Full and fractionated experimental designs for robustness testing in the high-performance liquid chromatographic analysis of codeine phosphate, pseudoephedrine hydrochloride and chlorpheniramine maleate in a pharmaceutical preparation

This paper describes the testing of a saturated factorial design using a full factorial design. Saturated factorial designs are often used to test the robustness of high-performance liquid chromatography (HPLC) methods, however they are based on several assumptions. A full factorial design relies on fewer assumptions and hence could be used to evaluate the effectiveness of the saturated design. Both designs were used to test a gradient HPLC method for the assay of codeine phosphate, pseudoephedrine hydrochloride and chorpheniramine maleate. Six HPLC conditions, including wavelength, mobile phase pH and ion pairing reagent concentration were tested using the saturated design. Three of these factors were selected for full evaluation using a full factorial design. The results showed that the main effects calculated by each design were comparable. However, the saturated design showed higher standard errors, probably due to the effects of changing several more factors. One interaction effect was indicated as a confounding effect by the saturated design and this was confirmed by the calculation of the same interaction effect using the full design. Overall the method was shown to be robust under the variety of HPLC conditions tested.     

Caging of particles in one-component plasmas

Strongly coupled Coulomb systems are characterized by localization ("caging") of particles trapped and oscillating in slowly fluctuating local potential wells. This observation constitutes the basic assumption underlying the quasilocalized charge approximation. Using molecular dynamics simulation we study the changes in the particles' surroundings (cages) in a classical three-dimensional one-component plasma. The results of our analysis show that at high coupling values, substantial changes occur only after several plasma oscillation cycles. We also analyze the oscillation frequencies of the caged particles and relate the decorrelation of the cages to the process of self-diffusion.     

甘氨酸衍生化β-环糊精键合硅胶液相色谱固定相的合成与评价

 β-环糊精键合硅胶经对甲苯磺酰化后,与甘氨酸反应得到甘氨酸衍生化β-环糊精键合硅胶固定相(GCDS)。考察了GCDS对位置异构体、丹磺酰化氨基酸异构体、苯丙酸类药物等的分离性能,研究了流动相中甲醇浓度、pH以及柱温对色谱保留行为的影响。     

On the vibrational state dependence of the asymmetry parameter of angular distribution in the photoelectron spectra

A discussion is given on the changes obtainable in the asymmetry parameter β with vibrational state of the ion in the approximation involving fixed direction of body-frame orientation during the electron ejection. The R dependence of the electronic matrix elements is taken into account by calculation of appropriate displaced oscillator integrals. Inclusion of a nuclear matrix element gives in most cases negligible effect for the direct ionization. β_ν′ are calculated for H₂ and N₂. Expected variations in β_ν′ are compared with recent experimental data on N₂ and CO. Higher partial waves and their effect on β_ν′ are discussed.