HPLC gradient assay

The case stndy of the SP development of an HPLC assay method for an OTC prodnct derived from natural materials illustrates the importance of optimizing both the extraction and filtration conditions to fully recover all the labile active components in the formulation. The HPLC gradient assay method, which separates all active ingredients from other... [Pg.139]

The results are qualitatively evaluated by making overlay plots. An example of an HPLC gradient separation for a typical assay and impurities analysis is shown in Figure 13a. The selectivity is evaluated on five different lots of the selected stationary phase. As can be observed, apart from two minor selectivity issues (indicated by the arrows in Figure 13a), the reproducibility on different lots of stationary phases is acceptable. [Pg.172]

Case study 4 shows several examples of problems caused by equipment malfunctions and their subsequent diagnosis and solution. The first one involved a situation of poor retention time reproducibility of a gradient assay. It involved the analysis of a complex natural product, using a narrowbore column (2-mm i.d.) at 0.5 mL/min. System suitability test showed retention times to be erratic and could vary by 1-2 minutes without any obvious trends. Flow rate accuracy was found to be acceptable, however, the compositional accuracy test failed (see Chapter 9 on HPLC calibration). The tentative diagnosis was that of a malfunctioning of the proportioning valve. After its replacement, the retention time precision performance was re-established. [Pg.261]

Fig. 3. QAE-Sephadex gradient separation of the B fruit extract. An 18 mg (uronic acid equivalents) sample of extract was dissolved in 20 ml of 125 mM imidazole-HCl buffer (pH 7.0) and applied to the column. The column was then eluted with 50 ml 125 mM buffer followed by a 125 mM to 1.5 M buffer gradient (500ml), and, finally, 50 ml of 1.5 M buffer. Fractions of 5 ml were collected and assayed for uronic acids. Groups of fractions (26-41, 45-50, 53-75 and 84-100) were pooled, concentrated by ultrafiltration and analyzed by HPLC.

$Fig. 3. QAE-Sephadex gradient separation of the B fruit extract. An 18 mg (uronic acid equivalents) sample of extract was dissolved in 20 ml of 125 mM imidazole-HCl buffer (pH 7.0) and applied to the column. The column was then eluted with 50 ml 125 mM buffer followed by a 125 mM to 1.5 M buffer gradient (500ml), and, finally, 50 ml of 1.5 M buffer. Fractions of 5 ml were collected and assayed for uronic acids. Groups of fractions (26-41, 45-50, 53-75 and 84-100) were pooled, concentrated by ultrafiltration and analyzed by HPLC.$

Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...