Rapid determination of three anticoagulant rodenticides in whole blood by liquid chromatography coupled with electrospray ionization mass spectrometry

A rapid, sensitive and selective method for the simultaneous determination of bromadiolone, flocoumafen and brodifacoum in whole blood using warfarin as internal standard (IS) by high-performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC/ESI-MS) has been developed and validated. The target compounds were extracted from the whole blood with ethyl acetate and separated on an XDB C18 column (150 mm x 2.1 mm i.d. x 5 microm) by using a mobile phase consisting of 0.2% acetic acid/methanol (12/88, v/v) at a constant flow rate of 0.50 mL/min. The analytes were detected using negative ESI-MS in the selected ion monitoring (SIM) mode. The molecular ions [M-H]- of m/z 527, 541,523 and 307 were selected for the quantification for bromadiolone, flocoumafen, brodifacoum and the IS, respectively. The calibration curves were linear (r2 > 0.995) in the concentration range of 0.50-100.00 ng/mL. The method showed a satisfactory sensitivity (0.05-0.5 ng/mL using 200 microL blood), precision (RSD < 11.9%), accuracy (recovery: 82.0-96.1%) and selectivity. This method was successfully applied to the determination of the analytes for the diagnoses of poisoned human beings and animals.     

Liquid chromatography/electrospray ionization mass spectrometry method for the quantification of valproic acid in human plasma

A simple, sensitive and rapid liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) method was developed and validated for the quantification of valproic acid, an antiepileptic drug, in human plasma using benzoic acid as internal standard (IS). Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase C18 column and analyzed by MS in the single ion monitoring mode using the respective [M-H]- ions, m/z 143 for valproic acid and m/z 121 for the IS. The assay exhibited a linear dynamic range of 0.5-60 microg/mL for valproic acid in human plasma. The lower limit of quantification was 500 ng/mL with a relative standard deviation of less than 10%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The average absolute recoveries of valproic acid and the IS from spiked plasma samples were 96.1+/-4.2 and 95.6+/-2.7%, respectively. A run time of 4.5 min for each sample made it possible to analyze more than 250 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability and bioequivalence studies.     

Simultaneous quantification of oxysophocarpine and its active metabolite sophocarpine in rat plasma by liquid chromatography/mass spectrometry for a pharmacokinetic study

A sensitive, rapid and specific method for the simultaneous quantification of oxysophocarpine (OSC) and its active metabolite sophocarpine (SC) in rat plasma was developed and validated, using a liquid-liquid extraction procedure followed by liquid chromatography/electrospray ionization mass spectrometric (LC/ESI-MS) analysis. The separation was performed on a Zorbax Extend-C(18) column (2.1 mm i.d. x 50 mm, 5 microm) with a C(18) guard column using methanol-water containing 5 mm ammonium acetate (15:85, v/v) as mobile phase. Analysis was performed in selected ion monitoring (SIM) mode with an electrospray ionization (ESI) interface. [M + H](+) at m/z 263 for OSC, [M + H](+) at m/z 247 for SC and [M + H](+) at m/z 249 for matrine (internal standard) were selected as detecting ions, respectively. The method was linear in the concentration ranges 10-1000 ng/mL for OSC and 5-500 ng/mL for SC. The intra- and inter-day precisions (coefficient of variation) were within 7% for both analytes. Their accuracy (relative error) ranged from -6.4 to 1.5%. The limits of detection for OSC and SC were 3 and 1.5 ng/mL, respectively. The limits of quantitation for OSC and SC were 10 and 5 ng/mL, respectively. Recoveries of both analytes were greater than 85% at the low, medium and high concentrations. Both analytes were stable during all sample storage, preparation and analytic procedures. The method was successfully applied to a pharmacokinetic study after an oral administration of OSC to rats with a dose of 15 mg/kg.     

