Determination and Pharmacokinetic Study of Methyl Nonyl Ketone in Rat Plasma by GC–MS

A rapid and sensitive method for determination of methyl nonyl ketone in rat plasma was developed based on GC–MS. The analyte and internal standard, propyl p-hydroxybenaoate, were extracted from plasma with methyl tert-butyl ether and then separated by an HP-5MS capillary analytical column (30 m × 0.25 mm, 0.25 µm) and determined by a quadrupole mass spectrometer detector operated under EI ionization and selected ion monitoring mode. Excellent linearity was found to be from 5.0 to 1,000 ng mL^?1 with a lower limit of quantitation of 5.0 ng mL^?1. The accuracy was between 96.0 and 106.3%, and the intra- and inter-day precision and accuracy values were found to be within the assay variability criteria limits according to the FDA guidelines. The developed method was successfully applied to the pharmacokinetic study of methyl nonyl ketone, a typical component in the traditional Chinese medicine Houttuynia cordata injection, in rats after a single oral dose of 100 mg kg^?1 and peritoneal injection dose of 5 mg kg^?1, respectively.     

Rapid and Selective LC�CMS�CMS Method for the Determination of cyclo-trans-4-l-Hydroxyprolyl-l-serine (JBP485) in Rat Plasma

A rapid and selective liquid chromatographic/tandem mass spectrometric method for the determination of JBP485 was developed and validated. Following protein precipitation, the analyte and internal standard (JBP923) were separated from human plasma using an isocratic mobile phase on an Elite Kromasil C18 column. An API 3200 tandem mass spectrometer equipped with a Turbo ionSpray ionization source was used as the detector and operated in the positive ion mode. Multiple reaction monitoring using the precursor to product ion combinations of m/z 201.2 ?? 86.2 and m/z 219.2 ?? 86.2 was performed to quantify JBP485 and JBP923, respectively. The method was linear in the concentration range of 0.10?C50.00 ??g mL^?1 using 100 ??L of plasma. The lower limit of quantification was 0.10 ??g mL^?1. The intra- and inter-day relative standard deviations over the entire concentration range were less than 6.65%. Accuracy determined at three concentrations (0.25, 4.00 and 25.00 ??g mL^?1 for JBP485) ranged from ?0.78 to 2.74% in terms of relative error. Each plasma sample was chromatographed within 2.0 min. The method was successfully applied to characterize the pharmacokinetic profiles of JBP485 in rats after an intravenous injection of 6.25 mg kg^?1 JBP485.     

Derivatization and Determination of MCPA in Soil by GC

A reliable and sensitive method for determination of MCPA in soil by derivatization through p-toluenesulfonic acid and 1,3-dichloro-2-propanol followed by gas chromatographic detection under ECD mode has been established. After treatment with hydrochloric acid, the soil samples were directly extracted without any clean-up with dichloromethane by vortexing. After derivatization and liquid–liquid extraction, the product was subjected to GC analysis. Under optimized conditions, recovery of MCPA reached 87–91%; intra- and inter-day precision values were recorded in the range 3.4–6.4% and 7.4–8.7%, respectively. Excellent linear relationship was observed within 0.1–10 μg mL^?1 (0.005–0.5 mg kg^?1) with linear correlation coefficient (R) of 0.9997. The LOD and LOQ were 0.001 and 0.0026 mg kg^?1, respectively, and the overall sensitivity for detection was found to be in the same range as with the conventional GC-MS technique.     

LC Determination of trans-3,5,3′,4′,5′-Pentamethoxystilbene in Rat Plasma

A simple LC method has been developed and validated to determine trans-3,5,3′,4′,5′-pentamethoxystilbene (PMS) in rat plasma. Chromatographic separation was achieved through gradient delivery of acetonitrile and water (1.5 mL min^?1) at 50 °C. PMS was quantified using UV detection at 320 nm. The standard curve ranged from 15 to 1,500 ng mL^?1. The intra- and inter-day precisions, in terms of CV, were all less than 10% while the inter-day and intra-day bias ranged from ?6.8 to 8.3%. The plasma PMS levels were monitored in Sprague-Dawley rats after drug administration. This simple LC method appears to be useful in the pharmacokinetic investigation of PMS.     

