Gradient Mobile Phase Research Articles

Development and validation of a UPLC-MS/MS method for simultaneous detection of doxorubicin and sorafenib in plasma: Application to pharmacokinetic studies in rats

An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the simultaneous quantitation of doxorubicin (DOX) and sorafenib (SOR) in rat plasma. Chromatographic separation was performed using a reversed-phase column C18 (1.7 μm, 1.0 × 100 mm Acquity UPLC BEH™). The gradient mobile phase system consisted of water containing 0.1% acetic acid (mobile phase A) and methanol (mobile phase B) with a flow rate of 0.40 mL/min over 8 min. Erlotinib (ERL) was used as an internal standard (IS). The quantitation of conversion of [M + H]+, which was the protonated precursor ion, to the corresponding product ions was performed using multiple reaction monitoring (MRM) with a mass-to-charge ratio (m/z) of 544 > 397.005 for DOX, 465.05 > 252.03 for SOR, and 394 > 278 for the IS. Different parameters were used to validate the method including accuracy, precision, linearity, and stability. The developed UPLC–MS/MS method was linear over the concentration ranges of 9–2000 ng/mL and 7–2000 ng/mL with LLOQ of 9 and 7 ng/mL for DOX and SOR, respectively. The intra-day and inter-day accuracy, expressed as % relative standard deviation (RSD%), was below 10% for both DOX and SOR in all QC samples that have drug concentrations above the LLOQ. The intra-day and inter-day precision, expressed as percent relative error (Er %), was within the limit of 15.0% for all concentrations above LLOQ. Four groups of Wistar rats (250–280 g) were used to conduct the pharmacokinetic study. Group I received a single intraperitoneal (IP) injection of DOX (5 mg/kg); Group II received a single oral dose of SOR (40 mg/kg), Group III received a combination of both drugs; and Group IV received sterile water for injection IP and 0.9% w/v sodium chloride solution orally to serve as a control. Non-compartmental analysis was used to calculate the different pharmacokinetic parameters. Data revealed that coadministration of DOX and SOR altered some of the pharmacokinetic parameters of both agents and resulted in an increase in the Cmax and AUC and reduction in the apparent clearance (CL/F). In conclusion, our newly developed method is sensitive, specific, and can reliably be used to simultaneously determine DOX and SOR concentrations in rat plasma. Moreover, the results of the pharmacokinetic study suggest that coadministration of DOX and SOR might cause an increase in exposure of both drugs.

HPLC-UV Analysis of Chrysophanol in Senna occidentalis Extract Obtained by Using the RSM-Optimized Ultrasonic Extraction Process

In this experiment, chrysophanol analysis in Senna occidentalis (aerial parts) extract obtained by optimizing ultrasound-assisted extraction (UAE) variables (temperature, time, and liquid-to-solid ratio) using response surface methodology (RSM) was performed by employing the HPLC-UV method. For UAE process optimization, a highly significant quadratic model (p < 0.001) was projected to attain maximum chrysophanol yield. The extraction temperature, time, and liquid-to-solid ratio for the best UAE method were determined to be 49.3 °C, 57.7 min, and 18.7 mL/g, respectively. The optimized extract was subjected to a chrysophanol analysis utilizing HPLC-UV (fitted with a Pinnacle C18 column), and a gradient mobile phase composed of 0.5% formic acid (solvent A), acetonitrile (solvent B), methanol (solvent C), at a flow rate of 1.0 mL/min, and an optimum wavelength of 279 nm, respectively. It furnished a compact and intense peak of chrysophanol at Rt = 23.809 min. The experimental value (20.47 mg/g) of chrysophanol obtained was close to the predicted value (19.32 mg/g), indicating that they agreed under the optimized extraction condition. UAE also displayed remarkable improvement in chrysophanol extraction compared with the conventional solvent extraction (CSE) method. Hence, our improved ultrasonic extraction process showed a potential use for effective chrysophanol extraction from commercial herbal supplements comprising the Senna species.

