Extractive ethoxycarbonylation in high-temperature gas chromatography-mass spectrometry based analysis of serum estrogens

A comprehensive gas chromatography-mass spectrometry (GC-MS)-based profiling was developed as a practical assay for quantification of 18 endogenous estrogens in serum samples. The present GC-MS method was conducted with the two-phase extractive ethoxycarbonlyation (EOC) of the phenolic hydroxy groups of estrogen with ethyl chlorformate combined with the non-polar n-hexane extraction. The subsequent perfluoroacylation of aliphatic hydroxy groups with pentafluoropropionyl anhydride (PFPA) was conducted. The serum samples were separated through a high temperature GC column (MXT-1) within an 8-min run and analyzed in selected-ion monitoring mode with good chromatographic properties for 18 estrogens as their EOC-PFP derivatives. The limit of quantification (LOQ) was 0.025-0.10 ng/mL for most estrogens analyzed except for E3 and 2-OH-E3 (0.5 ng/mL each). The devised method was found to be linear over a 10(3)-fold concentration range with a correlation coefficient (r(2)>0.992), whereas the precision (% CV) and accuracy (% bias) ranged from 3.1 to 16.3% and from 93.5 to 111.1%, respectively. Decreased 2-methoxy-17β-estradiol levels were confirmed in patients with preeclampsia than healthy pregnant women. This technique can be used for a clinical diagnosis as well as understanding the pathogenesis in estrogen-related disorders.     

Highly sensitive determination of estrone and estradiol in human serum by liquid chromatography-electrospray ionization tandem mass spectrometry

A highly sensitive and specific quantification method of estrone and estradiol in human serum was described based upon the use of picolinoyl derivatization and liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) in a positive mode. Estrogens were treated with picolinoyl chloride hydrochloride or picolinic acid and 2-methyl-6-nitrobenzoic anhydride followed by a solid-phase extraction with ODS cartridge. Picolinoyl derivatization proceeded quantitatively even in a microscale, and the picolinoyl esters provided simple positive ESI-mass spectra showing [M+H](+) as base peaks for these estrogens. The picolinoyl derivatives of these estrogens showed 100-fold higher detection response compared to underivatized intact molecules by LC-ESI-MS (selected reaction monitoring). Using this derivatization, estrogens spiked in the charcoal treated human serum samples were analyzed with limit of quantification (LOQ), intra-day accuracy and precision of 1.0pg/ml, 96.0% and 9.9% for estrone, and 0.5pg/ml, 84.4% and 12.8% for estradiol, respectively. Estrone and estradiol added to the crude serum samples were recovered with comparable LOQ and accuracy obtained for the charcoal treated serum samples as well.     

Determination of N,N-dimethyltryptamine and beta-carboline alkaloids in human plasma following oral administration of Ayahuasca

Ayahuasca is a South American psychotropic beverage prepared from plants native to the Amazon River Basin. It combines the hallucinogenic agent and 5-HT(2A/2C) agonist N,N-dimethyltryptamine (DMT) with beta-carboline alkaloids showing monoamine oxidase-inhibiting properties. In the present paper, an analytical methodology for the plasma quantification of the four main alkaloids present in ayahuasca plus two major metabolites is described. DMT was extracted by liquid-liquid extraction with n-pentane and quantified by gas chromatography with nitrogen-phosphorus detection. Recovery was 74%, and precision and accuracy were better than 9.9%. The limit of quantification (LOQ) was 1.6 ng/ml. Harmine, harmaline, and tetrahydroharmine (THH), the three main beta-carbolines present in ayahuasca, and harmol and harmalol (O-demethylation metabolites of harmine and harmaline, respectively) were measured in plasma by means of high-performance liquid chromatography (HPLC) with fluorescence detection. Sample preparation was accomplished by solid-phase extraction, which facilitated the automation of the process. All five beta-carbolines were measured using a single detector by switching wavelengths. Separation of harmol and harmalol required only slight changes in the chromatographic conditions. Method validation demonstrated good recoveries, above 87%, and accuracy and precision better than 13.4%. The LOQ was 0.5 ng/ml for harmine, 0.3 ng/ml for harmaline, 1.0 ng/ml for THH, and 0.3 ng/ml for harmol and harmalol. Good linearity was observed in the concentration ranges evaluated for DMT (2.5-50 ng/ml) and the beta-carbolines (0.3-100 ng/ml). The gas chromatography and HPLC methods described allowed adequate characterization of the pharmacokinetics of the four main alkaloids present in ayahuasca, and also of two major beta-carboline metabolites not previously described in the literature.     

