毛细管区带电泳的离子交换在柱预富集技术研究

提出了离子交换固相萃取的毛细管区带电泳在柱预富集技术。预富集毛细管和分离毛细管的端面靠紧,二者通过一段带侧孔的聚四氟乙烯（PTFE）套管固定。预富集毛细管内壁键合羧基阳离子交换基团,进样时分析离子被保留在预富集管的固定相上,用2mol／L的氯化铵溶液洗脱,再进行毛细管区带电泳分离。方法成功富集和分离了两种低浓度的药物阳离子,普萘洛尔和美托洛尔的灵敏度比常规电动进样分别提高4200和3400倍,其浓度检出限分别为0．02μg/L和0．14μg/L。     

Precision improvement for the analysis of flavonoids in selected Thai plants by capillary zone electrophoresis

A capillary zone electrophoresis (CZE) method for the analyses of kaempferol in Centella asiatica and Rosa hybrids and rutin in Chromolaena odorata was developed. The optimization was performed on analyses of flavonoids (e.g., rutin, kaempferol, quercetin, myricetin, and apigenin) and organic carboxylic acids (e.g., ethacrynic acid and xanthene-9-carboxylic acid) by investigation of the effects of types and amounts of organic modifiers, background electrolyte concentrations, temperature, and voltage. Baseline separation (R(s) = 2.83) of the compounds was achieved within 10 min in 20 mM NaH2PO4 - Na2HPO4 (pH 8.0) containing 10% v/v ACN and 6% v/v MeOH using a voltage of 25 kV, a temperature of 30 degrees C, and a detection wavelength set at 220 nm. The application of the corrected migration time (t(c)), using ethacrynic acid as the single marker, was efficient to improve the precision of flavonoid identification (% relative standard deviation (RSD) = 0.65%). The method linearity was excellent (r2 > 0.999) over 50-150 microg/mL. Precision (%RSD < 1.66%) and recoveries were good (> 96% and %RSDs < 1.70%) with detection and quantitation limits of 2.23 and 7.14 microg/mL, respectively. Kaempferol in C. asiatica and R. hybrids was 0.014 g/100 g (%RSD = 0.59%) and 0.044 g/100 g (%RSD = 1.04%), respectively, and rutin in C. odorata was 0.088 g/100 g (%RSD = 0.06%).     

Determination of Size Distribution of Nano-particles by Capillary Zone Electrophoresis

A new method was developed for the determination of the size distribution of nano-particles by capillary zone electrophoresis (CZE). Scattering effect of nanoparticles was studied. This method for the determination of size distribution was statistical.     

Physicochemical characterization of phosphinic pseudopeptides by capillary zone electrophoresis in highly acidic background electrolytes

Phosphinic pseudopeptides (i.e., peptide isosteres with one peptide bond replaced by a phosphinic acid moiety) were analyzed and physicochemically characterized by capillary zone electrophoresis in the pH range of 1.1-3.2, employing phosphoric, phosphinic, oxalic and dichloroacetic acids as background electrolyte (BGE) constituents. The acid dissociation constant (pK(a)) of phosphinate group in phosphinic pseudopeptides and ionic mobilities of these analytes were determined from the pH dependence of their effective electrophoretic mobilities corrected to standard temperature and constant ionic strength of the BGEs. It was shown that these corrections are necessary whenever precise mobility data at very low pH are to be determined. Additionally, it was found that the ionic mobilities of the phosphinic pseudopeptides and pK(a) of their phosphinate group are affected by the BGE constituent used. The variability of migration behavior of the pseudopeptides can be attributed to their ion-pairing formation with the BGE components.     

Novel combination of non-aqueous capillary electrophoresis and multivariate curve resolution-alternating least squares to determine phenolic acids in virgin olive oil

This paper presents the development of a non-aqueous capillary electrophoresis method coupled to UV detection combined with multivariate curve resolution-alternating least-squares (MCR-ALS) to carry out the resolution and quantitation of a mixture of six phenolic acids in virgin olive oil samples. p-Coumaric, caffeic, ferulic, 3,4-dihydroxyphenylacetic, vanillic and 4-hydroxyphenilacetic acids have been the analytes under study. All of them present different absorption spectra and overlapped time profiles with the olive oil matrix interferences and between them. The modeling strategy involves the building of a single MCR-ALS model composed of matrices augmented in the temporal mode, namely spectra remain invariant while time profiles may change from sample to sample. So MCR-ALS was used to cope with the coeluting interferences, on accounting the second order advantage inherent to this algorithm which, in addition, is able to handle data sets deviating from trilinearity, like the data herein analyzed. The method was firstly applied to resolve standard mixtures of the analytes randomly prepared in 1-propanol and, secondly, in real virgin olive oil samples, getting recovery values near to 100% in all cases. The importance and novelty of this methodology relies on the combination of non-aqueous capillary electrophoresis second-order data and MCR-ALS algorithm which allows performing the resolution of these compounds simplifying the previous sample pretreatment stages.