Development and validation of an LC-MS/MS method for quantification of favipiravir in human plasma

Favipiravir (FVP) is a broad-spectrum antiviral that selectively inhibits viral RNA-dependent RNA polymerase, first trialled for the treatment of influenza infection. It has been shown to be effective against a number of RNA virus families including arenaviruses, flaviviruses and enteroviruses. Most recently, FVP has been investigated as a potential therapeutic for severe acute respiratory syndrome coronavirus 2 infection. A liquid chromatography tandem mass spectrometry method for the quantification of FVP in human plasma has been developed and validated for use in clinical trials investigating favipiravir as treatment for coronavirus disease-2019. Samples were extracted by protein precipitation using acetonitrile, using 13C, 15N- Favipiravir as internal standard. Elution was performed on a Synergi Polar-RP 150 × 2.1 mm 4 µm column using a gradient mobile phase programme consisting of 0.2% formic acid in water and 0.2% formic acid in methanol. The assay was validated over the range 500–50,000 ng/mL; this method was found to be precise and accurate and recovery of FVP from the matrix was high. Stability experiments confirmed and expanded on the known stability of FVP, including under heat treatment and for a period of 10 months at − 80 °C.

Determination of sixteen antibiotics and four β-agonists in human urine samples using ultra-performance liquid chromatography-tandem mass spectrometry based on high-throughput automatic solid-phase extraction

An analytical method combining high-throughput automatic solid-phase extraction with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed to determine 16 antibiotics (macrolides, tetracyclines, quinolones, and sulfonamides) and 4 β-agonists (terbutaline, salbutamol, ractopamine, and clenbuterol) in human urine samples. After thawing at room temperature, 1 mL of urine was sampled and the internal standard was added, followed by the addition of 200 μL ammonium acetate buffer and 20 μL β-glucuronidase, and the mixture was incubated at 37 ℃ overnight. Automatic solid-phase extraction was used to extract the target compounds from the urine samples, and the recoveries were compared using different solid-phase extraction 96-well plates (PRiME MCX, Sep-Pak C18, PRiME HLB), types and volumes of rinse solutions and eluents. Satisfactory recoveries of the 20 target compounds were obtained using the Oasis PRiME HLB 96-well plate, with 1.5 mL 10% (v/v) methanol aqueous solution and 2.0 mL methanol as the rinse solution and eluent, respectively. The eluent was concentrated under nitrogen gas at 45 ℃, and the recoveries of the target compounds were compared under different conditions (completely or almost dry, drying to 1 mL, and adding water as a protective agent), and the recovery rate was optimal when water was added as a protective agent. In this study, two types of analytical columns (ACQUITY BEH C18 and ACQUITY HSS T3) and different gradient elution procedures and mobile phases were compared. The optimal chromatographic effect was realized using an HSS T3 column (100 mm×3.0 mm, 1.8 μm) and 0.1% (v/v) formic acid aqueous solution-0.1% (v/v) formic acid in acetonitrile as the mobile phase in gradient elution at a flow rate of 0.3 mL/min. Comparing the peaks observed using different proportions of methanol aqueous solution and the initial mobile phase as the injection solvent revealed that 30% (v/v) methanol aqueous solution was the optimal solution in terms of peak shape and signal-to-noise ratio. MS was conducted using positive electrospray ionization (ESI+) in multiple reaction monitoring (MRM) mode, and the MS parameters were optimized, including the curtain (CUR) and collision gases (CAD). The standard curve obtained using this method exhibited a good linearity (correlation coefficient>0.997), and the respective limits of detection and quantification were 0.02-0.12 ng/mL and 0.06-0.41 ng/mL. At spiked levels of 0.25, 2.5, and 12.5 ng/mL, the recoveries were in the range of 81.7%-120.0% (except that of tetracycline), the intra- and inter-day RSDs (n=6) were 1.1%-11.0% and 1.2%-13.0%, respectively. Azithromycin, trimethoprim, terbutaline, salbutamol, ractopamine, and clenbuterol displayed moderate matrix effects, but all targets exhibited weak matrix effects after correction using the isotope internal standard. To evaluate the accuracy of this method, BCR-503 (containing salbutamol and clenbuterol) and internal quality control samples were used and the concentrations of salbutamol and clenbuterol were within the reference ranges. Additionally, the mean concentrations of the 20 target compounds of two different internal quality control samples after 7 measurements were in the ranges of 0.44-0.59 ng/mL (0.5 ng/mL) and 1.72-2.16 ng/mL (2.0 ng/mL), respectively, which were satisfactory. In this study, the analytical method employed automatic sample pretreatment with a 96-well solid-phase extraction plate, and the detection efficiency was considerably improved. This method displays the advantages of simple operation, ideal recovery, a high sensitivity and weak matrix effect, which satisfies the requirements for the simultaneous determination of 16 antibiotics and 4 β-agonists in human urine samples. This study provides a crucial method for use in monitoring antibiotics and β-agonists in human urine and studying their exposure characteristics and health risks.

