Yuanpeng Wang

Magnetic ionic liquid-based dispersive liquid–liquid microextraction for the determination of triazine herbicides in vegetable oils by liquid chromatography

Magnetic ionic liquid-based dispersive liquid-liquid microextraction (MIL-based DLLME) was developed for extracting triazine herbicides from vegetable oils. The MIL, 1-hexyl-3-methylimidazolium tetrachloroferrate ([C6mim] [FeCl4]), was used as the microextraction solvent. The magnetic separation time was shortened by simply mixing carbonyl iron powder with the MIL in the sample after DLLME. The effects of several important experimental parameters, including the amount of MIL, the time of ultrasonic extraction, the type and the volume of cleanup solvent were investigated. The MIL-based DLLME coupled with liquid chromatography gave the limits of detection of 1.31-1.49ngmL(-1) and limits of quantification of 4.33-4.91 ng mL(-1) for triazine herbicides. When the present method was applied to the analysis of vegetable oil samples, the obtained recoveries were in the range of 81.8-114.2% and the relative standard deviations were lower than 7.7%. Compared with existing methods, the performances achieved by the present method were acceptable.

Magnetic solid-phase extraction of five pyrethroids from environmental water samples followed by ultrafast liquid chromatography analysis

In this study, the polystyrene-coated magnetic nanoparticles (MNPs/PSt) were successfully prepared and characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and vibrating sample magnetometry. The as-prepared MNPs/PSt were used as the adsorbent in magnetic solid phase extraction of five pyrethroids, including lambda-cyhalothrin, deltamethrin, esfenvalerate, permethrin, bifenthrin, in environmental water samples. The five pyrethroids were determined by ultra fast liquid chromatography-ultraviolet spectrometry. The influencing factors, including amount of MNPs/Pst, extraction time, pH value, type and volume of desorption solvent and desorption time, were examined and optimized. The extraction recoveries obtained with merely 50mg of MNPs/Pst were very satisfactory. The whole extraction process could be completed within 0.5h. The MNPs/PSt can be reused after an easy washing process. Thus, a simple, green, economical, time saving and effective method for pyrethroids analysis in environmental water samples was established. A high enrichment factor of 500 was achieved and the limits of detection for lambda-cyhalothrin, deltamethrin, esfenvalerate, permethrin, bifenthrin were 0.015±0.001 ng mL(-1), 0.012±0.001 ng mL(-1), 0.026±0.001 ng mL(-1), 0.020±0.001 ng mL(-1), 0.013±0.001 ng mL(-1), respectively. Recoveries obtained by analyzing spiked water samples at three concentration levels (0.100±0.001 ng mL(-1), 1.000±0.001 ng mL(-1), 10.000±0.001 ng mL(-1)) were between 78.97±8.38% and 96.05±8.38%. The standard curves for the five pyrethroids showed good linearity with the correlation coefficients in the range of 0.9994-0.9999. The intra-day and inter-day precision were satisfactory with the RSDs in the range of 2.05-5.52% and 2.73-8.38%, respectively.

Determination of five pyrethroids in tea drinks by dispersive solid phase extraction with polyaniline-coated magnetic particles.

The polyaniline-coated magnetic particles with bowl-shaped morphology (Fe3O4/C/PANI microbowls) were successfully prepared and characterized by scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. The prepared microbowls were used as the magnetic adsorbent in dispersive solid phase extraction of five pyrethroids, including cyhalothrin, beta-cypermethrin, esfenvalerate, permethrin and bifenthrin in plain tea drinks. The effects of experiment factors, including amount of Fe3O4/C/PANI microbowls, pH value, ultrasound extraction time and desorption conditions, were investigated. The extraction recoveries obtained with 8 mg of magnetic microbowls were satisfactory, and the microbowls can be reused after easy washing. Thus, a simple, selective and effective method for the determination of the pyrethroids was established successfully. The results showed that the method had good linearity (r=0.9992-0.9998), and the limits of detections (LODs) were from 0.025 to 0.032 ng mL(-1). The intra-day and inter-day relative standard deviations (RSDs) were in the range of 2.4-6.1% and 3.5-8.8%, respectively. Recoveries obtained by analyzing the real tea drinks were in the range of 72.1-118.4%.

Matrix solid-phase dispersion coupled with magnetic ionic liquid dispersive liquid-liquid microextraction for the determination of triazine herbicides in oilseeds.