LC Method for Quantification of Lutein in Rat Plasma: Validation, and Application to a Pharmacokinetic Study

A reversed-phase LC method has been developed for quantitative analysis of lutein in rat plasma and applied to a study of the pharmacokinetics of lutein in rats. From a variety of compounds and solvents tested, astaxanthin was selected as the internal standard. n-Hexane was found to be the best solvent for extracting lutein from plasma. LC analysis of the extracts was performed on a C₁₈ column equipped with a guard pre-column. Linearity was good (r > 0.99) over the range 10–100 ng mL^?1. Recovery from plasma was 82.7–92.9% the intra-day and inter-day precision were always better than 3%. The limits of detection (LOD) and quantification (LOQ) were 2.5 and 8.3 ng mL^?1, respectively. The LC method was used to quantify lutein and zeaxanthin in rat plasma in a 36-h pharmacokinetic study in which experimental rats received a single oral dose of lutein (20 mg kg^?1). The results are presented.     

DNA Damage and Effects on Antioxidative Enzymes in Earthworm (Eisenia fetida) Induced by Flumorph

Flumorph is an Oomycete fungicide, which is used extensively as an effective fungicide in vegetables and fruits, but little is known about its effect on nontarget soil organisms. In the present study, biochemical responses including changes in the activity of antioxidative enzymes catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST), malondialdehyde (MDA), and DNA damage induced by flumorph were investigated in earthworms (Eisenis fetida). The CAT concentrations were stimulated at 5.0 mg kg^?1 over 28 days and inhibited at 10 and 20 mg kg^?1, except 10 mg kg^?1 on days 21 and 28 compared with the controls. The overall SOD activities were inhibited except 5 mg kg^?1 on day 28 and 10 mg kg^?1 on days 7 and 14. Meanwhile, the GST activities were stimulated on day 7 and decreased on the other days in summary. The MDA activities were increased notably at 5, 10, and 20 mg kg^?1 after 14 days. Clear dose-dependent DNA damage to Eisenia fetida was observed by olive tail moments in comet assay compared with controls. The results demonstrate that flumorph induces oxidative stress and DNA damage to earthworms, and the effects may be the important mechanisms of its toxicity.     

Determination of Tetrandrine in Rat Whole Blood by RP-LC and Its Application to Pharmacokinetic Studies

A simple, specific and sensitive RP-LC method was developed and validated for the determination of tetrandrine in rat whole blood for the first time. Chromatographic separation was performed on a Welchrom^TM C18 analytical column at a flow rate of 1.0 mL min^?1, using a mixture of methanol-water containing 0.6% triethylamine and 0.16% phosphoric acid as mobile phase. The wavelength for UV detection was set at 225 nm. Sample preparation involved a liquid-liquid extraction using n-hexane. The calibration curve was linear with r ² > 0.99 over a concentration range of 0.03?C6.4 ??g mL^?1 in rat whole blood with a lower limit of quantification of 0.03 ??g mL^?1. The intra- and inter-day precisions were 1.33?C4.55 and 3.33?C4.65%, respectively, and the intra- and inter-day accuracy ranged from ?5.24 to 0.90% and ?1.05 to 0.63%, respectively. No endogenous compounds were found to interfere with the analytes. Tetrandrine was stable for 8 h at room temperature, 24 h at 4 °C in rat whole blood, and for 30 days at ?20 °C after being prepared. For the first time, the present method was successfully applied to the pharmacokinetic studies of tetrandrine in rats after intravenous administration of three different doses. The results indicated that the pharmacokinetics of tetrandrine on rats was a first-order process.     

LC-UV Column-Switching for Quantitation of Vitamin K1 in Infant Formula

This study was undertaken in order to develop an analytical method for vitamin K₁ in infant formula. The content of vitamin K₁ was investigated by using a column-switching LC-UV method. A Certified Reference Material sample of infant formula containing 0.94 ± 0.04 mg kg^?1 of vitamin K₁ was extracted with hexane followed by enzymatic digestion of fat and precipitation of the fatty acids. The linearity of this method was calculated using five consecutive standard curves, and the coefficient of determination (r ²) was found to be 0.9995. The limit of detection (LOD) and the limit of quantitation (LOQ) was 3.31 and 11.12 μg L^?1, respectively. The accuracy of intra- and inter-day measurements was in the range from 96.67 to 108.67%, and the precision of intra- and inter-day measurements was less than 5.13%. The recoveries were 109.27 ± 5.92%, and the recoveries of inter-laboratory results were in the range from 97.59 ± 1.29 to 109.27 ± 5.92%. The newly developed method uses the optimum conditions required to determine the content of vitamin K₁ in infant formula.     