Comparison of HPLC fingerprints and determination of main components of Viticis Fructus from different species

In order to comprehensively evaluate the quality of Viticis Fructus, this study established HPLC fingerprints and evaluated the quality of 24 batches of Viticis Fructus samples from different species by similarity evaluation and multivariate statistical analysis(PCA, HCA, PLS-DA). On this basis, an HPLC method was established to compare the content differences of the main components, including casticin, agnuside, homoorientin, and p-hydroxybenzoic acid. The analysis was performed on the chromatographic column(Waters Symmetry C_(18)) with a gradient mobile phase of acetonitrile(A)-0.05% phosphoric acid solution(B) at the flow rate of 1 mL·min~(-1) and detection wavelength of 258 nm. The column temperature was 30 ℃ and the injection volume was 10 μL. The HPLC fingerprint of 24 batches of Viticis Fructus samples was established with 21 common peaks, and nine peaks were identified. Similarity analysis was carried out based on chromatographic data of 24 batches of chromatographic data of Viticis Fructus, and the results showed that except for DYMJ-16, the similarity of Vitex trifolia var. simplicifolia was ≥0.900, while that of V. trifolia was ≤0.864. In addition, the similarity analysis of two different species showed that the similarity of 16 batches of V. trifolia var. simplicifolia was 0.894-0.997 and that of the eight batches of V. trifolia was between 0.990 and 0.997. The results showed that the similarity of fingerprints of these two species was different, but the similarity between the same species was good. The results of the three multivariate statistical analyses were consistent, which could distinguish the two different species. The VIP analysis results of PLS-DA showed that casticin and agnuside contributed the most to the distinction. The content determination results showed that there was no significant difference in the content of homoorientin and p-hydroxybenzoic acid in Viticis Fructus from different species, but the content of casticin and agnuside was significantly different in different species(P<0.01). The content of casticin was higher in V. trifolia var. simplicifolia, while agnuside was higher in V. trifolia. The findings of this study show that there are differences in fingerprint similarity and component content of Viticis Fructus from different species, which can provide references for the in-depth study of the quality and clinical application of Viticis Fructus.

A New UHPLC Analytical Method for St. John’s Wort (Hypericum perforatum) Extracts

Commonly used to treat mood disorders, St. John’s Wort (Hypericum perforatum) is a popular herb in the natural health products industry. The potency of its active ingredients can be determined using a number of different analytical methods, but it is more widely determined using high performance liquid chromatography (HPLC). While monographs in the United States Pharmacopeia (USP) can often be relied upon for suitable analytical methods, the method proposed for determining hypericin content in St. John’s Wort products is inefficient in carrying out this purpose. This paper presents a modified new HPLC method for determining the hypericin content that can also be used for St. John’s Worts capsules and tablets by making use of purified hypericin as a chemical standard instead of oxybenzone, applying a wavelength of 588 nm during analysis and utilizing a binary instead of ternary mobile phase gradient. The resulting method and sample chromatograms provide better resolved, more easily identifiable peaks, shorter run time, and increased sustainability compared to the original USP method. This proposed method was developed using the more refined ultra-high performance liquid chromatography (UHPLC) and serves as a more accurate and reliable method for determining hypericin content in St. John’s Wort.

