Method development and validation study for quantitative determination of nifedipine and related substances by ultra‐high‐performance liquid chromatography

A novel stability‐indicating reversed phase ultra‐high performance liquid chromatography (UPLC) coupled photodiode array gradient method was developed for determination of the nifedipine and related compounds. Furthermore, based on the chromatographic conditions and forced degradation studies performed through the development of the related substances method a UPLC isocratic method was validated for the determination of the assay of this active substance. An Acquity Shield RP₁₈ (50 × 3.0 mm 1.7 µm) column was used for separation of nifedipine and its five potential impurities within 11 min, which is 5‐fold less than the official method. A mobile phase consisting of 10 mm ammonium formate (pH 4.5) and methanol, delivered at a flow rate 0.5 mL/min, was employed to achieve a minimum resolution of 2.0 for all consecutive pairs of compounds. The precision value expressed as percentage relative standard deviation for method repeatability and reproducibility was <5.0%. The recoveries for all the related compounds were in the range of 99–105.0%. Linearity was found to be acceptable over the concentration range of 0.25–1.5 µg/mL for nifedipine and its impurities. The limit of quantification for nifedipine was 0.05 µg/mL, which is much less than the European Pharmacopoeia method. Copyright © 2014 John Wiley & Sons, Ltd.     

Study of gliquidone degradation behavior by high‐performance thin‐layer chromatography and ultra‐performance liquid chromatography methods

Gliquidone (GQ) is an oral hypoglycemic agent, belonging to second‐generation sulfonylurea derivatives. New high‐performance thin‐layer chromatography (HPTLC) and ultra‐performance liquid chromatography (UPLC) methods have been developed and validated and used for complete stability study of GQ following International Conference on Harmonization guidelines. GQ was subjected to stress and forced degradation under hydrolytic, oxidative and photolytic conditions. The drug was found to be unstable under acidic, alkaline and oxidative conditions with the formation of gliquidone sulfonamide (GQS), while a marked stability was confirmed under thermal and photolytic stress conditions. GQS is the British pharmacopeial impurity A of GQ and also considered as its synthesis intermediate. The developed chromatographic methods have been utilized for anticipating the degradation behavior of GQ under the studied conditions and then used for quantitation of GQ and GQS either in their pure forms or in laboratory prepared mixtures. The methods were successfully applied to GQ in pharmaceutical formulation. The methods have the advantages of being sensitive and less time consuming compared with the reported methods. The obtained results were statistically compared with a reported HPLC method showing no significant difference regarding both accuracy and precision.     

Hydrophilic interaction and reversed‐phase ultra‐performance liquid chromatography TOF‐MS for metabolomic analysis of Veratrum nigrum‐induced cardiotoxicity

The acute cardiotoxicity induced by Veratrum nigrum (VN) is explored by analyzing heart tissue metabolic profiles in mouse models and applying reversed‐phase liquid chromatography mass spectrometry and hydrophilic interaction liquid chromatography mass spectrometry that are based on ultra‐high‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry. An animal model of acute heart injury was established in mice via intra‐gastric administration of VN. Then, electrocardiogram and echocardiograph monitoring of cardiac function and pathological examination were performed on mice in both the control and VN groups, and it was verified that acute heart injury was caused. Meanwhile, comparing the results of the control and VN groups, we detected 36 differential endogenous metabolites of heart tissue, including taurine, riboflavin, purine and lipids, which are related to many possible pathways such as purine metabolism, taurine and hypotaurine metabolism and energy metabolism. Our study provides a scientific approach for evaluating and revealing the mechanisms of VN‐induced cardiotoxicity via the metabolomic strategy.     

Development and validation of an ultra‐performance convergence chromatography method for the quality control of Angelica gigas Nakai

Ultra‐performance convergence chromatography, which integrates the advantages of supercritical fluid chromatography and ultra high performance liquid chromatography technologies, is an environmentally friendly analytical method that uses dramatically reduced amounts of organic solvents. An ultra‐performance convergence chromatography method was developed and validated for the quantification of decursinol angelate and decursin in Angelica gigas using a CSH Fluoro‐Phenyl column (2.1 mm × 150 mm, 1.7 μm) with a run time of 4 min. The method had an improved resolution and a shorter analysis time in comparison to the conventional high‐performance liquid chromatography method. This method was validated in terms of linearity, precision, and accuracy. The limits of detection were 0.005 and 0.004 μg/mL for decursinol angelate and decursin, respectively, while the limits of quantitation were 0.014 and 0.012 μg/mL, respectively. The two components showed good regression (correlation coefficient (r²) > 0.999), excellent precision (RSD < 2.28%), and acceptable recoveries (99.75–102.62%). The proposed method can be used to efficiently separate, characterize, and quantify decursinol angelate and decursin in Angelica gigas and its related medicinal materials or preparations, with the advantages of a shorter analysis time, greater sensitivity, and better environmental compatibility.     