Determination of aranidipine and its active metabolite in human plasma by liquid chromatography/negative electrospray ionization tandem mass spectrometry

A simple, sensitive and rapid high-performance liquid chromatography/negative electrospray ionization tandem mass spectrometry method was developed and validated for the assay of aranidipine (AR) and its active metabolite (AR-M) in human plasma. Following a liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective [M-H]- ions, m/z 387.0 --> 164.0 for AR, m/z 389.1 --> 208.1 for AR-M and m/z 359.0 --> 121.8 for the internal standard. The assay exhibited a linear dynamic range of 0.02-10 ng x mL(-1) for AR and 0.2-100 ng x mL(-1) for AR-M in human plasma. The limits of quantitation were 0.02 ng x mL(-1) for AR and 0.2 ng x mL(-1) for AR-M. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.8 min for each sample exhibited its high-throughout analysis ability. The validated method can be applied to analyze human plasma samples for pharmacokinetic studies.     

Liquid chromatography/negative ion electrospray tandem mass spectrometry method for the quantification of fluvastatin in human plasma: validation and its application to pharmacokinetic studies

A simple, sensitive and rapid high-performance liquid chromatography/negative ion electrospray tandem mass spectrometry method was developed and validated for the assay of fluvastatin in human plasma. Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective [M-H]- ions, m/z 410/348 for fluvastatin and m/z 480/418 for the internal standard. The assay exhibited a linear dynamic range of 2-500 ng/mL for fluvastatin in human plasma. The lower limit of quantification was 2 ng/mL with a relative standard deviation of less than 5%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 1.5 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.     

Simultaneous quantification of chlorogenic acid and caffeic acid in rat plasma after an intravenous administration of mailuoning injection using liquid chromatography/mass spectrometry

A simple, rapid and sensitive method was developed for the simultaneous quantification of chlorogenic acid (CGA) and caffeic acid (CA) in rat plasma using a 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 followed by centrifugation. The analytes and internal standard ferulic acid were separated on an Intersil C8-3 column (5 mm; 250 x 2.1 mm) with acetonitrile/0.05% triethylamine solution (70:30, v/v) as mobile phase at a flow rate of 0.2 mL/min with an operating temperature of 30 degrees C. Detection was performed on a quadrupole mass spectrometer equipped with an electrospray ionization (ESI) source operated in selected ion monitoring (SIM) mode. Negative ion ESI was used to form deprotonated molecules at m/z 353 for chlorogenic acid, m/z 179 for caffeic acid, and m/z 193 for the internal standard ferulic acid. Linear detection responses were obtained for CGA concentrations ranging from 0.005 to 2.0 microg/mL and for CA concentrations ranging from 0.010 to 2.0 microg/mL and the lower limits of quantitation (LLOQs) for CGA and CA were 0.005 and 0.01 microg/mL, respectively. The intra- and inter-day precisions (RSD%) were within 9.0% for both analytes. Deviation of the assay accuracies was within +/-10.0% for both analytes. Their average recoveries were greater than 88.0%. Both analytes were proved to be stable during all sample storage, preparation and analytic procedures. The method was successfully applied to the pharmacokinetic study of CGA and CA following an intravenous dose of 5 mL/kg mailuoning injection to rats.     

Quantification of trandolapril and its metabolite trandolaprilat in human plasma by liquid chromatography/tandem mass spectrometry using solid-phase extraction

A sensitive high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (MS/MS) method was developed and validated for the simultaneous quantification of trandolapril and its metabolite trandolaprilat in human plasma using ramipril as an internal standard. Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M-H]- ions, m/z 429/168 for trandolapril, m/z 401/168 for trandolaprilat and m/z 415/166 for the internal standard. The method exhibited a linear dynamic range of 20-10,000 pg/mL for both trandolapril and trandolaprilat in human plasma. The lower limit of quantification was 20 pg/mL for both trandolapril and its metabolite. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.0 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.     

