在线净化-液相色谱-串联质谱法测定茶叶中5种烟碱类农药残留

建立了在线净化-液相色谱-串联质谱测定茶叶中吡虫啉、啶虫脒、噻虫啉、噻虫嗪和噻虫胺5种常见烟碱类农药残留量的方法。样品经水浸泡、乙腈提取和在线净化后,用液相色谱-串联质谱测定。结果表明,本方法对5种烟碱类农药的定量限均为0.01 mg/kg。5种烟碱类农药在1.0~10 μ g/L范围内具有良好的线性关系,相关系数均大于0.998。在0.01、0.02和0.05 mg/kg的添加水平下,回收率为68.0%~113.2%,相对标准偏差为3.2%~7.6%。本方法简便、快速、准确,适用于茶叶样品中烟碱类农药残留量的检测。     

液相色谱法检测水果蔬菜中的烟碱类农药残留

建立了果蔬样品中5种烟碱类农药(噻虫嗪、吡虫啉、啶虫脒、噻虫啉、噻虫胺)残留的液相色谱快速检测方法。样品采用乙腈提取,浓缩,水转溶后经ENVI-18固相萃取柱净化,0.02 mol/L NaOH预淋洗除去柱上中等极性干扰物,100%乙腈1 mL洗脱5种烟碱类残留,反相高效液相色谱-二极管阵列检测器检测。在黄瓜空白基质中0.1~1.0 mg/kg的加标浓度范围内,5种农药的回收率为50.8%~108.9%,相对标准偏差(RSD)小于15%;而苹果、梨、香蕉、西红柿和韭菜空白基质在0.1~1.0 mg/kg添加水平下,5种农药的回收率均大于80%,RSD小于11%。所测试的6种果蔬样品中噻虫嗪、噻虫胺、吡虫啉的检出限(LOD)为0.01~0.02 mg/kg,啶虫咪和噻虫啉的LOD为0.03~0.05 mg/kg,方法可满足水果蔬菜中烟碱类农药多残留分析的要求。     

固相萃取-高效液相色谱同时测定大米中的4种烟碱农药残留量

建立了高效液相色谱法同时测定大米样品中呋虫胺、噻虫胺、吡虫啉、吡虫清4种烟碱农药残留量的检测方法,对4种烟碱农药在ENVI-Florisil和Carb复合固相萃取柱上的保留行为进行了研究。样品用乙腈提取,固相萃取净化,HPLC-DAD分离检测,外标法定量。峰面积与标准溶液浓度在0.1～1.0 mg/L范围内呈良好的线性关系,相关系数大于0.9996。样品加标回收率为75.5%～96.0%,相对标准偏差为0.49%～4.36%(n=6),检出限达到0.004 mg/kg。     

QuEChERS-高效液相色谱法检测蔬菜中的吡虫啉、虫酰肼、阿维菌素和噻螨酮

将一种新的QuEChERS样品处理方法进行了提取及净化的改进,结合HPLC对蔬菜中吡虫啉、虫酰肼、阿维菌素和噻螨酮4种农药进行同时检测,取得了满意结果。以乙腈-水为流动相,梯度洗脱,269、240 nm双波长检测,流速1.0 mL/min。检出限分别为:吡虫啉0.02 mg/kg、虫酰肼0.02 mg/kg、阿维菌素0.10 mg/kg、噻螨酮0.05 mg/kg。在添加浓度为0.05~1.0 mg/kg范围内,4种化合物回收率在80%~100%之间,相对标准偏差1%~10%。方法适用于蔬菜中吡虫啉、虫酰肼、阿维菌素和噻螨酮4种农药残留量的同时检测。     

