A dual preconcentration method by combining micro matrix solid-phase dispersion extraction with field-enhanced sample injection and micelle to cyclodextrin stacking for sensitive analysis of neutral coumarins.

A rapid, sensitive, environmental friendly dual preconcentration method by combining micro matrix solid-phase dispersion extraction with field-enhanced sample injection and micelle to cyclodextrin stacking has been developed for the determination of furocoumarins. Molecular sieve, KIT-6, was used as an adsorbent in micro matrix solid-phase dispersion process. The important parameters affecting off-line and online CE preconcentration efficiency were optimized. Under the optimal experimental conditions, all analytes showed good linearity (R2 > 0.999). The LODs of notopterol, isoimperatorin, and imperatorin were 0.1 µg/mL, 1.2 mg/kg, and 1.0 mg/kg, respectively. Compared with the normal CE method, the enrichment times were up to 300. Moreover, Angelicae Dahuricae Radix was used as the mode of complex solid sample matrix to demonstrate the prospect of application of this methodology. The results showed the proposed strategy is promising for determining trace furocoumarins in complex matrix samples, which might be applied as a powerful and economic tool in monitoring illegal cosmetic adding.

Simultaneous determination of seven compounds in Chinese patent medicines Chenxiangqu by matrix solid-phase dispersion coupled with ultra high performance liquid chromatography and quadrupole time-of-flight mass spectrometry.

A simple, efficient, and sensitive strategy by coupling matrix solid-phase dispersion with ultra high performance liquid chromatography quadrupole time-of-flight mass spectrometry was proposed to extract and determine three types of components (including seven analytes) in Chinese patent medicines Chenxiangqu. The highly ordered mesoporous material Fe-SBA-15 synthesized under weakly acidic conditions was selected as a dispersant in matrix solid phase dispersion extraction for the first time. Several parameters including the mass ratio of sample to dispersant, the type of dispersant, the grinding time, and the elution condition were investigated in this work. Under the optimized conditions, 20 compounds were identified by quadrupole time-of-flight mass spectrometry and seven analytes were quantified. The results demonstrated that the developed method has good linearity (r > 0.9995), and the limits of detection of the analytes were as low as 0.55 ng/mL. The recoveries of all seven analytes ranged from 97.6 to 104.6% (relative standard deviation < 3.4%). Finally, the improved method was successfully applied to determination of five batches of Chenxiangqu samples, which provided a robust method in quality control of Chinese patent medicines Chenxiangqu. The developed strategy also shows its great potential in analysis of complex matrix samples.

Online preconcentration by electrokinetic supercharging for sensitive determination of berberine and jatrorrhizine in biological samples.

Electrokinetic supercharging, a convenient and powerful online preconcentration technique in capillary electrophoresis, was introduced and evaluated for the determination of two alkaloids, berberine and jatrorrhizine, in mice fecal samples for the first time. The method depended on using a bare fused silica capillary (50 cm × 50 µm i.d.) and applying the voltage of 25 kV with UV detection at 205 nm. Parameters that affect the separation and preconcentration efficiency have been optimized. The optimum conditions used were as follows: background electrolyte consisting of 40mM sodium dihydrogenphosphate containing 30% methanol (v/v); hydrodynamic injection of 20mM KCl (50 mbar × 150 s) as the leading electrolyte; electrokinetic injection of the sample (+15 kV, 120 s) followed by the hydrodynamic injection of 30mM dodecyl trimethyl ammonium chloride (50 mbar × 12 s) as the terminating electrolyte. The results showed that the detection sensitivity of berberine and jatrorrhizine was, respectively, improved up 2740- and 2928-fold compared with normal injection, providing limits of detection lower than 3 ng/mL with good repeatability in areas (relative standard deviation < 3%). In summary, the developed method proved its ability in analyzing trace alkaloids in complicated biological samples.

A sensitive two-step stacking by coupling field-enhanced sample injection and micelle to cyclodextrin stacking for the determination of neutral analytes.

To promote the detection sensitivity of neutral analytes, a sensitive two-step stacking strategy by coupling field-enhanced sample injection and micelle to cyclodextrin stacking in reverse migrating micelles MEKC has been established by selecting jujuboside A and B as models. The stacking mechanism, affecting factors as well as analytical performances of the proposed method were investigated. Compared with typical injection, the sensitivity enhancement factors of this method were up to 140- and 152-fold for jujuboside A and B, respectively. The enhancements were 8-10 times better than only single stacking strategy by MCDS. The LODs were 0.2-0.3 µg mL-1, interday and intraday%RSD were both lower than 4.3%, and a good linearity (r>0.999) was obtained. Feasibility in real samples analysis was evaluated by using Semen Ziziphi Spinosae dispensing granule and rat's urine. The results suggested that the strategy was simple, reliable, sensitive and promising for the analysis of neutral analytes in complex sample matrix.

On-line synergistic stacking in capillary zone electrophoresis featuring field-amplified sample stacking and micelle to cyclodextrin stacking in the determination of two alkaloids in complicated matrix samples.

A novel on-line synergistic proconcentration strategy coupling field-amplified sample stacking and micelle to cyclodextrin stacking for cationic analytes in capillary zone electrophoresis has been proposed and applied for the separation and determination of two alkaloids, matrine, and oxymatrine in complicated matrix samples. The approach was performed by the long injection of sample in a low-conductivity sodium dodecyl benzene sulfonate solution followed by the injection of hydroxypropyl-ß-cyclodextrin solution in higher conductivity. The stacking mechanism of this method has been expounded and parameters affecting stacking effect have been optimized in our study. Under the optimum experimental conditions, 169- and 218-fold sensitivity improvements were achieved for matrine and oxymatrine when compared with normal injection. Analytical indicators including linearity, limits of detection, and reproducibility (intra- and inter-day relative standard deviations) were evaluated. Moreover, sample matrix effect was studied using compound flavescent sophora and salicylic acid powder and spiked urine samples. The developed method is an attempt for the combination of micelle to cyclodextrin stacking with other stacking methods. It could be a good alternative choice for the determination of alkaloids in a complex sample matrix.