PubMed · 14180461
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M GUARNERI, P GIORI. 1964. [PYRAZOLO-PYRAZINE COMPOUNDS].. https://pubmed.ncbi.nlm.nih.gov/14180461/
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A portable system using light-induced fluorescence technology (LIF) was development as an analytical tool for on-line monitoring of various manufacturing process applications. The LIF system was verified in several laboratory scale process applications specifically in noninvasive real-time observations of blend kinetics in tumbler blenders. This technology, through careful selection of filters for specific formulations, can provide clean and unadulterated raw data that shows the actual blend characteristic behavior of powder mixtures such as homogeneity end point and blend stability. Consistent blend homogeneity end point was demonstrated for all runs with LIF where data were verified by thief sampling and UV spectrophotometric assays. A correlation between LIF signal and drug powder concentration was established with limits of detection below 0.02% w/w for the API, Triamterene.
Highly sensitive, simple and accurate reversed phase liquid chromatographic and first derivative spectrophotometric methods for determination of antihistaminic drug loratadine [I] and nasal decongestant drug pseudoephedrine sulfate [II] are described. The HPLC method involves separation of [I] and [II] on micro-BondaPak C18 column using mixture of (methanol:H(2)O:phosphoric acid:ammonium dihydrogen phosphate) (220:300:2:3 g) (V/V/V/W), 60 and 40% acetonitrile as mobile phase flowing at 2 ml/min with ultraviolet detection at 247 nm. The calibration graphs are linear from 5 to 100 microg/ml for [I] and from 120 to 1200 microg/ml for [II] the detection limits are 0.5 microg/ml for [I] and 60 microg/ml for [II]. The spectrophotometric method is based on recording the first derivative spectra for [I] and [II] at 307, 266 nm, respectively, of their solutions in 0.1 M hydrochloric acid using the acid as blank. The calibration graphs are linear in the range of 5-25 microg/ml for [I] and 240-720 microg/ml for [II]; the limits of detection are 0.16 microg/ml for [I] and 10 microg/ml for [II]. The mean percentage recoveries obtained for different synthetic mixtures by using this method are 97.6% with coefficient of variation 1.79 for [I] and 101.6% with coefficient of variation 1.95 for [II]. The two methods have been applied successfully for the determination of [I] in its combination with [II] Clarinase tablets and [I] alone in different pharmaceutical dosage forms.
A simple, selective, precise and stability-indicating high-performance thin-layer chromatographic method of analysis of tizanidine hydrochloride both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of toluene-acetone-ammonia (5:5:0.1, v/v/v). This system was found to give compact spots for tizanidine hydrochloride (R(f) value of 0.32+/-0.01). Tizanidine hydrochloride was subjected to acid and alkali hydrolysis, oxidation and photodegradation. Also, the degraded product was well separated from the pure drug. Densitometric analysis of tizanidine hydrochloride was carried out in the absorbance mode at 315 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r(2)=0.9922 in the concentration range 300-1000 ng per spot. The mean value of correlation coefficient, slope and intercept were 0.9922+/-0.002, 0.064+/-0.001 and 38.09+/-1.71, respectively. The method was validated for precision, recovery and robustness. The limits of detection and quantitation were 88 and 265 ng per spot, respectively. The drug does not undergo degradation under acidic and basic conditions. The samples degraded with hydrogen peroxide showed additional peak at R(f) value of 0.12. This indicates that the drug is susceptible to oxidation. Statistical analysis proves that the method is repeatable and selective for the estimation of said drug. As the method could effectively separate the drug from its degradation product, it can be employed as a stability-indicating one.