Simultaneous determination of lansoprazole enantiomers and their metabolites in plasma by liquid chromatography with solid-phase extraction

A simple and highly sensitive high-performance liquid chromatography (HPLC) method for the simultaneous quantitative determination of lansoprazole enantiomers and their metabolites, 5-hydroxylansoprazole enantiomers and lansoprazole sulfone, in human plasma have been developed. Chromatographic separation was achieved with a Chiral CD-Ph column using a mobile phase of 0.5M NaClO(4)-acetonitrile-methanol (6:3:1 (v/v/v)). The analysis required only 100 microl of plasma and involved a solid-phase extraction with Oasis HLB cartridge, with a high extraction recovery (>94.1%) and good selectivity. The lower limit of quantification (LOQ) of this assay was 10 ng/ml for each enantiomer of both lansoprazole and 5-hydroxylansoprazole, and 5 ng/ml for lansoprazole sulfone. The coefficient of variation of inter- and intra-day assay was <8.0% and accuracy was within 8.4% for all analytes (concentration range 10-1000 ng/ml). The linearity of this assay was set between 10 and 1000 ng/ml (r2>0.999 of the regression line) for each of the five analytes. This method is applicable for accurate and simultaneous monitoring of the plasma levels of lansoprazole enantiomers and their metabolites in the renal transplant recipients.     

Quantification of steroid glycosides from Hoodia gordonii in porcine plasma using high performance liquid chromatography-mass spectrometry

An HPLC-ESI-MS/MS method using collision induced dissociation - multiple reaction monitoring was developed for the quantification of eight Hoodia gordonii steroid glycosides and their metabolites in porcine plasma samples. The method was validated for the three most important glycosides and was successfully applied also for the related glycosides and metabolites. The limits of quantification were 0.04 ng ml(-1) for the two main steroid glycosides and 0.1 ng ml(-1) for the detiglated metabolites. These limits are sufficiently low to allow monitoring the concentration-time profiles in plasma after feeding H. gordonii. The standard deviations of the intra-day measurements were better than 20% for concentrations below 5 ng ml(-1) and better than 10% for concentrations above 5 ng ml(-1). The method was successfully applied to plasma samples collected from a porcine pharmacokinetics study.     

Sensitive quantification of omeprazole and its metabolites in human plasma by liquid chromatography-mass spectrometry

A sensitive method was developed for the simultaneous determination of omeprazole and its major metabolites 5-hydroxyomeprazole and omeprazole sulfone in human plasma by HPLC-electrospray mass spectrometry. Following liquid-liquid extraction HPLC separation was achieved on a ProntoSil AQ, C18 column using a gradient with 10 mM ammonium acetate in water (pH 7.25) and acetonitrile. The mass spectrometer was operated in the selected ion monitoring mode using the respective MH(+) ions, m/z 346 for omeprazole, m/z 362 for 5-hydroxy-omeprazole and omeprazol-sulfone and m/z 300 for the internal standard (2-{[(3,5-dimethylpyridine-2-yl)methyl]thio}-1H-benzimidazole-5-yl)methanol. The limit of quantification (LOQ) achieved with this method was 5 ng/ml for 5-hydroxyomeprazole and 10 ng/ml for omeprazole and omeprazole-sulfone using 0.25 ml of plasma. Intra- and inter-assay variability was below 11% over the whole concentration range from 5 to 250 ng/ml for 5-hydroxyomeprazol and from 10 to 750 ng/ml for omeprazole and omeprazole-sulfone. The method was successfully applied to the determination of pharmacokinetic parameters of esomeprazole and the two major metabolites after a single dose and under steady state conditions.     