Naturally occurring glucosinolates in plant extracts of rocket salad (Eruca sativa L.) identified by liquid chromatography coupled with negative ion electrospray ionization and quadrupole ion-trap mass spectrometry

A method for the comprehensive profiling of intact glucosinolates (GLSs), major and minor, occurring in leaves and seeds of rocket salad (Eruca sativa L.) is presented using optimized reversed-phase liquid chromatography (RP-LC) with electrospray ionization (ESI) ion trap mass spectrometry (ITMS). ESI-ITMS in the negative mode was confirmed to be very suitable to analyze these compounds in crude extracts. After extraction from the plant material with methanol/water (70:30 v/v) at 70 degrees C, the analytes of interest were separated on a C18 column using an eluent acidified with formic acid (0.1%) and modified with acetonitrile. All the GLSs found in leaves of rocket salad gave good signals corresponding to the deprotonated precursor ion, [M-H]-. Although the mass spectra also exhibited an analytically important non-covalent adduct ion at [2M-H]-, the structures of glucosinolates were confirmed by extensive sequential MS analysis, thereby substantially improving the identification of unknown compounds. The results obtained not only revealed in leaves of E. sativa at least twelve species of GLSs including seven aliphatic compounds (glucoraphanin with [M-H]- at m/z ratio of 436, glucoerucin at m/z 420, 4-mercaptobutyl-GLS at m/z 406, progoitrin/epiprogoitrin at m/z 388, sinigrin at m/z 358, 4-methylpentyl- and n-hexyl-GLS at m/z 402) and three indole glucosinolates (i.e., three N-heterocyclic compounds: 4-hydroxyglucobrassicin and 5-hydroxyglucobrassicin at m/z 463, and 4-methoxy-glucobrassicin at m/z 477), but also two structurally related compounds containing one intermolecular disulfide linkage (4-(beta-D-glucopyranosyldisulfanyl)butyl-GLS at m/z 600 and a dimeric 4-mercaptobutyl-GLS at m/z 811). This latter symmetric disulfide was previously considered as an artefact formed during extraction of GLSs from vegetative tissues. Glucosinolates were detected in the leaves with a wide range of contents (10-200 micromol/g) and a great variation in the composition. Only three GLSs were identified in seeds of rocket salad, namely glucoraphanin, glucoerucin and 4-methoxyglucobrassicin. As expected, the most abundant GLS in seeds is glucoerucin. The feasibility of the strategy was also demonstrated using a rapeseed extract of certified reference material (BCR367R). The results indicated the usefulness of this method for a rapid, sensitive and comprehensive profiling of the GLS family naturally occurring in extracts of crude plant matter.     

Characterization and quantification of soy isoflavone metabolites in serum of renal transplanted patients by high-performance liquid chromatography/electrospray ionization mass spectrometry

During a dietary intervention study on 16 renal transplanted patients, in which 25 g/day of animal proteins were replaced with 25 g of soy proteins, the metabolic profile of soy isoflavones in serum was characterized. This paper describes a reliable and fast liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) method, in negative ion mode, allowing the characterization and simultaneous quantification of several soy isoflavone metabolites. Six metabolites were identified and quantified: daidzein ([M-H](-) at m/z 252.8), dihydrodaidzein (DHD, [M-H](-) at m/z 254.8), equol ([M-H](-) at m/z 240.9), O-desmethylangolensin (O-DMA, [M-H](-) at m/z 256.8), genistein ([M-H](-) at m/z 268.8), and dihydrogenistein (DHG, ([M-H(+)](-) at m/z 270.8). Quantification was assessed using two deuterated internal standards, D(3)-daidzein and D(4)-genistein. This method permitted a limit of quantification (LOQ, S/N = 10) and a limit of detection (LOD, S/N = 3) of 0.05 microM and 0.005 microM for all analytes, except for genistein, where the LOQ and LOD were 0.005 microM and 0.001 microM, respectively. The linearity ranges were from 0.005 to 1.5 microM for genistein, from 0.05 to 1.5 microM for DHG, and from 0.05 to 0.7 microM for the other metabolites. The relative standard deviations (RSDs) were between 0.19% and 13.9% at the LOQ concentration for all metabolites, and between 0.6% and 4.8% at the maximum concentration. On the basis of the results obtained in the dietary intervention study, it was possible to split the patients into five groups characterized by different metabolic pathways.     

