Column preconcentration and electrothermal atomic absorption spectrometric determination of rhodium in some food and standard samples

In the present work, an electrothermal atomic absorption spectrometric method has been developed for the determination of ultra‐trace amounts of rhodium after adsorption of its 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol/tetraphenylborate ion associated complex at the surface of alumina. Several factors affecting the extraction efficiency such as the pH, type of eluent, sample and eluent flow rates, sorption capacity of alumina and sample volume were investigated and optimized. The relative standard deviation for eight measurements of 0.1 ng/mL of rhodium was ±6.3%. In this method, the detection limit was 0.003 ng/mL in the original solution. The sorption capacity of alumina and the linear range for Rh(III) were evaluated as 0.8 mg/g and 0.015–0.45 ng/mL in the original solution, respectively. The proposed method was successfully applied for the extraction and determination of rhodium content in some food and standard samples with high recovery values.     

Solid‐phase extraction based on a molecularly imprinted polymer for the selective determination of four benzophenones in tap and river water

This work reports the preparation of molecularly imprinted polymer particles for the selective extraction and determination of four benzophenones from aqueous media. The polymer was prepared by using 4‐vinylpridine as functional monomer, ethylene glycol dimethacrylate as cross‐linker, acetonitrile as porogenic solvent and 2,2’,4,4’‐tetrehydroxybenzophenone as template. Good specific adsorption capacity (Q_max = 27.90 μmol/g) for 2,2’,4,4’‐tetrehydroxybenzophenone was obtained in the sorption experiment and good class selectivity for 2,2’,4,4’‐tetrehydroxybenzophenone, 2,4‐dihydroxybenzophenone, 2,2’‐dihydroxy‐4‐methoxybenzophenone, 2,2’‐dehydroxy‐4,4’‐dimethoxybenzophenone was demonstrated by the chromatographic evaluation experiment. Factors affecting the extraction efficiency of the molecularly imprinted solid‐phase extraction procedure were investigated systematically. An accurate and sensitive analytical method based on the molecularly imprinted solid‐phase extraction coupled with high‐performance liquid chromatography and diode array detection has been successfully developed for the simultaneous determination of four benzophenones from tap water and river water with method detection limits of 0.25–0.72 ng/mL. The recoveries of benzophenones for water samples at two spiking levels (500 and 5000 ng/mL for each benzophenone) were in the range of 86.9–103.3% with relative standard deviations (n = 3) below 9.2%.     

Preparation of 17β‐estradiol‐imprinted material by surface‐initiated atom transfer radical polymerization and its application

A novel 17β‐estradiol molecularly imprinted polymer was grafted onto the surface of initiator‐immobilized silica by surface‐initiated atom transfer radical polymerization. The resulting molecularly imprinted polymer was characterized by elemental analysis and thermogravimetric analysis. The binding property of molecularly imprinted polymer for 17β‐estradiol was also studied with both static and dynamic methods. The results showed that the molecularly imprinted polymer possessed excellent recognition capacity for 17β‐estradiol (180.65 mg/g at 298 K), and also exhibited outstanding selectivity for 17β‐estradiol over the other competitive compounds (such as testosterone and progesterone). Then, the determination of trace 17β‐estradiol in beef samples was successfully developed by using molecularly imprinted polymer solid‐phase extraction coupled with high‐performance liquid chromatography. The limit of detection was 0.25 ng/mL, and the amount of 17β‐estradiol in beef samples was detected at 2.83 ng/g. This work proposed a sensitive, rapid, reliable, and convenient approach for the determination of trace 17β‐estradiol in complicated beef samples.     