盐析辅助均相液液萃取/分散固相萃取-超高效液相色谱串联质谱法测定蜂蜜中新烟碱类农药残留

以盐析辅助均相液液萃取结合分散固相萃取作为前处理方法,建立了超高效液相色谱串联质谱快速检测蜂蜜中吡虫啉、噻虫嗪、噻虫胺、噻虫啉、啶虫脒及氯噻啉6种新烟碱类农药残留的分析方法。样品用乙腈提取,氯化钠盐析分层,提取液经分散固相萃取法净化,采用超高效液相色谱串联质谱检测器进行分析。考察了萃取剂种类、体积及氯化钠质量对萃取效率的影响,评估了在优化实验条件下的基质效应和方法性能。结果表明:除吡虫啉外,其余5种新烟碱类农药的基质效应均大于10%。6种新烟碱类农药在0.2~100μg/L范围内线性关系良好,相关系数(r2)为0.998 1~0.999 7。加标浓度为1.0~50.0μg/kg时,6种新烟碱类农药的加标回收率为77.0%~106%,相对标准偏差为2.4%~19.8%。方法的检出限为0.2~0.4μg/kg,定量下限为1.0μg/kg。该方法前处理简单,分析时间短,准确度和灵敏度高,重现性好,适用于蜂蜜中6种新烟碱类农药微量残留的快速测定。     

韭菜中吡虫啉和啶虫脒残留的微波处理-逆固相分散法净化及液相色谱检测

建立了韭菜中两种烟碱类农药吡虫啉和啶虫脒残留的快速检测方法.韭菜样本用微波炉加热处理,使酶钝化消除含硫基质干扰,然后用乙腈提取、逆固相分散净化,用反相高效液相色谱-二极管阵列检测器检测.在0.05～2.0 mg/kg添加水平范围内,吡虫啉的平均添加回收率在95.2%～105.3%之间;相对标准偏差在0.8%～7.8%之间;啶虫脒的平均添加回收率在97.4%～108.8%之间;相对标准偏差在1.3%～8.3%之间.本方法对吡虫啉的检出限(LOD)为0.0078 mg/kg,定量检出限(LOQ)为0.026 mg/kg;对啶虫脒的检出限为0.0075 mg/kg,定量检出限为0.025 mg/kg.     

QuEChERS-高效液相色谱/串联质谱法同时测定蜂蜜中9种新烟碱类杀虫剂残留

建立了蜂蜜中吡呀酮、吡虫啉、啶虫脒、噻虫嗪、噻虫啉、烯啶虫胺、噻虫胺、呋虫胺和氯噻啉9种新烟碱类杀虫剂的QuEChERS-高效液相色谱/串联质谱(HPLC-MS/MS)检测方法。样品以水提取,采用N-丙基乙二胺(PSA)和酸性Al2O3净化,用Zorbax Eclipse Plus C18柱(100×3.0mm,1.8μm)分离,以乙腈-0.1%甲酸水溶液为流动相,梯度洗脱,采用电喷雾正离子模式(ESI+)、多重反应监测(MRM)检测目标分析物,基质匹配标准溶液外标法定量。结果表明:9种杀虫剂均具有良好的线性关系(r20.9969);方法检出限为0.3~0.8μg/kg;定量限为1.0~2.5μg/kg;在2.5、10、25μg/kg三个添加水平下,杂花蜜、油菜蜜、棉花蜜和葵花蜜四种基质样品中9种杀虫剂的平均回收率在81.7%~106.7%范围,相对标准偏差(RSDs)在4.2%~9.4%之间。该方法分析速度快、灵敏度高、重现性好,适用于蜂蜜中新烟碱类杀虫剂残留的快速检测和确证。     

