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  • Author or Editor: Raman Singh x
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A simple, precise, rapid, selective, and economic high-performance thin-layer chromatographic (HPTLC) method has been established for simultaneous analysis of domperidone (DMP) and paracetamol (PAR) in tablet dosage forms. The chromatographic separation was performed on precoated silica gel 60 GF 254 plates with acetone-toluene-methanol 4:4:2 ( v/v ) as mobile phase. The plates were developed to a distance of 8.0 cm at ambient temperature. The developed plates were scanned and quantified at their single wavelength of maximum absorption at approximately 285 and 248 nm for domperidone and paracetamol, respectively. Experimental conditions such as band size, chamber saturation time, migration of solvent front, slit width, etc. were critically studied and the optimum conditions were selected. The drugs were satisfactorily resolved with R F 0.52 ± 0.02 for domperidone and 0.74 ± 0.02 for paracetamol. The method was validated for linearity, accuracy, precision, and specificity. The calibration plot was linear between 16–48 ng per band for DMP and 800–2400 ng per band for PAR. The limits of detection and quantification for DMP were 0.022 and 0.186 ng per band, respectively; for PAR they were 0.307 and 0.931 ng per band. This HPTLC procedure is economic, sensitive, and less time consuming than other chromatographic procedures. It is a user-friendly and important tool for analysis of combined tablet dosage forms.

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Although liquid sodium has proved to be a technologically superior and economically viable coolant in the heat-exchange circuits of fast reactors, it is fraught with the serious problems of fire hazards in the event of accidental leakages into the ambient air. For the rapid and effective suppression of sodium fires, sodium bicarbonate has emerged as a potential extinguishant. This paper attempts a description of the thermal decomposition behaviour of sodium bicarbonate fine powder in vacuum on the basis of thermogravimetry and differential thermal analysis. The analog percentage mass change data, transformed into dimensionless extents of reaction and calculated rates of reaction, are then analysed by a generalized computational technique. The results indicate that the most probable rate-controlling step is a process of three-dimensional contraction of the bicarbonate particle surface, with activation energyE=82.94 kJ mol−1 and frequency factorA=34.73×106 s−1. The decomposition temperature of sodium bicarbonate shows an upward trend with increasing heating rate.

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A simple, sensitive, precise, rapid, and reliable HPTLC method for quantitative analysis of artemether and lumefantrine in tablets has been established and validated. The method uses aluminum foil plates precoated with silica gel 60 F 254 as the stationary phase and nhexaneethyl acetate 8:2 ( v/v ) as mobile phase. Bands were scanned at 357 nm, the wavelength of maximum absorption. The method is linear ( r 2 > 0.995), precise (RSD < 2%), accurate (average recovery of 100.5% for artemether and 99.5% for lumefantrine), specific, and robust. The artemether content of the tablets varied from 98.50 to 102.45% and that of lumefantrine from 97.80 to 100.64%. The limits of detection and quantification for artemether were 50 and 150 ng per band, respectively, and those for lumefantrine were 300 and 900 ng per band, respectively. The suitability of this HPTLC method for quantitative analysis of artemether and lumefantrine was proved by validation in accordance with the requirements of pharmaceutical regulatory standards. The method was successfully applied to the analysis of a commercial pharmaceutical tablet dosage form. The method is simple, rapid, reproducible, and accurate and is a more effective option than other chromatographic techniques used for routine quality control.

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Abstract  

A rotary fluidized bioreactor (RFBR) designed for treatment of wastewater was required to be investigated for its hydrodynamic behaviour and validation of design. A radiotracer investigation was carried out to measure residence time distribution (RTD) of wastewater in the RFBR using 82Br as a radiotracer. The radiotracer was instantaneously injected into the inlet feed line and monitored at the inlet and outlet of the reactor using collimated scintillation detectors connected to a data acquisition system. The measured RTD data was treated and simulated using a tanks-in-series model and model parameters i.e. number of tanks describing the degree of mixing was obtained. The results of the investigation showed no flow abnormalities and the reactor behaved as an ideal continuously stirred-tank reactor at all the operating conditions. Based on the results, the design of the reactor was validated.

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