A validated method for analysis of chromium picolinate in nutraceuticals by reversed phase high performance liquid chromatography

A validated high performance liquid chromatographic method was developed for the determination of chromium picolinate in pharmaceutical dosage forms. The analysis was performed at room temperature using a reversed-phase Supelcosil LC-18 (250 x 4.6 mm, 5 microm) column. The mobile phase consisted of acetonitrile:water (40:60 v/v) at a fl ow rate of 0.8 mL/min. The UV-detector was set at 264 nm. The developed method showed a good linear relationship in the concentration range from 0.125 to 12.5 microg/mL with a correlation coefficient from 0.999. The limit of detection and limit of quanti fi cation were 0.091 and 0.181 microg/mL, respectively.     

Pharmacokinetic study of dendrobine in rat plasma by ultra‐performance liquid chromatography tandem mass spectrometry

Dendrobine, considered as the major active alkaloid compound, has been used for the quality control and discrimination of Dendrobium which is documented in the Chinese Pharmacopoeia. In this work, a sensitive and simple ultra‐performance liquid chromatography tandem mass spectrometry (UPLC‐MS/MS) method for determination of dendrobine in rat plasma is developed. After addition of caulophyline as an internal standard (IS), protein precipitation by acetonitrile–methanol (9:1, v/v) was used to prepare samples. Chromatographic separation was achieved on a UPLC BEH C₁₈ (2.1 ×100 mm, 1.7 µm) column with acetonitrile and 0.1% formic acid as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reaction monitoring mode was used for quantification using target fragment ions m/z 264.2 → 70.0 for dendrobine and m/z 205.1 → 58.0 for IS. Calibration plots were linear throughout the range 2–1000 ng/mL for dendrobine in rat plasma. The RSDs of intra‐day and inter‐day precision were both <13%. The accuracy of the method was between 95.4 and 103.9%. The method was successfully applied to pharmacokinetic study of dendrobine after intravenous administration. Copyright © 2015 John Wiley & Sons, Ltd.     

Precolumn derivatization liquid chromatography method for analysis of dietary supplements for glucosamine: single laboratory validation study

A precolumn derivatization liquid chromatography (LC) method was developed for the analysis of various dietary supplement formulations and raw materials for glucosamine. A 1 mL sample or standard water solution (containing about 0.05 mg glucosamine) was mixed with 1 mL pH 8.3 buffer, 1 mL 5% phenylisothiocyanate methanolic solution, and derivatized at 80 degrees C in a water bath for 30 min. After derivatization, the solution was cooled in a cold water bath and centrifuged at 3000-5000 rpm. The clear upper layer was ready for injection. The LC system was equipped with a C18 reversed-phase column and an ultraviolet detector set at 240 nm. The column was developed with a linear gradient composed of 0.1% phosphoric acid in deionized water and 0.1% phosphoric acid in methanol. The method was subjected to Single Laboratory Validation. The method precision was 0.50% relative standard deviation, accuracy was less than +/-1.5%, method linearity in the range 0-2 mg glucosamine/mL was 1.00, the detection limit was 0.0705 microg/mL, and the quantitation limit was 0.235 microg/mL. Chondroitin sulfate, amino acids, and excipients did not interfere with glucosamine testing. After derivatization, both standard and sample preparations were stable for at least 48 h. Due to its high sensitivity, this method can be used to assay glucosamine in functional foods and pet foods. The validation data will be published separately.     

