Dysprosium sorption by polymeric composite bead: Robust parametric optimization using Taguchi method

Publication date: Available online 27 January 2015 Source:Journal of Chromatography A Author(s): Kartikey K. Yadav , Kinshuk Dasgupta , Dhruva K. Singh , Lalit K. Varshney , Harvinderpal Singh Polyethersulfone based beads encapsul…

Development and validation of a RP-HPLC method for the quantitation of tofacitinib in rat plasma and its application to a pharmacokinetic study

A novel, simple, specific, sensitive and reproducible high-performance liquid chromatography (HPLC) assay method has been developed and validated for the estimation of tofacitinib in rat plasma. The bioanalytical procedure involves extraction of tofacitinib and itraconazole (internal standard, IS) from rat plasma with a simple liquid–liquid extraction process. The chromatographic analysis was performed on a Waters Alliance system using a gradient mobile phase conditions at a flow rate of 1.0 mL/min and C18 column maintained at 40 ± 1 °C. The eluate was monitored using an UV detector set at 287 nm. Tofacitinib and IS eluted at 6.5 and 8.3 min, respectively and the total run time was 10 min. Method validation was performed as per US Food and Drug Administration guidelines and the results met the acceptance criteria. The calibration curve was linear over a concentration range of 182–5035 ng/mL (r2 = 0.995). The intra- and inter-day precisions were in the range of 1.41–11.2 and 3.66–8.81%, respectively, in rat plasma. The validated HPLC method was successfully applied to a pharmacokinetic study in rats. Copyright © 2015 John Wiley & Sons, Ltd.

High-throughput salting-out assisted liquid–liquid extraction with acetonitrile for the determination of anandamide in plasma of hemodialysis patients with liquid chromatography tandem mass spectrometry

Anandamide (AEA) is an endocannabinoid present in human plasma that is associated with several physiological functions and disease states. However, low AEA plasma levels pose challenges in terms of analytical characterization. Classical liquid-based lipid extraction and solid-phase extraction require complicated procedures and the drying down of relatively large volumes of solvents, making them unsuitable for high-throughput analysis. Here a high-throughput salting-out assisted liquid–liquid extraction (SALLE) method with acetonitrile and mass spectrometry compatible salts for liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis of AEA in human plasma has been developed and validated. The seamless interface of SALLE and LC-MS eliminated the drying-down step, only 100 μL of plasma is required and minimal volumes of organic solvent are used. Good reproducibility, accuracy and precision were demonstrated during the method validation. The method is linear up to 10 ng/mL with a lower limit of quantitation of 0.1 ng/mL for AEA, the accuracy for AEA was from 93.3 to 96.7% and the precision was <8.57%. This new methodology was successfully applied to analysis of clinical samples from maintenance hemodialysis patients. Copyright © 2015 John Wiley & Sons, Ltd.

Boronate affinity adsorption of cis-diol-containing biomolecules in nonaqueous solvent

Boronate affinity has attracted much attention in recent years. It has been broadly used for selective isolation and enrichment of cis-diol-containing molecules. Conventionally, the cis-diols are adsorbed in mild alkaline aqueous solutions. In this work, for the first time, we found that boronate affinity adsorption could also be performed in nonaqueous solvent at nonbasic pH. Cis-diol-containing compounds present in herbal medicines were used for the adsorption test. The results indicated that all compounds obtained higher recoveries in the organic solvents (methanol, acetonitrile, ethyl acetate) compared with alkaline buffer. The adsorption of vicinal cis-diol-containing molecules in organic solvents could be accomplished rapidly, with high selectivity and high recoveries (>80%). These results shed light on the possibility of boronate affinity adsorption in nonaqueous solvents. The results are very important for the isolation and enrichment of cis-diols, which have poor solubility in water, especially for those in herbal medicines. Copyright © 2015 John Wiley & Sons, Ltd.