Determination of Acephate in Vegetables by Magnetic Molecularly Imprinted Polymer Isolation Coupled with High-Performance Liquid Chromatography

Magnetic molecularly imprinted polymers based on carbon nanotubes were prepared and characterized by infrared spectrometry, transmission electron microscopy, and vibrating sample magnetometry and were employed for the isolation of acephate from cabbage, spinach, lettuce, leeks, and celery. Kinetic and recognition studies were carried out in order to investigate the adsorption properties of the polymers. During the application process, the acephate extracted from vegetables was purified with the magnetic molecularly imprinted polymers and determined by high performance liquid chromatography with an ultraviolet detector. The recoveries of acephate at three fortified concentrations (0.015, 0.15, and 1.5 mg kg^?1) were between 89.2% and 93.4%. The limits of detection and quantification of acephate were 0.0025 and 0.0077 mg kg^?1, respectively. The linear dynamic range was from 0.01 to 5 mg kg^?1. The relative standard deviations of intra- and inter-day precision were 1.1% to 5.9% and 2.7% to 6.4%, respectively. The developed method was demonstrated to be rapid and selective for the extraction and determination of acephate in vegetables.     

Analysis of bioaccessible concentration of trace elements in plant based edible materials by INAA and ICPMS methods

The total metal concentration and bioaccessible concentration of Cr, Mn, Fe, Cu, Zn, Se in Momordica charantia, Asparagus racemosus, Terminalia arjuna and Syzyzium cumini were measured by instrumental neutron activation analysis and by inductively coupled plasma mass spectrometry analysis (ICP-MS). The bioaccessible concentrations were determined in the gastrointestinal digest obtained after treating dried powdered samples sequentially in gastric and intestinal fluid of porcine origin at physiological conditions. The bioaccessible concentration of Fe was in the range of 58–67 mg kg^?1, Mn was 10.2–14.6 mg kg^?1, Cu was 3.7–4.8 mg kg^?1 and Zn was 10.6–18.4 mg kg^?1, were within the safety limits set for vegetable food stuff set by Joint FAO/WHO. The bioaccessibility of Zn, an essential element, was high (40–50 %) in M. charantia and in S. cumini. In addition, the total metal contents and bioaccessible concentration of Ni, Se, Cd and Pb in these samples were measured by ICP-MS. The total Cd content in S. cumini (2.6 ± 0.2 mg kg^?1) and its bioaccessible concentration (0.6 mg kg^?1) were strikingly high as compared to the other samples. Though total Hg contents were determined by ICP-MS, but their bioaccessible concentrations were below the detection limit (0.036 mg kg^?1).     

HPLC Analysis and Pharmacokinetic Study of Paeoniflorin after Intravenous Administration of a New Frozen Dry Powder Formulation in Rats

A simple and specific high performance liquid chromatographic (HPLC) method with UV detection using picroside II as the internal standard was developed and validated to determine the concentration of paeoniflorin in rat plasma and study its pharmacokinetics after an single intravenous administration of 40 mg kg^?1 paeoniflorin to Wistar rats. The analytes of interest were extracted from rat plasma samples by ethyl acetate after acidification with 0.05 mol L^?1 NaH₂PO₄ solution (pH 5.0). Chromatographic separation was achieved on an Agilent XDB C₁₈ column (250 × 4.6 mm I.D., 5 μm) with a Shim-pack GVP-ODS C₁₈ guard column (10 × 4.6 mm I.D., 5 μm) using a mobile phase consisting of acetonitrile–water–acetic acid (18:82:0.4, v/v/v) at a flow rate of 1.0 mL min^?1. The UV detection was performed at a wavelength of 230 nm. The linear calibration curves were obtained in the concentration range of 0.05–200.0 μg mL^?1 in rat plasma with the lower limit of quantification (LLOQ) of 0.05 μg mL^?1. The intra- and inter-day precisions in terms of % relative standard deviation (RSD) were lower than 5.7 and 8.2% in rat plasma, respectively. The accuracy in terms of % relative error (RE) ranged from ?1.9 to 2.6% in rat plasma. The extraction recoveries of paeoniflorin and picroside II were calculated to be 69.7 and 56.9%, respectively. This validated method was successfully applied to the pharmacokinetic study of a new paeoniflorin frozen dry power formulation. After single intravenous administration, the main pharmacokinetic parameters t _1/2, AUC_0-∞, CL_TOT, V _Z, MRT_0-∞ and V _ss were 0.739 ± 0.232 h, 43.75 ± 6.90 μg h mL^?1, 15.50 ± 2.46 L kg^?1 h^?1, 1.003 ± 0.401 L kg^?1, 0.480 ± 0.055 h and 0.444 ± 0.060 L kg^?1, respectively.     

