Determination of Bezafibrate and Ciprofibrate in Pharmaceutical Formulations by Densitometric and Videodensitometric TLC

JPC – Journal of Planar Chromatography – Modern TLC - New simple TLC methods with densitometry and videoscanning have been developed for the quantitation of bezafibrate in Bezamidin...     

Synthesis and anti-HCV activity of 1-(1′,3′-O-anhydro-3′-C-methyl-β-d-psicofuranosyl)uracil

Synthesis of a novel 1′,2′-oxetane-uridine bearing a 2′-C-methyl substituent, [1-(1′,3′-O-anhydro-3′-C-methyl-β-d-psicofuranosyl)uracil], is described. Key to its construction was the use of 6-O-(p-toluoyl)-1,2:3,4-di-O-isopropylidene-3-C-methyl-d-psicofuranose as a nucleosidation substrate, which itself was derived from d-fructose. Anti-HCV activity was examined for the corresponding triphosphate which was not found to be an inhibitor of HCV NS5B 1b wild type polymerase in vitro. The 1′,2′-oxetane uridine triphosphate without 2′-C-methyl substitution was similarly inactive, however, the guanosine analog displayed modest inhibition (IC₅₀ = 10 μM).     

The Retention Behavior of Some Atypical Antipsychotic Drugs in Normal-Phase TLC

JPC – Journal of Planar Chromatography – Modern TLC - Chromatographic behavior in normal-phase thin-layer chromatog-raphy has been investigated for six atypical antipsychotic drugs...     

Application of Self Modelling Multivariate Curve Resolution to Thin-Layer Chromatographic Data Obtained by Densitometric Detection

JPC – Journal of Planar Chromatography – Modern TLC - The paper discusses the usefulness of self modelling multivariate curve resolution (nonnegative matrix factorization) as a...     

Validation of NP-HPTLC and RP-HPTLC Methods with Videodensitometric Detection for Analysis of Ziprasidone in Pharmaceutical Formulations

JPC – Journal of Planar Chromatography – Modern TLC - Two new simple and accurate HPTLC methods for analysis of ziprasidone in capsules have been developed and validated. The first...     

Reversed-Phase Chromatographic Retention Behavior of Some Fibrate-Type Antihyperlipidemic Drugs

JPC – Journal of Planar Chromatography – Modern TLC - Relationships between RM values and mobile phase composition have been examined for six fibrate-type drugs–bezafibrate,...     

Densitometric HPTLC Method for Analysis of Triterpenoids in the Leaves of Jovibarba sobolifera (Sims.) Opiz (Hen and Chickens Houseleek)

JPC – Journal of Planar Chromatography – Modern TLC - High performance thin-layer chromatography (HPTLC) combined with densitometry has been used for analysis of the triterpenoid...     

Quick prediction of the retention of solutes in 13 thin layer chromatographic screening systems on silica gel by classification and regression trees

The use of classification and regression trees (CART) was studied in a quantitative structure-retention relationship (QSRR) context to predict the retention in 13 thin layer chromatographic screening systems on a silica gel, where large datasets of interlaboratory determined retention are available. The response (dependent variable) was the rate mobility (RM) factor, while a set of atomic contributions and functional substituent counts was used as an explanatory dataset. The trees were investigated against optimal complexity (number of the leaves) by external validation and internal crossvalidation. Their predictive performance is slightly lower than full atomic contribution model, but the main advantage is the simplicity. The retention prediction with the proposed trees can be done without computer or even pocket calculator.     

Being Uncertain in Chromatographic Calibration—Some Unobvious Details in Experimental Design

This is an introductory tutorial and review about the uncertainty problem in chromatographic calibration. It emphasizes some unobvious, but important details influencing errors in the calibration curve estimation, uncertainty in prediction, as well as the connections and dependences between them, all from various perspectives of uncertainty measurement. Nonuniform D-optimal designs coming from Fedorov theorem are computed and presented. As an example, all possible designs of 24 calibration samples (3–8, 4–6, 6–4, 8–3 and 12–2, both uniform and D-optimal) are compared in context of many optimality criteria. It can be concluded that there are only two independent (orthogonal, but slightly complex) trends in optimality of these designs. The conclusions are important, as the uniform designs with many concentrations are not the best choices, contrary to some intuitive perception. Nonuniform designs are visibly better alternative in most calibration cases.