A novel method was developed for the determination of six triazine herbicides from oilseeds by matrix solid-phase dispersion combined with magnetic ionic liquid dispersive liquid-liquid microextraction (MSPD-MIL-DLLME), followed by ultrafast liquid chromatography with ultraviolet detection (UFLC-UV). The MIL, 1-butyl-3-methylimidazolium tetrachloroferrate ([C4mim][FeCl4]), was used as the microextraction solvent to simplify the extraction procedure by magnetic separation. The effects of several important experimental parameters, including type of dispersant, ratio of sample to dispersant, type and volume of collected elution solvent, type and volume of MIL, were investigated. Using the present method, UFLC-UV gave the limits of detection (LODs) of 1.20-2.72 ng g(-1) and the limits of quantification (LOQs) of 3.99-9.06 ng g(-1) for triazine herbicides. The recoveries were ranged from 82.9 to 113.7% and the relative standard deviations (RSDs) were equal or lower than 7.7%. The present method is easy-to-use and effective for extraction of triazine herbicides from oilseeds and shows the potentials of practical applications in the treatment of the fatty solid samples.

Magnetic solid‐phase extraction and ultrafast liquid chromatographic detection of Sudan dyes in red wines, juices, and mature vinegars

A nanocomposite of polystyrene-coated magnetic nanoparticles was successfully synthesized and employed as adsorbent for magnetic solid-phase extraction of four Sudan dyes (I, II III, and IV) in red wines, juices, and mature vinegars. The prepared magnetic nanoparticles with highly hydrophobic properties have excellent adsorption capacity for these lipophilic Sudan dyes. Extraction conditions were optimized. Experimental results showed that the recoveries of the four Sudan dyes were very satisfactory when 70 mg of polystyrene-coated magnetic nanoparticles were used and the extraction could be completed within 20 min. It was proved that these magnetic nanoparticles can be reused after an easy washing process. By coupling the magnetic solid-phase extraction with ultrafast liquid chromatography-ultraviolet spectrometry, a rapid, green, effective, and sensitive method for the determination of Sudan dyes was developed. The LOD for Sudan I, Sudan II, Sudan III, and Sudan IV were 0.0039, 0.0063, 0.0057, and 0.017 ng/mL, respectively. Recoveries obtained by analyzing spiked water samples at three concentration levels (0.1, 1.0, and 10.0 ng/mL) were between 76.3 and 96.6%. The intra- and interday RSDs for the analytes were lower than 9.6%.

Liquid-solid extraction coupled with magnetic solid-phase extraction for determination of pyrethroid residues in vegetable samples by ultra fast liquid chromatography.

In this study, liquid-solid extraction coupled with magnetic solid-phase extraction was successfully developed for the extraction of pyrethroid residues in vegetable samples. The analytes were determined by ultra fast liquid chromatography. The pyrethroids were extracted by liquid-solid extraction and then adsorbed onto magnetic adsorbent. Magnetic adsorbent, C18-functionalized ultrafine magnetic silica nanoparticles, was synthesized by chemical coprecipitation, silanization and alkylation. The analytes adsorbed onto the magnetic adsorbent can be simply and rapidly isolated from sample solution with a strong magnet on the bottom of the extraction vessel. The extraction parameters, such as liquid-solid extraction solvent, liquid-solid extraction time, the amount of magnetic adsorbent, magnetic solid-phase extraction time and magnetic solid-phase extraction desorption solvent, were optimized to improve the extraction efficiency. The analytical performances of this method, including linear range, detection limit, precision, and recovery were evaluated. The limits of detection for pyrethroid were between 0.63 and 1.2 ng g(-1). Recoveries obtained by analyzing the four spiked vegetable samples were between 76.0% and 99.5%. The results showed that the present method was a simple, accurate and high efficient approach for the determination of pyrethroids in the vegetable samples.

Determination of Sudan dyes in environmental water by magnetic mesoporous microsphere-based solid phase extraction ultra fast liquid chromatography

The magnetic mesoporous microsphere-based extraction method coupled with ultra fast liquid chromatography (UFLC) was applied for the extraction and determination of Sudan dyes in environmental water samples. Fe3O4@SiO2 microspheres consisting of a Fe3O4 particle core and an ordered mesoporous silica shell were used. The Fe3O4 particles were prepared simply by a solvothermal reduction method. The mesoporous silica was prepared and coated on the Fe3O4 particles via a surfactant-templating approach by stirring at room temperature. The obtained Fe3O4@SiO2 microspheres possess superparamagnetism and a good mesoporous structure. The experimental parameters, including the amount of Fe3O4@SiO2 microspheres, the pH value of sample solution, extraction time, separation time, elution solvent, volume of elution solvent and elution time, were optimized. Under the optimized conditions, Fe3O4@SiO2 microspheres were successfully used to extract Sudan dyes in the environmental water samples and the enrichment factor is 500-fold. The result showed that the method had good linearity (r = 0.990–0.997), and the limits of detection (LODs) were from 0.082 to 0.12 ng ml−1. Recoveries obtained by analyzing the five spiked water samples were in the range of 87.10–111.4% and the intra-day and inter-day relative standard deviations (RSDs) were between 0.590 and 7.94%. The results indicated that the novel method could be applied successfully for the determination of Sudan dyes in environmental water samples.