A new Approach for the Voltammetric Sensing of the Phytoestrogen Genistein at a Non-modified Boron-doped Diamond Electrode

An effective electrochemical sensor was constructed using an unmodified boron-doped diamond electrode for determination of genistein by square-wave voltammetry. Cyclic voltammetric investigations of genistein with HClO₄ solution indicated that irreversible behavior, adsorption-controlled and well-defined two oxidation peaks at about +0.92 (P_A1) & +1.27 V (P_A2). pH, as well as supporting electrolytes, are important in genistein oxidations. Quantification analyses of genistein were conducted using its two oxidation peaks. Using optimized experiments as well as instrumental conditions, the current response with genistein was proportionately linear in the concentrations range of 0.1 to 50.0 μg mL⁻¹ (3.7×10⁻⁷−1.9×10⁻⁴ mol L⁻¹), by the detection limit of 0.023 μg mL⁻¹ (8.5×10⁻⁸ mol L⁻¹) for P_A1 and 0.028 μg mL⁻¹ (1.1×10⁻⁷ mol L⁻¹) for P_A2 in 0.1 mol L⁻¹ HClO₄ solution (in the open circuit condition at 30 s accumulation time). Ultimately, the developed method was effectively applied to detect genistein in model human urine samples by using its second oxidation peak (P_A2).     

Preparation of flower-like molybdenum disulfide for solid-phase extraction of N-nitrosoamines in environmental water samples

In this paper, a flower-like molybdenum disulfide material was prepared by hydrothermal method and was first used as adsorbents in the solid-phase extraction process for enriching N-nitrosoamines. Molybdenum disulfide exhibited three-dimensional petal-like microspheres with about 500 nm in diameter. The relevant analyte extraction and elution parameters (sample volumes, solution pH, washing solvents, elution solvents, and elution volumes) were optimized to improve the solid-phase extraction efficiency. The solid-phase extraction process coupled with high-performance liquid chromatography-tandem mass spectrometry for determining N-nitrosoamines in environmental water samples was established. The limits of detection were in the range of 0.01–0.05 ng/mL. The satisfactory recoveries (68.9–106.1%) were obtained at three different spiked concentrations (2, 5, and 8 ng/mL) in water samples, and the relative standard deviations were between 1.96 and 8.38%. This proposed method not only showed high sensitivity and good reusability but also provided a new adsorbent for enriching trace N-nitrosoamines in environmental water samples.     

New method of identifying morphine in urine samples using nanoparticle-dendrimer-enzyme hybrid system

The incorporation of morphine (MOR) into the nanoparticle structure is a viable alternative to traditional enzyme usage. It has good biological potential to separate MOR from real urine samples. In this study, a new method of MOR identification in real urine samples was synthesized using the β-glucuronidase-dendrimer poly amidoamine (PAMAM) enzyme hybrid system. Replacing MOR in dendrimer cavities significantly reduces enzyme consumption. The replacement technique is done in dendrimer cavities in two stages as an alternative to β-glucuronidase enzyme and even MOR. In this paper, firstly, PAMAM dendrimer G2 was synthesized based on silica. The β-glucuronidase enzyme was replaced inside its dendrimer cavities and the compound was released into a real urine sample containing MOR. The enzyme was extracted from dendrimer cavities. The MOR- β-glucuronidase enzyme bond broke. In the next stage of the process, free MOR entered the PAMAM dendrimer G2 cavities. MOR was detected in real urine samples.     

植物油中脂肪酸不同定量方法的比较分析

比较峰面积归一化法与标准曲线法两种方法分析植物油中脂肪酸百分比含量的差异。利用气相色谱-质谱联用仪(GC-MS)检测10种市售食用植物油中的8种主要脂肪酸,峰面积归一化法和标准曲线法计算脂肪酸的百分比含量。结果表明,标准曲线法与峰面积归一化法相比,肉豆蔻酸、棕榈酸、十七烷酸、硬脂酸和棕榈油酸所占的百分比升高,而油酸、亚油酸和亚麻酸比例降低;饱和脂肪酸比例升高,不饱和脂肪酸百分比降低。利用峰面积归一化法计算植物油中脂肪酸百分比时,降低了饱和脂肪酸比例,升高了不饱和脂肪酸比例,可能对健康有潜在的不利影响。建议使用标准曲线法计算不同植物油中脂肪酸的百分比。     