Simultaneous determination of major B-trichothecenes and the de-epoxy-metabolite of deoxynivalenol in pig urine and maize using high-performance liquid chromatography-mass spectrometry

A selective analytical method based on high-performance liquid chromatography (HPLC), combined with atmospheric pressure chemical ionisation (APCI-) mass spectrometry (MS), has been developed for simultaneous determination of B-trichothecenes and the major metabolites of deoxynivalenol. The method allows simultaneous analysis of nivalenol (NIV), deoxynivalenol (DON), 15-acetyldeoxynivalenol (15-AcDON), 3-acetyldeoxynivalenol (3-AcDON), fusarenon X (Fus-X) and de-epoxydeoxynivalenol (DOM-1). The method is based on one-step sample clean-up using a multifunctional MycoSep column. A linear gradient mobile phase system, consisting of water:acetonitrile:methanol (H2O:ACN:MeOH) at a flow-rate of 1 ml/min, and a Polar-RP C18 column, were utilised to obtain the best resolution of all tested compounds along with column and equilibrating within 30 min. Dexamethasone (Dex) was used as internal standard. The developed method shows good repeatability for inter- and intra-day precisions as well as good linearity of calibration curves (r2 ranged from 0.9936 to 0.9998). Average recoveries for tested compounds in both matrices have been determined ranging from 63.7 to 102.3% and limit of quantification (LOQ) ranged from 25 to 150 ng/g. The utility and practical impact of the method is demonstrated using contaminated pig urine and maize samples.     

Determination of amiodarone and desethylamiodarone in horse plasma and urine by high-performance liquid chromatography combined with UV detection and electrospray ionization mass spectrometry

A rapid method for the quantification of amiodarone and desethylamiodarone in animal plasma using high-performance liquid chromatography combined with UV detection (HPLC-UV) is presented. The sample preparation includes a simple deproteinisation step with acetonitrile. In addition, a sensitive method for the quantification of amiodarone and desethylamiodarone in horse plasma and urine using high-performance liquid chromatography combined with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) is described. The sample preparation includes a solid-phase extraction (SPE) with a SCX column. Tamoxifen is used as an internal standard for both chromatographic methods. Chromatographic separation is achieved on an ODS Hypersil column using isocratic elution with 0.01% diethylamine and acetonitrile as mobile phase for the HPLC-UV method and with 0.1% formic acid and acetonitrile as mobile phase for the LC-MS/MS method. For the HPLC-UV method, good linearity was observed in the range 0-5 microg ml(-1), and in the range 0-1 microg ml(-1) for the LC-MS/MS method. The limit of quantification (LOQ) was set at 50 and 5 ng ml(-1) for the HPLC-UV method and the LC-MS/MS method, respectively. For the UV method, the limit of detection (LOD) was 15 and 10 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The LODs of the LC-MS/MS method in plasma were much lower, i.e. 0.10 and 0.04 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The LODs obtained for the urine samples were 0.16 and 0.09 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The methods were shown to be of use in horses. The rapid HPLC-UV method was used for therapeutic drug monitoring after amiodarone treatment, while the LC-MS/MS method showed its applicability for single dose pharmacokinetic studies.     

Determination of di(2-ethylhexyl)phthalate and mono(2-ethylhexyl)phthalate in human serum using liquid chromatography-tandem mass spectrometry

Concentrations of mono(2-ethylhexyl)phthalate (MEHP), and di(2-ethylhexyl)phthalate (DEHP), in serum of healthy volunteers were determined by high performance liquid chromatography (HPLC) with tandem mass spectrometry (LC/MS/MS). The serum was extracted with acetone, followed by hexane extraction under acidic conditions, and then applied to the LC/MS/MS. Recoveries of 20 ng/ml of MEHP and DEHP were 101+/-5.7 (n=6) and 102+/-6.5% (n=6), respectively. The limits of quantification (LOQ) of MEHP and DEHP in the method were 5.0 and 14.0 ng/ml, respectively. The concentration of MEHP in the serum was at or less than the LOQ. The concentration of DEHP in the serum was less than the LOQ. Contaminations of MEHP and DEHP from experimental reagents, apparatus and air during the procedure were less than the LOQ and were estimated to be <1.0 and 2.2+/-0.6 ng/ml, respectively. After subtraction of the contamination, the net concentrations of MEHP and DEHP in the serum were estimated at or <5 and <2 ng/ml, respectively. To decrease contamination by DEHP, the cleanup steps and the apparatus and solvent usage were minimized in the sample preparation procedures. The high selectivity of LC/MS/MS is the key for obtaining reliable experimental data from in the matrix-rich analytical samples and for maintaining a low level contamination of MEHP and DEHP in this experimental system. This method would be a useful tool for the detection of MEHP and DEHP in serum.     

