Molecular-sieve-based matrix solid-phase extraction combined with field-amplified sample stacking in capillary electrophoresis for the determination of three organic acids in a complex solid matrix

A simple and sensitive preconcentration strategy by coupling salting-out assisted liquid-liquid extraction with online three-step stacking for the determination of potent anti-tumour compound vinblastine and its precursor in biological samples by capillary electrophoresis

A sensitive capillary electrophoresis strategy was developed by combining salting-out assisted liquid-liquid extraction and online three-step stacking to detect trace quantities of antitumour indole alkaloids in complex biological samples. The proposed strategy fully exploits these two technologies such that extraction, online stacking and separation are combined in a fast and efficient manner. First, salting-out assisted liquid-liquid extraction was used to extract three indole alkaloids (vinblastine sulfate, catharanthine sulfate and vindoline) from complex biomasses. An appropriate volume of acetonitrile (ACN) was mixed with a faecal aqueous solution to precipitate proteins. The mixed solution was vortexed, followed by the addition of ammonium sulfate ((NH₄)₂SO₄) to induce two-phase separation. Alkaloids were effectively extracted into the organic phase, which was then subjected to capillary electrophoresis (CE) analysis. The sensitivity of capillary electrophoresis was effectively improved by online three-step stacking. Good linearity of the calibration curve for each indole alkaloid was obtained in the concentration range of 0.1-1 μg/mL. Under optimal conditions, the sensitivity of ordinary injection was increased by up to 2366-fold, confirming the applicability of the proposed strategy for the sensitive determination of trace indole alkaloids in complex biological samples.

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.

Recent advances of green pretreatment techniques for quality control of natural products

A few advancing technologies for natural product analysis have been widely proposed, which focus on decreasing energy consumption and developing an environmentally sustainable manner. These green sample pretreatment and analysis methods following the green Analytical Chemistry (GAC) criteria have the advantage of improving the strategy of chemical analyses, promoting sustainable development to analytical laboratories, and reducing the negative effects of analysis experiments on the environment. A few minimized extraction methodologies have been proposed for replacing the traditional methods in the quality evaluation of natural products, mainly including solid-phase microextraction (SPME) and liquid phase microextraction (LPME). These procedures not only have no need for large numbers of samples and toxic reagent, but also spend a small amount of extraction and analytical time. This overview aims to list out the main green strategies on the application of quality evaluation and control for natural products in the past 3 years.