比较液-质联用法与高效液相色谱法对水中苯胺和联苯胺的同步测定

比较了液-质联用法与高效液相色谱法两种方法同时测定水中苯胺和联苯胺。液-质联用法中,苯胺、联苯胺的检出限分别为0.11μg/L和0.03μg/L,回收率为93.5%～112.2%,相对标准偏差为1.2%～3.2%。高效液相色谱法中,采取直接进样,两种物质检出限为4.6μg/L和2.4μg/L,回收率为104.4%～112.8%;富集后进样,检出限为0.06μg/L和0.01μg/L,回收率为83.5%～94.0%,相对标准偏差均不超过6%。经比较,液-质联用法无需富集即可实现低检出限、高灵敏度,可以作为首选的检测方法。     

吹扫捕集-气相色谱/质谱法测定医用口罩中痕量环氧乙烷

建立了吹扫捕集-气相色谱/质谱法测定医用口罩中痕量环氧乙烷的方法。采用吹扫捕集法对医用口罩中环氧乙烷进行富集,热脱附后导入气相色谱/质谱仪,并选用选择离子模式(SIM)进行检测,内标法定量。结果表明:环氧乙烷在5.0～200μg/L质量浓度范围内线性关系良好,相关系数为0.9992,方法检出限为0.03μg/g,定量限为0.10μg/g。三个不同浓度加标水平(5.0μg/L、20μg/L、80μg/L)的回收率为97.59%～115.95%,相对标准偏差(RSD,n=6)为3.07%～7.48%。该方法操作简单、富集效率高、快速准确,适用于大批量医用口罩样品测定。     

HPLC–AFS联用测定海产品中砷的形态

建立了高效液相色谱–原子荧光分光光度法测定海产品中无机砷(As V,AsⅢ)、有机砷(DMA,MMA,AsB)含量的方法。样品经含10%(体积分数)HCl的提取液振荡提取、离心分离、二路形态分析预处理、高效液相色谱分离,用原子荧光光度计检测As(Ⅲ),DMA,MMA,As(V);四路条件(过氧化氢氧化和开启紫外灯)形态分析预处理装置处理,高效液相色谱分离,原子荧光光度计测定AsB。As(Ⅲ)线性范围为0～100.00μg/L,r2=0.999 7;DMA线性范围为0～100.00μg/L,r2=0.999 3;MMA线性范围为0～100.00μg/L,r2=0.999 0;As(V)线性范围为0～100.00μg/L,r2=0.999 1;AsB线性范围为0～200.00μg/L,r2=0.999 4。3个样品加标回收率为As(Ⅲ)86.7%～89.4%,DMA 111.2%～117.0%,MMA 109.7%～111.6%,As(V)83.8%～90.7%,AsB 88.3%～90.4%。用该方法测定虾仁(干)5个价态测定结果的相对标准偏差为3.07%～9.93%(n=6)。5个价态的检出限(S/N=2)为As(Ⅲ)0.29μg/L,DMA 0.36μg/L,MMA 0.27μg/L,As(V)0.56μg/L,AsB 1.46μg/L。该方法适用于海产品中As(Ⅲ),DMA,MMA,As(V),AsB含量的测定。     

石墨炉原子光谱法测定工业废渣中痕量元素砷、铅、铬、钡、银

建立了石墨炉原子吸收光谱法测定检测工业废渣中痕量元素砷、铅、铬、钡、银的方法。采用悬浮进样,硝酸-硫酸混合酸溶解样品。10g/L Mg(NO3)2作基体改进剂,提高了砷的灰化温度,加入10g/L CaCO3防止钡在石墨炉中形成不易挥发的碳化钡,增加了钡的灵敏度。回收率为98%～112%,测定结果的相对标准偏差为2.22%～4.46%。As的线性范围2～80μg/L,Pb的线性范围1～60μg/L,Cr的线性范围0.5～20μg/L,Ba的线性范围5～150μg/L,Ag的线性范围1～100μg/L。     