Metabolic profiles of dioscin in rats revealed by ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry

Dioscin (DIS), one of the most abundant bioactive steroidal saponins in Dioscorea sp., is used as a complementary medicine to treat coronary disease and angina pectoris in China. Although the pharmacological activities and pharmacokinetics of DIS have been well demonstrated, information regarding the final metabolic fates is very limited. This study investigated the in vivo metabolic profiles of DIS after oral administration by ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry method. The structures of the metabolites were identified and tentatively characterized by means of comparing the molecular mass, retention time and fragmentation pattern of the analytes with those of the parent compound. A total of eight metabolites, including seven phase I and one phase II metabolites, were detected and tentatively identified for the first time. Oxidation, deglycosylation and glucuronidation were found to be the major metabolic processes of the compound in rats. In addition, a possible metabolic pathway on the biotransformation of DIS in vivo was proposed. This study provides valuable and new information on the metabolism of DIS, which will be helpful for further understanding its mechanism of action. Copyright © 2015 John Wiley & Sons, Ltd.     

Rapid simultaneous quantification of fructooligosaccharides in Morinda officianalis by ultra‐high performance liquid chromatography

Many Chinese herbal medicines with tonifying effects contain high levels of inulin fructooligosaccharides. These herbal medicines have high development and utilization value because of their effects against dementia, depression, and oxidative stress; on improving learning and memory ability; and on enhancing immunity. In this study, a method was developed for the separation and simultaneous quantitation of fructose, glucose, sucrose, and ten inulin fructooligosaccharides by ultra‐high‐performance liquid chromatography with evaporative light scattering detection within 10 min. Separation was performed on an Amide column with gradient elution. The calibration curves for the 13 constituents showed good linearity (R² > 0.9991). The limits of detection and quantification were 10.78–33.44 and 35.94–124.81 μg/mL, respectively, and the recoveries ranged from 98.90 to 103.67%. This method was successfully used to quantify the 13 constituents in the Chinese herbal medicine Morinda officinalis. The contents of the ten inulin fructooligosaccharides ranged from 56.28 to 60.71%. This method is accurate, rapid and simple and can be used for quantitative analysis in the quality control of herbal medicines and functional foods.     

Tissue distribution and excretion study of neopanaxadiol in rats by ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry

Neopanaxadiol (NPD), a major ginsenoside in Panax ginseng C. A. Meyer (Araliaceae), was reported to have neuroprotective effect. In this study, a method of ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry (UPLC/QTOF‐MS) was developed and validated for quantitative analysis of NPD in tissues, urine and feces, using liquid–liquid extraction (LLE) to isolate NPD from different biological samples, and chromatographic separation was performed on an Agilent Zorbax Stable Bond C₁₈ (2.1 × 50 mm, 1.8 µm) column with 0.1% formic acid in water and acetonitrile. All standard calibration curves were linear (all r² > 0.995) within the test range. After oral administration, NPD was extensively distributed to most of the tissues without long‐term accumulation. The higher levels were observed in stomach and intestine, followed by kidney and liver. Approximately 64.56 ± 20.32% of administered dose in feces and 0.0233 ± 0.0356% in urine were found within 96 h, which indicated that the major elimination route was fecal excretion. This analytical method was applied to the study of NPD distribution and excretion in rats after oral intake for the first time. The results we found here are helpful for us to understand the pharmacological effects of NPD, as well as its toxicity. Copyright © 2014 John Wiley & Sons, Ltd.     

Metabolite profiles of epimedin C in rat plasma and bile by ultra‐performance liquid chromatography coupled with quadrupole‐TOF‐MS

Epimedin C is one of the major bioactive constituents of Herba Epimedii. In this study, the metabolite profiles of epimedin C in rat plasma and bile were qualitatively investigated, and the possible metabolic pathways of epimedin C were subsequently proposed. After oral administration of epimedin C at a single dose of 80 mg/kg, rat biological samples were collected and pretreated by protein precipitation. Then these pretreated samples were injected into an Acquity UPLC BEH C₁₈ column and detected by ultra‐performance liquid chromatography/quadrupole‐time‐of‐flight mass spectrometry. In all, 12 metabolites were identified in the biosamples. Of these, eight, two from plasma and six from bile, are, to our knowledge, reported here for the first time. The results indicated that epimedin C was metabolized via desugarization, dehydrogenation, hydrogenation, dehydroxylation, hydroxylation, demethylation and glucuronidation pathways in vivo. Thus, this study revealed the possible metabolite profiles of epimedin C in rat plasma and bile. Copyright © 2014 John Wiley & Sons, Ltd.     

