[Solid phase extraction and high performance liquid chromatography with tetraaza[2]arene[2]triazine-bonded silica gel adsorbent for determination of nitrophenols and diethylstilbestrol in river water]

A novel method based on solid phase extraction (SPE)-high performance liquid chromatography (HPLC) was developed for the simultaneous determination of nitrophenols and diethylstilbestrol in river water. Tetraaza[2]arene[2]triazine-bonded silica gel, a homemade SPE adsorbent, was used to enrich the nitrophenols and diethylstilbestrol, and the optimal SPE and HPLC conditions were established. The sample solution was adjusted to pH 5, purified with a lab-made solid phase extraction column, and then eluted with 2 mL ammonia-methanol (2:98, v/v). The enriched sample was separated on a C8 column with methanol and 0.1% phosphoric acid solution as mobile phases in a gradient elution. Under the optimized conditions, the limits of detection (LOD, S/N=3) for the four target analytes were 0.03-0.3 μg/L, and the limits of quantification (LOQ, S/N=10) were 0.1-1.0 μg/L. The recoveries were 75.5%-104.2%, and the relative standard deviations (RSD, n=5) were less than 6.3%. The proposed method is accurate and reliable, and it has been successfully used for determining nitrophenols and diethylstilbestrol in river water.

[Detection Method, Distribution, and Risk Assessment of Pharmaceuticals and Personal Care Products in the Yellow Sea and the East China Sea]

At present, research findings on pharmaceuticals and personal care products (PPCPs) in coastal areas are still unclear, and there is a need to develop a method to detect more PPCPs simultaneously in seawater. In this study, nine compounds of non-steroidal anti-inflammatory drugs, antibiotics, lipid regulators. and stimulants were selected as analytes. Solid phase extraction (SPE) was used to extract the compounds, which were then analyzed by high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS). The optimum experimental conditions, such as the filler, eluent, pH, flow rate, and the reduction of matrix effect were optimized during the SPE. The results showed that the best extraction column was CNW HLB, the best eluent was methanol:acetonitrile (1:1, volume ratio), the best eluent volume was 6 mL, the best pH was 7, the best flow rate was 5 mL·min^-1, the amount of EDTA-Na₂ added was 1 g, and the best concentration multiple was 500. The linear regression equations of all PPCPs had good linearity. Correlation coefficients were>0.999, recovery rates were between 82%-106%, relative standard deviations were between 1.6%-14%, and detection limits were between 0.01-2 ng·L^-1, thus satisfying the requirement of trace analysis in seawater. Distribution characteristics and sources of PPCPs were studied in the Yellow Sea and the East China Sea during summer 2018. All nine PPCPs were detected and the main pollutants were NAP, IBU, GEM, CAF, and ASA. High concentrations of PPCPs were generally detected in the nearshore area and displayed conspicuous decreasing tendencies from the inshore towards the offshore. The concentrations of PPCPs in the Yellow Sea were higher than of those in the East China Sea, and this was related to there being more sources of pollutions and poor water exchange capacity in the Yellow Sea. Principal component analysis showed that the main source of PPCPs was terrestrial input. The environmental risk assessment of PPCPs indicated that risk quotients (RQs) of IBU and NAP (0.1-1) posed a medium risk to the aquatic environment, while others posed low risk to organisms.

[Preparation and application of magnetic reversed-phase restricted access material]

Using magnetic silica (Fe₂O₃@SiO₂) as the matrix material, a magnetic reversed-phase restricted access material was prepared via surface-initiation atom transfer radical polymerization (SI-ATRP) on the surface of modified Fe₂O₃@SiO₂. Stearyl methacrylate (SMA) was grafted on the inner surface of the modified Fe₂O₃@SiO₂, and glycidylmethacrylate (GMA) was grafted on the outer surface of the modified Fe₂O₃@SiO₂. The magnetic reversed-phase restricted access material was prepared via acid hydrolysis. This material was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and elemental analysis. The exclusion ability of the opened magnetic reversed-phase restricted access material to bovine serum albumin (BSA) was 90.4%. The maximum adsorbed amounts of sulfisoxazole (SIZ), sulfadimethoxine (SDM), trimethoprim (TMP) and sulfamerazine (SMR) were 2.76, 2.24, 1.51 and 1.34 mg/g, respectively. This material was applied to extract and enrich SIZ, SMR and SDM in milk and bovine serum samples. The spiked recoveries of SIZ, SMR and SDM were 88.7%-90.8%, and the relative standard deviations were 3.3%-5.3%. Thus, the magnetic phase restricted access material can simplify the pretreatment of biological matrix samples, and can be applied to the analysis and detection of blood samples or food samples.

[Determination of sulfonylurea herbicide residues in tobacco leaves by molecularly imprinted-solid phase extraction-high performance liquid chromatography]

Molecularly imprinted polymer (MIP) micro-particles were prepared in dichloromethane (DCM) by precipitation polymerization using chlorsulfuron (CS) as a template molecule, α -methacrylic acid (MAA) as a functional monomer, and trimethylolpropane trimethacrylate (TRIM) as a cross-linker. The pretreatment process of the tobacco sample spiked with chlorsulfuron, metsulfuron-methyl, bensulfuron-methyl, tribenuron-methyl, ethametsulfuron, and nicosulfuron, was performed using a chlorsulfuron molecularly imprinted polymer solid phase extraction (CS-MIP-SPE) column prepared with CS-MIP as the sorbent. High performance liquid chromatography (HPLC) was subsequently used for quantitative analysis. In this way, a detection technique for sulfonylurea herbicide residues in tobacco leaves was developed using CS-MIP-SPE as a pretreatment method and HPLC as an analytical tool. The results showed that the methods can be applied to the determination of the six sulfonylurea herbicides in tobacco samples. At spiking contents ranging from 0.50 to 50 μg/g, the recoveries for the six sulfonylurea herbicides in tobacco samples were 77.60%-102.05%, with relative standard deviations of 0.16% to 7.07%, and detection limits of 0.08-0.46 μg/g. With its unique advantages, the MIP-SPE-HPLC method provides a multi-residue analytical platform that can meet the requirements of simultaneous determination of sulfonylurea herbicides in tobacco samples.