固相萃取与超高效液相色谱-质谱联用测定生物样品中芬太尼类物质

建立了固相萃取与液相色谱-质谱(LC-MS)联用分析血清和尿液中10种芬太尼类物质的方法。样品经C18固相萃取(SPE)柱富集分离后,甲醇洗脱,洗脱液采用LC-MS测定。结果表明,尿样基质中,10种芬太尼物质质量浓度在1～100μg/L范围内线性关系良好,相关系数(R~2)大于0.99,检出限(LODs)和定量限(LOQs)范围分别为0.18～0.32μg/L和0.61～1.00μg/L。血清基质中,10种芬太尼含量在2～100μg/L范围内呈现良好的线性关系,其R~2大于0.99,LODs为0.15～0.33μg/L,LOQs为0.50～1.00μg/L。尿样中芬太尼类物质萃取回收率为84.2%～107.7%,血清中萃取回收率为84.7%～99.7%。该方法适用于生物流体中芬太尼类物质的同步测定。     

高效液相色谱-串联质谱法同时测定动物源性食品中24种磺胺类药物残留

利用高效液相色谱-电喷雾串联四极杆质谱(HPLC-MS/MS)联用技术,建立了一种在28 min内快速分离和测定鸡肉、猪肉、牛肉、羊肉、蜂蜜、牛奶中24种磺胺类药物残留的方法.方法检出限(LOD)为0.27～7.45μg/kg,定量限(LOQ)0.957～9.89 μg/kg;在5～300μg/L范围内线性关系良好,在10、20、50μg/kg 3个添加浓度上回收率为60.8%～122.9%,相对标准偏差(PSD)为0.01%～19%.     

毛细管电泳-激光诱导荧光检测法分离检测谷胱甘肽及其构成氨基酸

以4-氯-7-硝基苯并-2-氧杂-1,3-二唑(NBD-Cl)为柱前衍生试剂,建立了一种毛细管电泳-激光诱导荧光直接检测氧化型和还原型谷胱甘肽及其构成氨基酸(谷氨酸、半胱氨酸和甘氨酸)的新方法。经过实验条件的优化,采用25 mmol/L硼砂-20 mmol/L聚氧乙烯月桂醚(Brij-35)-5%乙腈(pH 9.5)的缓冲体系,在柱温为25°C、分离电压为20 kV的条件下,压力进样3447.5 Pa(0.5 psi)×3 s,五种物质在11 min内实现高效基线分离。在该方法下,还原型谷胱甘肽、氧化型谷胱甘肽、谷氨酸、半胱氨酸和甘氨酸的线性范围分别为:1～50μg/mL,1～50μg/mL,0.5～25μg/mL,1～50μg/mL,0.1～20μg/mL;检测限分别为:0.1μg/mL,0.1μg/mL,0.005μg/mL,0.1μg/mL,0.001μg/mL。以还原型谷胱甘肽钠粉针剂为样品,方法的加标回收率为99.5%～110.7%,相对标准偏差为0.26%～3.272%(n=3)。该方法准确、快速、灵敏、检测限低,有望用于样品中氧化型和还原型谷胱甘肽及其构成氨基酸的含量分析。     

分散液相微萃取-高效液相色谱法测定水中α-萘酚和β-萘酚

以氯苯为萃取剂,丙酮为分散剂,采用分散液相微萃取-液相色谱联用技术对水体中的α-萘酚和β-萘酚进行分析,优化了实验条件。该方法对α-萘酚和β-萘酚的线性范围分别为1.5～50μg/L和1.0～50μg/L,检出限分别为0.9μg/L和0.5μg/L,6次重复测定的相对标准偏差分别为3.3%和1.5%。方法应用于自来水、地下水和湖水样品的分析测定,回收率在91.3%～101.0%之间。     

ICP-MS法测定镍基单晶高温合金DD416中的镓、锡、锑、铅、铋

建立电感耦合等离子体质谱法测定镍基单晶高温合金DD416中镓、锡、锑、铅、铋元素的含量。以盐酸–硝酸(体积比3∶1)混合酸为消解剂,利用微波消解仪消解样品,以Rh(10μg/L)为内标元素。镓的线性范围为0～50μg/g,锡、锑、铅的线性范围为0～20μg/g,铋的线性范围为0～2μg/g,线性相关系数均大于0.999,检出限分别为0.01,0.2,0.1,0.07,0.006μg/g。用该方法对标准物质进行测定,测定结果与标准值之间的相对误差在7.7%～22.7%范围内。样品加标回收率为98.2%～108.0%,测定结果的相对标准偏差为0.1%～1.5%(n=5)。该方法可以快速、准确地对镍基单晶高温合金DD416中镓、锡、锑、铅、铋元素进行同时测定。     

