•APBA/GO hybrid monolithic column was prepared by in situ polymerization.•The APBA/GO hybrid monolithic column showed higher dynamic adsorption capacity.•The interaction behavior of APBA/GO hybrid monolithic column was investigated.•An online selective preconcentration procedure for glycoprotein was developed.A hybrid monolithic column based on aminophenylboronic acid (APBA)-functionalized graphene oxide (GO) has been developed and used for selective enrichment of glycoproteins. The APBA/GO composites were homogeneously incorporated into a polymer monolithic column with the help of oligomer matrix and followed by in situ polymerization. The effect of dispersion of APBA/GO composites in the polymerization mixture on the performance of the monolithic column was explored in detail. The presence of graphene oxide not only enlarged the BET surface area from 6.3 m2/g to 169.4 m2/g, but also provided abundant boronic acid moieties for glycoprotein extraction, which improved the enrichment selectivity and efficiency for glycoproteins. The APBA/GO hybrid monolithic column was incorporated into a sequential injection system, which facilitated online extraction of proteins. Combining the superior properties of extraordinary surface area of GO and the affinity interaction of APBA to glycoproteins, the APBA/GO hybrid monolithic column showed higher enrichment factors for glycoproteins than other proteins without cis-diol-containing groups. Also, under comparable or even shorter processing time and without the addition of any organic solvent, it showed higher binding capacity toward glycoproteins compared with the conventional boronate affinity monolithic column. The practical applicability of this system was demonstrated by processing of egg white samples for extraction of ovalbumin and ovotransferrin, and satisfactory results were obtained by assay with SDS-PAGE.

Cytokinins play a critical role in controlling plant growth and development, but it is difficult to be determined in plant samples due to the extremely low concentration level of picomole/gram. So it is important for efficient sample preparation with selective enrichment and rapid separation for accurate analysis of cytokinins. Herein, a supramolecular perhydroxy-cucurbit[8]uril (PCB[8]) was fabricated into the Fe3O4 magnetic particles via chemical bonding assembly and magnetic perhydroxy-cucurbit[8]uril (MPC) materials were obtained. The MPC had good enrichment capability to cytokinins and the enrichment factors were more than 208. The interaction of MPC and cytokinins was investigated by adsorption test and density functional theory (DFT) calculation, the results showed that the main drive forces were the host–guest interaction and hydrogen-bonding interaction between the perhydroxy-cucurbit[8]uril with analytes. Combined with ultra performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS), the MPC was used as a sorbent of magnetic solid-phase extraction for the analysis of cytokinins in plant samples. A sensitive and selective UPLC–MS/MS method was developed with low detection limits of 0.14–0.32 ng/L for cytokinins analysis. Five cytokinins including zeatin riboside, meta-topolin, kinetin, kinetin riboside, and zip with 6.12–87.3 ng/kg were determined in the soybean sprout and Arabidopsis thaliana. The recoveries were in the range of 76.2–110% with relative standard deviations (n = 5) of 2.3–9.7%. On the basis of these results, magnetic perhydroxy-cucurbit[8]uril materials with selective enrichment capability have good potential on the analysis of ultratrace targets from complicated sample matrixes.

•An efficient MAE coupled with CCC and prep-HPLC method was developed.•Six furocoumarins with high purity were prepared from original A. Pubescentis.•The method was effective for the preparation of furocoumarins from natural product.An efficient separation and purification method by microwave-assisted extraction coupled with counter-current chromatography and preparative liquid chromatography was developed. The extracts obtained from microwave-assisted extraction were rapid separated with counter-current chromatography, and then the fractions were further purified with preparative liquid chromatography. With this method, six furocoumarins including xanthotoxin, bergapten, columbianetin acetate, osthole, isoimperatorin and columbianadin can be obtained from original Angelica Pubescentis Radix samples within total time of 450 min. Their purities were 98%, 98%, 99%, 99%, 99% and 99% respectively, as determined by HPLC. The structures of these compounds were identified by 1H NMR and MS spectroscopy. The proposed method was economic, rapid and effective, and it can be used to prepare and purify targets from natural products.