Determination of methylnaltrexone in clinical samples by solid-phase extraction and high-performance liquid chromatography for a pharmacokinetics study

A high-performance liquid chromatographic (HPLC) method with electrochemical detection and solid-phase extraction (SPE) using cartridges of weak cation-exchange capacity as the primary retention mechanism is described for the separation and determination of methylnaltrexone (MNTX) in small clinical samples of plasma or urine. The procedure was performed using a Phenomenex Prodigy ODS-2, 5 microm, 150x3.2 mm analytical column and 50 mM potassium acetate buffer, with 11% methanol as organic modifier at pH* 4.5 at a flow-rate of 0.5 ml/min. The detection potential was 700 mV. The six-point standard calibration curves were linear over three consecutive days in the range from 2 to 100 ng/ml. The average goodness of fit (r) was 0.9993. The lower limit of detection (LOD) and limit of quantification (LOQ) were found to be 2.0 and 5.0 ng/ml, respectively. At the LOQ, the coefficient of variation for the entire method was 8.0% and the accuracy was 10.0% (n = 10). Recovery of the drug from plasma was in the region of 94%. The method was applied to a pharmacokinetics study of methylnaltrexone after subcutaneous administration and in numerous assays of analytes in blood plasma and urine. The pharmacokinetics parameters for a single dose of 0.1 or 0.3 mg/kg in plasma were C(max) = 110 (+/-55) and 287 (+/-101) ng/ml and t(max) = 16.7 (+/-10.8) and 20.0 (+/-9.5) min, respectively. The method is simple, yet sensitive for the detection and determination of methylnaltrexone in biological samples at the level of the physiological response.     

Improved and validated method for the determination of Delta(9)-tetrahydrocannabinol (THC), 11-hydroxy-THC and 11-nor-9-carboxy-THC in serum,and in human liver microsomal preparations using gas chromatography-mass spectrometry

A validated method for the quantification of Delta(9)-tetrahydrocannabinol (THC) and its main metabolites 11-hydroxy-tetrahydrocannabinol (OH-THC) and 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH) in serum is presented. The substances were isolated by solid-phase extraction, derivatised by methylation, and analysed by means of GC-MS in the selected ion monitoring mode. Quantitation was achieved by the addition of deuterated analogues as internal standards. The method was linear up to 10 ng/ml for THC and OH-THC, and up to 50 ng/ml for THC-COOH. The limits of quantification were 0.62 ng/ml for THC, 0.68 ng/ml for OH-THC and 3.35 ng/ml for THC-COOH. The limits of detection for the least intensive ions were 0.52 ng/ml for THC, 0.49 ng/ml for OH-THC and 0.65 ng/ml for THC-COOH. The method was validated according to the requirements of the Journal of Chromatography B. The method has been routinely used on samples from drivers suspected of "driving under the influence". In addition to the forensic application, a cross-validation was carried out by applying the method developed for serum to human liver microsomal preparation samples.     

High-throughput selected reaction monitoring liquid chromatography-mass spectrometry determination of methylphenidate and its major metabolite,ritalinic acid,in rat plasma employing monolithic columns

This work presents a high-throughput selected reaction monitoring (SRM) LC-MS method for the determination of methylphenidate (MPH), a central nervous stimulant, and its de-esterified metabolite, ritalinic acid (RA) in rat plasma samples. A separation of these two compounds was achieved in 15 s by employing a 3.5-ml/min flow-rate, a porous monolithic column and a TurboIonSpray source compatible with relatively high flow-rates. In addition, a relatively fast autosampler and a new data acquisition system resulted in a time lag of less than 17 s between consecutive injections. Overall, 768 protein-precipitated rat plasma samples (eight 96-well plates) containing both MPH and RA were analyzed within 3 h and 45 min. The partial method validation described in this report included an assessment of linearity, intra and inter-assay precision and accuracy, and method robustness. Deuterated internal standards for the target compounds, d(3)-MPH and d(5)-RA, were employed. The calibration curves ranged from 0.1 to 50 ng/ml for MPH and from 0.5 to 50 ng/ml for RA. The limit of quantification (LOQ) for MPH and RA was 0.1 and 0.5 ng/ml, respectively. For both analytes, the intra- and inter-assay precision (relative standard deviation, % C.V.) and accuracy (relative error) did not exceed 15% for the quality control samples (QCs) QC1, QC2 or QC3 (0.3, 1.5 and 40 ng/ml for MPH and 0.15, 15 and 40 ng/ml for RA) for either analyte and did not exceed 20% at the lower limit of quantitation (LOQ) level. No carry-over from the autosampler was detected. The retention times remained constant throughout the experiment. Baseline resolution of MPH and RA was consistently observed throughout the plates analyzed. The described method demonstrates the feasibility for employing monolithic HPLC columns to effect rapid bioanalytical SRM LC-MS analysis of representative biological samples.     

