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Study on the separation of triterpene saponins from Panax notoginseng by off-line two-dimensional supercritical fluid chromatography–ultrahigh-performance liquid chromatography

Xing Q., Fu Q., Liang X.

Acta Chromatographica

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2017

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Vol. 29, no. 4

497--502

EN

The off-line two-dimensional supercritical fluid chromatography (SFC)–ultrahigh-performance liquid chromatography (UHPLC) was selected to separate the triterpene saponins from Panax notoginseng. The separation by SFC was performed on an Atlantis® HILIC silica column. Methanol was selected as a modifier, and the most time-saving gradient was developed. The decrease of the column temperature and the increase of the back pressure could shorten the retention time but had no effect on the separation selectivity. Then, the back pressure, column temperature, and flow rate were set as 131 bar, 45 °C, and 4.0 mL min−1, respectively. The retention behavior of the saponins from P. notoginseng was different between SFC and reversed-phase liquid chromatography (RPLC), which facilitated to construct an off-line SFC/RPLC–mass spectrometry (MS) system. In first dimension, a total of eight fractions were collected under SFC and further analyzed by RPLC–MS in second dimension. The result indicated that the retention behavior of triterpene saponins was mainly controlled by the hydrogen bonding interactions which were affected by the number and types of sugars, as well as the aglycone in the structure of triterpene saponins. Thus, the presence of “clustering effect” under SFC was observed, namely, one SFC peak always contained several saponins with same number of sugars and similar structure of aglycone. The clustering effect of triterpene saponins promised SFC to be used as first dimension to complete the preliminary crude separation in the two-dimensional liquid chromatography.

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Forced degradation study and validated stability-indicating RP-LC method for determination of nilotinib in bulk and capsules

Fouad M. A., Elkady E. F.

Acta Chromatographica

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2014

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Vol. 26, no. 4

637--647

EN

A simple, selective, and precise stability-indicating reversed-phase liquid chromatographic method was developed and validated for the determination of nilotinib. Nilotinib was subjected to acid and alkali hydrolysis, oxidation, thermal, and photo-degradation. The degradation products were well separated from the pure drug. The method was based on isocratic elution of nilotinib and its degradation products on reversed phase C18 column (100 mm × 4.6 mm, 3.5 μm) — Zorbax Eclipse Plus using a mobile phase consisting of 10 mM KH2PO4:acetonitrile (54.5:45.5%, v/v) at a flow rate of 1 mL min−1. Quantitation was achieved with UV detection at 265 nm. Linearity, accuracy and precision were found to be acceptable over the concentration range of 0.1–80 μg mL−1. The drug was found to be susceptible to acid and base hydrolysis but resistant to oxidation, dry heat degradation, and photodegradation. The proposed method was successfully applied to the determination of nilotinib in bulk and in its pharmaceutical preparation.

3

Simultaneous estimation of atorvastatin calcium and aspirin in combined dosage form by liquid chromatographic method

Shah D. A, Bhatt K. K, Baldania S. L

Acta Chromatographica

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2012

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Vol. 24, no. 1

51--64

EN

An isocratic reversed-phase liquid chromatograpic assay method was developed for the quantitative determination of atorvastatin and aspirin (ASP) in combined dosage form. A Phenomenex Gemini C-18, 5-μm column with mobile phase containing 0.02 M potassium dihydrogen phosphate-acetonitrile-methanol (30:30:40, v/v/v) adjusted to pH 3 using o-phosphoric acid was used. The flow rate was 1.0 mL min -1 and effluents were monitored at 240 nm. The retention times (RTs) of atorvastatin calcium (ATV) and ASP were 10.5 and 3.8 min, respectively. ATV and ASP stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation, and dry heat degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their RT values. Stressed samples were assayed using developed LC method. The proposed method was validated with respect to linearity, accuracy, precision, and robustness. The method was successfully applied to the estimation of ATV and ASP in combined capsule dosage forms.