A novel on-line solid-phase microextraction–high-performance liquid chromatography (SPME–HPLC) system was developed for the determination of heterocyclic aromatic amines (HAAs) in food samples. A poly(vinylphenylboronic acid-co-ethylene glycol dimethacrylate) polymer monolith was prepared for on-line efficient extraction and large-volume injection was used to increase the sensitivity of detection. The polymermonolith, based on a ternary porogen, was prepared by in situ polymerization of vinylphenylboronic acid (VPBA) and ethylene glycol dimethacrylate (EGDMA) in a fused-silica capillary column. It showed good permeability, high extraction capacity, and high selectivity. The column-to-column reproducibility was satisfactory, and the enrichment factors for HAAs were 3746–7414. Conditions influencing the on-line extraction efficiency, including pH of sample solutions, flow rate of extraction and desorption, and desorption volume, were investigated. The proposed method had low limit of detection (0.10–0.15 ng/L) and good linearity. Trace HAAs in roast beef and lamb samples were determined, and the amounts of 2-amino-3-methylimidazo[4,5-f]quinoline, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, and 2-amino-3,4,7,8-tetramethyl-3H-imidazo[4,5-f]quinoxaline in these samples were 0.235–2.08 ng/g. The recoveries for the five HAAs ranged from74.3% to 119%, and the relative standard deviation (RSDs) were less than 8.2%. The results showed that the proposed on-line method was highly sensitive for monitoring HAAs in different food samples.A novel on-line solid-phase microextraction–high-performance liquid chromatography (SPME-HPLC) system was developed for the determination of heterocyclic aromatic amines (HAAs) in food samples.

•A SERS method was developed for the rapid analysis of ractopamine.•Ritodrine used as the dummy-template of ractopamine for molecularly imprinted polymer.•The dummy-template MIP showed high selectivity to ractopamine used for SPE.•The method was successfully applied for the rapid analysis of ractopamine in pig tissues.Ritodrine has similar skeleton structure to ractopamine and it was selected as the dummy-template molecule to synthesize the molecular imprinted polymers (MIPs). The MIPs exhibited better selectivity to ractopamine than to the dummy-template molecule: the imprint factor for ractopamine was 8.9, while 7.6 for ritodrine. The MIPs were used as sorbents in solid-phase extraction for selective enrichment of ractopamine, and some key parameters were optimized. After that, a rapid surface-enhanced Raman spectroscopy method was developed for analysis of ractopamine and isoxuprine in pig tissue samples. Under the optimal conditions, good linearity was achieved in the range of 20.0–200.0 μg/L for ractopamine and isoxsuprine at 842 cm−1 and 993 cm−1, respectively. The limits of detection were 3.1–4.3 μg/L, which were lower than the maximum allowed by U. S. Food and Drug Administration. The recoveries of ractopamine and isoxsuprine were 72.4–79.7% and 71.0–78.2% for the spiked pork and pig liver, respectively, while the relative standard deviations ranging from 7.4% to 13.0%. The results suggest that the proposed method is sensitive and selective, and it has good potential on the quantitative analysis of trace amounts of β-agonists in complex samples.

•μ-SPE column of acrylamide modified graphene (AMG) was initially fabricated.•An ultrasensitive online method based on AMG μ-SPE–HPLC was established.•The method was successfully applied to online analysis of trace HAs in food samples.Heterocyclic amines (HAs) are considered as potential mutagens and carcinogens, and are found in trace quantities (ng/g level) in food samples. Therefore, it is important to develop a selective and effective method to determine trace HAs in complex matrices. In this study, acrylamide-modified graphene (AMG) was successfully synthesised and showed good stability and permeability in aqueous and organic phases. AMG was used as an efficient adsorbent in the online micro-solid-phase extraction (μ-SPE) of trace HAs. The enrichment factors of the AMG μ-SPE column were determined as 78–166 for six HAs. An online method based on AMG μ-SPE coupled to high-performance liquid chromatography was developed. The limits of detection ranged from 0.70 to 2.5 ng/L. Trace HAs in spicy salted duck, baked fish, and fried chicken samples were determined and the concentrations of 2-amino-3-methylimidazo[4,5-f]quinoine, 2-amino-3,4-dimethylimidazo[4,5-f]quinoine, and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline in these samples were 4.7–37.3, 8.1–15.4, and 43.3–109 ng/g, respectively. The recoveries for the six HAs ranged from 65.9% to 118%, and the relative standard deviation (RSDs) were less than 10.8%. The proposed online method was sensitive, reliable, and convenient for the analysis of trace HAs in food samples.

