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High-performance thin-layer chromatographic (HPTLC) densitometric method for analysis of arbutin in commercial whitening creams was developed and validated. Aluminum-backed silica gel 60 F254 plates were used as stationary phase while methanol-chloroform-acetic acid 3.5:6:0.5 (%, v/v/v) mixture was used as mobile phase. Under these chromatographic conditions, arbutin was well separated from other ingredients. This system was found to give a well defined, sharp, and compact spot of arbutin at retention factor (R F) value of 0.40 ± 0.02. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 42.25 and 112.45 ng per spot respectively. The proposed method with high degree of precision and accuracy was employed for the analysis of arbutin both qualitatively and quantitatively in commercial whitening creams. Due to the efficiency of the method in separating arbutin from other ingredients including its degradation products, it can be applied as a stability-indicating method.

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A densitometric high-performance thin-layer chromatographic (HPTLC) method for analysis of hydroquinone has been developed and validated. Chromatography was performed on aluminum foilbacked silica gel 60 F254 plates with chloroform-methanol 85:15 (% v/v) as mobile phase. This system furnished a compact band for hydroquinone at R F 0.51. Hydroquinone was quantified densitometrically at 289 nm. The limits of detection (LOD) and quantification (LOQ) were 38.50 and 115.50 ng per band, respectively. High precision and accuracy were achieved. The method was used for both qualitative and quantitative analysis of hydroquinone in commercial formulations. Because the method can effectively separate the hydroquinone in the presence of its degradation products, it can be used as a stability-indicating method.

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Fenugreek is one of the oldest medicinal plants known by mankind. The aim of this study is to evaluate the effect of environmental conditions on the saponin contents of the plant. The amount of diosgenin in different samples of fenugreek was estimated by high-performance thin-layer chromatography (HPTLC). The developed method was validated, in accordance with the International Conference on Harmonization (ICH) guidelines for precision, accuracy, and robustness. HPTLC was carried out using hexane‒acetone (8:2%, v/v) on 20 cm × 10 cm glass coated silica gel 60 F254 plates. The developed plates were scanned and quantified densitometrically at λ = 430 nm. Linear regression analysis revealed a good linear relationship between the area under the peak and the amount of diosgenin in the range of 50–400 ng per band. The amount of diosgenin which reflects the total saponin contents varied according to the country of origin. The sample obtained from Yemen showed the highest amount of diosgenin followed by the Saudi sample. Both locations represent areas with the highest altitude (Yemen) and the highest temperature (Saudi).

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ICH Q2B, “Validation of analytical procedure: methodology”, in: Proceedings of the International Conference on Harmonization, Geneva, March 1996. P.D. Sethi , Quantitative analysis of drugs in pharmaceutical

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(Bozeman and Corley 2004 ; Fontana et al. 2005 ; D'Este and Patel 2007 ), and a quantitative evaluation of such sectoral collaboration has also been demonstrated using bibliometric analysis (Tijssen 2004 ). The role of the government has also been

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Abstract  

The paper examines a not too comprehensive set of quantitative aspects of technology. It concentrates mainly on the quantification of management tools.

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Quantitative thermal analysis, II

Design of equipment and technique of quantitative thermal analysis

Journal of Thermal Analysis and Calorimetry
Authors: L. G. Berg and V. P. Egunov

Some problems on adjustment of the equipment and on data evaluation, in view of the equations derived earlier for the calculation of specific heat and heat of transformation are discussed. It is shown that quantitative determinations are possible also if the adjustment is “non-ideal” and that both air and an inert material, respectively, may be used as reference material.

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quantitative fluorescent method for measurement of bacterial adherence and phagocytosis. J. Immunol. Methods 90 , 257-264. A quantitative fluorescent method for measurement of bacterial adherence and phagocytosis

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surfactant (CTAB)on the reactions of MV with hydroxyl ions has been thoroughly investigated. The micellar data have been quantitatively analyzed and also the counterion effect has been studied. Experimental section

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Abstract  

The important existing quantitative PCR techniques, including the classification, description, evaluation and effect factors have been reviewed. Emphases are put on the types and evaluation of quantitative internal standard substances as well as the theoretical consideration of PCR quantitative process. The purpose is reasonably to establish our own detection protocol for quantification of HCMV in clinical samples.

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