Development of Methods of Quality Control of the Tablets «Ramipril»

Our main target was to develop methods for the quality control of the tablet «ramipril» according to the indicators of «Quantitative determination», «Impurities» and «Dissolution». New, precise, accurate and green HPLC methods were developed for the determination of ramipril and its impurities in tablets. The separation was accomplished using a diode array detector at 210 nm with an isocratic and gradient mobile phase consisting of a 0.2 g/L solution of sodium hexanesulfonate (pH 2.7) and the acetonitrile and chromatographic columns Acclaim 120 C18 and Inertsil ODS-3. The developed method was validated in accordance with ICH guidelines. The analysis of impurities was performed within a run duration of less than 25 min, which is about a two times shorter than that of the official Ph. Eur. method. The analysis of ramipril in tablets was performed with a run duration of less than 4.5 min, which is about three times shorter than that of the official USP method. The developed methods were successfully applied for the quality control of the tablet «ramipril» according to the indicators of «Quantitative determination», «Impurities» and «Dissolution». In addition, they proved its superiority over the reported methods in terms of greenness using different assessment tools.

A novel anastrozole intravaginal ring for endometriosis: Pharmacokinetic characteristics and mucosal irritation.

In order to achieve the long-term management of endometriosis, a more economical and environmentally friendly material, ethylene vinyl acetate (EVA), was used to prepare a intravaginal ring with anastrozole (ATZ). This paper has compared the pharmacokinetic parameters with oral tablets (Aida®) in mini pigs and evaluated the uterine targeted effect and mucosal irritation of the ring. A bioassay method was developed and validated for the determination of ATZ in mini pigs. The determination of ATZ was achieved by LC-MS/MS using terfenadine as the internal standard. Separation was achieved on a Kinetex-C18 110A chromatographic column (3 × 30 mm, 2.6μm; Phenomenex) with a gradient mobile phase consisting of methanol (0.1% formic acid) and water (0.1% formic acid). The method has been proved to be scientific and sensitive through methodological validation and can be easily and quickly applied to the determination of the content of anastrozole in mini pigs. The pharmacokinetic test results show that there was no significant difference in pharmacokinetic parameters between the two formulations. The intravaginal ring has a passive targeting effect on the uterus, and its mucosal irritation is acceptable. The intravaginal ring provides a new method for long-term management of endometriosis.

Analytical Quality by Design: Achieving Robustness of an LC-CAD Method for the Analysis of Non-Volatile Fatty Acids.

An alternative to the time-consuming and error-prone pharmacopoeial gas chromatography method for the analysis of fatty acids (FAs) is urgently needed. The objective was therefore to propose a robust liquid chromatography method with charged aerosol detection for the analysis of polysorbate 80 (PS80) and magnesium stearate. FAs with different numbers of carbon atoms in the chain necessitated the use of a gradient method with a Hypersil Gold C18 column and acetonitrile as organic modifier. The risk-based Analytical Quality by Design approach was applied to define the Method Operable Design Region (MODR). Formic acid concentration, initial and final percentages of acetonitrile, gradient elution time, column temperature, and mobile phase flow rate were identified as critical method parameters (CMPs). The initial and final percentages of acetonitrile were fixed while the remaining CMPs were fine-tuned using response surface methodology. Critical method attributes included the baseline separation of adjacent peaks (α-linolenic and myristic acid, and oleic and petroselinic acid) and the retention factor of the last compound eluted, stearic acid. The MODR was calculated by Monte Carlo simulations with a probability equal or greater than 90%. Finally, the column temperature was set at 33 °C, the flow rate was 0.575 mL/min, and acetonitrile linearly increased from 70 to 80% (v/v) within 14.2 min.

Direct Chiral Supercritical Fluid Chromatography-Mass Spectrometry Analysis of Monoacylglycerol and Diacylglycerol Isomers for the Study of Lipase-Catalyzed Hydrolysis of Triacylglycerols.

