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Brucine (2,3-dimethoxystrychnidin-lO-one) under acidic conditions has been reported to be an effective reagent for the spectrophotometric determination of NO3-, NO2-and Ce4+. 1.2 Subsequent investigations have shown that in combination with potassium persulphate, it can also be used for the spectrophotometric determination of halides3 and c y ~t e i n e . ~ Potassium persulphate was found to be a specific reagent for cysteine, as other thiols tested and amino acids (thioglycollic acid, S-methylcysteine, N-acetylcysteine, cystine, homocystine and glutathione) did not interfere. However, the stability of the blue species formed and the precision and accuracy of this method was not good.Sodium metaperiodate (104-) is an efficient oxidant for converting methyl-substituted o-dihydric phenols into o-qui-nones5 and is also a colour stabiliser.6 This investigation was concerned with the development of a spectrophotometric method for the routine determination of thiols and biologically active amino acids (thioglycollic acid, P-mercaptoethanol, P-mercaptopropionic acid, thiosalicylic acid, cystamine hydrochloride, 2-aminothiophenol, 4-aminothiophenol, cysteine , cystine , tryptophan, glutathione and penicillamine) using brucine -104-. The purple colour (hmax, 500-510 nm) developed was stable for 10 h and hence was suitable for routine work with good precision and accuracy. Experimental ApparatusAbsorbance measurements were carried out with a Systronics Model 105 (MKl) spectrophotometer using 1-cm glass cells.

A novel, simple, precise, accurate stability indicating liquid chromato-graphy method was developed for the separation and simultaneous quantification of bictegravir, emtricitabine, tenofovir in bulk drug and pharmaceutical formulations. Separation was achieved on ProntoSILHypersorb ODS C18 column using mobile phase of 0.1 M sodium perchlorate, methanol in the ratio of 65:35 (v/v), pH 4.8 at a flow rate of 1.0 mL/min and UV detection was monitored at a wavelength of 258 nm. In these conditions, well resolved peaks were observed with acceptable system suitability at a retention time of 4.6 min for bictegravir, 7.0 min for emtricitabine and 10.1 min for tenofovir. Very high correlated linearity range was found to be 5-30 μg/mL for bictegravir, 20-120 μg/mL for emtricitabine and 2.5-15 μg/mL for tenofovir. The method can separate and identify the unknown degradation compounds formed during stress degradation study.

The purpose of the present research was to develop a suitable simple and reproducible RP-HPLC method for a quantification of dapagliflozin propanediol in spiked human plasma samples. The liquidliquid extraction plasma spiked samples of dapagliflozin propanediol were analyzed by using a ODS C18 Prontosil column under isocratic conditions. The extracted plasma spiked samples were carried using methanol, acetonitrile and pH 5.6 acetate buffer in the ratio of 50:20:10 (v/v) with a flow rate of 0.9 mL/min. The detector response was monitored at 228 nm using UV detector. The method was validated as per the ICH guidelines for bio analytical method validation and all the validation parameters were found to be within the acceptance limit The plasma spiked samples shows stability at room temperature over a period of 48 h. Thus, this method would be employed for routine quantification of dapagliflozin in human plasma samples.

Highly resolved and validated Liquid Chromatography method was developed for the separation and quantification of fosamprenavir and its related impurity 2 and 5 in bulk and pharmaceutical formulations. Separation of fosamprenavir and its impurities was achieved on prontosil ODS C18 column using mobile phase composition of methanol and 0.1 m sodium acetate in the ratio of 40:60 (v/v) at pH 5.9 as mobile phase at a flow rate of 0.9 mL/min in isocratic condition. Uv detection of the eluents was monitored at a wavelength of 246nm. In these conditions, well resolved peaks were observed at a retention time of 8.67, 5.73 and 4.00 min for fosamprenavir, Impurity 2 and 5, respectively. Calibration curve was plotted in the concentration range of 75-450 µg/mL for fosamprenavir and 1-6 µg/mL for impurity 2 and 5. Forced degradation study confirms that the method can separate the known and unknown impurities of fosamprenavir and the % degradation was found to be very less in all the stress conditions. Hence the method is suitable for the identification and quantification of impurities 2 and 5 along with fosamprenavir in bulk drug and formulations.