•A novel porous MIMCC was synthesized by in situ technique with ternary porogen.•A selective and sensitive on-line MIMCC microextraction/HPLC method was developed.•On-line method was successfully applied to antimicrobials analysis in food samples.A novel porous molecularly imprinted monolithic capillary column (MIMCC) based on ternary porogen was synthesized by in situ technique with sulfaquinoxaline as the template molecule. The characteristics of the MIMCC were investigated by scanning electron microscopy, infrared spectrum, thermogravimetric analysis and solvent resistance test. The saturated adsorption amount of sulfaquinoxaline on MIMCC was 2.7 times over that on the non-imprinted monolithic capillary column (NIMCC). The MIMCC also exhibited good enrichment ability to its analogs and the enrichment factors were 46–211 for five antimicrobials. High permeability and imprinting factors as well as good stability, reproducibility and long lifetime were obtained. An on-line method based on MIMCC solid-phase microextraction coupled with high-performance liquid chromatography was developed for the determination of trace antimicrobials in complex samples. The good linearity for sulfametoxydiazine, sulamethoxazole and sulfaquinoxaline was 0.05–10 µg/L, the limits of detection (LODs) were 10.0–14.0 ng/L. The linear range for mequindox and quinocetone were 0.10–10.0 µg/L, the LODs were 20.0–27.0 ng/L respectively. The recoveries were 71.0–108.2% with relative standard deviation of 1.6–8.5%, correspondingly. The results showed that MIMCC could effectively enrich antimicrobials from complex matrices. The on-line method based on MIMCC and HPLC was selective, sensitive and convenient for trace determination of antimicrobials in complex samples.

•Dynamic pH junction high-speed counter-current chromatography was developed.•An online MAE coupling with dynamic pH junction HSCCC method was presented.•Consecutive separation of alkaloids by online MAE-dynamic pH junction HSCCC.•Five alkaloids with high purity were directly separated and purified from S. cepharantha.A simple and efficient dynamic pH junction high-speed counter-current chromatography method was developed and further applied to the online extraction, separation and purification of alkaloids from Stephania cepharantha by coupling with microwave-assisted extraction. Mineral acid and organic base were added into the mobile phase and the sample solution, respectively, leading to the formation of a dynamic pH junction in the column and causing focus of alkaloids. Selective focus of analytes can be achieved on the basis of velocity changes of the pH junction through appropriate selection of solvent systems and optimization of additive concentrations. The extract can be directly introduced into the HSCCC for the online extraction, separation and purification of alkaloids from S. cepharantha. Continuous separation can be easily achieved with the same solvent system. Under the optimum conditions, 6.0 g original sample was extracted with 60 mL of the upper phase of hexane–ethyl acetate–methanol–water (1:1:1:1, v/v/v/v) containing 10% triethylamine under 50 °C and 400 W irradiation power for 10 min, the extracts were directly separated and purified by high-speed counter-current chromatography. A total of 5.7 mg sinomenine, 8.3 mg 6,7-di-O-acetylsinococuline, 17.9 mg berbamine, 12.7 mg isotetrandrine and 14.6 mg cepharanthine were obtained with purities of 96.7%, 93.7%, 98.7%, 97.3% and 99.3%, respectively. The online method provides good selectivity to ionizable compounds and improves the separation and purification efficiency of the high-speed counter-current chromatography technique. It has good potential for separation and purification of effective compounds from natural products.

Microwave accelerated selective Soxhlet extraction (MA-SSE), a novel selective extraction technique, was investigated in this study. A Soxhlet extraction system containing a glass filter was designed as an extractor. During the procedure of MA-SSE, both the target analytes and the interfering components were extracted from the sample into the extraction solvent enhanced by microwave irradiation. After the solvent flowed though the sorbent, the interfering components were adsorbed by the sorbent, and the target analytes remaining in the solvent were collected in the extraction bottle. No cleanup or filtration was required after extraction. The efficiency of the MA-SSE approach was demonstrated in the determination of organophosphorus and carbamate pesticide residues in ginseng by gas chromatography/mass spectrometry (GC/MS). Under the optimized conditions, low limits of detection (0.050–0.50 μg/kg) were obtained. The recoveries were in the range of 72.0–110.1% with relative standard deviations less than 7.1%. Because of the effect of microwave irradiation, MA-SSE showed significant advantage compared with other extraction techniques. The sorbent used in this study showed good cleanup ability. The mechanism of MA-SSE was demonstrated to be based on the rupture of the cell walls according to the structural changes of ginseng samples. On the basis of the results, MA-SSE as a simple and effective sample preparation technique for the analysis of pesticide residues in complex matrixes shows great promise.