The fast and selective separation method of intact monoacylglycerol (MG) and diacylglycerol (DG) isomers using chiral supercritical fluid chromatography-mass spectrometry (SFC-MS) was developed and employed to study lipase selectivity in the hydrolysis of triacylglycerols (TGs). The synthesis of 28 enantiomerically pure MG and DG isomers was performed in the first stage using the most commonly occurring fatty acids in biological samples such as palmitic, stearic, oleic, linoleic, linolenic, arachidonic, and docosahexaenoic acids. To develop the SFC separation method, different chromatographic conditions such as column chemistry, mobile phase composition and gradient, flow rate, backpressure, and temperature were carefully assessed. Our SFC-MS method used a chiral column based on a tris(3,5-dimethylphenylcarbamate) derivative of amylose and neat methanol as a mobile phase modifier, which provides baseline separation of all the tested enantiomers in 5 min. This method was used to evaluate hydrolysis selectivity of lipases from porcine pancreas (PPL) and Pseudomonas fluorescens (PFL) using nine TGs differing in acyl chain length (14-22 carbon atoms) and number of double bonds (0-6) and three DG regioisomer/enantiomers as hydrolysis intermediate products. PFL exhibited preference of the fatty acyl hydrolysis from the sn-1 position of TG more pronounced for the substrates with long polyunsaturated acyls, while PPL did not show considerable stereoselectivity to TGs. Conversely, PPL preferred hydrolysis from the sn-1 position of prochiral sn-1,3-DG regioisomer, whereas PFL exhibited no preference. Both lipases showed selectivity for the hydrolysis of outer positions of DG enantiomers. The results show complex reaction kinetics of lipase-catalyzed hydrolysis given by different stereoselectivities for substrates.

Development of a Rapid LC-MS/MS Method for Simultaneous Quantification of Donepezil and Tadalafil in Rat Plasma: Its Application in a Pharmacokinetic Interaction Study after Oral Administration in Rats.

This study aimed to establish a simple and sensitive analytical method to simultaneously quantify donepezil (DPZ) and tadalafil (TAD) in rat plasma using lansoprazole (LPZ) as an internal standard (IS) by using liquid chromatography tandem mass spectrometry. The fragmentation pattern of DPZ, TAD, and IS was elucidated using multiple reaction monitoring in electrospray ionization positive ion mode for the quantification of precursor to production at m/z 380.1 → 91.2 for DPZ, m/z 390.2 → 268.1 for TAD, and m/z 370.3 → 252.0 for LPZ. The extracted DPZ and TAD from plasma using acetonitrile-induced protein precipitation was separated using Kinetex C18 (100 × 2.1 mm, 2.6 µm) column with a gradient mobile phase system consisting of 2 mM ammonium acetate and 0.1% formic acid in acetonitrile at a flow rate of 0.25 mL/min for 4 min. The selectivity, lower limit of quantification, linearity, precision, accuracy, stability, recovery, and matrix effect of this developed method was validated according to the guidelines of the U.S. Food and Drug Administration and the Ministry of Food and Drug Safety of Korea. The established method achieved acceptance criteria in all validation parameters, ensuring reliability, reproducibility, and accuracy, and was successfully implemented in a pharmacokinetic study on the co-administration of DPZ and TAD orally in rats.

A Simple, Precise, and Sensitive RP-HPLC Method for Quantification of Teneligliptin Hydrobromide and Metformin Hydrochloride: Development and Validation

Simple, rapid, sensitive, robust, and validated reverse phase- high-performance liquid chromatography RP_(HPLC) was developed for the quantification of anti-diabetic drugs Teneligliptin hydrobromide (TH) and Metformin hydrochloride (MH) in bulk and in formulation. The RP-HPLC method was developed using an HPLC system with a PDA detector. A simple, accurate and cost-effective gradient approach is used by using C18 Inertsil ODS (150×4.6)mm, 5µ. A method was developed and validated as per ICH Q2 (R1) guideline. The efficient separation of both drugs was achieved using an optimised solvent mixture of Buffer: ACN (85:15% v/v) and Methanol: ACN (50:50% v/v) used as a gradient mobile phase, during this experiments flow rate was maintained 0.8 ml/min and at the end the detection of peak carried out by PDA detector at wavelength 249nm. The method has been validated for TH and MH for a range of 16-64μg/ml and 400 - 1600μg/ml with regression coefficient (r2) was 1 and 0.9979 respectively. The optimal approach has been validated in accordance with ICH guideline Q2(R1). The results demonstrated that the method’s accuracy (99.89–100.34 percent w/w and 99.91–100.01 percent w / w TH and MH, respectively) and method is precise as percentage of relative standard deviation <2.0. The proposed LC method used as qualitative as well as quantitative applications for simultaneous quantification of Teneligliptin hydrobromide and Metformin hydrochloride in bulk and tablet dosage form and also sufficient to apply regulatory purpose.