固相萃取-超高效液相色谱-串联质谱法同时测定果蔬中6种酰胺类农药残留量

建立了同时测定果蔬中6种酰胺类农药的固相萃取-超高效液相色谱-串联质谱(SPE-UPLC-MS/MS)方法。样品经乙腈高速匀浆提取、Florisil固相萃取柱净化,采用超高效液相色谱-串联质谱法测定6种农药。质谱分析采用电喷雾电离,正负双离子扫描,多反应监测(MRM)模式。结果表明:6种农药在0.0005~1.00 mg/L范围内均呈现良好的线性关系,相关系数均大于0.999;在0.01、0.1和1.0 mg/kg(氟苯虫酰胺为0.001、0.01和0.1 mg/kg) 3个浓度添加水平下的平均回收率为72.4%~119.4%,相对标准偏差(n=5)小于15%;定量限为0.01 mg/kg(溴氰虫酰胺、双炔酰菌胺、啶酰菌胺、氟吡菌胺和噻呋酰胺)和0.001 mg/kg(氟苯虫酰胺)。该方法简单、快速、重现性好、灵敏度高,可满足果蔬中6种酰胺类农药残留检测的要求。     

QuEChERS-高效液相色谱-串联质谱法同时测定生活饮用水中11种新烟碱类杀虫剂的含量

提出了QuEChERS-高效液相色谱-串联质谱法(HPLC-MS/MS)同时测定生活饮用水中11种新烟碱类杀虫剂(吡虫啉、烯啶虫胺、啶虫脒、噻虫啉、氯噻啉、环氧虫啶、噻虫嗪、噻虫胺、呋虫胺、氟啶虫胺腈、氟啶虫酰胺)含量的方法。5 mL过滤后的水样用含1%(体积分数)甲酸的二氯甲烷溶液提取两次,合并下层提取液,氮吹至干,加入50 mg N-丙基乙二胺(PSA)和1 mL体积比65:35的0.2%(体积分数,下同)甲酸溶液-乙腈的混合溶液,涡旋后过0.22μm聚醚砜滤膜。以不同体积比的0.2%甲酸溶液-乙腈的混合溶液为流动相进行梯度洗脱,分离后的11种目标物经电喷雾离子源正离子模式扫描,以多反应监测模式检测,外标法定量。结果表明：11种新烟碱类杀虫剂的质量浓度在一定范围内与对应的峰面积呈线性关系,测定下限(10S/N)为0.02～0.08μg·L^-1;在3个加标浓度水平下,11种目标物的回收率为62.1%～101%,测定值的相对标准偏差(n=6)为5.0%～15%。方法用于8份自来水、4份河水和3份水库水样品分析,结果显示4份河水样品和2份水库水样品中检出新烟碱类杀虫...     

超高效液相色谱-串联质谱法测定柑橘及柑橘精油中4种农药残留

建立了柑橘及柑橘精油中吡虫啉、多菌灵、咪鲜胺和高效氯氰菊酯4种农药的多残留分析方法。前处理方法以乙腈为提取剂、N-丙基乙二胺(PSA)为分散净化剂的QuEChERS方法,并利用超高效液相色谱-串联质谱(UPLC-MS/MS)在多反应离子监测模式(MRM)下进行检测,外标法定量。结果表明:在0.01～1.00mg/kg添加水平范围内,4种农药的平均回收率为72.6%～113.3%;相对标准偏差(RSD,n=5)为0.9%～19.6%;方法检出限(LOD)在0.02～0.60μg/kg范围内;定量限(LOQ)在0.06～2.00μg/kg范围内。     

气相色谱-质谱法测定水体中三氟乙酸

用多级浓缩的预处理富集水中微量的三氟乙酸,再将富集的三氟乙酸通过甲酯衍生化生成适合顶空进样的三氟乙酸甲酯,以气相色谱-质谱法对水体中三氟乙酸进行测定。试验对顶空进样的条件进行了优化,采用全扫描模式进行定性分析,选择离子扫描模式,以质荷比59,69的特征离子进行定量检测。检出限(3s)为1μg.L-1,对空白溶液进行加标回收试验,回收率在64.3%～68.1%之间,相对标准偏差(n=6)在5.62%～5.78%之间。     

Headspace-programmed temperature vaporizer-fast gas chromatography-mass spectrometry coupling for the determination of trihalomethanes in water