A novel one-step sample preparation technique termed hybrid field-assisted solid–liquid–solid dispersive extraction (HF-SLSDE) was developed in this study. A simple glass system equipped with a condenser was designed as an extraction vessel. The HF-SLSDE technique was a three-phase dispersive extraction approach. Target analytes were extracted from the sample into the extraction solvent enhanced by the hybrid field. Meanwhile, the interfering components were adsorbed by dispersing sorbent. No cleanup step preceded chromatographic analysis. The efficiency of the HF-SLSDE approach was demonstrated in the determination of organochlorine pesticide (OCP) residues in tobacco with a gas chromatography-electron capture detector (GC-ECD). Various operation conditions were studied systematically. Low detection limits (0.3–1.6 μg/kg) and low quantification limits (1.0–4.5 μg/kg) were achieved under the optimized conditions. The recoveries of OCPs ranged from 70.2% to 118.2%, with relative standard deviations of <9.6%, except for the lowest fortification level. Because of the effect of the hybrid field, HF-SLSDE showed significant predominance compared with other extraction techniques. The dispersing sorbent with good cleanup ability used in this study was also found to be a microwave absorption medium, which could heat the nonpolar extraction solvent under microwave irradiation. Different microstructures of tobacco samples before and after extractions demonstrated the mechanism of HF-SLSDE was based on an explosion at the cell level. According to the results, HF-SLSDE was proved to be a simple and effective sample preparation method for the analysis of pesticide residues in solid samples and could potentially be extended to other nonpolar target analytes in a complex matrix.

In this paper, a simple method for the rapid extraction, separation and purification of bergenin from Ardisia crenata sims and Rodgersia sambucifolia hemsl by microwave-assisted extraction (MAE) coupled with high-speed counter-current chromatography (HSCCC) was developed. The MAE conditions were optimized and 2.0 g sample was extracted using 60% (v/v) aqueous methanol as extraction solvent with liquid/solid ratio of 10/1 (mL/g) at 60 °C for 15 min. The crude extract of MAE was separated and purified directly by HSCCC using ethyl acetate–n-butanol–water (3:2:5, v/v/v) solvent system. In less than 3.5 h, 18.6 or 25.0 mg of bergenin was obtained from 160 mg crude extract of A. creanta or R. sambucifolia in one-step separation, respectively. The purity of bergenin was over 99% determined by HPLC and its chemical structure was further identified by ESI-MS, 1H NMR and UV. The results indicate that microwave-assisted extraction coupled with high-speed counter-current chromatography is very suitable for the extraction, separation and purification of bergenin from A. creanta and R. sambucifolia.

In this paper, a simple method for the rapid extraction, separation and purification of bergenin from Ardisia crenata sims and Rodgersia sambucifolia hemsl by microwave-assisted extraction (MAE) coupled with high-speed counter-current chromatography (HSCCC) was developed. The MAE conditions were optimized and 2.0 g sample was extracted using 60% (v/v) aqueous methanol as extraction solvent with liquid/solid ratio of 10/1 (mL/g) at 60 °C for 15 min. The crude extract of MAE was separated and purified directly by HSCCC using ethyl acetate–n-butanol–water (3:2:5, v/v/v) solvent system. In less than 3.5 h, 18.6 or 25.0 mg of bergenin was obtained from 160 mg crude extract of A. creanta or R. sambucifolia in one-step separation, respectively. The purity of bergenin was over 99% determined by HPLC and its chemical structure was further identified by ESI-MS, 1H NMR and UV. The results indicate that microwave-assisted extraction coupled with high-speed counter-current chromatography is very suitable for the extraction, separation and purification of bergenin from A. creanta and R. sambucifolia.