Use of liquid chromatography-tandem mass spectrometry for the analysis of pentoxifylline and lisofylline in plasma

A method was developed for the quantitation of pentoxifylline [1-(5-oxohexyl)-3,7-dimethylxanthine] and a primary active metabolite, lisofylline [1-(5-hydroxyhexyl)-3,7-dimethylxanthine], using high-performance liquid chromatography (HPLC)-tandem mass spectrometry. This method was developed in order to overcome problems encountered with HPLC-ultraviolet detection. The operating parameters of the electrospray interface (PE SCIEX, TurboIon Spray) and lens voltages of the triple-quadrupole detector (PE SCIEX 365) were optimized in positive ion mode to obtain the best sensitivity of the analytes. Collision-induced dissociation was used to produce fragment ions, and multiple reaction monitoring was used to quantitate pentoxifylline (m/z 279/181) and lisofylline (m/z 263/181). Dichloromethane was used to extract the drug, metabolite, and the internal standard (3-isobutyl-1-methylxanthine) from plasma. A reverse-phase C8(2) 150 x 1.0 mm HPLC column was used to resolve all three compounds in less than 6 min. Calibration curves were generated using peak area and were linear from 1 to 1000 ng/mL (R(2) > 0.99). The small sample volume, ease of extraction, and sensitivity provide advantages over more conventional methods of quantitation.     

Simultaneous quantification of a non-nucleoside reverse transcriptase inhibitor efavirenz, a nucleoside reverse transcriptase inhibitor emtricitabine and a nucleotide reverse transcriptase inhibitor tenofovir in plasma by liquid chromatography positive ion electrospray tandem mass spectrometry

A high-performance liquid chromatography/positive ion electrospray tandem mass spectrometry method for the simultaneous quantification of efavirenz, emtricitabine and tenofovir was developed and validated with 100 microL human plasma. Following solid-phase extraction, the analytes were separated using a gradient mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M + H]+ ions, m/z 316 to 168 for efavirenz, m/z 248-130 for emtricitabine and m/z 288-176 for tenofovir, m/z 482-258 for rosuvastatin (IS), m/z 260-116 for propranolol (IS). The method exhibited a 100-fold linear dynamic range for all the three analytes in human plasma (20-2000, 2-200 and 20-2000 ng/mL for efavirenz, emtricitabine and tenofovir respectively). The lower limit of quantification was 2 ng/mL for emtricitabine and 20 ng/mL for both efavirenz and tenofovir with a relative standard deviation of less than 11%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The total chromatographic run time of 4 min for each sample made it possible to analyze more than 250 human plasma samples per day. The method is precise and sensitive enough for its intended purpose. The method is also successfully applied to quantify efavirenz, emtricitabine and tenofovir concentrations in a rodent pharmacokinetic study.     

Liquid chromatography-electrospray ionization mass spectrometry of the diarrhetic shellfish-poisoning toxins okadaic acid, dinophysistoxin-1 and pectenotoxin-6 in bivalves

Determination of diarrhetic shellfish-poisoning (DSP) toxins, okadaic acid (OA), dinophysistoxin-1 (DTX1) and pectenotoxin-6 (PTX6) was carried out by liquid chromatography (LC) followed by on-line atmospheric pressure electrospray ionization-mass spectrometric (ESI-MS) detection with a heated capillary interface. Mass spectra of authentic OA, DTXI and PTX6 standards exhibited abundant [M-H] at m/z 803, 817 and 887, respectively. Linearity of peak area obtained by selected-ion monitoring (SIM) for [M-H]- of each toxin was confirmed over a wide range of concentrations from 10 pg to 30 ng. LC-ESI-MS analysis of OA, DTX1 and PTX6 in scallops and mussels, collected at the same site (Mutsu Bay, Japan), was carried out. Scallops and mussels collected at the same site showed different toxin profiles. Although PTX6 was detected from scallops, it was not detected from mussels.     