A new method based on the use of a headspace autosampler in combination with a GC equipped with a programmable temperature vaporizer (PTV) and an MS detector has been developed for the screening and quantitative determination of trihalomethanes (THMs) in different aqueous matrices. The use of headspace generation to introduce the sample has the advantage that no prior sample treatment is required, thus minimizing the creation of analytical artifacts and the errors associated with this step of the analytical process. The PTV inlet used was packed with Tenax-TA. The injection mode was solvent vent, in which the analytes are retained in the hydrophobic insert packing by cold trapping, while the water vapour is eliminated through the split line. This allows rapid injection of the sample in splitless mode, very low detection limits being achieved without the critical problem of initial sample bandwidth. The capillary column used allowed rapid separations with half-height widths ranging from 1.68 s (chloroform) to 0.66 s (bromoform). The GC run time was 7.3 min. The use of mass spectrometry allows the identification and quantification of the analytes at the low ppt level. The S/N ratio was at least 10-fold higher when the SIM mode was used in data acquisition as compared to the scan mode. The proposed method is extremely sensitive, with detection limits ranging from 0.4 to 2.6 ppt.     

Field-amplified sample injection and in-capillary derivatization for sensitivity improvement of the electrophoretic determination of histamine

The feasibility of the combination of field-amplified sample injection (FASI) and in-capillary derivatization was explored for improving sensitivity of histamine in capillary electrophoresis (CE). Naphthalene-2,3-dicarboxaldehyde (NDA) was used as derivatization reagent. The reagent and sample was introduced by tandem mode. The derivatization was accomplished by at-inlet mode with standing time of 1.5 min. The combination of FASI and in-capillary derivatization was successfully achieved with about 400-fold concentration sensitivity enhancement compared to pre-capillary derivatization at the same set-up. The detection limit of concentration for histamine reached 1.25 x 10(-11) M by CE and fluorescence detection with S/N = 3. Parameters affecting FASI and in-capillary derivatization process including sample matrix, buffer concentration and reagent injection amount, were investigated.     

Optimization of the separation and on-line sample concentration of phenethylamine designer drugs with capillary electrophoresis-fluorescence detection

Five 2C-series of phenethylamine designer drugs, including 2,5-dimethoxy-4-ethylthio-phenethylamine (2C-T-2), 2,5-dimethoxy-4-(n)-propylthiophenethylamine (2C-T-7), 4-chloro-2,5-dimethoxyphenethylamine (2C-C), 4-bromo-2,5-dimethoxy-phenethylamine (2C-B), 2,5-dimethoxy-4-iodo-phenethylamine (2C-I), were synthesized and standard GC/MS and fluorescence spectra are reported for them. A mixture of the five drugs was separated and detected by means of capillary electrophoresis (CE) with native fluorescence and light emitting diode (LED)-induced fluorescence (LIF) detection, respectively, for comparison. In the former case, exciting at a wavelength of 300 nm from a Xe lamp was used. The detection limits were found to be only in the range of approximately 10(-4) M by the micellar electrokinetic chromatography (MEKC) mode but were improved to approximately 10(-7) M when the sweeping-MEKC mode was used. For a highly sensitive analysis, LED-induced fluorescence detection was examined by derivatizing the compounds with a fluorescent dye, fluorescein isothiocyanate isomer I (FITC). A blue-LED (approximately 2 mW) was used as the fluorescence excitation source. The detection limits were improved to approximately 10(-7) and approximately 10(-8) M, respectively, when the MEKC and stacking-MEKC modes were applied. A mimic urine sample was obtained by spiking urine from a volunteer with the five standards, and after liquid-liquid extraction, the sample was examined by means of the MEKC-LIF mode. The extraction procedures used for the urine sample and the CE conditions for the separation were optimized.     