Routine and sensitive method for determination of nicorandil in human plasma developed for liquid chromatography with ultraviolet and m0ass spectrometric detection

A rapid and sensitive method using HPLC has been developed for the quantification of nicorandil (SG-75) in human plasma samples for routine bioequivalence studies. The sample preparation needs two liquid–liquid extractions, first with CH₃Cl and HClO₄ as denaturation reagent and second with addition of ethyl acetate and Na₂CO_3(aq). Detection wavelength was 256 nm. The obtained correlation coefficient for weighted linear curve in the range from 5.0 to 300 ng/ml was higher than 0.9950. The limit of quantitation (LOQ) was established at 5.0 ng/ml. The HPLC separation was accomplished on Nucleosil Phenyl (5 μm) stainless steel column within 7 min. The mixture of 0.01 M ammonium acetate buffer (pH 6.2) and acetonitrile 10:3 (v/v) was used as the mobile phase. The same separation method was examined on HPLC–MS system. Using this system, the LOQ was established at 1.0 ng/ml and the linearity was obtained in the range from 1.0 to 150 ng/ml.     

Solid-phase micro-extraction-gas chromatography-mass spectrometry and headspace-gas chromatography of tetrahydrocannabinol,amphetamine, methamphetamine,cocaine and ethanol in saliva samples

In the present work, a method was developed aiming at the serial detection of tetrahydrocannabinol (THC), amphetamine, methamphetamine, cocaine and ethanol in saliva. Saliva samples were submitted to an initial headspace procedure for ethanol determination by gas chromatography/flame ionization detector (GC-FID). After this step, two consecutive solid-phase micro-extractions (SPME) were carried out: THC was extracted by submersing a polydimethylsiloxane fiber (100 micro m) in the vial for 20 min; amphetamine, methamphetamine and cocaine were subsequently extracted after alkalinization. Derivatization of the amphetamines was carried out directly in the solution by adding 2 micro l of butylchloroformate. Gas chromatography-mass spectrometry (GC-MS) was used to identify the analytes in selected ion monitoring (SIM) mode. Confidence parameters of validation of the method were: recovery, linearity, intra- and inter-assay precision as well as limits of detection and quantification of the analytes. The limits of quantification (LOQ) obtained were: ethanol (0.010 g/l); amphetamine (5.0 ng/ml); methamphetamine (0.5 ng/ml); cocaine (5 ng/ml) and THC (5 ng/ml). The method proved to be highly precise (coefficient of variation<8%) for all detected substances.     

Simultaneous quantification of alprazolam, 4- and alpha-hydroxyalprazolam in plasma samples using liquid chromatography mass spectrometry

A sensitive and specific method was developed for quantification of alprazolam and its two metabolites 4-hydroxyalprazolam and alpha-hydroxyalprazolam in plasma. The work up procedure was solid phase extraction. Liquid chromatography-mass spectrometry (LC-MS) was used for separation, detection and quantification of the analytes. The limit of quantitation (LOQ) was 0.05 ng/mL for alprazolam and the two metabolites. The extraction recovery was more than 82% for alprazolam and its metabolites. The within- and between-assay coefficients of variation were in the range of 1.9-17.9%. The method was used for determination of the pharmacokinetics parameters of alprazolam and its two metabolites in healthy Caucasian subjects who ingested 1mg of alprazolam.     

Development and validation of column-switching high-performance liquid chromatographic methods for the determination of a potent AII receptor antagonist, TCV-116, and its metabolites in human serum and urine

Column-switching HPLC methods have been developed and validated for the determination of a new antihypertensive prodrug, TCV-116 (I), and its metabolites, CV-11974 (II) and CV-15959 (III), in human serum and urine. Initial sample cleanup was achieved by extracting the analytes into an organic solvent. After chromatographing on an ODS column with a mobile phase consisting of acetonitrile and an acidic phosphate buffer, the zone of the analyte's retention was heart-cut onto a second ODS column with a mobile phase of acetonitrile and a phosphate buffer at a higher pH. Complete separation of the analytes and the endogenous peaks was accomplished by the two-dimensional chromatography. Good precision and linearity of the calibration standards, as well as the inter-day and intra-day precision and accuracy of quality control samples, were achieved. The limit of quantitation (LOQ), using 0.5 ml of serum, was 2 ng/ml for I, 0.8 ng/ml for II, and 0.5 ng/ml for III. The LOQ for urine sample was 10 ng/ml for II and III. Stability of the analytes during storage, extraction, and chromatography processes was established. The results illustrate the versatile application of column switching to method development of multiple analytes in various biological matrices. The methods have been successfully used for the analyses of I and its metabolites in thousands of clinical samples to provide pharmacokinetics data.     

