrometer equipped with electrospray ionization (ESI) source operated under selected ion monitoring (SIM) mode. [M+HCOO]- at m/z 539 for harpagoside, [M-H]- at m/z 147 for cinnamic acid and [M-H]- at m/z 137 for salylic acid (internal standard) were selected as detecting ions, respectively. The method was validated over the concentration range 7-250 ng/mL for harpagoside and 5-500 ng/mL for cinnamic acid. The lower limits of quantitation for harpagoside and cinnamic acid were 7 and 5 ng/mL, respectively. The intra- and inter-day precisions (RSD%) were within 9.5% and the assay accuracies (RE%) ranged from -5.3 to 3.0% for both analytes. Their average recoveries were greater than 86%. Both analytes were proved to be stable during all sample storage, preparation and analysis procedures. The method was successfully applied to the pharmacokinetic study of harpagoside and cinnamic acid following oral administration of Radix Scrophulariae extract to rats.     

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.     

Simple and rapid determination of the drug naproxen in pharmaceutical preparations by heavy atom-induced room temperature phosphorescence

A simple, selective and sensitive heavy atom-induced room temperature phosphorimetric method (HAI-RTP) is described for the determination of naproxen (NAP) in pharmaceutical preparations. The phosphorescence signals are a consequence of intermolecular protection when analytes are, exclusively, in presence of a heavy atom salt and sodium sulfite as an oxygen scavenger to minimize RTP quenching. These variables selection constitute the basis of a HAI-RTP method for the determination of naproxen (detection limit 17.6 ng ml(-1); 1.71% relative standard deviation at 250 ng ml(-1)). The method has been applied satisfactorily to the analysis of pharmaceutical preparations.     

Ionic liquid-based dynamic liquid-phase microextraction: application to the determination of anti-inflammatory drugs in urine samples

Dynamic liquid-phase microextraction (dLPME) using an ionic liquid as acceptor phase is proposed for the determination of six non-steroidal anti-inflammatory drugs (NSAIDs) in human urine samples for the first time. The extraction is carried out in a simple and automatic flow configuration. The chemical affinity between the extractant (1-butyl-3-methylimidazolium hexafluorophosphate) and the analytes permits a selective isolation of the drugs from the sample matrix allowing also their preconcentration. The whole analytical method has been optimized taking into account all the chemical, physical and hydrodynamic variables. The proposed method is a valuable alternative for the analysis of these drugs in urine within the concentration range 0.1-10 microg mL(-1), allowing their determination at therapeutic and toxic levels. Limits of detection were in the range from 38 ng mL(-1) (indomethacin) to 70 ng mL(-1) (naproxen). The repeatability of the proposed method expressed as RSD (n=5) varied between 2.1% (flurbiprofen) and 3.8% (tolmetin).     

Ultrasound‐assisted magnetic dispersive solid‐phase microextraction: A novel approach for the rapid and efficient microextraction of naproxen and ibuprofen employing experimental design with high‐performance liquid chromatography

A simple, rapid, and sensitive method for the determination of naproxen and ibuprofen in complex biological and water matrices (cow milk, human urine, river, and well water samples) has been developed using ultrasound‐assisted magnetic dispersive solid‐phase microextraction. Magnetic ethylendiamine‐functionalized graphene oxide nanocomposite was synthesized and used as a novel adsorbent for the microextraction process and showed great adsorptive ability toward these analytes. Different parameters affecting the microextraction were optimized with the aid of the experimental design approach. A Plackett–Burman screening design was used to study the main variables affecting the microextraction process, and the Box–Behnken optimization design was used to optimize the previously selected variables for extraction of naproxen and ibuprofen. The optimized technique provides good repeatability (relative standard deviations of the intraday precision 3.1 and 3.3, interday precision of 5.6 and 6.1%), linearity (0.1–500 and 0.3–650 ng/mL), low limits of detection (0.03 and 0.1 ng/mL), and a high enrichment factor (168 and 146) for naproxen and ibuprofen, respectively. The proposed method can be successfully applied in routine analysis for determination of naproxen and ibuprofen in cow milk, human urine, and real water samples.     

A novel chemiluminescent method for the determination of salicylic acid in bactericidal solutions

A new flow-injection procedure has been developed for the determination of salicylic acid based on the enhancement of the chemiluminescence from the cerium(IV)-Tween 20 reaction by salicylic acid in acidic medium. The method is simple, selective and sensitive with a detection limit of 2.5x10(-9) g mL(-1). It is applicable to the determination of salicylic acid in the concentration range of 4.0x10(-9)-1.1x10(-6) g mL(-1). The relative standard deviation (RSD) is 0.85% for 4.0x10(-7) g mL(-1) salicylic acid (n=11). The method has been successfully applied to the determination of salicylic acid in bactericidal solutions. Furthermore, it is suggested that light emission from cerium(IV)-Tween 20 reaction is probably because of the formation of singlet oxygen 1O2* and the emitter is excited oxygen molecular pairs O2(1delta(g))O2(1sigma(g)-).     