Rapid and Sensitive RP-LC Method for the Quantification and Pharmacokinetic Study of p-Hydroxyphenethyl Anisate in Rat Plasma

A rapid, sensitive and specific reversed-phase liquid chromatographic method was developed and validated for the quantification of p-hydroxyphenethyl anisate (HPA), which is one of the main constituents of Notopterygium Radix (underground parts of Notopterygium incisum and N. forbesii), in rat plasma, and study its pharmacokinetics after the intravenous administration of 40 mg kg^?1 HPA to rats. The method involves a plasma clear-up step using liquid–liquid extraction by ethyl acetate, followed by RP-LC separation and detection. Separation of HPA was performed on an analytical Diamonsil ODS C₁₈ column equipped with a Dikma ODS C₁₈ EasyGuard column using a mobile phase consisting of MeOH–H₂O (75:25, v/v) at a flow-rate of 1.0 mL min^?1. The UV detection was performed at a wavelength of 256 nm. The linear calibration curves were obtained in the concentration range of 0.05–5.0 μg mL^?1 (r = 0.9992, n = 5) in rat plasma with the lower limit of detection of 0.01 μg mL^?1 and the lower limit of quantification of 0.04 μg mL^?1, and the extraction recovery of HPA was calculated to be the range of 82.01–86.66%. The intra- and inter-day precisions in terms of % relative standard deviation were lower than 2.33 and 3.99% in rat plasma, respectively, with accuracies ranging from 91.22 to 110.5%. The developed method was suitable for the determination and pharmacokinetic study of HPA in rat plasma.     

A Rapid Method for the Analysis of Ten Compounds in Psoralea corylifolia L. by UPLC

The objective of this study was to develop a simple, efficient and reliable method for routine quantitative analysis for Psoralea corylifolia L. An ultra performance liquid chromatography with DAD detector system was employed for simultaneous quantification of ten compounds. The chromatographic analysis was performed by UPLC with C₁₈ column and gradient elution of 0.05% formic acid aqueous solution and acetonitrile in 16 min. All calibration curves were linear (R ² ≥ 0.9990) over the tested ranges. The LOD and LOQ were lower to 13.07 and 39.22 ng mL^?1 with 2 μL of injection volume, respectively. The intra- and inter-day precisions as determined from sample solutions were below 4.1 and 4.2%. The average recoveries were ranged from 94.2 to 108.8% with RSDs ≤ 4.6%. This validated method was applied for the analysis of ten analytes in P. corylifolia L. from different origins. The variation of the content of ten compounds was remarkable among the tested samples: psoralenoside increased from 7.42 to 17.04 mg g^?1, isopsoralenoside from 6.05 to 14.34 mg g^?1, psoralen from 2.37 to 3.90 mg g^?1, isopsoralen from 2.53 to 3.65 mg g^?1, neobavaisoflavone from 1.59 to 2.96 mg g^?1, bavachin from 1.02 to 2.35 mg g^?1, psoralidin from 0.45 to 1.91 mg g^?1, isobavachalcone from 1.33 to 4.71 mg g^?1, corylifol A from 1.02 to 2.40 mg g^?1 and bakuchiol from 28.10 to 63.89 mg g^?1.     