A new rapid ultra‐performance liquid chromatography method for the pharmacokinetic and bioavailability study of diclofenac sodium aqueous injection and lipid microsphere injection in rats

A novel, rapid and selective ultra performance liquid chromatography mass spectrometric method had been developed for the pharmacokinetic study of diclofenac sodium (DS) after single intravenous injection of DS aqueous injection and DS lipid microsphere (LM) injection in rats. Ketoprofen (KP) was used as internal standard. Samples were treated by a one‐step liquid liquid extraction. Separation was performed on an Acquity UPLC? BEH C₁₈ column (50 × 2.1 mm i.d., 1.7 μm). The mobile phase consisted of acetonitrile–0.1% ammonium hydroxide aqueous solution (20 : 80, v/v) initially in the gradient mode. The detection was carried out by means of electrospray ionization mass spectrometry in negative ion mode with multiple‐reaction monitoring mode. Standard curves showed good linearity (r > 0.99) from the plasma concentration of 0.1–50 μg/mL. The lower limit of quantification was 0.1 μg/mL. The intra‐ and inter‐day precisions and the accuracy all satisfied the acceptance criteria. The developed method was validated and successfully applied to the pharmacokinetics study of DS aqueous injection and LM injection. The results showed that the two preparations were bioequivalent in rats. Copyright © 2009 John Wiley & Sons, Ltd.     

Validation of an ultra‐performance liquid chromatography–tandem mass spectrometry method for the determination of flecainide in human plasma and its clinical application

A simple and reproducible bioanalytical method for the determination of flecainide in human plasma was developed and validated using an ultra‐performance liquid chromatography with tandem mass spectrometry (UPLC‐MS/MS) to obtain higher sensitivity than the current available methods. After simple protein precipitation, flecainide and a stable isotope‐labeled internal standard (IS) were chromatographed on an Acquity UPLC BEH C₁₈ column (2.1 × 100 mm, 1.7 µm) with isocratic elution of mobile phase consisting of 45% methanol containing 0.1% formic acid at a flow rate 0.25 mL/min. Detection was performed in positive electrospray ionization by monitoring the selected ion transitions at m/z 415.4/301.1 for flecainide and m/z 419.4/305.1 for the IS. The method was validated according to current bioanalytical method validation guidelines. The calibration standard curve was linear from 2.5 to 1000 ng/mL using 0.1 mL of plasma. No significant interferences were detected in blank human plasma. Accuracy and precision in the intra‐ and inter‐batch reproducibility study were within acceptance criteria. Neither hemolysis effects nor matrix effects were observed. The UPLC‐MS/MS method developed was successfully applied to determine plasma flecainide concentrations to support clinical studies and incurred sample reanalysis also ensured the reproducibility of the method. Copyright © 2015 John Wiley & Sons, Ltd.     

Development and validation of a high‐performance liquid chromatography method for the simultaneous determination of aspirin and folic acid from nano‐particulate systems

Attention has shifted from the treatment of colorectal cancer (CRC) to chemoprevention using aspirin and folic acid as agents capable of preventing the onset of colon cancer. However, no sensitive analytical method exists to simultaneously quantify the two drugs when released from polymer‐based nanoparticles. Thus, a rapid, highly sensitive method of high‐performance liquid chromatography analysis to simultaneously detect low quantities of aspirin (hydrolyzed to salicylic acid, the active moiety) and folic acid released from biodegradable polylactide‐co‐glycolide (PLGA) copolymer nanoparticles was developed. Analysis was done on a reversed‐phase C₁₈ column using a photodiode array detector at wavelengths of 233 nm (salicylic acid) and 277 nm (folic acid). The mobile phase consisted of acetonitrile–0.1% trifluoroacetic acid mixture programmed for a 30 min gradient elution analysis. In the range of 0.1–100 μg/mL, the assay showed good linearity for salicylic acid (R² = 0.9996) and folic acid (R² = 0.9998). The method demonstrated good reproducibility, intra‐ and inter‐day precision and accuracy (99.67, 100.1%) and low values of detection (0.03, 0.01 μg/mL) and quantitation (0.1 and 0.05 μg/mL) for salicylic acid and folic acid, respectively. The suitability of the method was demonstrated by simultaneously determining salicylic acid and folic acid released from PLGA nanoparticles. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of itraconazole and its photodegradation products with kinetic evaluation by ultra‐performance liquid chromatography/tandem mass spectrometry

