UiO-66 metal–organic frameworks (MOFs) can be endowed with greatly enhanced photocatalytic properties by introducing titanium into the frameworks. A microwave-assisted method was developed to substitute the zirconium with titanium in UiO-66, which was accomplished within a few hours compared to several days reported previously, with the crystallinity well maintained and photocatalytic activities tremendously improved.

In this work, Au nanoparticles self-assembled with covalent-organic frameworks via a 1 min process at room temperature, and the obtained nanocomposite was employed as a new type of surface-enhanced Raman scattering sensor for the recognition of polycyclic aromatic hydrocarbons with high sensitivity.

•A colorimetric sensor for Pb2 + was developed with bimetallic lanthanide metal-organic frameworks (MOFs).•The MOFs was prepared by using a simple and fast synthetic procedure.•The color change of the sensor could be visually observed by the naked eyes.•It is rapid, cost-effective and selective for field screen analysis of lead-polluted environmental water.A new colorimetric sensor for Pb2 + based on bimetallic (Eu-Tb) lanthanide (Ln) metal-organic frameworks (MOFs) was developed for field screen analysis of lead-polluted environmental water. The Ln-MOFs were prepared by using a simple and fast synthetic method, with Tb3 +/Eu3 + and 1,4-benzenedicarboxylate (BDC) as precursors. The color of the luminescent Ln-MOFs could be fine-tuned from green to red by doping the MOFs with different ratios of Tb3 +/Eu3 +, and a specific MOFs Tb1.7Eu0.3(BDC)3·(H2O)4 was synthesized and employed as the sensing probe. With the existence of Pb2 + in an appropriate concentration range with a certain amount of Tb1.7Eu0.3(BDC)3·(H2O)4, the emission color of the MOFs changed from red-orange to green, which could be visually observed by the naked eyes. This colorimetric sensing method turned out to be simple, rapid, cost-effective and highly selective, without any requirement for complicated instrumentation. Furthermore, lead-polluted environmental water samples were analyzed for Pb2 +, illustrating the promising perspective of the developed method for field screen analysis.

•CTF-1 was quickly synthesized with a simple microwave-assisted ionothermal polymerization method.•CTF-1 without any modification was verified to have dual enzyme activities: peroxidase-like and oxidase-like activity.•Using CTF-1 as oxidase mimic, a simple and fast colorimetric platform for biothiol detection was developed.•The advantages also include low cost, easy preparation and highly stability.A triazine-based covalent organic framework, CTF-1, for the first time, was found to possess both intrinsic peroxidase-like activity and oxidase-like activity and be capable to catalyze the oxidation of chromogenic substrates with or without H2O2 with high efficiency as a robust catalyst. Related oxidization mechanism was thoroughly studied, and the according catalytic properties of CTF-1 was also evaluated. What's more, a facile and effective colorimetric assay was established to detect biothiols without using any oxidizing agents. Compared to natural enzymes and other reported artificial enzymes, CTF-1 has also demonstrated the advantages including low cost, easy preparation, good stability, and high catalytic activity, which made it a very promising enzyme-mimetic alternative in potential applications in biosensors for the future.

•Effective adsorption of arsenic with Fe3O4@ZIF-8 core-shell magnetic nanoparticles•Easy separation of the Fe3O4@ZIF-8 with a magnet from water sample after the adsorption•Sensitive determination of the absorbed arsenic by AFS without matrix interference•Simple and facile step-by-step preparation of the Fe3O4@ZIF-8In this work, magnetic Fe3O4@ZIF-8 core-shell nanoparticles (MNPs) were employed for effective adsorption of inorganic arsenic for preconcentration, with adsorption mechanism thoroughly discussed. The adsorbed inorganic arsenic was easily separated by a magnet along with the MNPs from the sample matrix, with possible matrix interference eliminated. The MNPs were then completely dissolved in hydrochloric acid prior to the determination of inorganic arsenic by hydride generation-atomic fluorescence spectrometry. The Fe3O4@ZIF-8 MNPs were prepared with a facile step-by-step assembly method in aqueous solution at room temperature. Under the optimized conditions, the sensitivity for inorganic arsenic determination was significantly increased through preconcentration, with satisfactory analytical merits obtained.