Resolution, quantification and confirmation of betamethasone and dexamethasone in equine plasma by liquid chromatography/tandem mass spectrometry

This method describes the simultaneous separation, identification, quantification and confirmation of betamethasone (BTM) and dexamethasone (DXM) in equine plasma by liquid chromatography (LC) integrated with multidimensional tandem mass spectrometry. Analytes were directly extracted from equine plasma by methyl tert-butyl ether (MTBE). The residues were reconstituted with sample solvent. LC separation of the analytes was performed on a Hypercarb column using acetonitrile/water/formic acid (95:5:0.5, v/v/v) as the mobile phase. Sample screening, quantification and confirmation were performed in multiple reaction monitoring (MRM) mode. The method was linear over the concentration range of 0.1-75 ng/mL for both analytes. Limit of detection (LOD) was 50 pg/mL and that of quantification (LOQ) was 100 pg/mL for both analytes. The limit of confirmation (LOC) for the presence of BTM or DXM by MRM was 0.5 ng/mL. The intra-and inter-day precisions expressed as coefficient of variation (CV) for quantification of DXM and BTM from 0.1 to 50 ng/mL were less than 7% and the accuracy was in the range of 97-105%. This method is capable of distinguishing BTM from DXM when both analytes are simultaneously present in equine plasma. Measurement uncertainty for both analytes was estimated at less than 16%. The method is rapid, specific, selective, sensitive, simple and reliable. The importance of this method is its usefulness in directly identifying and differentiating BTM from DXM without derivatization.     

Flow system exploiting multicommutation to increase sample residence time for improved sensitivity. Simultaneous determination of ammonium and ortho-phosphate in natural water

A flow system for the simultaneous determination of ammonium and phosphate in river water at the mug ml(-1) level employing a low expensive LED-based photometer is described. The manifold of the flow system comprised four analytical pathways containg a set of three-way solenoid valves and an automatic injector commutator. The signal measurements of both analytes were carried out using two LED-based photometers attached to the flow cells. A microcomputer running a programme written in quickbasic 4.5 provided facilities to control the system and to carry out simultaneously two analytical procedures also performing data acquisition. For the determination of ortho-phosphate the method based on reaction with molybdate and ascorbic acid was employed, while for ammonium the method based on reaction with hypochlorite and salicylic acid was selected. The four-pathway structure of the manifold allowed the sample incubation time to be increased to 130 s to permit the reaction to occur without a decrease in sample throughput. The usefulness of the system was ascertained by analyzing a set of water samples. Applying the paired t-test to results obtained employing reference methods, no significant difference at the 95% confidence level was observed for both analytes. Other profitable features such as an analytical throughput of 112 analyte determination per hour; relative standard deviations of 1.1 and 0.7% (n=6) ammonium and phosphate, respectively, reagent consumption of 0.3 mg ammonium molybdate, 0.75 mg salicylic acid, 3.3 mg ascorbic acid and sodium hypochlorite per determination; detection limits of 7.0 mug l(-1) NH(4)(+) and 17.0 mug l(-1) PO(4)(3-) were also achieved.     

Gas chromatographic-tandem mass spectrometric method for the quantitation of carbofuran, carbaryl and their main metabolites in applicators' urine

A new gas chromatographic-tandem mass spectrometric method has been developed and validated for the determination of two N-methylcarbamates, carbofuran and carbaryl and their metabolites in applicators' urine specimens. Mild conditions were used for sample preparation based on enzymic hydrolysis and solid-phase extraction using Oasis HLB sorbent cartridges. Amides, phenols and ketones were first converted to volatile derivatives of trifluoroacetic acid anhydride (TFAA) and afterwards were quantitated using tandem mass spectrometry. Linear calibration equations (1-200 ng mL(-1) urine) were obtained from fortified urine samples for all eight compounds, carbaryl, 1-naphthol, 2-naphthol, and carbofuran, 3-hydroxycarbofuran, 7-phenol, carbofuran-3-keto, 3- hydroxycarbofuranphenol. For all compounds, the limit of detection was lower than 0.1 ng mL(-1). Precision for all compounds, at the concentrations of 1, 10 and 100 ng mL(-1) (n = 5) in-fortified urine samples ranged from 0.7% to 18%. Accuracy was calculated at two concentrations 8 and 80 ng mL(-1) (n = 5) and ranged from -8.4% to 8.2%. Relative recoveries at concentrations of 1, 10 and 100 ng mL(-1), ranged from 71% to 116%. The method was successfully applied to five male applicators and 10 non-applicators (including both smokers and non-smokers).     

A solid phase extraction method for the screening and determination of pyrethroid metabolites and organochlorine pesticides in human urine.

A screening method has been developed for the determination of 23 organochlorine pesticides (OCPs) and 3-pyrethroid metabolities [cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid, cis-3-(2,2-dibromovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid and 3-phenoxybenzoic acid] from human urine. OCPs were directly detected in urine samples while pyrethroid metabolites required acid-induced hydrolysis to convert their conjugates into free acids; all compounds were then cleaned-up/preconcentrated using solid phase extraction. Determination and quantitation was achieved by gas chromatography with a mass spectrometer detector operating in selected ion monitoring mode. Limits of detection varied between 0.1 and 0.3 ng/mL with linear ranges from 0.3 to 700 ng/mL; the precision of the method was high (4.3-7.2%). Recoveries of all analytes from urine samples fortified at levels of 30 ng/mL for each OCP and 15 ng/mL for each pyrethroid metabolite ranged from 88 to 101% (captan gave the lowest recovery). The results obtained from the analysis of real urine samples show the suitability of the proposed method for monitoring people exposed to organochlorine and pyrethroid pesticides.