Enhancing sensitivity of surface plasmon resonance biosensor by Ag nanocubes/chitosan composite for the detection of mouse IgG.

A novel surface plasmon resonance (SPR) biosensor based on Ag nanocubes/chitosan composite was fabricated for mouse IgG detection. Ag nanocubes (AgNCs) were successfully synthesized with sulfide-mediated protocol. They were characterized with transmission electron microscopy (TEM) and UV-vis adsorption spectrum. AgNCs were etched by 3-Mercaptopropinic acid (MPA) and simply mixed with chitosan and glutaraldehyde. The Ag nanocubes/chitosan composite was deposited on Au film by the spin-coating. The electronic coupling between the AgNCs and the surface plasmon wave leads to the amplification of the SPR response, which results in the sensitivity enhancement of SPR biosensor. Moreover, antibody can be immobilized on Au film with aldehyde groups via Schiff alkali reaction. The traditional SPR biosensor based on MPA shows a response for mouse IgG in the concentration range of 2.50-40.00 μg mL(-1). The SPR biosensor based on AgNCs/chitosan composite shows a good response for mouse IgG in the concentration range of 0.60-40.00 μg mL(-1). The limit of quantification by the biosensor based on AgNCs/chitosan composite substrate is about 4 times lower than traditional biosensor, which has proved the SPR biosensor here proposed with more sensitivity and better performance than traditional SPR biosensor.

Molecularly imprinted solid phase extraction in a syringe filter for determination of triazine herbicides in Radix Paeoniae Alba by ultra-fast liquid chromatography

A novel, cost-effective and simple solid phase extraction (SPE) method, by using a syringe connected with a nylon membrane filter as the adsorbent container, was developed for the extraction of triazine herbicides from Radix Paeoniae Alba (RPA) samples. The selective molecularly imprinted polymers (MIPs) synthesized with the template of atrazine were employed as the adsorbents for the enrichment and purification of analytes. The extraction parameters, including the volume and type of loading solvent, the type of washing solvent and eluting solvent, were investigated. Under the optimized conditions, the final extracts were analyzed by ultra-fast liquid chromatography (UFLC). Recoveries of the developed method range from 92.4% to 107.3% with intra- and inter-day relative standard deviations (RSDs) lower than 8.2%. The calibration curve is linear in the concentration range of 0.005-2.4 µg g(-1) for desmetryn, atrazine and terbumeton, and 0.005-1.5 µg g(-1) for dimethametryn and dipropetryn, with the correlation coefficient (R(2)) higher than 0.9995. The limits of detection (LODs) of five triazine herbicides are in the range of 0.09-0.39 ng g(-1), which are lower than the maximum residue levels (MRLs) established by various official organizations. Analytical results of three real Radix Paeoniae Alba samples indicate that the proposed method is cost-effective and easy-to-use than other routine pretreatment methods.

Magnetic solid-phase extraction based on Fe3O4@polyaniline particles followed by ultrafast liquid chromatography for determination of Sudan dyes in environmental water samples

Magnetic Fe3O4@polyaniline (Fe3O4@PANI) particles were successfully prepared and used as an adsorbent in the magnetic solid-phase extraction of Sudan dyes in environmental water samples. The Fe3O4@PANI particles adsorbed analytes were isolated from the sample matrix using an external magnetic field. The analytes were separated and determined by ultrafast liquid chromatography. Significant influential factors, including amount of Fe3O4@PANI particles, pH value, ion strength, extraction time, type of desorption solvent, volume of desorption solvent, desorption time and sample volume, were optimized. Satisfactory extraction recoveries were obtained with only 8 mg of Fe3O4@PANI particles. In addition, the Fe3O4@PANI particles can be reused after a facile washing process. The limits of detection for Sudan I, II, III and IV were 0.041, 0.080, 0.147 and 0.151 ng mL−1, respectively. The intra-day and inter-day precisions with relative standard deviations were 1.3–5.4% and 2.6–7.3%, respectively. Recoveries obtained by analyzing spiked environmental water samples were between 92.4% and 106.9%.