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.

A Simple and Sensitive Dispersive Micro-Solid-Phase Extraction Coupled with High-Performance Liquid Chromatography for Quantification of Honokiol and Magnolol in Complex Matrices.

BACKGROUND: Honokiol and magnolol were considered as markers for the analysis of Cortex Magnoliae Officinalis, its related Chinese Patent Medicines and their metabolites. However, the determination of these two analytes in a water-soluble sample is difficult and therefore requires a more efficient method. OBJECTIVE: To develop a sensitive method for the determination of honokiol and magnolol in a water-soluble sample for better quality control of Cortex Magnoliae Officinalis and its related Chinese Patent Medicines. METHOD: In this work, a combination of dispersive micro-solid-phase extraction (DMSPE) and high-performance liquid chromatography (HPLC) has been developed for simultaneous preconcentration and determination of honokiol and magnolol in complex bio-samples. Several experimental factors affecting the extraction efficiency were optimized by single factor test. RESULTS: Under the optimized extraction conditions, the proposed method exhibited good linearity of not less than 0.9998, satisfactory precision with relative standard deviation of less than 1.3%, and acceptable mean recoveries of 97.3% and 101.5% for honokiol and magnolol, respectively. Furthermore, the method exhibits extremely high sensitivity with detection limits of 0.0097 and 0.0231 ng/mL, which is even more sensitive than those methods developed by MS. CONCLUSIONS: The method established in this study is fast, economic, accurate, easy to operate, and importantly well suited to the extraction and analysis of honokiol and magnolol in a real complex sample matrix.

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.

Microwave-assisted ionic liquid-based micelle extraction combined with trace-fluorinated carbon nanotubes in dispersive micro-solid-phase extraction to determine three sesquiterpenes in roots of Curcuma wenyujin.

INTRODUCTION: Germacrone, furanodiene and ß-elemene are the representative bioactive compounds in Curcuma species. The conventional extraction methods of these three sesquiterpenes are usually time-consuming and require a large volume of hazardous organic solvents. Thus, a fast and reliable method for extracting these sesquiterpenes from Curcuma plant is required urgently. OBJECTIVE: To establish a novel and simple extraction method for quantitative analysis of small amounts of sesquiterpenes in C. wenyujin plant. METHODOLOGY: A method using microwave-assisted ionic liquid-micelle extraction combined with dispersive micro-solid-phase extraction (DMSPE) has been proposed for the extraction of three sesquiterpenoids in Curcuma plant. Fluorinated carbon nanotubes (FCNTs) were used as an adsorbent in DMSPE for the first time. Parameters concerning the microwave-assisted extraction (MAE) conditions and the DMSPE were investigated and evaluated to achieve optimum extraction efficiency of target analytes. RESULTS: The final conditions of ionic liquid-micelle based MAE were selected to be 0.25 M of 1-decyl-3-vinylimidazolium bromide as the extraction solvent, microwave irradiation for 10 min at 60°C. And the optimal DMSPE conditions were found to be 2 µg/mL of FCNTs as the adsorbent, extraction time of 2 min and 100 µL of acetonitrile as the elution solvent. The developed method exhibited good linearities (R > 0.9990), high repeatability and recoveries. The proposed method has been successfully applied in determination of sesquiterpenes in C. wenyujin samples. CONCLUSION: The work shows a potential in analysing small amounts of sesquiterpenes in complex samples and represents the first attempt of using FCNTs as an adsorbent for the microextraction mode.

New Vortex-Synchronized Matrix Solid-Phase Dispersion Method for Simultaneous Determination of Four Anthraquinones in Cassiae Semen.