A simple and reproducible UPLC‐MS/MS method for the determination of itraconazole (ITZ) and its photodegradation products formed during exposure to UV‐A radiation was developed. Chromatographic separations were carried out using an Acquity UPLC BEH C₁₈ column (2.1 × 100 mm, 1.7 μm particle size). The column was maintained at 40°C, and eluted under gradient conditions from 100% to 50% of eluent A over 13 min, at a flow rate of 0.3 mL min^?1. Eluent A was 0.1% (v/v) formic acid in water; eluent B was 0.1% (v/v) formic acid in acetonitrile. The linear regression analysis for the calibration curve showed a good linear correlation over the concentration range 0.0066–0.15 mg mL^?1 with determination coefficient > 0.99. The activities of some photocatalysts during degradation process of ITZ were compared. It was found that indirect photodegradation of ITZ was more effective than direct photolysis. Under our experimental conditions the photodegradation rate constant depended on the applied catalysts with catalytic activity decreasing in the following pattern: FeCl₃ > TiO₂/FeCl₃ > TiO₂. The kinetic analysis of the photodegradation data revealed that the degradation of the ITZ follows first‐order kinetics. The photodegradation products of ITZ were identified, and their fragmentation pathways, derived from MS/MS data, were proposed. Copyright © 2016 John Wiley & Sons, Ltd.     

Development and validation of a magnetic solid‐phase extraction with high‐performance liquid chromatography method for the simultaneous determination of amphetamine and methadone in urine

The simultaneous determination of amphetamine and methadone was carried out by magnetic graphene oxide nanoparticles, a magnetic solid‐phase extraction adsorbent, as a new sample treatment technique. The main factors (the amounts of sample volume, amount of adsorbent, type and amount of extraction organic solvent, time of extraction and desorption, pH, the ionic strength of extraction medium, and agitation rate) influencing the extraction efficiency were investigated and optimized. Under the optimized conditions, good linearity was observed in the range of 100–1500 ng/mL for amphetamine and 100–1000 ng/mL for methadone. The method was evaluated for determination of AM and methadone in positive urine samples, satisfactory results were obtained, therefore magnetic solid‐phase extraction can be applied as a novel method for the determination of drugs of abuse in forensic laboratories.     

Characterization of metabolites in rats after intravenous administration of salvianolic acid for injection by ultra‐performance liquid chromatography coupled with quadrupole‐time‐of‐flight mass spectrometry

It is an essential requirement to clarify the metabolites of traditional Chinese medicine (TCM) injections, which contain numerous ingredients, to assess their safe and effective use in clinic. Salvianolic acid for injection (SAFI), made from hydrophilic phenolic acids in Salvia miltiorrhiza Bunge, has been widely used for the treatment of cerebrovascular diseases, but information on its metabolites in vivo is still lacking. In the present study, we aimed to holistically characterize the metabolites of the main active ingredients in rat plasma, bile, urine and feces following intravenous administration of SAFI. An ultra‐performance liquid chromatography coupled with quadrupole‐time‐of‐flight mass spectrometry (UPLC/Q‐TOF‐MS) method was developed. Combining information on retention behaviors, multistage mass spectra and literature data, a total of eight prototypes and 52 metabolites were tentatively characterized. Metabolites originated from rosmarinic acid and salvianolic acid B comprised the majority of identified compounds. Meanwhile, four metabolites derived from salvianolic acid D and five from salvianolic acid B are reported for the first time. This study revealed that methylation, sulfation and glucuronidation were the major metabolic pathways of phenolic acids in SAFI in vivo. Furthermore, the developed UPLC/Q‐TOF‐MS method could also benefit the metabolic investigation of extracts and preparations in TCM with hydrophilic ingredients. Copyright © 2016 John Wiley & Sons, Ltd.     

