This study details the isolation, identification, and characterization of ambroxol’s unknown impurity. One unknown impurity of ambroxol was formed in the formulated drug under stress conditions [40°C /75% relative humidity (RH) for 6 months] with the relative retention time (RRT) 0.68 in RP-HPLC. The impurity was enriched by exposing it to heat and it was isolated by using preparative HPLC. The enriched impurity was purified and characterized using the following sophisticated techniques: 2D NMR (gDQ-COSY, gHSQC, and gHMBC), FTIR, and LC-MS/MS. On the basis of the spectral data, the impurity was characterized as trans-4-(6,8-dibromoquinazolin-3(4H)-yl)cyclohexanol.
Traffic noise is one of the major factors causing noise pollution in schools, interfering with learning and teaching activities. School going children are reported to have difficulty in processing the acoustic signals that are presented in noisy environment. The present study provides a reliable estimate of the decibel levels inside chosen class rooms of three selected schools of Tiruchiurapalli, Tamilnadu, India. The students and teachers of all the above schools felt that their school environments were noisy which interfered with their learning / teaching activities. Based on the self reported health status, audiometric tests were conducted on selected students suspected to have hearing problems, which revealed that the chosen children suffer from mild to moderate hearing impairment. In all the schools studied, the ambient sound levels were found to be above the threshold limit of 50 dB (A) for a silent zone prescribed by the Central Pollution Control Board, India.
Macroalgae were identified as third generation carbon source for bioethanol production and possess several advantages over terrestrial biomass. Hence, two common seaweeds, P. tetrastromatica and S. vulgare have been evaluated as substrates for ethanol production. They were collected from coast of the Bay of Bengal at Visakhapatnam, Andhra Pradesh, India. Samples were cleaned, dried and crushed to powder which were subjected to separate treatments with dilute sulphuric acid, sodium hydroxide and a combination of both. Based on the quantities of sugars released from these treatments, pretreatment with 1% and 2% v/v sulphuric acid for 45 min at 121˚C were chosen for P. tetrastromatica and S. vulgare respectively and the quantities of sugars released were 0.32 and 0.44 g/g. The resulting hydrolyzates were detoxified by sequential treatment with ethyl acetate and calcium oxide and were then fermented employing Saccharomyces cerevisiae strain R3DSC5 which was deposited at IMTECH, India, with accession number MTCC 12377. Ethanol yield obtained with P. tetrastromatica (0.66 g/g) during the present work is more than the highest yield (0.45 g/g) reported so far for any marine algal biomass while that obtained with S. vulgare (0.38 g/g) is on par with the highest yield (0.386 g/g) reported for other species of Sargassum. This study shows that both the seaweeds are potential sources for bioethanol production and of the two, P. tetrastromatica is better.
A sensitive, stability-indicating gradient RP-HPLC method with PDA detection has been developed for the simultaneous analysis of drotaverine impurities in active pharmaceutical ingredient (API) and pharmaceutical formulations. Efficient chromatographic separation was achieved on an XTerra RP18, 150 × 4.6 mm, 5 μm column using gradient elution at 230 nm detection wavelength. The optimized mobile phase consisted of a 0.02 M potassium dihydrogen orthophosphate buffer of pH 3.0 as solvent A and acetonitrile as solvent B. The flow rate of the mobile phase was 1.0 mL min−1 with a column temperature of 25°C. The method showed linearity over the range of 0.251–10.033 μg/mL, 0.231–9.995 μg/mL, 0.230–10.089 μg/mL, 0.334–10.011 μg/mL, and 0.324–10.050 μg/mL for impurities 1, 2, 3, 4, and drotaverine, respectively, with a correlation coefficient greater than 0.999. The relative retention times and relative response factors of impurities 1, 2, 3, 4 were 0.36, 0.90, 1.42, 1.55 and 1.04, 0.84, 1.10, 1.30, respectively. The drotaverine formulation sample was subjected to the stress conditions of acid, base, oxidative, thermal, humidity, and photolytic degradation. Drotaverine was found to degrade significantly in peroxide, base, and heat stress conditions. The degradation products were well-resolved from drotaverine and its impurities. The peak purity test results confirmed that the drotaverine peak was homogenous and pure in all stress samples and the mass balance was found to be more than 98%, thus proving the stability-indicating power of the method. The developed method was validated according to ICH guidelines with respect to specificity, linearity, limit of detection and quantification, accuracy, precision, and robustness.
A novel, sensitive, stability-indicating HPLC method has been developed for the quantitative estimation of Tolperisone-related impurities in both bulk drugs and pharmaceutical dosage forms. Effective chromatographic separation was achieved on a C18 stationary phase with a simple mobile phase combination delivered in a simple gradient programme, and quantitation was by ultraviolet detection at 254 nm. The mobile phase consisted of a buffer and acetonitrile delivered at a flow rate 1.0 ml/min. The buffer consisted of 0.01 M potassium dihydrogen phosphate with the pH adjusted to 8.0 by using diethylamine. In the developed HPLC method, the resolution between Tolperisone and its four potential impurities was found to be greater than 2.0. Regression analysis showed an R value (correlation coefficient) of greater than 0.999 for the Tolperisone impurities. This method was capable of detecting all four impurities of Tolperisone at a level of 0.19 μg/mL with respect to the test concentration of 1000 μg/mL for a 10 µl injection volume. The tablets were subjected to the stress conditions of hydrolysis, oxidation, photolysis, and thermal degradation. Considerable degradation was found to occur in base hydrolysis, water hydrolysis, and oxidation. The stress samples were assayed against a qualified reference standard and the mass balance was found to be close to 100%. The established method was validated and found to be linear, accurate, precise, specific, robust, and rugged.
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