Sensitive and validated LC-MS/MS methods to evaluate mycophenolic acid pharmacokinetics and pharmacodynamics in hematopoietic stem cell transplant patients

Monitoring of pharmacodynamics in addition to pharmacokinetics is one of strategies to individualize mycophenolate mofetil therapy. The purpose of this study was to develop sensitive liquid chromatography–tandem mass spectrometry (LC-MS/MS) methods for evaluation of the pharmacokinetics and pharmacodynamics of mycophenolic acid (MPA). Concentrations of mycophenolic acid glucuronide (MPAG), mycophenolic acid acyl-glucuronide, as well as unbound MPA and MPAG, were determined, and inosine-5′-monophosphate dehydrogenase activity was calculated by measuring concentrations of produced xanthosine-5′-monophosphate (XMP) and intracellular adenosine-5′-monophosphate after incubation of peripheral blood mononuclear cell (PBMC) lysates. A metal-free MastroTM column and two gradient patterns were used to improve the quantification limit of XMP to 0.1 μm. In the clinical MPA concentration range, the linearity of the calibration curve, inter- and intra-day precision and accuracy satisfied the relevant US Food and Drug Administration guidelines. The MPA concentrations in hematopoietic stem cell transplant (HSCT) patients determined by the enzyme assay and the present LC-MS/MS method showed a good correlation (r2 = 0.95, p < 0.001). In this study, we report sensitive and validated LC-MS/MS methods to evaluate the pharmacokinetics and pharmacodynamics of MPA, which are sufficiently sensitive to assess small quantities of PBMC lysates collected shortly after HSCT. Copyright © 2015 John Wiley & Sons, Ltd.

Rapid Identification and Susceptibility Testing of Uropathogenic Microbes via Immunosorbent ATP-Bioluminescence Assay on a Microfluidic Simulator for Antibiotic Therapy

Analytical ChemistryDOI: 10.1021/ac504428t

Rapid Quantification of Digitoxin and Its Metabolites Using Differential Ion Mobility Spectrometry-Tandem Mass Spectrometry

Analytical ChemistryDOI: 10.1021/ac503187z

Key Factors for Stable Retention of Fluorophores and Labeled Biomolecules in Droplet-Based Microfluidics

Analytical ChemistryDOI: 10.1021/ac504736e

Correction to Cavity-Enhanced Absorption Measurements Across Broad Absorbance and Reflectivity Ranges

Analytical ChemistryDOI: 10.1021/ac504826x

Balancing the False Negative and Positive Rates in Suspect Screening with High-Resolution Orbitrap Mass Spectrometry Using Multivariate Statistics

Analytical ChemistryDOI: 10.1021/ac503426k

Ultrasound-Enhanced Attenuated Total Reflection Mid-infrared Spectroscopy In-Line Probe: Acquisition of Cell Spectra in a Bioreactor

Analytical ChemistryDOI: 10.1021/ac504126v

Identification of Polybrominated Diphenyl Ether Metabolites Based on Calculated Boiling Points from COSMO-RS, Experimental Retention Times, and Mass Spectral Fragmentation Patterns

Analytical ChemistryDOI: 10.1021/ac504107b

A Method for Determining the Actual Rate of Orientation Switching of DNA Self-Assembled Monolayers Using Optical and Electrochemical Frequency Response Analysis

Analytical ChemistryDOI: 10.1021/ac503919a

Electrografted Diazonium Salt Layers for Antifouling on the Surface of Surface Plasmon Resonance Biosensors

Analytical ChemistryDOI: 10.1021/ac504513a

Micro Propulsion by Acoustic Bubble for Navigating Microfluidic Spaces

Lab Chip, 2015, Accepted ManuscriptDOI: 10.1039/C4LC01266F, PaperJian Feng, Junqi Yuan, Sung Kwon ChoThis paper describes an underwater micro propulsion principle where a gaseous bubble trapped in a suspended microchannel and oscillated by an external …

Microfluidic timer for timed valving and pumping in centrifugal microfluidics

Lab Chip, 2015, Accepted ManuscriptDOI: 10.1039/C4LC01269K, PaperFrank Schwemmer, Steffen Zehnle, Daniel Mark, Felix von Stetten, Roland Zengerle, Nils PaustAccurate timing of microfluidic operations is essential for the automation of complex laborator…

Protein Footprinting by Pyrite Shrink-Wrap Laminate

Lab Chip, 2015, Accepted ManuscriptDOI: 10.1039/C4LC01288G, Technical InnovationMicheal Leser, Jonathan Pegan, Mohammed El Makkaoui, Joerg C. Schlatterer, Michelle Khine, Matt Law, Michael BrenowitzThe structure of macromolecules and their complexes di…

Label-Free Imaging and Spectroscopic Analysis of Intracellular Bacterial Infections

Analytical ChemistryDOI: 10.1021/ac503316s

Redox Cycling Behavior of Individual and Binary Mixtures of Catecholamines at Gold Microband Electrode Arrays

Analytical ChemistryDOI: 10.1021/ac5042022

High-Throughput Profiling of Nanoparticle–Protein Interactions by Fluorescamine Labeling

Analytical ChemistryDOI: 10.1021/ac5036814