Chromatographic methods for the separation and determination of paracetamol and tramadol

Two chromatographic methods have been developed for the separation and determination of paracetamol [P] and tramadol [T]. The methods are applicable for the determination of both drugs either separately or in mixture. The first method is TLC scanning method in which the two drugs were separated on silica gel plate using methanol: water: glacial acetic acid 50: 50: 25 v/v as a developing system and spots were detected by UV scanning at 250nm for paracetamol and 275nm in case of tramadol. The calibration curve was found linear from 3 to 15 micro g/spot and from 14 to 80 micro g/spot in case of paracetamol and tramadol, respectively. The method was applied for the determination of both drugs in pure form with mean percent recoveries of 100.34 +/- l. 124 and 100.59 +/- 1.104 for paracetamol and tramadol, respectively. The method was successfully applied for the determination of both drugs in laboratory prepared mixture. The second method is an HPLC method in which the two drugs were separated on Hypersil MOS CIS [200x4.6mm] column using a mixture of 0.5M solution of potassium dihydrogen phosphate pH 3.3 and methanol 35:65 as a mobile phase. Detection was carried out by ultraviolet detection at 280nm. Linear relationship between the peak areas and concentrations were given over a range of 10-360 micro g/ml and from 20 to 360 micro g/ml for paracetamol and tramadol, respectively. The HPLC method was applied for the determination of both drugs in pure form with mean percent recoveries of 100.43 +/- 0.84 and 100.19 +/- 0.78 for paracetamol and tramadol, respectively. The method was successfully applied to the determination of both drugs in laboratory prepared mixture. The validity of TLC method and HPLC method was assessed applying the standard addition technique for the determination of paracetamol and tramadol in acetamadol tablets. Statistical comparison between the reference methods and the proposed methods showed no significant difference

Stability indication densitometric determination of some antidiabetic drugs using chromatographic technique

The most commonly used antidiabetic sulfonylurea drugs [gliclazide, glipizide and glibenclamide] were determined using stability indicating densitometric method. The degradation products were prepared by acid hydrolysis of the intact drugs. Thin layer chromatography was carried out using silica gel 60 F254 plates and different mobile phases followed by scanning of the developed chromatograms. Laboratory prepared mixtures of the investigated drugs and their degradation products were prepared and analyzed using the proposed method and the mean% recovery ranged 100.01-100.99%. Pharmaceutical dosage forms were also assayed and gave results of the same accuracy and reproducibility as that of the official or reference method

Potentiometric and spectrocolorimetric methods for the estimation of chlorzoxazone in presence of paracetamol

In this work two methods were developed for the determination of chlorzoxazone without any interference of paracetamol. The first method depends on determination of the chlorine contents of the drug after oxygen flask combustion by addition of excess silver nitrate and filtration. The residual silver nitrate was determined potentiometrically using standard ammonium thioyanate solution. Detection of the end point electrically showed more accurate results than those obtained by using an indicator. Myolgin capsules were determined successfully using the proposed potentiometric method after extraction of the drug with methyl alcohol to guard against any interference due to inorganic ions, if present. The standard addition technique was applied and the mean percent recovery was shown to be 100.64%. The colorimetric method is based on measurements of the greenish blue color developed as a result of the reaction of chlorzoxazone with alkaline sodium nitroprusside reagent. Absorbances were measured at 670 nm against blank. Myolgin capsules were also estimated applying the standard addition technique, and the mean percent recovery was 101.67%

Stability indicating method for the quantitation of trazodone hydrochloride in tablet form

A thin layer chromatographic separation followed by dye-salt partition technique was employed to estimate the antidepressant drug trazodone hydrochloride in its tablet preparations. The chromatographic separation was carried out on silica gel plates using cyclohexane- benzene-diethylamine [5: 4: 1] as a mobile phase. The separated drug is determined colorimetrically using two acid dyes [tropeolin OO and bromocresol green]. Chloroform was used as a solvent for the extraction of the formed ion pair. Absorbances were measured at 540 nm and 620 nm after libration of the free dye from the formed dye- salt. Beer's law was obeyed over the concentration ranges of 2-8 ug ml-1 and 8-24 ug ml-1, respectively