In this study, a green ionic-liquid based vortex-synchronized matrix solid-phase dispersion (VS-MSPD) combined with high performance liquid chromatography (HPLC) method was developed as a quantitative determination method for four anthraquinones in Cassiae Semen. Two conventional adsorbents, C18 and silica gel were investigated. The strategy included two steps: Extraction and determination. Wasted crab shells were used as an alternative adsorbent and ionic liquid was used as an alternative solvent in the first step. Factors affecting extraction efficiency were optimized: A sample/adsorbent ratio of 2:1, a grinding time of 3 min, a vortex time of 3 min, and ionic liquid ([Domim]HSO4, 250 mM) was used as eluent in the VS-MSPD procedure. As a result, the established method provided satisfactory linearity (R > 0.999), good accuracy and high reproducibility (RSD < 4.60%), and it exhibited the advantages of smaller sample amounts, shorter extraction time, less volume of elution solvent, and was much more environmental-friendly when compared with other conventional methods.

A sensitive dispersive micro solid-phase extraction coupled with high performance liquid chromatography for determination of three flavonoids in complex matrics by using crab shell as a sorbent.

A sensitive dispersive micro solid-phase extraction coupled with HPLC has been developed for preconcentration and determination of three flavonoids (quercetin, kaempferol, and isorhamnetin) in complex matrix samples. Parameters that affect extraction efficiency have been optimized. The optimal extraction conditions are using 2 µg/mL of crab shell as the sorbent, extraction for 2 min at pH 7, and then eluting with 100 µL of methanol. As a result, the method shows good linearity (R > 0.9994), low LODs (even 0.08 ng/ml) and satisfactory recovery in real honey and rat urine samples. As an eco-friendly biomaterial, crab shell powder is used as sorbent in pretreatment of flavonoids, and its adsorption mechanism has been investigated for the first time. Compared with the other reported methods, the proposed strategy is time-saving, eco-friendly, and highly sensitive using HPLC (even achieving MS grade sensitivity).

Over 1000-fold improvement in an online preconcentration of trace anionic compounds by capillary electrophoresis with ionic liquid micelle-based three-step stacking.

A sensitive, simple, and environmentally friendly online three-step stacking strategy combining field-enhanced sample injection, sweeping and micelle to solvent stacking has been developed to determine trace amounts of organic anionic analytes in complex biological samples. A green ionic liquid, 1-dodecyl-3-methylimidazolium hydrogen sulfate, was first introduced as a micellar solution and used for electroosmotic flow reversal in this stacking strategy. The mechanism of stacking has been discussed, and parameters affecting three-step stacking preconcentration efficiency have been optimized. The capillary coated with an ionic liquid was easy to prepare, regenerable and repeatable (RSD<2.16%) and yielded a high efficiency. Under optimal conditions, the sensitivity improvement increased up to 2424-fold when compared with the normal capillary zone electrophoresis mode. The peak shape and separation efficiency of the model basic organic acids showed a significant enhancement when compared to traditional capillary zone electrophoresis. The optimized method showed great potential for quantitative analysis of trace concentration analytes in complex matrices.

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, convenient, and sensitive method that involves combining matrix solid-phase dispersion extraction with field-amplified sample stacking in capillary electrophoresis has been developed for the determination of organic acids in a complex solid matrix. Mesoporous molecular sieve, MCM-48, was synthesized by a hydrothermal method and selected as the adsorbent in matrix solid-phase dispersion. After fast extraction, the enriched analytes were back-extracted into a basic aqueous solution for field-amplified sample stacking in capillary electrophoresis. Parameters that affect extraction efficiency and sample stacking were optimized. Under the optimal conditions, approximately 42-, 49-, and 56-fold sensitivity enhancements were achieved for danshensu, protocatechuic acid, and cinnamic acid, respectively, when compared to normal injection. A satisfactory correlation coefficient (r > 0.99) was obtained. Both intra- and interday precision were lower than 2.53%. And the limits of detection of the three organic acids ranged between 0.01 and 0.029 µg/mL. Finally, the newly proposed method was successfully applied to the determination of organic acids in Fufang Danshen tablets, which indicates its great potential in analyzing organic acids in a complex matrix.