离子交换色谱-氢化物发生双道原子荧光法同时测定砷和硒形态

建立了离子交换色谱-氢化物发生双道原子荧光联用同时测定4种As形态和3种Se形态的方法,并优化了各种实验参数。采用PRP-X100阴离子交换分析柱可以在10min内同时分离、检测As和Se形态。在8%HCl和1.5%(m/V)KBH4的氢化物反应条件下,进样量100μL,各形态的检出限为:As(Ⅲ)0.2μg/L、DMA0.3μg/L、MMA0.2μg/L、As(Ⅴ)0.3μg/L、SeCys0.6μg/L、Se(Ⅳ)0.5μg/L、SeMet3μg/L。当各As形态浓度为100μg/L、各Se形态浓度为200μg/L,各形态的精密度RSD(n=7)均小于5%。当各As形态浓度范围为5～100μg/L、SeCys和Se(Ⅳ)浓度范围为10～200μg/L、SeMet浓度范围为50～200μg/L时,各形态均可得到良好的线性关系,线性相关系数均大于0.9992。用建立的方法测定了富硒营养品中的As和Se形态,加标回收率在91%～115%之间。     

Determination of 19 sulfonamides residues in pork samples by combining QuEChERS with dispersive liquid–liquid microextraction followed by UHPLC–MS/MS

A new simple and rapid pretreatment method for simultaneous determination of 19 sulfonamides in pork samples was developed through combining the QuEChERS method with dispersive liquid–liquid microextraction followed by ultra‐high performance liquid chromatography with tandem mass spectrometry. The sample preparation involves extraction/partitioning with QuEChERS method followed by dispersive liquid–liquid microextraction using tetrachloroethane as extractive solvent and the acetonitrile extract as dispersive solvent that obtained by QuEChERS. The enriched tetrachloroethane organic phase by dispersive liquid–liquid microextraction was evaporated, reconstituted with 100 μL acetonitrile/water (1:9 v/v) and injected into an ultra‐high performance liquid chromatography with a mobile phase composed of acetonitrile and 0.1% v/v formic acid under gradient elution and separated using a BHE C₁₈ column. Various parameters affecting the extraction efficiency were investigated. Matrix‐matched calibration curves were established. Good linear relationships were obtained for all analytes in a range of 2.0–100 μg/kg and the limits of detection were 0.04–0.49 μg/kg. Average recoveries at three spiking levels were in the range of 78.3–106.1% with relative standard deviations less than 12.7% (n = 6). The developed method was successfully applied to determine sulfonamide residues in pork samples.     

Development of microextraction techniques in combination with GC–MS/MS for the determination of mycotoxins and metabolites in human urine

Simple and highly efficient sample preparation procedures, namely, dispersive liquid–liquid microextraction and salting‐out liquid–liquid extraction for the analysis of ten Fusarium mycotoxins and metabolites in human urine were compared. Various parameters affecting extraction efficiency were carefully evaluated. Under optimal extraction conditions, salting‐out liquid–liquid extraction showed a better accuracy (84–96%) and precision (<14%) than dispersive liquid–liquid microextraction. Hence, a multibiomarker method based on salting‐out liquid–liquid extraction followed by gas chromatography with tandem mass spectrometry was proposed. Satisfactory results in terms of validation were achieved. The method resulted in low limits of detection and quantitation within the range of 0.12–4 and 0.25–8 μg/L, respectively. The method accuracy and precision were evaluated at three spiking levels (8, 25 and 100 μg/L) and the recoveries were in a range from 70 to 120% with relative standard deviations lower than 15%. Matrix effect was evaluated and matrix‐matched calibrations were used for quantitation purpose. The developed method was applied in 12 human urine samples as a pilot study before and after sample treatment with β‐glucuronidase before the analysis to quantify the mycotoxin conjugates. Total deoxynivalenol (free + conjugated) was found in 83% of samples at an average concentration in positive samples of 31.6 μg/L.     

