Targeting Enrichment and Correlation Studies of Glutathione and Homocysteine in IgAVN Patient Urine Based on a Core-Shell Zr-Based Metal-Organic Framework.

Aminothiols are closely related to chronic kidney disease, but little is known regarding levels of related aminothiols in the urine of immunoglobulin A vasculitis with nephritis (IgAVN) patients. Herein, a well-defined core-shell Zr-based metal-organic framework (Zr-MOF) composite SiO2@50Benz-Cys was constructed as a mercury ion affinity material via a solvent-assisted ligand exchange strategy for the selective extraction and enrichment of low-concentration aminothiols in IgAVN patient urine. SiO2@50Benz-Cys was competent to enrich the total glutathione (GSH) and total homocysteine (Hcy) in virtue of the excellent affinity after chelation with mercury ions. The extraction efficiencies were closely related to the pH, dithiothreitol amount, and the dose of functional Zr-MOF. Coupled with HPLC-MS/MS in optimized conditions, GSH and Hcy were determined with low detection limits of 0.5 and 1 nmol L-1, respectively. The recoveries of GSH and Hcy for the urine sample at three spiked levels were in the range of 85.3-105% and 79.5-103%, which showed good precision and accuracy. Benefiting from the matrix interference elimination in the process of extraction, the simultaneous detection of aminothiols in the urine of the healthy group and immunoglobulin A vasculitis (IgAV) and IgAVN patients was successfully carried out, suggesting that the Zr-MOF and the robust method together provided a potential application in the analysis of urinary biomolecules. The analysis of variance (ANOVA) showed that the levels of GSH and Hcy had significant differences between the patients and the control. This work is very valuable as it provides a better understanding of concentration alterations of GSH and Hcy in urine involved with IgAVN for clinical research.

Sheathed in-situ room-temperature growth covalent organic framework solid-phase microextraction fiber for detecting ultratrace polybrominated diphenyl ethers from environmental samples.

The extraction performance of solid-phase microextraction (SPME) fiber is significantly influenced by coating materials and fabricating process. It is urgently needed for fabricating robust SPME fiber with facile preparation methods. Herein, a novel polyimide (PI) @ covalent organic framework (COF) synthesized by 1,3,5-Tris (4-aminophenyl) benzene (TPB) and 2,5-dimethoxyterephthalaldehyde (DMTP) fiber, named PI@TPB-DMTP fiber, was successfully fabricated with facile method at room temperature. Firstly, a COF crystals TPB-DMTP was in situ grown on stainless steel fiber, where the COF crystals was synthesized by the Schiff-base reaction between TPB and DMTP. Subsequently, the COF coating was covered with an ultrathin layer of PI through a simple dip-coating method to improve the fiber stability. By coupled PI@TPB-DMTP SPME fiber with gas chromatography-negative chemical ion-mass spectrometry (GC-NCI-MS), a sensitive analytical method was established for the determination of ultratrace polybrominated diphenyl ethers (PBDEs) in water sample. To achieve the best efficiency and sensitivity for the analysis of PBDEs, six potential influencing factors in extraction step and desorption step were optimized. Under optimized conditions, the established method showed high enhancement factors of 1470-3555, wide linear range of 0.05-100 ng L-1, low detection limits of 0.0083-0.0190 ng L-1, good repeatability for intra-day in the range of 3.71%-7.62% and inter-day in the range of 5.12%-8.81%, good reproducibility in the range of 6.83%-9.21%. The satisfactory recovery was ranged from 79.2% to 117.3% in determining real water samples. The excellent experimental performance was mainly attributed to the large specific surface area of TPB-DMTP, as well as the high permeability of porous PI film. The results demonstrated that the COF-based fiber showed great potential for analysis of PBDEs in complex environmental samples.

[Preparation and chromatographic performance of a silica-bonded (4-cyclopentadienyl benzoic acid-iron-toluene) hexafluorophosphoric acid stationary phase].

Based on the unique molecular structure of ferrocene and its potential as a new liquid chromatography separation medium, a new silica-bonded (4-cyclopentadienyl benzoic acid-iron-toluene) hexafluorophosphoric acid stationary phase was prepared. The structure of this new material was characterized by infrared spectroscopy, elemental analysis, thermogravimetric analysis et al. The chromatographic performance and retention mechanism of this new stationary phase were evaluated using different solute probes, including polycyclic aromatic hydrocarbons (PAHs), positional isomers of naphthylamine, positional isomers of nitro-aniline, nitroimidazoles, organic phosphorus et al. It could provide various action sites for different solutes in normal-phase chromatography such as π electron transfer, π-π electron interactions, dipole-dipole interactions, and electrostatic interactions with the substrates. And the possible separation mechanisms are discussed.

Determination of trace acrylamide in starchy foodstuffs by HPLC using a novel mixed-mode functionalized calixarene sorbent for solid-phase extraction cleanup.

In this paper, a rapid and effective HPLC method, using tetraazacalix[2]arene[2]triazine-modified silica gel (NCSi) as solid-phase extraction (SPE) sorbent, was developed for the purification and determination of trace acrylamide in starchy foodstuffs. The main influence factors of SPE including amount of NCSi sorbent, sample flow rate, and volume and composition of washing solution were investigated and evaluated in the sample pretreatment step. The optimized purification effect was achieved at the sample flow rate of 3 mL/min with 100 mg of NCSi and 2 mL of washing solution (water, 100%). The HPLC separation was carried out on a C18 column (250×4.6 mm i.d., 5 µm) with a mobile phase of methanol/water (10:90, v/v). The linear range of the calibration curve was 4-4000 ng/mL with s correlation coefficient of >0.9999. The intraday and interday RSDs (n=5) of peak areas of acrylamide were 0.22 and 0.90% and the intraday and interday RSDs (n=5) of retention times were 0.50 and 1.63%, respectively. In addition, overall recoveries through the extraction and NCSi-SPE purification ranged from 73.13 to 98%. Compared with the commercial SPE sorbents, NCSi featured excellent selectivity to retain polar and nonpolar interferences in the sample matrices. The improved method was simple, rapid, accurate, and promising for the determination of trace acrylamide in starchy foods with a complex matrix.