Preparation of novel ionic‐liquid‐modified magnetic nanoparticles by a microwave‐assisted method for sulfonylurea herbicides extraction

Ionic liquids immobilized on magnetic nanoparticles were prepared by an efficient microwave‐assisted synthesis method, and the properties of the ionic liquids were tuned based on the aromatic functional modification of its anion through a simple metathesis reaction. The novel as‐synthesized magnetic materials were characterized by various instrumental techniques. The magnetic nanoparticles have been utilized as adsorbents for the extraction of four sulfonylurea herbicides in tea samples, in combination with high‐performance liquid chromatography analysis. Significant extraction parameters, including type and volume of desorption solvent, extraction time, amount of adsorbent, and ionic strength were investigated. Under the optimum conditions, good linearity was obtained in the concentration range of 1–150 μg/L for metsulfuron‐methyl and bensulfuron‐methyl, and 3–150 μg/L for sulfometuron‐methyl and chlorimuron‐ethyl, with correlation coefficients R² > 0.9987. Low limits of detection were obtained ranging from 0.13 to 0.81 μg/L. The relative standard deviations were 1.8–3.9%. Comparisons of extraction efficiency with conventional solid‐phase extraction equipped with a commercial C₁₈ cartridge were performed. Results indicated that magnetic solid‐phase extraction is simple, time‐saving, efficient and inexpensive with the reusability of adsorbents. The proposed method has been successfully used to determine sulfonylurea herbicides from tea samples with satisfactory recoveries of 80.5–104.2%.     

Efficient extraction of proteins from recalcitrant plant tissue for subsequent analysis by two‐dimensional gel electrophoresis

Protein extraction for two‐dimensional electrophoresis from tissues of recalcitrant species is quite problematic and challenging due to the low protein content and high abundance of contaminants. Proteomics in Shorea robusta is scarcely conducted due to the lack of a suitable protein preparation procedure. To establish an effective protein extraction protocol suitable for two‐dimensional electrophoresis in Shorea robusta, four procedures (borate buffer/trichloroacetic acid extraction, organic solvent/trichloroacetic acid precipitation, sucrose/Tris/phenol, and organic solvent/phenol/sodium dodecyl sulfate) were evaluated. Following these, proteins were isolated from mature leaves and were analyzed for proteomics, and also for potential contaminants, widely reported to hinder proteomics. The borate buffer/trichloroacetic acid extraction had the lowest protein yield and did not result in any banding even in one‐dimensional electrophoresis. In contrast, organic solvent/phenol/sodium dodecyl sulfate extraction allowed the highest protein yield. Moreover, during proteomics, organic solvent/phenol/sodium dodecyl sulfate extracted protein resolved the maximum number (144) of spots. Further, when proteins were evaluated for contaminants, significant (77–95%) reductions in the nucleic acids, phenol, and sugars were discernible with refinement in extraction procedure. Accumulated data suggested that the organic solvent/phenol/sodium dodecyl sulfate extraction was the most effective protocol for protein isolation for proteomics of Shorea robusta and can be used for plants that have a similar set of contaminants.     

Determination of phthalate esters from environmental water samples by micro‐solid‐phase extraction using TiO2 nanotube arrays before high‐performance liquid chromatography

We describe a highly sensitive micro‐solid‐phase extraction method for the pre‐concentration of six phthalate esters utilizing a TiO₂ nanotube array coupled to high‐performance liquid chromatography with a variable‐wavelength ultraviolet visible detector. The selected phthalate esters included dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, bis(2‐ethylhexyl)phthalate and dioctyl phthalate. The factors that would affect the enrichment, such as desorption solvent, sample pH, salting‐out effect, extraction time and desorption time, were optimized. Under the optimum conditions, the linear range of the proposed method was 0.3–200 μg/L. The limits of detection were 0.04–0.2 μg/L (S/N = 3). The proposed method was successfully applied to the determination of six phthalate esters in water samples and satisfied spiked recoveries were achieved. These results indicated that the proposed method was appropriate for the determination of trace phthalate esters in environmental water samples.     