A validated LC–MS/MS method for clinical pharmacokinetics and presumptive phase II metabolic pathways following oral administration of Andrographis paniculata extract

Andrographis paniculata, a medicinal plant in Thailand national list of essential medicines, has been proposed for treatment of patients with mild to moderate coronavirus disease 2019. This study aims to develop a highly selective and sensitive liquid chromatography triple quadrupole tandem mass spectrometry method for quantitative determination of major diterpenoids in plasma and urine with application in pharmacokinetics. Chromatographic separation was performed on C18 column using a gradient mobile phase of water and acetonitrile. Mass spectrometry was analyzed using multiple reaction monitoring with negative ionization mode. This validated analytical method was very sensitive, less time consuming in analysis, and allowed the reliability and reproducibility on its application. The clinical pharmacokinetics was evaluated after single oral administration of A. paniculata extract (calculated as 60 mg of andrographolide). The disposition kinetics demonstrated that major diterpenoids could enter into systemic circulation, but they are mostly biotransformed (phase II) into conjugated glucuronide and sulfate metabolites. These metabolites are predominantly found in plasma and then extremely eliminated, in part through urinary excretion. The successful application of this analytical method supports its suitable uses in further clinical benefits after oral administration of A. paniculata.

Simultaneous Determination of Three Compounds in Rat Plasma by UHPLC-QQQ-MS/MS and Its Application to Pharmacokinetics of Banxia Baizhu Tianma Tang.

A rapid and highly selective and sensitive ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC-QQQ-MS/MS) method was applied to simultaneously determine ephedrine, gastrodin, and liquiritin in rat plasma. The three analytes and vitexin-2″-O-rhamnoside (I.S.) were analyzed on a Waters Acquity UPLC C18 column (1.7 μm, 2.1 mm × 100 mm) at 30°C with gradient mobile phase consisting of 0.1% formic acid aqueous solution (A) and acetonitrile (B) after one-step direct protein precipitation with acetonitrile. The detection was performed by multiple reaction monitoring (MRM) mode via electrospray ionization (ESI) source in positive and negative ion modes. The product ions m/z 166.1⟶148.1, 285.1⟶123.1, 417.1⟶255.1, and 579.0⟶433.1 were used for determination of ephedrine, gastrodin, liquiritin, and I.S., respectively. The calibration curves of the three analytes were linear with r 2 greater than 0.994. The intra and interday precision RSD% was less than 11.5 and 13.4. The intra and interday precision RE% was between -10.4% and 9.33%. The average extraction recoveries of the three analytes were no less than 86.88 ± 1.08%. The developed and validated method was for the first time applied to the pharmacokinetics of three compounds in rat plasma after intragastric administration of Banxia Baizhu Tianma Tang.

Quantitive analysis of flavonoids in ainaxiang tablets by high-performance liquid chromatography

Blumea balsamifera is a very famous medicinal plant and functional tea in many countries of Asia. Ainaxiang tablets are a preparation consisting of flavonoids from B. balsamifera. Today, a high performance liquid chromatography method was developed for simultaneous quantification of 15 flavonoids in Ainaxiang Tablets. The analysis was performed on a Kromasil C18 column (250 × 4.6 mm, 5 µm) with a binary gradient mobile phase of acetonitrile and 0.2% aqueous acetic acid. The method was validated in terms of linearity, sensitivity, stability, precision and accuracy. It was found that this method had linearity with R2 at 0.9992- 0.9999 in the test range of 0.15-276.40 µg/mL. The limit of detection (LOD) and limit of quantification (LOQ) for 15 tested reference compounds were 0.01-0.28µg/mL and 0.02 - 0.55µg/mL, respectively. The relative standard deviations (RSD%) for intra-day and inter-day repeatability were not more than 3.18%. The analyzed samples were stable for at least 18 h. The spike recoveries for 15 analyzed samples were 106.17 - 95.02%. The results suggested that this newly developed HPLC method could be used for quantitative analysis of flavonoids in Ainaxiang Tablets and its raw materials.