Rapid and simple liquid chromatography tandem mass spectrometry method for the quantification of zidovudine in rat plasma

A high-performance liquid chromatography/electrospray ionization tandem mass spectrometry method was developed and validated for the quantification of zidovudine in rat plasma. Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reverse phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M+H]+ ions, m/z 268/127 for zidovudine and m/z 230/112 for the internal standard. The method exhibited a linear dynamic range of 5-500 ng/mL for zidovudine in rat plasma. The lower limit of quantification was 5 ng/mL with a relative standard deviation of less than 8%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 1.5 min for each sample made it possible to analyze more than 400 plasma samples per day. The validated method was applied for pharmacokinetic studies of the novel drug delivery systems of zidovudine in rats.     

Development and validation of a method for the confirmation of nicarbazin in chicken liver and eggs using LC-electrospray MS-MS according to the revised EU criteria for veterinary drug residue analysis.

A method is described for the quantitative confirmation of 4,4'-dinitrocarbanilide (DNC), the marker residue for nicarbazin in chicken liver and eggs. The method is based on LC coupled to negative ion electrospray MS-MS of tissue extracts prepared by liquid-liquid extraction. The [M-H]- ion at m/z 301 is monitored along with two transition ions at m/z 137 and 107 for DNC and the [M-H]- ion at m/z 309 for the internal standard, d8-DNC. The method has been validated according to the new EU criteria for the analysis of veterinary drug residues at 100, 200 and 300 microg kg(-1) in liver and at 10, 30 and 100 microg kg(-1) in eggs. Difficulties concerning the application of the new analytical limits, namely the decision limit (CCalpha) and the detection capability (CCbeta) to the determination of DNC in both liver and eggs are discussed.     

Simultaneous determination of amiloride and hydrochlorothiazide in human plasma by liquid chromatography/tandem mass spectrometry with positive/negative ion-switching electrospray ionisation

A new method for simultaneous determination of amiloride and hydrochlorothiazide by liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) operated in positive and negative ionization switching mode was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation. The analytes were separated on a Phenomenex Curosil-PFP (250x4.6 mm, 5 microm) column by a gradient elution with a mobile phase consisting of 0.15% formic acid solution containing 0.23% ammonium acetate and methanol pumped at a flow rate of 1.0 mL.min(-1). Rizatriptan was used as the internal standard (IS) for quantification. The determination was carried out on a Waters Quattro-micro triple-quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using the following transitions monitored simultaneously: positive m/z 230-->171 for amiloride, m/z 270-->158 for rizatriptan, and negative m/z 296-->205 for hydrochlorothiazide. The lower limits of quantification (LLOQs) were 0.1 and 1.0 ng.mL(-1) for amiloride and hydrochlorothiazide, respectively, which were lower than other published methods by using ultraviolet (UV), fluorimetric or mass spectrometric detection. The intra- and inter-day precision and accuracy were studied at three different concentration levels and were always better than 15% (n=5). This simple and robust LC/MS/MS method was successfully applied to the pharmacokinetic study of compound amiloride and hydrochlorothiazide tablets in healthy male Chinese volunteers.     

Development of a rapid and sensitive liquid chromatography/tandem mass spectrometry method for the determination of 1,2-[bis(1,2-benzisoselenazolone-3(2H)-ketone)]-ethane (BBSKE), a novel anti-cancer agent in rat plasma

A rapid and sensitive liquid chromatography/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method has been developed to determine 1, 2-[bis(1,2-benzisoselenazolone-3(2H)-ketone)]-ethane (BBSKE), a novel antineoplastic agent, in rat plasma. The analytes were separated on a C18 column with a mobile phase of methanol-water (75:25, v/v) and detected using a triple-quadrupole mass spectrometer in positive mode with the selective reaction monitoring. The characteristic ion dissociation transitions were m/z 603.0 --> 448.9 for derivatized BBSKE and m/z 631.0 --> 476.8 for derivatized internal standard. The assay was linear over a range of 1-1000 ng/mL with a lower limit of quantification of 1 ng/mL. Intra- and inter-day precisions were less than 9.6 and 5.0%, respectively, and the accuracy ranged from -5.2 to 4.0%. The validated method was successfully applied to the characterization of pharmacokinetic profile of BBSKE after oral administration in rats. Cop     

