EFFECT OF BONDING VARIABLES IN THERMAL BONDING OF POLYPROPYLENE NONWOVENS

The aim of this research was to investigate the effect of some of the process variables on the structure and properties of the webs in a thermal point bonding process. The main objectives were to understand the changes taking place in the fiber structure due to applied heat and pressure, the effect of bond area and bond size on fiber morphology, and the physical properties of the web. Thermally bonded carded webs were produced and characterized in order to determine the role of bond area and bond size on strength and stiffness of the point bonded fabrics and fiber morphology. The webs were also characterized to see the changes taking place in fiber morphology on thermal bonding. It was observed that the bond strength increases with bond area and bond size. The effect of bond area and bond size on fiber morphology were negligible. Significant morphological differences were observed in the bonded and the unbonded regions of the thermally bonded webs. To see how the staple fiber studies relate to the behavior of continuous filaments, similar sets of samples were produced and characterized using the spunbond system. The observed trends for properties with respect to bonding conditions were similar for spunbond samples. However, actual values of tensile and other physical properties were much higher for spunbond webs

Simultaneous determination of candesartan and hydrochlorothiazide in human plasma by LC-MS/MS

A simple, sensitive, rapid and highly efficient LC-MS/MS method was developed for the determination of Candesartan and Hydrochlorothiazide simultaneously in human plasma. The method employed Zorbax eclipse C18 (150 X 4.6 mm, 5µ) column using acetate buffer: acetonitrile (25:75%, v/v) as the mobile phase. The mobile phase flow rate is 1 mL/min which was delivered into the mass spectrometer electron spray ionization chamber. The Liquid/liquid extraction procedure was used in the method for the extraction of analytes. The chromatograph was attached to a negative ion mode tandem mass spectrometer and the method was validated for all the parameters as per the guidelines of US-FDA. The ions were detected in multiple reaction monitoring mode and the transitions are m/z 439.00®309.10 and 295.80®268.80 for candesartan and hydrochlorothiazide respectively. Isotopic standards were used as internal standards for effective recovery of the analytes. The drugs were analyzed over a calibration range of 1.027-302.047 ng/mL for candesartan and 1.044-306.945 ng/mL for hydrochlorothiazide respectively with regression coefficient greater than 0.99. The mean extraction recoveries are 96.95±5.61 and 100.55±4.82 for candesartan and hydrochlorothiazide respectively. The precision and accuracy values for all the studies were within the range of ≤15% and 85-115%. The performed stability studies indicate that the developed method is stable in plasma for 15 h at room temperature (bench top); 52 h (in injector); for 112 days at -70 ºC for long term stability; five successive freeze and thaw cycles. The developed method could be successfully employed for the determination of selected drugs in biological samples