Ionic liquid and aqueous two‐phase extraction based on salting‐out coupled with high‐performance liquid chromatography for the determination of seven rare ginsenosides in Xue‐Sai‐Tong injection

A method of ionic liquid salt aqueous two‐phase extraction coupled with high‐performance liquid chromatography has been developed for the analysis of seven rare ginsenosides including Rg₆, F₄, 20(S)‐Rg₃, 20(R)‐Rg₃, Rk₃, Rk₁, and Rg₅ in Xue‐Sai‐Tong injection. The injection was mixed with ionic liquid 1‐butyl‐3‐methylimidazolium bromide aqueous solution, and a mixture was obtained. With the addition of sodium dodecyl sulfate and dipotassium phosphate into the mixture, the aqueous two‐phase mixture was formed after ultrasonic treatment and centrifuged. Rare ginsenosides were extracted into the upper phase. To obtain a high extraction factors, various influences were considered systematically, such as the volume of ionic liquid, the category and amount of salts, the amount of sodium dodecyl sulfate, the pH value of system, and the time of ultrasonic treatment. Under the optimal condition, rare ginsenosides in Xue‐Sai‐Tong injection were enriched and detected, the recoveries of seven rare ginsenosides ranged from 90.05 to 112.55%, while relative standard deviations were lower than 2.50%. The developed method was reliable, rapid and sensitive for the determination of seven rare ginsenosides in the injections.     

固相萃取/高效液相色谱-串联质谱法测定黄瓜及土壤中的春雷霉素残留

建立了测定黄瓜和土壤中春雷霉素残留的固相萃取/高效液相色谱-串联质谱(SPE/HPLC-MS/MS)方法。黄瓜和土壤样品分别经1%甲酸的甲醇、0.5%甲酸水提取后,采用MCX固相萃取柱净化,以Waters Xbridge BEH Amide色谱柱分离,0.2%甲酸水-乙腈溶液进行梯度洗脱,电喷雾正离子(ESI+)模式电离,多反应监测(MRM)模式检测,基质匹配标准曲线外标法定量。该方法灵敏、准确、简单快速、重复性好,在2~250μg/L浓度范围内,不同基质中春雷霉素的线性相关系数均大于0.999,检出限为0.002 mg/kg,定量下限为0.008 mg/kg;在0.008、0.040、0.200、0.400 mg/kg 4个加标水平下,春雷霉素在黄瓜和土壤样品中的平均回收率为77.5%~97.0%,相对标准偏差为2.6%~10.7%,能够满足黄瓜及土壤中春雷霉素残留的检测需求。应用该法对田间样品进行检测,结果表明,春雷霉素在黄瓜中的残留量不超过0.053 mg/kg,小于我国规定的黄瓜中最大残留限量(0.2 mg/kg);土壤中春雷霉素的残留量不超过0.013 mg/kg。     

气相色谱-串联质谱检测烟草中15种苯氧羧酸类除草剂残留

建立了气相色谱-串联质谱技术对烟草中15种苯氧羧酸类除草剂农药残留量的分析方法。样品采用乙腈提取、Carbon TPT固相萃取柱净化、三甲基硅烷化重氮甲烷衍生化,采用气相色谱-串联质谱对15种苯氧羧酸类除草剂进行测定,通过保留时间、选择离子及相对丰度定性,外标法定量。结果表明,15种苯氧羧酸类除草剂在20~1 000μg/L浓度范围内均呈良好线性关系,相关系数大于0.992,检出限为0.9~3.3μg/kg,定量下限为3.2~10.8μg/kg。在20,100,200μg/kg 3个加标水平下的平均回收率为71.5%~105.6%,相对标准偏差(RSD)为4.5%~14.9%。该方法简便、快速、灵敏,适用于烟草中15种苯氧羧酸类除草剂的同时检测。     