Determination of Tectorigenin in Rat Plasma: Application to a Pharmacokinetic Study After Oral Administration of Tectorigenin or Its Prodrug Tectoridin

A simple, sensitive, and validated liquid chromatographic method has been developed for the determination of tectorigenin in rat plasma and application to a pharmacokinetic study after oral administration of tectorigenin or its prodrug tectoridin. The analysis was performed on a Kromasil C₁₈ analytical column using gradient elution with acetonitrile 0.1% phosphonic acid water at 0.8 mL min^?1. The detection wavelength for UV detection was set at 264 nm. The established method was fully validated with parameters as follows: the intra- and inter-day assay precisions (CV) of three analytes were in the range of 4.2–13.3% and accuracies were between 98.0 and 107.5%; the calibration curve was linear with r ² > 0.99 over a concentration range of 0.02–2 μg mL^?1; the lower limit of quantification was 0.02 μg mL^?1; tectorigenin showed stable in rat plasma after 12 h incubation at room temperature, 15 days storage at ?80 °C and three freeze/thaw cycles, as well as in reconstitute buffer for 24 h at 25 °C; and the mean recoveries of tectorigenin were 92.3 ± 3.2, 95.5 ± 2.9 and 94.5 ± 3.0% with quality control levels of 0.02, 0.2 and 2 μg mL^?1, respectively. In conclusion, this method is simple, economic, and sensitive enough for in vivo pharmacokinetic studies of tectorigenin.     

Simultaneous Determination of Escin Ia and Its Isomer Isoescin Ia by LC�CMS�CMS: Application to a Pharmacokinetic Study of Escin Ia in Rats

A rapid and sensitive LC?CMS?CMS method for the simultaneous determination of escin Ia and isoescin Ia in rat plasma, urine, feces and bile samples was developed and validated. Analytes and telmisartan [internal standard (IS)] were extracted by solid-phase extraction on C₁₈ cartridges. Components in the extract were separated on an HC-C₁₈ column (5 ??m, 150 × 4.6 mm i.d.) using 10 mM ammonium acetate?Cmethanol?Cacetonitrile (40:30:30, v/v/v) as the mobile phase. The method demonstrated good linearity from 5 ng mL^?1 (LLOQ) to 1,500 ng mL^?1 for both escin Ia and isoescin Ia. Intra- and inter-day precision measured as RSD was within ±15%. Recoveries and matrix effects of both escin Ia and isoescin Ia were satisfactory in all four matrices examined. The method was successfully applied to a pharmacokinetic study in Wistar rats after a single intravenous administration of escin Ia at the dose of 1.0 mg kg^?1.     

Enantioselective Separation and Determination of Carnosine in Rat Plasma by Fluorescence LC for Stereoselective Pharmacokinetic Studies

A sensitive fluorescence liquid chromatographic analytical method was developed for the simultaneous determination of carnosine enantiomers in rat plasma. The method was applied to pharmacokinetic studies. Chiral separation of carnosine enantiomers was achieved by pre-column derivatization with o-phthaldialdehyde and the thiol N-acety-l-cysteine as derivating reagents. They were separated on an ODS column and detected by fluorescence detection (λ_ex = 350 nm, λ_em = 450 nm). γ-Aminobutyric acid was used as internal standard. The method was linear up to 6,000 ng mL^?1 for l-carnosine, 4,000 ng mL^?1 for d-carnosine. Low limit of quantitation (LLOQ) was 40 ng mL^?1 for each isomer. The relative standard deviations obtained for intra- and inter-day precision were lower than 12% and the recoveries were higher than 75% for both enantiomers. The method was applied to a stereoselective study on the pharmacokinetics of carnosine after oral administration with a single dose (carnosine, 75 mg kg^?1 for each isomer) to a rat. The initial data indicated that l-carnosine had a larger value of the highest plasma concentration than d-carnosine (C _max 5,344 vs. 1,914 ng mL^?1), and that of l-carnosine had a lower value of AUC_(0?∞) and t _1/2(h) (AUC_(0?∞) 5,306 vs. 6,321 ng h mL^?1, t _1/2 1.43 vs. 3.37 h). Our results indicated that the pharmacokinetic of l-carnosine and d-carnosine revealed enantioselective properties significantly.     