Analysis of amphetamines and metabolites in urine with ultra performance liquid chromatography tandem mass spectrometry

A simple, rapid and sensitive ultra performance liquid chromatography tandem mass spectrometry method was developed and fully validated for the quantitative determination of seven amphetamines and metabolites in urine. The method was validated for selectivity, linearity, LOQ, LOD, imprecision, bias, analyte and processed sample stability, matrix effect, recovery, carryover and dilution integrity. A classic liquid–liquid extraction with ethyl acetate was used as sample preparation procedure. The compounds were separated on an Acquity UPLC HSS C₁₈ column in 6.8 min. The linear dynamic range was established from 25 to 500 ng/mL. The limit of quantification was fixed to the lowest calibrator level and the limit of detection ranged from 0.125 to 2.5 ng/mL. The method presented an excellent intra- and inter-assay imprecision and bias (<10.7%) at each measured concentration of two external quality controls (QC) and three “in house” QC. No matrix effects were observed and good recoveries (>70%) were obtained for all the compounds. No carryover was observed after the analysis of high concentrated samples (8000 ng/mL). The method was subsequently applied to authentic samples.     

Determination of menthol in plasma and urine of rats and humans by headspace solid phase microextraction and gas chromatography--mass spectrometry

A method for the determination of menthol and menthol glucuronide (M-G) after enzymatic hydrolysis in plasma and urine of rats and humans was developed using headspace solid phase microextraction and gas chromatography-mass spectrometry in the selected ion monitoring mode (HS-SPME/GC-MS). The assay linearity for plasma ranged from 5 to 1000 ng/ml. The limit of quantification (LOQ) in plasma was 5 ng/ml. The intra- and inter-day precision for menthol and M-G were < or = 18.1% R.S.D. at the LOQ and < or = 4.0% at higher concentrations. Menthol and M-G were determined in rat and human plasma and urine after administration of menthol.     

Determination of metformin in human plasma by high-performance liquid chromatography

A simple, selective and sensitive high-performance liquid chromatographic method with spectrophotometric detection was developed for the determination of antihyperglycemic agent metformin in human plasma using a novel sample extraction procedure. Liquid-liquid extraction of metformin and ranitidine (as internal standard) from plasma samples was performed with 1-butanol/n-hexane (50:50, v/v) in alkaline condition followed by back-extraction into diluted acetic acid. Chromatography was carried out using a silica column (250 mmx4.6 mm, 5 microm) under isocratic elution with acetonitrile-40 mM aqueous sodium dihydrogen phosphate (25:75, v/v), pH 6. The limit of quantification (LOQ) was 15.6 ng/ml and the calibration curves were linear up to 2000 ng/ml. The mean absolute recoveries for metformin and internal standard using the present extraction procedure were 98 and 95%, respectively. The intra- and inter-day coefficient of variation and percent error values of the assay method were all less than 8.3%.     

Rapid analytical method for the determination of 220 pesticide with their isomers by GCMS-TIC

This paper presents a cost-effective and validated multi residue modified and miniaturized method for the determination of 220 chemically different groups of pesticides and their isomers. This determination method is performed with single Quaid Gas Chromatography Mass Spectrometry -Total Ion Chromatogram GCMS-TIC. Two methods was experimented and modified with different GCMS parameters to analyses most common used pesticide and their residues in the standers solution and can be applied for real environmental samples. The results showed by single Quaid GCMS-TIC it can analyze 220 pesticides including their isomers within 49.6 min and low detection limit by using modified method 2 as described in this research. Limit of detection (LOD) was ranged from 0.78 to 14.74 ng/ml (ppb) with good separation and resolution. Limit of quantification (LOQ) was ranged between 2.34 and 44.22 ng/ml (ppb). Method 2 was more accurate, shorter, and clear separation rather than method 1. This method can be successfully applied in real environmental samples proven to be a good option for routine analysis of pesticide within the maximum residue limits (MRL) referenced to European commission especially with the most common GCMS-TIC which exists in most of labs and low income countries.