气相色谱-质谱法测定地下水中多氯萘

建立了地下水中1-氯萘、2-氯萘、1,4-二氯萘、1,2,3,4-四氯萘、1,3,5,7-四氯萘、1,2,3,5,7-五氯萘、1,2,3,5,6,7-六氯萘、1,2,3,4,5,6,7-七氯萘和八氯萘9种多氯萘(PCNs)的气相色谱-质谱(GC-MS)分析方法。对比研究了液液萃取(LLE)和固相萃取(SPE)萃取地下水中PCNs的提取效率,优选二氯甲烷-液液萃取为PCNs检测的前处理方法。在优化条件下,9种PCNs的线性范围为5~100μg/L,各组分的相关系数(r)大于0.995,方法检出限(S/N=3)为4.21~7.41 ng/L,地下水的平均加标回收率为70.7%~112%,相对标准偏差(RSD,n=5)均小于9.9%。该方法已用于地下水样中多氯萘的检测。     

固相萃取/高效液相色谱-串联质谱法同时检测多类食品中二甲基黄、二乙基黄含量

建立了豆干、辣椒酱、豆腐乳、腐竹和饼干等样品中二甲基黄和二乙基黄残留量的液相色谱-串联质谱分析方法。基于二甲基黄和二乙基黄的化学结构特性,采用乙腈溶液提取。提取液酸化后经Bond Elut Plexa PCX阳离子交换树脂固相萃取净化,吹干复溶后,使用反相C_(18)色谱柱分离,电喷雾串联四极杆质谱正离子化多反应监测(MRM)模式检测。二甲基黄和二乙基黄的方法定量下限均为0.50μg/kg。对5种不同基质样品进行二甲基黄和二乙基黄0.50,5.0,80μg/kg 3个浓度水平的加标回收实验,得到二甲基黄和二乙基黄的平均回收率分别为76.4%~93.0%和76.1%~92.4%;相对标准偏差分别为1.7%~6.3%和1.9%~7.4%,可以满足食品中二甲基黄和二乙基黄快速筛查和定量分析的要求。     

花生壳活性炭固相萃取/超高效液相色谱法测定河水中的18种多环芳烃

建立了固相萃取/超高效液相色谱-二极管阵列检测(SPE/UPLC-PDA)联用技术测定河水中18种痕量多环芳烃(PAHs)的快速分析方法。通过优化固相萃取条件、流动相体系、色谱条件等因素,7 min内实现了18种多环芳烃的高效分离。在0.05~50 mg/L浓度范围内,18种多环芳烃的浓度与对应峰面积呈良好线性关系,相关系数为0.999 1~0.999 9,检出限为0.08~2.03 ng/L,样品加标回收率为74.5%~103.6%,相对标准偏差(RSD,n=6)为0.5%~2.3%。将该方法应用于九龙江流域龙岩段周边水样的检测,结果可靠。该方法简单环保、灵敏准确、操作快速,可显著提高河水中痕量PAHs的分析效率。     

固相萃取-超高效液相色谱-同位素稀释串联质谱法测定蜂蜜中的甲硝唑和氯霉素

建立了同时测定蜂蜜中甲硝唑和氯霉素残留量的固相萃取-超高效液相色谱-同位素稀释串联质谱方法。蜂蜜样品中的甲硝唑和氯霉素经乙酸乙酯提取后,采用InertSep RP-1固相萃取柱对目标物进行富集和净化。经超高效液相色谱分离后,在三重四极杆质谱的多反应监测模式(MRM)下,甲硝唑通过正离子模式(ESI+)采集,氯霉素通过负离子模式(ESI-)采集,采用同位素稀释的内标法定量。本方法在浓度1~100ng/mL范围内具有良好的线性关系,相关系数R20.999。在添加水平为0.5、2.5、25μg/kg时,回收率在71.4%~123.4%之间,相对标准偏差为5.0%~12.3%。本方法采用一种前处理方式,可以同时测定蜂蜜中的甲硝唑与氯霉素残留,缩短了分析时间,提高了检测效率。