Protein A Membrane Shows an Advantage Over Protein A Resin in Purifying Antibodies/FcFusions Forming Noncovalent Aggregates

Certain mAbs, bispecific antibodies (bsAbs) and Fc-fusion proteins are prone to form aggregates in cell culture. We previously showed that in these cases large aggregates do not bind to Protein A resin as their sizes prevent them from entering the pores of resin beads, leading to reduced step yield. Nevertheless, such aggregates can bind to Protein A membrane, which has larger pore size. We also showed in a previo...

Mercury Measurements in Environmental Matrices by ICPMS and HPLC-ICPMS: Nine Considerations

Here we discuss our experiences with various approaches for measuring total Hg concentrations and speciation of Hg in environmental matrices. First, what Hg concentrations the method needs to measure should be considered as low Hg concentrations in samples will require pre-concentration before ICPMS analyses. Total Hg concentration measurements in waters require digestion with HNO3-HCl to release Hg from particula...

Chlorpyrifos Acute Fatal Poisoning in Humans: Analysis of Whole Blood Samples by a Validated High-Performance Thin-Layer Chromatography

An optimized extraction procedure followed by a validated High–Performance Thin– Layer Chromatography (HPTLC) was applied for the assay of chlorpyrifos (CPF) levels in postmortem blood obtained in seven fatal intoxication cases. The proposed method involved liquid–liquid extraction of CPF with different solvents over a sample pH 3 to 7 and separation was achieved on precoated silica gel 60F254 TLC plates by using...

Correction of Some Thermodynamic Surface Properties of Sodium Alginate Determined by Inverse Gas Chromatography

In their paper published in the Journal of Chemical Engineering Data, Ugraskan, et al. made several inaccuracies in the determination of the surface properties of sodium alginate by using the Inverse Gas Chromatography (IGC) technique. The proposed method to determine the dispersive component of the surface energy, , cannot be correctly evaluated, because it depends on the surface area of n-alkanes or of methylene...

New Methods to Characterize the Surface and Interface Acid-Base Properties of Polylactides Polymers by Inverse Gas Chromatography

The thermodynamic and acid base properties of some polymeric materials such as polylactides used in many industrial applications were determined by using the inverse gas chromatography technique at infinite dilution. Retention volume of the injected organic probes into the chromatographic column containing the investigated polymer was obtained by using this powerful technique. The curves RTlnVn = f(1/T) of n-alkan...

Simultaneous Estimation of Water Soluble Vitamin in Five Wild Edible Plants Consumed By the Tribal People of North-Eastern Region in India by High Performance Liquid Chromatography (HPLC) Method

A reversed-phase high-performance liquid chromatographic method has been developed for the simultaneous quantitation of water-soluble vitamins like ascorbic acid (C), thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6) and folic acid (B9) in five potent wild edible plants named Castanopsisindica, Fagopyrum cymosum, Ficus clavata, Ficus geniculata and Ficus pomifera consumed by the t...

A Comprehensive Approach to Two-Dimensional Alignment

The two-dimensional alignment of chromatograms remains the subject of ongoing research. The shift of a Sample chromatogram compared to a Reference chromatogram is a challenge to calculate, particularly when the interest lies in smaller signal peaks. Previous attempts include a variety of different methods: peak selection approaches, two-dimensional correlation and the Smith-Waterman method taken from genetics. Thi...

Development and Validation of a Stability Indicating RP-HPLC-UV Method for the Simultaneous Determination of Epalrestat and Pregabalin in Combined Pharmaceutical Formulation

An accurate, rapid, selective and specific stability indicating RP-HPLC-UV method was developed for the simultaneous determination of Epalrestat and Pregabalin in combined pharmaceutical formulation. Chromatographic separation was achieved on Discovery ODS C18 column (250 × 4.6 mm, 5 μm) with UV detection at 241 nm. The mobile phase consisting of 0.1% Ortho Phosphoric Acid (OPA) and acetonitrile in a ratio of 50:5...