Validation HPLC-DAD Method for Quantification of Gallic and Ellagic Acid from Eugenia punicifolia Leaves, Extracts and Fractions

Eugenia punicifolia (Kunth) DC, known as “pedra ume-caá” or “pitanguinha do cerrado”, is popularly used to treat infectious diseases like inflammation, and diabetes. Therefore, this study aimed to develop and validate an analytical method by high-performance liquid chromatography with diode array detector (HPLC-DAD) for the seasonal quantification of gallic acid (GA) and ellagic acid (EA), and to co-validate the method for quantification from the ethanol extract and fractions of the E. punicifolia leaves. Chromatographic separations were performed with a mobile phase gradient of acetonitrile/methanol/water acidified with 0.2% formic acid, a flow of 0.8 mL min‑1, detection at 254 nm, and a C18 column (250 × 4.6 mm, 5 μm). Method validation parameters were determined following Brazilian legislation. The HPLC-DAD analytical method developed for the quantification of GA and EA was validated and demonstrated to be selective, linear, precise, accurate, robust, and without matrix effect. Accordingly, it is helpful for the analysis of these tannins in crude ethanol extracts and fractions from E. punicifoila leaves. Thus, our results may be of great help for quality control assessment and standardization of raw materials containing Eugenia punicifolia.

Evaluation on the Metabolic Activity of Two Carboxylesterase Isozymes in Mouse Liver Microsomes by a LC-MS/MS Method.

An applicable method for the precise measurement of major carboxylesterase (CESs) activity in liver still limited. Clopidogrel and irinotecan are specific substrates for CES1 and CES2, respectively. Clopidogrel is metabolized to the inactive metabolite clopidogrel carboxylate (CCAM) by CES1. Irinotecan is metabolized to the active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38) by CES2. In the present study, the LC-MS/MS method for the determination of CCAM and SN-38 were separately developed to characterize the metabolic activities of CES1 and CES2 in mouse liver microsomal. CCAM was separated on a Ecosil ODS column with an isocratic mobile phase consisted of 5mmol/L ammonium formate and 0.1% formic acid in water and acetonitrile (15:85, V:V) at a flow rate of 0.4mL/min. SN-38 was separated on a Waters symmetry C18 column with an gradient mobile phase consisted of 5mmol/L ammonium formate and 0.1% formic acid in water and acetonitrile at a flow rate of 0.3mL/min. Calibration curves were linear within the concentration range of 100-20,000ng/mL for CCAM and 1-200ng/mL for SN-38. The results of method showed excellent accuracy and precision. The recovery rate, matrix effect and stability inspection results were within the acceptance criteria. The optimized incubation conditions were as follows: protein concentration of microsomes were all 0.1mg/mL, incubation time was 60min for clopidogrel and 30min for irinotecan, respectively. This method was sensitive and applicable for the determination of the activity of CESs in the mouse liver microsomes.

UHPLC-MS/MS method for simultaneous quantification of doripenem, meropenem, ciprofloxacin, levofloxacin, pazufloxacin, linezolid, and tedizolid in filtrate during continuous renal replacement therapy.