Liquid structure of benzene and its derivatives as studied by means of X-ray scattering

The liquid structures of benzene, toluene, aniline, benzaldehyde and nitrobenzene were investigated by the X-ray scattering method. The X-ray scattering data were analysed by a method without constructing any structure models. The obtained liquid structure of benzene is different from the previous X-ray scattering results which were derived from the quasi-lattice structure for the liquid based on the crystal structure of benzene. This is because a molecular arrangement which is not found in the crystal structure is left out of consideration. In liquid toluene, benzaldehyde and nitrobenzene, two molecules are associated with the dipole–dipole interaction in the antiparallel fashion. Two aniline molecules are hydrogen-bonded in liquid aniline. The third molecule weakly interacts with the other two in liquid toluene, aniline and benzaldehyde. In liquid nitrobenzene, the parallel dipole–dipole interaction of the third molecule with another one is present in the coplanar form. The substituent effect on the liquid structures is discussed.     

In situ ionic liquid dispersive liquid–liquid microextraction combined with ultra high performance liquid chromatography for determination of neonicotinoid insecticides in honey samples

An efficient in situ ionic liquid dispersive liquid–liquid microextraction followed by ultra‐performance liquid chromatography was developed to determine four neonicotinoid insecticides in wild and commercial honey samples. In this method, a hydrophobic ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate, formed by in situ reaction between potassium hexafluorophosphate and 1‐butyl‐3‐methylimidazolium bromide in sample solution, was used as the extraction solvent. In comparison with the traditional dispersive liquid–liquid microextraction method, the developed method required no dispersive solvent. To achieve high extraction efficiency and enrichment factor, the effects of various experimental parameters were studied in detail. Under the optimized conditions, the limits of detection and quantification were in the ranges of 0.30–0.62 and 1.20–2.50 μg/L, respectively. The method showed high enrichment factors (74–115) with the recoveries between 81.0 and 103.4%. The proposed method was finally applied to different wild and commercial honey samples.     

Solid‐phase extraction combined with dispersive liquid–liquid microextraction for the determination of pyrethroid pesticides in wheat and maize samples

A rapid, selective and sensitive sample preparation method based on solid‐phase extraction combined with the dispersive liquid–liquid microextration was developed for the determination of pyrethroid pesticides in wheat and maize samples. Initially, the samples were extracted with acetonitrile and water solution followed phase separation with the salt addition. The following sample preparation involves a solid‐phase extraction and dispersive liquid–liquid microextraction step, which effectively provide cleanup and enrichment effects. The main experimental factors affecting the performance both of solid‐phase extraction and dispersive liquid–liquid microextration were investigated. The validation results indicated the suitability of the proposed method for routine analyze of pyrethroid pesticides in wheat and maize samples. The fortified recoveries at three levels ranged between 76.4 and 109.8% with relative standard deviations of less than 10.7%. The limit of quantification of the proposed method was below 0.0125 mg/kg for the pyrethoroid pesticides. The proposed method was successfully used for the rapid determination of pyrethroid residues in real wheat and maize samples from crop field in Beijing, China.     

Accelerated solvent extraction combined with dispersive liquid–liquid microextraction before gas chromatography with mass spectrometry for the sensitive determination of phenols in soil samples

A method combining accelerated solvent extraction with dispersive liquid–liquid microextraction was developed for the first time as a sample pretreatment for the rapid analysis of phenols (including phenol, m‐cresol, 2,4‐dichlorophenol, and 2,4,6‐trichlorophenol) in soil samples. In the accelerated solvent extraction procedure, water was used as an extraction solvent, and phenols were extracted from soil samples into water. The dispersive liquid–liquid microextraction technique was then performed on the obtained aqueous solution. Important accelerated solvent extraction and dispersive liquid–liquid microextraction parameters were investigated and optimized. Under optimized conditions, the new method provided wide linearity (6.1–3080 ng/g), low limits of detection (0.06–1.83 ng/g), and excellent reproducibility (<10%) for phenols. Four real soil samples were analyzed by the proposed method to assess its applicability. Experimental results showed that the soil samples were free of our target compounds, and average recoveries were in the range of 87.9–110%. These findings indicate that accelerated solvent extraction with dispersive liquid–liquid microextraction as a sample pretreatment procedure coupled with gas chromatography and mass spectrometry is an excellent method for the rapid analysis of trace levels of phenols in environmental soil samples.     