A Validated High Performance Liquid Chromatography Method for the Determination of Metformin in Human Plasma and its Application to Pharmacokinetic Study

High performance liquid chromatographic method for determination of metformin in human plasma was developed. The method involved deproteinisation of the sample with methanol and analysis of the supernatant using Zorbax 300 – SCX, 4.6 X 150mm ID and UV detection at a wavelength of 233 nm. The assay was specific for metformin and linear from 0.0625 to 2.5µg/ml. The relative standard deviation of intra- and inter-day...

Crystallization of Membrane and Soluble Proteins: Difference in Approach

X-ray crystallography is the most efficient technique to decipher 3D structure of a protein at atomic resolution with high accuracy. Obtaining protein crystals is often considered the bottleneck of this technique. Crystallization involve high precision of protein-protein contacts in the crystals which is governed by the prevailing solution conditions and many other factors. The equilibrium between various factors...

Hydrophobic (lipophilic) Interaction Liquid Chromatography

The retention mechanism in reversed-phase liquid chromatography was quantitatively described using log P (octanol-water partition coefficient). The hydrophobic (lipophilic) interaction liquid chromatography was then used to measure the hydrophobicity. Furthermore, a combination of log P and pKa (dissociation constant) was used for the optimization of reversed-phase liquid chromatography. However, log P values cann...

Extraction of Quercetin from Red Onion (Allium cepa L.) with Ionic Liquids

The application of soluble in water Ionic Liquids (ILs) as alternatives to conventional organic solvents in liquid-liquid extraction of Quercetin (Q) from frozen red onion (Allium cepa L.) was investigated. The parameters affecting the extraction ability of ILs such as chemical structures of the IL cation and anion and the phase volume ratio of extracting solvent water-IL, as well as type of organic solvent such a...

HPLC Analysis of Water-Soluble Vitamins (B1, B2,B3, B6, B7 and B9) in Milk, Human Urine and Pharmaceutical Formulations

A HPLC method was developed for the simultaneous determination of six water-soluble vitamins, thiamine (B1), riboflavin (B2), nicotinic acid (B3), pyridoxine (B6), biotin (B7) and folic acid (B9) in milk, human urine and multivitamin pharmaceutical formulations. Experimental designs have been applied for the optimization of the method in order to determine the experimental conditions for maximized resolution and m...

Development and Validation of GC-MS Method for Cocaine in Human Urine

This paper describes a gas chromatography-mass spectrophotometry (GC-MS) method with selected-ion monitoring (SIM ) for the measurement of urine cocaine levels. Cocaine and codeine (internal standard, IS) were extracted from human urine with a mixture of diethylether and ethylacetate at basic pH with liquid-liquid extraction. Calibration curve was linear over the concentration range 50-2000 ng mL-1. Intra- and int...

Identification of Natural Madder and Indigo Dyes by Novel HPTLC Method

In this communication an attempt has been made to compare the two major classes of natural dyes-Anthraquinoid and Indigoid with their synthetic analog. Madder (Rubia cordifolia n Rubia tinctorum L.) and Indigo (Indigofera tinctoria) dyes were used for this study. Both the dyes are of pharmacological importance as they are used in TCM (Traditional Chinese Medicine) and Ayurveda (Traditional Indian Medicine). HPTLC...

Quantification of Anti-Inflammatory Drugs Retained in Different Layers of Skin after in Vitro Permeation Studies by Liquid Chromatography Assay

Over the past decades, in vitro and in vivo permeation studies have been widely used in the pharmaceutical area due to their ability to provide important pharmaceutical data for the rational development of topical and transdermal delivery systems. In order to achieve success on topical or transdermal therapy, the drug must be able to penetrate into the skin - a semi permeable barrier which controls the entrance of...

Pharmaceutically Active Compounds in the Environment: Are we Protected?

Occurrence of pharmaceutically active compounds in the environment is of great concern and has been the focus of an increasing number of recent studies. Although the use of pharmaceuticals has positive effects on treating many diseases in animals and humans, their improper use has become a new environmental problem. More than 600 pharmaceutical substances have been detected in different environmental matrices worl...