LC-MS-MS Determination of (S,R)-Penehyclidine in Rat Plasma

A sensitive and selective method for determination of (S,R)-penehyclidine in rat plasma by liquid chromatography-tandem mass spectrometry is described. The procedure employed the use of an internal standard (I.S.) and a simple protein precipitation step. The method developed was linear from 0.1 to 100 ng mL^?1, with a sensitivity of 0.1 ng mL^?1 as the lower limit of quantification. The intra- and inter-day assay accuracy (relative error) was within 8.27% and precision (RSD) was below 6.7%. It was successfully applied to pharmacokinetic studies of (S,R)-penehyclidine in rat plasma.     

QuEChERS and solid phase extraction methods for the determination of energy crop pesticides in soil,plant and runoff water matrices

QuEChERS and solid phase extraction (SPE) methods were applied for determining four herbicides (metazachlor, oxyfluorfen, quizalofop-p-ethyl, quinmerac) and one insecticide (α(±)-cypermethrin) in runoff water, soil, sunflower and oilseed rape plant matrices. Determination was performed using gas chromatography mass spectrometry (GC-MS), whereas high-pressure liquid chromatography mass spectrometry (HPLC-MS) was used for quinmerac. In all substrates linearity was evaluated using matrix-matched calibration samples at five concentration levels (50–1000 ng L^?1 for water, 5–500 μg kg^?1 for soil and 2.5–500 μg kg^?1 for sunflower or oilseed rape plant). Correlation coefficient was higher than 0.992 for all pesticides in all substrates. Acceptable mean recovery values were obtained for all pesticides in water (65.4–108.8%), soil (70.0–110.0%) and plant (66.1–118.6%), with intra- and inter-day RSD% below 20%. LODs were in the range of 0.250–26.6 ng L^?1 for water, 0.10–1.8 μg kg^?1 for soil and 0.15–2.0 μg kg^?1 for plants. The methods can be efficiently applied for field dissipation studies of the pesticides in energy crop cultivations.     

LC�CMS�CMS Method for Quantification of Hydralazine in BALB/C Mouse Plasma and Brain: Application to Pharmacokinetic Study

A rapid, sensitive and accurate high performance liquid chromatography method using tandem mass spectrometry detection for hydralazine in BALB/C mouse plasma and brain was developed and validated. The method involved a derivatization with 2,4-pentanedione at 50 °C for 1 h, and a step of solid phase extraction to purify and concentrate hydralazine derivative. Chromatographic separation was carried out on an Agilent ZORBAX SB-C18 column by elution with methanol?C0.01 mol L^?1 ammonium acetate (60:40, v/v). The multiple reaction monitoring transition used for quantification was m/z 225.2 ?? 129.5 in the electrospray positive ionization mode. Good linearity was obtained over the concentration range of 10?C200 ng mL^?1. The limits of detection were 0.49 and 1.05 ng mL^?1 for hydralazine in mouse plasma and brain, respectively. The limits of quantitation were 1.5 and 3.18 ng mL^?1 for hydralazine in mouse plasma and brain, respectively. Sample analysis time was 6 min including sample separation. The method was successfully applied to a pharmacokinetic study following intraperitoneal injection of hydralazine in BALB/C mice at the dose of 20 mg kg^?1.     

Determination of Jasminoidin in Rabbit Plasma for the Pharmacokinetic Investigation after Single Dose Oral Administration of Gardenia jasminoides Ellis and Gardenia jasminoides Ellis Coupling Coptis chinensis Franch Extracts

A simple, sensitive and rapid method for the analysis of jasminoidin in rabbit plasma by liquid chromatography coupled to tandem mass spectrometry was developed. Detection was by positive ion electrospray ionization in multiple reactions monitoring mode. The method included a chromatographic run of 5.0 min using a C₁₈ analytical column and the calibration curve was linear over the concentration range of 0.5–2,000 ng mL^?1 with a correlation coefficient R of 0.998 or better. The intra- and inter-day precision ranged from 3.4 to 5.6% and 4.3 to 8.2%. The intra- and inter-day assay accuracy was between ?7.4 and 8.6%. The method was successfully applied for the pharmacokinetic study on jasminoidin in rabbit after a single dose oral administration of Gardenia jasminoides Ellis (Gardenia) and Gardenia coupling Coptis chinensis Franch (Coptidis) extracts.