Simultaneous quantification of fexofenadine and pseudoephedrine in human plasma by liquid chromatography/tandem mass spectrometry with electrospray ionization: method development, validation and application to a clinical study

To support the pharmacokinetic and bioavailability study of a once-daily fexofenadine/pseudoephedrine combination, a high-performance liquid chromatography/positive ion electrospray tandem mass spectrometry (HPLC/ESI-MS/MS) method for the simultaneous quantification of fexofenadine and pseudoephedrine was developed and validated with 500 microL human plasma using mosapride as an internal standard (IS). Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M+H]+ ions, m/z 502/466 for fexofenadine, m/z 166/148 for pseuoephedrine and m/z 422/198 for the IS. The method exhibited linear dynamic ranges of 1-500 ng/mL and 2-1000 ng/mL for fexofenadine and pseudoephedrine, respectively, in human plasma. The lower limits of quantification were 1 and 2 ng/mL with a relative standard deviation of less than 10% for fexofenadine and pseudoephedrine, respectively. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The total chromatographic run time was 2 min and more than 400 human plasma samples could be analyzed in one day by running the system overnight. The method is precise and sensitive enough for its intended purpose.     

Determination of bradykinin and arg-bradykinin in rat muscle tissue by microdialysis and capillary column-switching liquid chromatography with mass spectrometric detection

Quantification of bradykinin peptides in limited amounts of rat muscle tissue dialysate has been performed using a packed capillary LC-ESI-TOF-MS method. The micro dialysate samples (450 microL) with added internal standard were loaded onto a 1 mm x 5 mm loading column packed with 5 microm Kromasil C18 particles by a carrier solution of 0.1% formic acid in ACN/water (5:95, v/v) at a flow rate of 250 microL/min for online preconcentration of the analytes. Back-flushed elution onto a 150 mm x 0.5 mm Zorbax C18 column packed with 5 microm particles was conducted using a linear solvent ACN/H2O gradient containing 0.1% formic acid. (Tyr8)-bradykinin was used as an internal standard and was added to the dialysis sample prior to injection. Baseline separation of bradykinin, arg-bradykinin and (tyr8)-bradykinin was achieved within 10 min. Positive ESI was performed in the m/z range of 200-1300. The method was validated in the range 0.2-1.0 ng/mL dialysate, yielding correlation coefficients of 0.995 and 0.990 for bradykinin and arg-bradykinin, respectively. The within-assay and between-assay precisions were between 4.3-9.6% and 6.2-10.6%, respectively. Both arg-bradykinin and bradykinin were detected in dialysate from rat muscle tissue, at concentrations of 0.1 and 0.4 ng/mL for bradykinin and arg-bradykinin, respectively, confirming the presence of arg-bradykinin in rat muscles.     

Determination and pharmacokinetics of manidipine in human plasma by HPLC/ESIMS

A sensitive HPLC/ESIMS method was established for the determination of manidipine in human plasma and pharmacokinetics study. After basified plasma with ammonia, manidipine and the internal standard (IS) (felodipine) were extracted with n-hexane and separated on a Hypersil ODS2 column with a mobile phase of methanol-5 mm ammonium acetate solution containing 0.1% acetic acid (85:15, v/v). MS determination was performed by electrospray ionization in the selected ion monitoring mode. Manidipine was monitored at m/z 611.4 and IS at m/z 384. The assay had a calibration range from 0.2 to 20 ng/mL and a lower limit of quantification of 0.1 ng/mL. The method has been successfully applied to the pharmacokinetic study in healthy volunteers.