•Alumina nanoshell coated porous silica microbeads were prepared.•A complete alumina nanoshell coating could be obtained in the mesopore of silica.•NanoAl2O3/mesoSiO2 particles were successfully applied to anions separation.•The column efficiency of 3.8 × 104 plates per meter was obtained for I−.It had been reported that alumina nanoshell coating could be obtained on the external surface of various substrates in one-nanometer precision in aqueous solution. In this work, alumina nanoshell coated mesoporous silica microbeads (nanoAl2O3/mesoSiO2) were prepared with the similar method, and were successfully applied to inorganic anions separation. As the mass transfer speed is largely constrained in the mesopore compared with that on the open surface, it was found that a complete alumina nanoshell coating could be obtained within the mesopore until the five-time coating was carried out. After characterization by BET, SEM and FTIR, it was found that the obtained nanoAl2O3/mesoSiO2 particles are smooth and well dispersed, and the mesopores are well reserved. In addition, the full coverage of nanoAl2O3 shell in mesopores was also confirmed by the binding capacity experiments with berberine. Finally, the nanoAl2O3/mesoSiO2 particles were packed in silica capillary for the separation of inorganic anions I−, SCN−, Br−, NO2− and NO3− with ion chromatography (IC), and a column efficiency of 3.8 × 104 plates per meter was obtained for I−.

•A simple and ultra-sensitive PT-SPE-UPLC-MS/MS method was established for BRs.•A quaternary ammonium derivatization reagent was first developed.•A pipette-tip solid-phase extraction strategy was proposed.•MDA of 27–94 amol was achieved for BRs.•Endogenous BRs were quantified in 0.5 mg FW of rice leaf segments.Determination of endogenous brassinosteroids (BRs) in limited sample amount is vital to elucidating their tissue- and even local tissue-specific signaling pathway and physiological effects on plant growth and development. In this work, an ultra-sensitive quantification method was established for endogenous BRs in milligram fresh plant by using pipette-tip solid-phase extraction coupled with ultra-performance liquid chromatography tandem mass spectrometry (PT-SPE-UPLC-MS/MS), in which a quaternary ammonium phenyl boronic acid, 4-borono-N,N,N-trimethylbenzenaminium iodide (BTBA) was first developed for chemical derivatization of BRs. Due to the cationic quaternary ammonium group of BTBA, the ionization efficiencies of the BRs chelates with BTBA (BTBA-BRs) were enhanced by 1190–448785 times, which is the highest response enhancement factor among all derivatization reagents reported for BRs. In addition, PT-SPE packed with C18 sorbent was first used for purifying BRs from plant extracts, so the required sample amount was minimized, and recoveries higher than 91% were achieved. Under the optimized conditions, the minimal detectable amounts (MDA) of five target BRs were in the range of 27–94 amol, and the correlation coefficients (R2) were >0.9985 over four orders of magnitude. The relative recoveries of 75.8–104.9% were obtained with the intra- and inter-day relative standard deviations (RSDs) less than 18.7% and 19.6%, respectively. Finally, three BRs were successfully quantified in only 5 mg fresh rice plant samples, and 24-epiBL can even be detected in only 0.5 mg FW rice leaf segments. It is the first time that the BRs content in sub-milligram fresh plant sample has been quantified.

•An integrated and ultrafast GC based on microtrap and LTM column was developed.•Both microtrap and LTM column could be cooled by liquid CO2 to −20 °C in 30 s.•Efficient enrichment, narrow injection band, and high GC loadability were obtained.•TO-14 was analyzed within 3 min with LODs down to 0.22 ppb.•Peak capacity of 67 per minute was obtained.An integrated instrumentation of a cryogenic microtrap-thermal desorption-low thermal mass (LTM) fast gas chromatographic (GC) system had been designed and evaluated for the ultrafast enrichment and separation of trace amounts of highly volatile organic compounds (VOCs) in air. The LTM fast GC column was wrapped uniformly on outer surface of a thin metal heating cylinder of 65 mm O.D. and 0.5 mm in thickness. Both of microtrap and LTM column could be rapidly cooled by liquid CO2 down to −35 °C, and heated by resistive heating. A 10 m×100 µm i.d. micro-bore capillary column was used in the LTM GC column module to provide a high separation speed. Key operational parameters, including adsorbent mass, trapping temperature, thermal desorption temperature and injection time were optimized. Under the optimized condition, the 39 species of TO-14 VOCs were well resolved and quantified in less than 3 min. The detection limits were in the range of 8 ppt–0.22 ppb at sampling volume of 50 mL and trapping temperature of −10 °C. The average peak width was 0.9 s, and the peak capacity of ~150 (at unit resolution) was obtained. The applicability of the setup was evaluated by analyzing three real environmental samples, where some typical VOCs at sub ppb level were detected.

Modified nucleosides are important biomarkers of cancers. For their analysis, boronate adsorbents were widely used to selectively capture them from urine, but often suffered from serious secondary hydrophobic interaction and harsh alkaline extraction condition. In this work, the hybrid titania–zirconia nanoparticles coated on porous silica spheres (TiO2–ZrO2/SiO2) were developed for the first time as a selective adsorbent for nucleosides under neutral conditions based on specific recognition of its Lewis acid sites to the cis-diol group. It was found here that TiO2–ZrO2 has higher binding constants than pure TiO2 or ZrO2, and a significant improvement of binding efficiencies was obtained by decreasing calcination temperature to 400 °C. Moreover, physiological pH of urine (pH 6–7) was found optimal to adsorb nucleosides and resist other Lewis base interferences. By self-assembly of TiO2–ZrO2 nanoparticles on silica, unprecedentedly high binding capacity (35 mg/g) for nucleosides was obtained due to high surface area (350 m2/g) and abundant Lewis acid sites on the surface. Due to efficient reduction of secondary hydrophobic interaction on the inorganic surface, cis-diol nucleosides could be captured from 500-fold non-cis-diol interferences. In the real sample application, nine nucleosides have been quantified with relative recoveries in 83%–126%, and 42 ribosylated metabolites had been identified with only 100 μL of urine at physiological pH. Among them, two nucleosides have never been identified in most previous studies using boronate adsorbents for capture.

In vivo analysis poses higher requirements about the biocompatibility, selectivity and speed of analytical method. In this study, an in vivo fast equilibrium microextraction method was developed with a biocompatible core–sheath electrospun nanofiber membrane sandwiched within a microfluidic unit. The polystyrene/collagen core–sheath nanofiber membrane was coaxially electrospun and strengthened with in situ glutaraldehyde cross-linking. This membrane not only kept high mass transfer rate, large extraction capacity and biomatrix resistance as our previously proposed membrane (Anal. Chem. 2013, 85 (12), 5924–5932), but also got much better mechanical strength and stability in water. The microfluidic device was designed to sandwich the membrane, and the blood in vivo can be introduced into it and get contact with the membrane repetitively. With this membrane and device, a 2-min equilibrium in vivo extraction method was established, validated in a simulated blood circulation system, and was used to monitor the pharmacokinetic profiles of desipramine in rabbits. The free and total concentration of desipramine in vivo was monitored with 10-min interval almost without rabbit blood consumed. The results met well with those of in vitro extraction, and a correlation factor of 0.99 was obtained.