Determination of trans,trans‐muconic acid in workers' urine through ultra‐performance liquid chromatography coupled to tandem mass spectrometry

A novel method for the biological monitoring of benzene‐exposed workers has been developed through ultra‐performance liquid chromatography coupled to tandem mass spectrometry. The method uses trans,trans‐muconic acid in urine as the benzene‐exposure biomarker. The method was developed using a triple quadrupole mass spectrometer with enough sensitivity to facilitate diluting and injecting the urine samples directly, rather than performing a solid‐phase extraction procedure as is common in the available protocols. Moreover, compared with a conventional high‐pressure liquid chromatography system, the separation power provided by the ultra‐performance liquid chromatography system allows a 10‐fold reduction in run time. The method was adjusted to a dynamic range of between 198.9 and 4916.7 µg/L to cover the biological exposure index of trans,trans‐muconic acid in urine. Also, the method demonstrated intra‐day and inter‐day precision at 98%, and accuracy within an acceptable range of 101 ± 8%. The method has been used to quantify various types of urine samples, such as workers' urine and inter‐laboratory proficiency tests. Depending on the sample, the quantified levels ranged from less than the limit of quantitation to 3836.7 µg/L. No levels exceeding the calibration range were detected in the urine of workers, and the reported concentrations in urine for the proficiency tests were, as expected, based on known values. Moreover, the new method using sample dilution and faster chromatographic run was more effective, facilitating fast communication of results, as needed, to decision‐makers. Copyright © 2012 John Wiley & Sons, Ltd.     

Identification of the metabolites of gigantol in rat urine by ultra‐performance liquid chromatography combined with electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

Gigantol is a typical bibenzyl compound isolated from Dendrobii Caulis that has been widely used as a medicinal herb in China for the treatment of diabetic cataract, cancer and arteriosclerosis obliterans and as a tonic for stomach nourishment, saliva secretion promotion and fever reduction. However, few studies have been carried out on its in vivo metabolism. In the present study, a rapid and sensitive method based on ultra‐performance liquid chromatography/electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry (UPLC‐Q/TOF‐MS) in positive ion mode was developed and applied to identify the metabolites of gigantol in rat urine after a single oral dose (100 mg/kg). Chromatographic separation was performed on an Acquity UPLC HSS T3 column (100 × 2.1 mm i. d., 1.8 µm) using acetonitrile and 0.1% aqueous formic acid as mobile phases. A total of 11 metabolites were detected and identified as all phase II metabolites. The structures of the metabolites were identified based on the characteristics of their MS, MS² data and chromatographic retention times. The results showed that glucuronidation is the principal metabolic pathway of gigantol in rats. The newly identified metabolites are useful to understand the mechanism of elimination of gigantol and, in turn, its effectiveness and toxicity. As far as we know, this is the first attempt to investigate the metabolic fate of gigantol in vivo. Copyright © 2014 John Wiley & Sons, Ltd.     

Stability‐indicating ultra‐performance liquid chromatography method for the estimation of thymoquinone and its application in biopharmaceutical studies

Thymoquinone (THQ) is known for its neuroprotective and anti‐convulsant properties in preclinical studies. We herewith describe a simple, rapid, selective, sensitive and stability‐indicating UPLC method for the estimation of THQ and its application to biopharmaceutical studies such as in vitro release from nanoparticulate system and in vivo pharmacokinetic study. The method employed gradient elution using a Waters Acquity HSS‐T3 C₁₈ (100 × 2.1 mm, 1.8 µm) UPLC column. The mobile phase consisted of water and acetonitrile, pumped at a flow rate of 0.5 mL/min. The injection volume was 5 µL and THQ was monitored at 294 nm wavelength with a total run time of 6 min. In solution as well as in plasma, the method was found to be linear (r ≥ 0.998), precise (CV ≤ 2.45%) and accurate (recovery ≥ 84.8%) in the selected concentration range of 0.1–0.8 µg/mL. Forced degradation studies revealed that THQ undergoes degradation under acidic, basic, oxidation and UV light stress conditions. However, the developed UPLC method could effectively resolve degradation product peaks from THQ. Further, no interference was found at the retention time of THQ from any plasma components, indicating selectivity of the developed method. For solutions, the limits of detection and quantitation of the method were found to be 0.001 and 0.0033 µg/mL, respectively; while in plasma they were 0.006 and 0.02 µg/mL, respectively. The validated method was successfully applied to quantify THQ in dissolution medium as well as oral in vivo pharmacokinetic study of THQ suspension and THQ‐ solid lipid nanoparticle (THQ‐SLN) formulation. A 2‐fold increase in the relative bioavailability was observed with the THQ‐SLN compared with THQ. The results indicate that the SLN significantly increased plasma concentrations and retention within the systemic circulation. Copyright © 2010 John Wiley & Sons, Ltd.