Since severe infections frequently cause acute kidney injury (AKI), continuous renal replacement therapy (CRRT) is often initiated for regulation of inflammatory mediators and renal support. Thus, it is necessary to decide the antibiotic dosage considering the CRRT clearance in addition to residual renal function. Some of the hemofilters used in CRRT are known to adsorb antibiotics, and clearance of antibiotics may differ depending on the adsorptive characteristics of hemofilters. Although assay systems for blood and CRRT filtrate concentrations are required, no method for measuring antibiotics concentrations in filtrate has been reported. We developed a UHPLC-MS/MS method for simultaneous quantification of antibiotics commonly used in ICU, comprising carbapenems [doripenem (DRPM) and meropenem (MEPM)], quinolones [ciprofloxacin (CPFX), levofloxacin (LVFX) and pazufloxacin (PZFX)] and anti-MRSA agents [linezolid (LZD), and tedizolid (TZD)] in CRRT filtrate samples. Filtrate samples were pretreated by protein precipitation. The analytes were separated with an ACQUITY UHPLC CSH C18 column under a gradient mobile phase consisting of water and acetonitrile containing 0.1% formic acid and 2 mM ammonium formate. The method showed good linearity over wide ranges. Within-batch and batch-to-batch accuracy and precision for each drug fulfilled the criteria of the US Food and Drug Administration guidance. The recovery rate was more than 87.20%. Matrix effect ranged from 99.57% to 115.60%. Recovery rate and matrix effect did not differ remarkably between quality control samples at different concentrations. This is the first report of a simultaneous quantification method of multiple antibiotics in filtrate of CRRT circuit.

Development of an LC/MS/MS Method for Simultaneous Detection of 11 Polyphenols in Rat Plasma and Its Pharmacokinetic Application after Oral Administration of Coreopsis tinctoria Extract.

Eleven polyphenols, classified as flavonoid glycosides, flavonoid aglycones, and phenolic acids, are important bioactive components in the capitula of Coreopsis tinctoria (CCT). Nevertheless, their full pharmacokinetic profiles have not been demonstrated simultaneously. Therefore, a liquid chromatography - tandem mass spectrometry (LC/MS/MS) method was developed in the present work and used it to study the pharmacokinetics of these 11 compounds. We performed LC/MS/MS with a gradient mobile phase composed of water containing 0.1 % formic acid and acetonitrile containing 0.1 % formic acid on a Proshell 120 SB C18 column (2.1 mm×100 mm, 2.7 μm). We achieved a good chromatographic peak shape, resolution, and mass signal response, and multiple reaction monitoring facilitated the simultaneous detection of 11 analytes. In addition, we validated the selectivity, correlation coefficient, precision, extraction recovery, matrix effects, and stability of the LC/MS/MS method to be acceptable for 11 analytes in rat plasma. Subsequently, rats were orally administered with 50 % ethanol eluent of CCT (ECCT). Nine of 11 polyphenols were absorbed quickly (except for QCD and TCA), and their plasma levels peaked within 40 min. The exposure and Cmax values of flavonoid glycosides and phenolic acids were lower than those of flavonoid aglycones. This is the first report to demonstrate the pharmacokinetics of 11 polyphenols in ECCT, which may play an important role in future studies of the bioactive components of ECCT and their bioactive mechanisms.

Quantification of Remimazolam Besylate (CNS7056B) and Its Metabolite (CNS7054X) by LC-MS/MS in Human Plasma Using Midazolam-d4 Maleate as Internal Standard.

A new assay was developed to measure the concentration of remimazolam besylate (CNS7056B) and its major carboxylic acid metabolite (CNS7054X) in human plasma. For this new assay method, midazolam-d4 maleate was used as an internal standard. After setting up a previously described assay method, using CNS7056-d4 and CNS7054-d4 as internal standards, analytical results of both methods were compared. For the new analytical method, ultra-high-performance liquid chromatography (UHPLC) with tandem mass spectrometry was applied. A purification method, using solid phase extraction, was developed and validated. The chromatographic separation of the analytes was achieved with a mobile phase gradient using a Water Acquity™ UHPLC-System. The Kinetex™ biphenyl 50 × 2.1mm UHPLC column was used with a particle diameter of 1.7μm (Phenomenex, Germany). A measuring range of 0.6-2,000ng/mL for CNS7056B and of 6-20,000ng/mL for CNS7054X could be achieved with this new assay. The lower limit of quantification was 0.6ng/mL for CNS7056B and 6ng/mL for CNS7054X. The assay was validated according to US Food and Drug Administration guidelines. The new method showed an accuracy of 96.9-110.4% and a precision of 2.1-6.7% for both analytes.