9-(2-hydroethyl) -acridone (hea), a novel ultraviolet and fluorescence labelling reagent, has been utilized as pre-column derivatization reagent for the analysis of 10 bile acids by high performance liquid chromatography ( hplc) with fluorescence detection. hea reacts with bile acids in the presence of the coupling agent 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride ( edc . hcl) and the base catalyst 4-dimethylaminopyridine ( dmap) to give the corresponding sensitively fluorescent derivatives with an excitation maximum at lambda(ex) 404 nm and an emission maximum at lambda(em) 440 nm. the labeled derivatives exhibit high stability under reversed-phase conditions. the method, in conjunction with a gradient elution, offers a baseline resolution of the 10 bile acids derivatives on a reversed-phase hypersil bds c-18 column. the average detection limit ( at a signal-to-noise ratio of 3) for per injection is 8.3 fmol.
The effect of solute absorbed on the solid phase on its distribution in electro-chromatographic column was investigated according to relaxation theory. The distribution equation was theoretically gotten by production function. The result shows that neutral solute can be stayed in a narrow band near column head at ultra-long injecting time, indeed longer than dead-time. This process is similar to a solid-extraction. As an example,benzoin can be enriched 20000 fold with this method.
The intercept (ln k'w) and slope (S) of the retention equation in k' = ln k'w - SC in micellar electrokinetic capillary chromatography (MECC) have been studied through linear solvation energy relationships (LSER). It has been observed that the ln k'w is dependent on the properties of micelle and solute but independent of the properties of organic modifier, while the slope (S) is related to the organic modifier and the solute. The LSER results show that the ln k'w of solute is primarily determined by its molecular size and hydrogen bond acceptor (HBA) basicity, whereas the S of solute is primarily determined by its properties in terms of the type of organic modifier, of which molecular size is the most important factor. Additionally, the LSER results show that the interactions of micelle-water and water-organic modifier are also important factors for the retention of solute.
A new mass spectrometry, matrix-assisted laser desorption/ionization time-of-night mass spectrometry was used for analysis of oligasaccharides in plants. Different sample preparation methods and sample detection modes were compared. This paper presented the absolute molecular weight distributions and molecular weights of repeat units and end groups of oligasaccharides.
Post-operative outcomes after simultaneous bilateral total knee arthroplasty in 115 patients randomly assigned to two rehabilitation protocols were compared. The traditional-protocol group performed a series of exercises on one leg and then repeated the same sequence on the other leg. The alternate-protocol group performed the same exercises, but alternated between legs with each individual repetition. Symptoms and function were assessed pre-operatively and at 1, 3, 6 and 12 months post-operatively. The alternate-protocol group had lower visual analogue pain scale scores in the early post-operative period, as well as higher Knee Society Scores and SF-12 physical and mental health summary scores after 1 and 3 months compared with the traditional-protocol group, but there were no differences between the two groups from 6 months post-operatively. There were no significant differences between the groups in terms of range of knee motion or incidence of deep vein thrombosis. The alternate-protocol for rehabilitation resulted in an early return to function and decreased pain levels following simultaneous bilateral total knee arthroplasty and was associated with the potential to produce more positive emotional states and earlier functional independence.
On-line enrichment of neutral analytes by the sweeping technique in micellar electrokinetic chromatography is presented. The equations for describing the effect of sample injection length and the difference between the nature of the sample zone and that of the buffer zone on enhancement factors were obtained on the basis of the relaxation theory. With the further study of sample injection length and the relationship between the capacity factors of solutes in two different zones and enhancement factors, it can he proved that the solubility of solutes in the micelle is the most important factor to affect the enhancement factors. The appropriate increase in the sample injection length could be favorable to the enrichment without loss in resolution.
A novel method for the fast optimization of binary multi-step gradient elution in reversed phase-high performance liquid chromatography was proposed. the retention equation of solutes can be obtained by running several linear gradient elutions and then the multi-step gradient elution was optimized using: them overlapping separation range mapping (osrm only several hours were needed to complete the optimization process. this method was validated by the separation of chinese medicine chuanxiong extract,. in which good prediction precision and separation performance were obtained.
A detailed analysis of the synchrotron radiation intensity and energy of runaway electrons is presented for the Experimental Advanced Superconducting Tokamak (EAST). In order to make the energy of the calculated runaway electrons more accurate, we take the Shafranov shift into account. The results of the analysis show that the synchrotron radiation intensity and energy of runaway electrons did not reach the maximum at the same time. The energy of the runaway electrons reached the maximum first, and then the synchrotron radiation intensity of the runaway electrons reached the maximum. We also analyze the runaway electrons density, and find that the density of runaway electrons continuously increased. For this reason, although the energy of the runaway electrons dropped but the synchrotron radiation intensity of the runaway electrons would continue rising for a while.
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