Kamran Abro

Application of microwave heating for the fast extraction of fat content from the poultry feeds.

A rapid method has been developed to extract and quantitatively measure the total oil content in poultry feeds using a domestic microwave oven. The optimized extraction procedure involves the replicate (6x) extraction of 5 g of ground feed with 12 ml of hexane for 20 s in a 900 W oven. Each replicate involves the collection of the resulting miscella and its replacement with fresh solvent for re-extraction. The collected extracts were centrifuged and transferred to a vial. The solvent was evaporated to a constant weight and the residual lipid weighed. In comparison to conventional Soxhlet extraction method, lipid contents obtained using the optimized microwave procedure was not significantly different. However, FTIR analysis indicated that the microwave procedure was superior in minimizing the formation of free fatty acids (FFA) relative to the Soxhlet procedure if the temperature of the sample was kept within the range of 45-50 degrees C. This simple, sequential extraction procedure is rapid, highly efficient and provides a simple mean of quantitating the lipid content of poultry feed in less than 40 min without the need for specialized microwave oven.

MULTI-COMPONENT QUANTITATION OF LORATADINE, PSEUDOEPHEDRINE AND PARACETAMOL IN PLASMA AND PHARMACEUTICAL FORMULATIONS WITH LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY UTILIZING A MONOLITHIC COLUMN

The purpose of this study was to develop a rapid, simple and sensitive quantitation method for pseudoephedrine (PSE), paracetamol (PAR) and loratadine (LOR) in plasma and pharmaceuticals using liquid chromatography-tandem mass spectrometry with a monolithic column. Separation was achieved using a gradient composition of methanol-0.1% formic acid at a flow rate of 1.0 mL min-1. Mass spectral transitions were recorded in SRM mode. System validation was evaluated for precision, specificity and linearity. Limit of detection for pseudoephedrine, paracetamol, and loratadine were determined to be 3.14, 1.86 and 1.44 ng mL-1, respectively, allowing easy determination in plasma with % recovery of 93.12 to 101.56%.

LC/UV determination of cefradine, cefuroxime, and cefotaxime in dairy milk, human serum and wastewater samples

Cephalosporins type antibiotics are widely used to treat infectious diseases. Their determination is not only important in blood/serum of patients under treatment but also in diverse matrices like wastewaters, milk etc. as contaminant. Keeping in view the need, a new high performance liquid chromatographic method for the determination of three cephalosporins (cefradine, cefuroxime and cefotaxime) has been developed. Separation was performed on an ODS column with binary solvent elution of aqueous formic acid (0.05%) and methanol in the ratio of 45: 55 (v/v) at a flow rate of 1 mL min-1 and UV detection at 260 nm. Under optimised conditions, all three cephalosporins were baseline separated within 5 min. Linear responses for cefradine 5–20 μg mL-1, cefuroxime 0.5-15 μg mL-1 and cefotaxime 1.0-20 μg mL-1 were established. LOD of 0.05-0.25 μg mL-1 after preconcentration was achieved. The method was applied to serum samples of patients under treatment with these antibiotics and to screen the selected cephalosporins from hospital wastewater and milk samples. Moreover, method was applied to study stability of aqueous solutions and acid/base induced degradation of all three drugs.

Quantification of malachite green in fish feed utilising liquid chromatography-tandem mass spectrometry with a monolithic column

The purpose of this study was to develop a rapid and sensitive method for the quantification of malachite green (MG) in fish feed using LC-ESI-MS/MS with a monolithic column as stationary phase. Fish feed was cleaned using ultrasonic assisted liquid–liquid extraction. The separation was achieved on a Chromolith® Performance RP-18e column (100 × 4.6 mm) using gradient mobile phase composition of methanol and 0.1% formic acid at the flow rate of 1.0 ml min–1. The analyte was ionised using electrospray ionisation in positive mode. Mass spectral transitions were recorded in selected reaction monitoring (SRM) mode at m/z 329.78 → m/z 314.75 with a collision energy (CE) of 52% for MG. The system suitability responses were calculated for reproducibility tests of the retention time, number of theoretical plates and capacity factor. System validation was evaluated for precision, specificity and linearity of MG. The linearity and calibration graph was plotted in the range of 15.0–250 ng ml−1 with the regression coefficient of >0.997. The lower limits of detection and quantification for MG were 0.55 and 1.44 ng ml−1, respectively, allowing easy determination in fish feed with accuracy evaluated as a percentage recovery of 92.1% and precision determined as % CV of < 5. The method was also extended to the determination of MG in an actual fish feed. The sensitivity and selectivity of LC-ESI-MS/MS using monolithic column offers a valuable alternative to the methodologies currently employed for the quantification of MG in fish feeds.

Comparative Study of Electrospray and Atmospheric Pressure Chemical Ionization with Liquid Chromatography–Mass Spectrometry for Quantification of Five Antihyperglycemic Agents Utilizing Monolithic Column

Liquid chromatography-mass spectrometry (LC-MS) in atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) modes were studied for a multi-component plasma and urine quantification of 5 antihyperglycemic agents (metformin, pioglitazone, gliclazide, glibenclamide, and glimperide). The separation of the compounds was achieved using Chromolith Performance RP-18e column (100 × 4.6 mm), with gradient mobile phase composition of acetonitrile −0.1% formic acid. MS parameters for APCI and ESI were optimized individually and were operated in positive mode. The detection limits for the metformin, pioglitazone, glibenclamide, and glimepiride were determined to be 6.84, 6.22, 13.03, and 44.38 ng mL−1 using LC-ESI-MS; and for LC-APCI-MS, it was determined to be 48.39, 8.02, 17.02, and 144.55 ng mL−1, respectively. Gliclazide was the only exception as it exhibited a lower limit of detection (LOD) using APCI than ESI which was found to be 5.61 and 23.43 ng mL−1, respectively. The method was validated for system suitability, linearity, precision and accuracy, specificity, stability, and robustness. The ESI as compared to APCI was found superior in many analytical parameters. The assay has been applied successfully to biological fluids (plasma and urine) of healthy volunteers.

Determination of Vitamins E, D3, and K1 in Plasma by Liquid Chromatography-Atmospheric Pressure Chemical Ionization-Mass Spectrometry Utilizing a Monolithic Column

This paper reports a rapid, simple, and sensitive method for determination of vitamin D3, vitamin E acetate, and vitamin K1 in plasma using atmospheric pressure chemical ionization –high performance liquid chromatography–mass spectrometry. Plasma samples were prepared using solid phase extraction. The separation of compounds was achieved using a C18 monolithic column and a mobile phase composed of methanol and 0.1% formic acid in gradient elution mode at a flow rate of 1.0 mL min−1. Analytes were ionized using atmospheric chemical ionization in positive mode. Mass spectra were recorded at m/z = 385.23, 473.47, and 451.41 for vitamin D3, vitamin E, and vitamin K1, respectively. Vitamin D2 was used as an internal standard and its mass spectra was recorded at 397.28 m/z. The method was validated using ICH guidelines. The system suitability responses were calculated for retention time, number of theoretical plates, capacity factor, resolution, and the selectivity factor. System validation was evaluated for precision, specificity, and linearity of all compounds. The limits of detection for vitamin D3, vitamin E, and vitamin K1 were determined to be 0.1, 1.36, and 0.052 ng mL−1, respectively. The accuracy, evaluated as % of recovery, was in the range of 96.4 to 102.4% and precision determined as the coefficient of variation was between 1.24 and 3.6%. The validated method was applied to real plasma samples.