QuEChERS-超高效液相色谱-串联质谱法快速测定3种叶菜中矮壮素和丙环唑残留

建立了菜心、芥蓝和小白菜中矮壮素和丙环唑残留的分析方法.以QuEChERS法进行样品前处理,采用含1％ HAc的乙腈溶液提取,无水MgSO4、C18及PSA吸附剂净化,超高效液相色谱-串联质谱(UPLC-MS/MS)法测定.对提取溶剂、吸附剂和色谱柱的选择进行了研究探讨.结果表明矮壮素在1～1 000 μg/L、丙环唑在1～500 μg/L浓度范围内均有良好的线性关系.矮壮素和丙环唑的检出限分别为0.1 μg/kg和0.01 μg/kg;在0.010、0.10和0.50 mg/kg 3个添加浓度水平下,菜心、芥蓝和小白菜中矮壮素和丙环唑回收率为75.0％～96.2％;相对标准偏差为0.9％～8.3％;方法定量限为最低添加浓度0.010 mg/kg.该方法快速、简便、准确,满足叶菜中矮壮素和丙环唑残留分析的要求.     

AgNP/Bi/Nafion‐modified Disposable Electrodes for Sensitive Zn(II), Cd(II), and Pb(II) Detection in Aerosol Samples

A new method for modifying electrodes with Ag nanoparticles (AgNPs) using electrospray deposition for sensitive, selective detection of Zn(II), Cd(II), and Pb(II) in aerosol samples when combined with Bismuth and Nafion coating and square‐wave anodic stripping voltammetry (SWASV) is reported. Carbon stencil‐printed electrodes (CSPEs) fabricated on a polyethylene transparency (PET) sheet were produced for an inexpensive, simple to fabricate, disposable sensor that can be used with the microliter sample volumes for analysis. Sensor performance was improved by modifying the electrode surface with electrospray‐deposited AgNPs. The use of electrospray deposition resulted in more uniform particle dispersion across the electrode surface when compared to drop‐casting. Using AgNP‐modified electrodes combined with Bi and Nafion, experimental detection limits (LODs) of 5.0, 0.5, and 0.1 μg L⁻¹ for Zn(II), Cd(II), and Pb(II), respectively, were achieved. The linear working ranges were 5.0–400.0 μg L⁻¹, 0.5–400.0 μg L⁻¹, and 0.1–500.0 μg L⁻¹ for Zn(II), Cd(II), and Pb(II), respectively. Interference studies showed Cu(II) was the only metal that interfered with this assay but inference could be eliminated with the addition of ferricyanide directly to the sample solution. This electrochemical sensor was applied for the simultaneous determination of Zn(II), Cd(II), and Pb(II) within source particulate matter (PM) samples collected on filters using an aerosol test chamber.     

金属-有机纳米管分散固相萃取-气相色谱-串联质谱高灵敏分析环境水样中痕量多氯联苯

采用含铅金属-有机纳米管为吸附剂,基于分散固相萃取和气相色谱-串联质谱建立了一种高灵敏分析环境水样中痕量多氯联苯的方法.采用正交设计响应面法对影响萃取效果的重要因素(如离子强度、萃取时间和吸附剂用量等)进行了优化.获得的最优条件为:离子强度4.92 %(w/V)NaCl,萃取时间4.5 min,正己烷为解吸剂,吸附剂用量62.5 mg.在优化条件下,方法的线性范围为2~1000 ng/L,检出限为0.26~0.82 ng/L. 日内和日间相对标准偏差分别为0.8%~5.5% (200 ng/L, n=6)和2.7%~7.4% (200 ng/L, n=6).将本方法应用于实际环境水样中多氯联苯的分析,回收率为78.9%~113.3%,结果满意.