Fast and sensitive analysis of beta blockers by ultra‐high‐performance liquid chromatography coupled with ultra‐high‐resolution TOF mass spectrometry

This paper presents a method for the determination of acebutolol, betaxolol, bisoprolol, metoprolol, nebivolol and sotalol in human serum by liquid–liquid extraction and ultra‐high‐performance liquid chromatography coupled with ultra‐high‐resolution TOF mass spectrometry. After liquid–liquid extraction, beta blockers were separated on a reverse‐phase analytical column (Acclaim RS 120; 100 × 2.1 mm, 2.2 μm). The total run time was 6 min for each sample. Linearity, limit of detection, limit of quantification, matrix effects, specificity, precision, accuracy, recovery and sample stability were evaluated. The method was successfully applied to the therapeutic drug monitoring of 108 patients with hypertension. This method was also used for determination of beta blockers in 33 intoxicated patients.     

Application of liquid–liquid microextraction for the effective separation and simultaneous determination of 11 pharmaceuticals in wastewater samples using high‐performance liquid chromatography with tandem mass spectrometry

A dispersive liquid–liquid microextraction method for the simultaneous determination of 11 pharmaceuticals has been developed. The method is based on a microextraction procedure applied to wastewater samples from different regions of Hungary followed by high‐performance liquid chromatography with mass spectrometry. The effect of the nature of the extractant, dispersive solvent, different additives, and extraction time were examined on the extraction efficiently of the dispersive liquid–liquid microextraction method. Under optimal conditions, the linearity for determining the pharmaceuticals was in the range of 1–500 ng/mL, with the correlation coefficients ranging from 0.9922 to 0.9995. The limits of detection and limits of quantification were in the range of 0.31–6.65 and 0.93–22.18 ng/mL, respectively.     

Determination of melamine residue in liquid milk by capillary electrophoresis with solid-phase extraction

A novel solid-phase extraction-capillary electrophoresis (SPE-CE) method was developed for the determination of melamine residue in liquid milk. The conditions of SPE and CE were investigated and optimized. A 1% trichloroacetic acid plus 2.2% lead acetate solution were used for the extraction of analyte and the removal of protein. A Cleanert PCX SPE cartridges column was used for clean up. The 50 mM sodium dihydrogenphosphate running buffer (pH adjusted to 3.2 with citric acid) was used as a running buffer. The linearity is satisfactory in the range of 0.8-100 μg/mL with a correlation coefficient of 0.9998. Under the optimal conditions, the method limit of detection (LOD) and method limit of quantification were 0.12 mg/kg and 0.37 mg/kg, respectively. The recovery of melamine from different liquid milk samples was in the range of 89.5-98.5% with a relative standard deviation of 1.8-3.5%. The intra- and inter-day assay precision was 2.8% (n = 6) and 4.1% for five days, respectively. The developed method has been applied successfully for the determination of melamine residue in liquid milk samples. The results obtained by the proposed method agree with those obtained by high-performance liquid chromatographic method. The proposed method enables the quantitative determination of melamine residues at levels as low as 0.37 mg/kg in different liquid milk.     

Liquid crystals purity assay using nonaqueous capillary electrokinetic chromatography

A method for purity control of newly synthesized lactic acid–based liquid crystals has been developed. The electrokinetic chromatography proved to be suitable for the separation of these electroneutral substances from their impurities. The separations were performed in an acidic acetonitrile-based background electrolyte (BGE) with a pseudostationary phase formed by a cationic surfactant. During the optimization step, appropriate concentrations of cetyltrimethylammonium bromide, acetic acid, and water were seeked. In the optimized method, separations were carried out in acetonitrile with 1-mol/L acetic acid, 80-mmol/L cetyltrimethylammonium bromide, and 6% (v/v) water. Interesting positive effects of a small water content in the BGE on electroosmotic flow and resolution of liquid crystal substances from their impurities were observed and discussed. Samples of five liquid crystal substances, both pure and containing impurities from synthesis, were analyzed. The identification of analytes was based on a comparison of relative migration times related to the migration time of mesityl oxide. For all five samples, impurities were separated from the liquid crystals and the method thus showed its viability. To the best of our knowledge, this method is used for the first time for the purity control of newly synthesized liquid crystals. This method can be used to confirm or complement the results obtained by commonly used high-performance liquid chromatography and supercritical fluid chromatography methods. Furthermore, the electrokinetic chromatography method requires very small amounts of sample, solvents, and buffer constituents. Overall, its operational costs are significantly lower.