•MOFs was used as peroxidase mimics without H2O2 for colorimetric sensing.•Photocatalytic property of MOFs was used for TMB oxidization.•Good affinity of MOFs to TMB substrate was obtained.•The developed method was facile, sensitive, low-cost and green for real analysis.A facile colorimetric sensing method for biothiols was developed, based on photocatalytic property of metal-organic frameworks (MOFs), UiO-66(NH2) nanoparticles (NPs), as peroxidase mimics under light irradiation. By the irradiation of a light emitting diode (LED) source, the colorless chromogenic substrate, 3,3′,5,5′-tetramethylbenzydine (TMB), was oxidized into blue oxTMB with the aid of the catalytic UiO-66(NH2) NPs. With the existence of biothiols, the oxidization was prohibited, with the blue color paled and absorbance intensity decreased with the concentration of biothiols in a linear manner. Real samples of cysteine, glutathione, and homocysteine were analyzed under the optimized conditions, with high sensitivity (the limit of detection was calculated as 306 nM, 310 nM, and 330 nm respectively) and selectivity. The recovery ranged from 93% to 107% with good precisions (RSD%≤5%). This photocatalytic property of UiO-66(NH2) as peroxidase mimics was studied based on steady-state kinetics, and the mechanism of oxidization process was also briefly discussed. This developed MOFs-based colorimetric sensing method demonstrated advantages over others for biothiols sensing, including high photo-catalytic activity compared to other nanomaterials, oxidation without H2O2, ease of regulation with the LED source, and low cost without expensive instrument and technically demanding.A facile colorimetric method using UiO-66(NH2) as a peroxidase mimic without H2O2 was developed for biothiol sensing.

A miniaturized atomic emission spectrometer composed of a corona discharge source and a handheld charge-coupled device detector was assembled for the sensitive determination of trace mercury, with photochemical vapor generation for sample introduction. By using formic acid, mercury vapor was generated under the irradiation of UV light, and then the vapor was introduced into the corona discharge area with the carrier gas flow of argon. The optical signals were captured and analyzed by the charge-coupled device detector at 253.7 nm. Under the optimized conditions of 4% formic acid, discharge voltage of 90 V, and at carrier gas flow rate of 200 mL min−1, the stable detection signals were obtained (RSD = 2.5%). The calibration curve was plotted with the concentration of mercury ranging from 0.5 ng mL−1 to 1000 ng mL−1, with a correlation coefficient > 0.99 and the limit of detection of 0.03 ng mL−1. Two certified reference materials were analyzed, and a t-test demonstrated that the determined results by the proposed method had no significant difference with the certified values at the confidence level of 95%. Water samples collected from both Funan River in Chengdu and Lotus Pond on campus of Sichuan University were analyzed as well, with the recoveries of standard addition between 93.8% and 103%. The miniaturized instrumentation demonstrated several advantages such as easy construction, low power consumption, high sensitivity, and portability for field analysis.A miniaturized atomic emission spectrometer composed of a corona discharge source and a handheld charge-coupled device detector was assembled for the sensitive determination of trace mercury in real water samples, with photochemical vapor generation technique employed for the sample introduction.

Stable layered MoS2 nanosheets were employed as a stationary phase in gas chromatography. A wide range of different analytes were screened with excellent separation efficiency.

•5 mogrosides in Luo-Han-Guo were firstly determined with UPLC–QTOFMS and LC–MS/MS.•Good extraction of the 5 mogrosides out of Luo-Han-Guo real samples was achieved.•Good reproducibility of the analytical results was obtained.•The method could be used for future assessment of real Chinese herbal medicines.An effective and rapid method involving high performance liquid chromatography–triple quadrupole linear ion trap tandem mass spectrometry (HPLC–QTrap–MS/MS) was developed for identification and quantification of five major mogrosides (mogroside III, mogroside IV, siamenoside I, mogroside V and 11-oxomogroside V) contained in real samples of Siraitia grosvenorii (Luo-Han-Guo) for the first time. High extraction efficiency was obtained for the five mogrosides by using microwave-assisted extraction compared with other common extraction methods during sample pretreatment prior to determination. Mass measurement for molecular ions and characteristic fragment ions well accorded with corresponding identification criteria. Quantitative data acquisition was accomplished in multiple reaction monitoring (MRM) mode, and further identification of target compounds was achieved by using ultra performance liquid chromatography–quadrupole-time-of-flight mass spectrometry. The proposed method could be used as a rapid and reliable approach for effective assessment of Luo-Han-Guo, and also provided use for reference in terms of real analysis of other traditional Chinese medicines in the future.

A simple and rapid fluorescence sensing platform based on the MIL-53(Fe) MOF was developed for fast, highly selective and ultrasensitive direct determination of MeHg+.

•Speciation analysis of Hg with MOF as fluorescence sensing probe was firstly reported.•The method was characterized with rapidness, high sensitivity and selectivity.•The procedure for preparing small-sized MOF NPs was easy and fast.•Good reproducibility (RSD ≤ 4.5%) and detection limit (≤6 ng mL−1) were obtained.A fluorescence sensing platform based on metal–organic frameworks (MOFs) nanoparticles (NPs) of both zeolitic imidazolate framework-7 (ZIF-7) and zeolitic imidazolate framework-60 (ZIF-60) was developed for speciation analysis of inorganic Hg [Hg(II)] and methylmercury (MeHg+). Microwave-ultrasound assisted synthesis was employed for the preparation of ZIF-7 and ZIF-60 NPs, with short reaction time, easy procedure, and small particle size obtained. Based on strict cavity confinement of the ZIF-7 and ZIF-60 structures, the proposed method exhibited excellent selectivity for both Hg(II) and MeHg+, even in the presence of the other Hg species or various cations or anions with the concentration of 50 times high. Effect of pH and ionic strength on sensing behaviour of the ZIF MOF was studied as well. The calculated detection limit is 3 ng mL−1 and 6 ng mL−1 for Hg(II) and MeHg+, respectively. Furthermore, the application of the developed method to the analysis of local drinking water was demonstrated to be feasible, and the obtained recovery was 102% and 96.2% for Hg(II) and MeHg+, respectively.Metal–organic frameworks employed as fluorescence sensing probe for fast, sensitive, reproducible and highly selective speciation analysis of Hg.

•PLE–LC–MS/MS was firstly used for analyzing Curcuma wenyujin Y.H.chen et C.Ling.•A green and efficient method was used for pretreating traditional Chinese medicine.•Similar Curcuminoids were determined simultaneously without complete separation.•Operating parameters of PLE–LC–MS/MS were thoroughly optimized.A sensitive and efficient method based on pressurized liquid extraction (PLE) followed by liquid chromatography–tandem mass spectrometry (LC–MS/MS) was developed for simultaneous identification and quantification of three Curcuminoids in Curcuma wenyujin Y.H.chen et C.Ling., a well known traditional Chinese medicinal herb. PLE was performed using methanol as the extractant, and with the temperature set at 100 °C and the pressure at 1500 psi. Shorter extraction time and less solvent consumption were obtained compared to other extraction methods. LC was performed by using a Waters XBridge™ C18 column (150 mm × 2.1 mm i.d., 3.5 μm) and a mobile phase of acetonitrile containing 0.1% acetic acid. The operating parameters were thoroughly optimized. The recoveries ranged from 92.4% to 104.1% and relative standard deviations were lower than 3.6%. The method was applied to the determination of Curcumin, Demethoxycurcumin and Bisdemethoxycurcumin contained in Curcuma wenyujin Y.H.chen et C.Ling. samples, which provided a new analytical approach for analysis and quality assessment of traditional Chinese medicines.A method based on pressurized liquid extraction (PLE) followed by determination with liquid chromatography–tandem mass spectrometry (LC–MS/MS) was developed for identification and quantification of Curcumin, Demethoxycurcumin and Bisdemethoxycurcumin in Curcuma wenyujin Y.H.chen et C.Ling., a well known traditional Chinese medicinal herb. The operating parameters were thoroughly optimized. Shorter extraction time and less solvent consumption were obtained from PLE compared to other extraction methods. The recoveries ranged from 92.4% to 104%, and relative standard deviations were lower than 3.6%. The method provided a new analytical approach for quality assessment on traditional Chinese medicines.

A simple and rapid fluorescence sensing platform based on the MIL-53(Fe) MOF was developed for fast, highly selective and ultrasensitive direct determination of MeHg+.

UiO-66 metal–organic frameworks (MOFs) can be endowed with greatly enhanced photocatalytic properties by introducing titanium into the frameworks. A microwave-assisted method was developed to substitute the zirconium with titanium in UiO-66, which was accomplished within a few hours compared to several days reported previously, with the crystallinity well maintained and photocatalytic activities tremendously improved.