On-line isotachophoretic preconcentration and gel electrophoretic separation of sodium dodecyl sulfate-proteins on a microchip

A microchip for integrated isotachophoretic (ITP) preconcentration with gel electrophoretic (GE) separation to decrease the detectable concentration of sodium dodecyl sulfate (SDS)-proteins was developed. Each channel of the chip was designed with a long sample injection channel to increase the sample loading and allow stacking the sample into a narrow zone using discontinuous ITP buffers. The pre-concentrated sample was separated in GE mode in sieving polymer solutions. All the analysis steps including injection, preconcentration, and separation of the ITP-GE process were performed continuously, controlled by a high-voltage power source with sequential voltage switching between the analysis steps. Without deteriorating the peak resolution, four SDS-protein analyses with integrated ITP-GE system resulted in a decreased detectable concentration of approximately 40-fold compared to the GE mode only. A good calibration curve for molecular weights of SDS-proteins indicated that the integrated ITP-GE system can be used for qualitative analysis of unknown protein samples.     

高效液相色谱-串联质谱法同时测定鳗鱼和虾中残留的33种喹诺酮和磺胺类药物

建立了鳗鱼和虾中33种喹诺酮类(QNs)和磺胺类(SAs)药物残留量的高效液相色谱-串联质谱(HPLC-MS/MS)测定方法。以氘代试剂为内标,样品经酸性乙腈萃取后,用正己烷脱脂,旋转蒸发浓缩,采用LC-MS/MS选择反应监测(SRM)正离子模式测定,同时对鳗鱼和虾中的33种QNs和SAs进行定性和定量。33种QNs和SAs的检出限(S/N=3)为1.0 μg/kg,定量限(S/N=10)为2.0 μg/kg;在10.0～200.0 μg/L时目标物的峰强度与质量浓度的线性关系良好(r>0.99);平均回收率为66%～123%。该法简便快捷,降低了分析成本,也在一定程度上实现了药物残留的快速检测。     

Dielectric modes in antiferroelectric liquid crystal observed at low temperatures

A broad temperature antiferroelectric binary mixture has been investigated by means of dielectric spectroscopy. The sample was cooled down to –70°C. It was found that the sample was still in antiferroelectric phase. This is the widest antiferroelectric mixture ever seen (～170°) in which three well-separated modes have been detected at room temperature. In addition, the bias field influence on existing modes has been observed. All modes change their strengths with bias field. Results show that the fastest mode, called X mode previously, gradually disappears around –30°C. When the temperature decreases below –40°C, one can indisputably observe additional mode, faster than X mode. This mode (named as Y mode) observed for extra low temperatures is bias independent. It can be the molecular mode, connected with rotation around long molecular axis. The rotation around short molecular axis seems to be blocked in antiferroelectric packing. To calculate parameters of observed modes, Cole–Cole model was used. The parameters of Y mode are discussed in this article.     

New zwitterionic polymethacrylate monolithic columns for one‐ and two‐dimensional microliquid chromatography

We prepared 0.53 and 0.32 mm id monolithic microcolumns by in situ copolymerization of a zwitterionic sulfobetaine functional monomer with bisphenol A glycerolate dimethacrylate (BIGDMA) and dioxyethylene dimetacrylate crosslinkers. The columns show a dual retention mechanism (hydrophilic‐interaction mode) in acetonitrile‐rich mobile phases and RP in highly aqueous mobile phases. The new 0.53 mm id columns provided excellent reproducibility, retention, and separation selectivity for phenolic acids and flavonoids. The new zwitterionic monolithic columns are highly orthogonal, with respect to alkyl silica stationary phases, not only in the hydrophilic‐interaction mode but also in the RP mode. The optimized monolithic zwitterionic microcolumn of 0.53 mm id was employed in the first dimension, either in the aqueous normal‐phase or in the RP mode, coupled with a short nonpolar core‐shell column in the second dimension, for comprehensive 2D LC separations of phenolic and flavonoid compounds. When the 2D setup with the sulfobetaine–BIGDMA column was used for repeated sample analysis, with alternating gradients of decreasing (hydrophilic‐interaction mode), and increasing (RP mode) concentration of acetonitrile on the sulfobetaine–BIGDMA column in the first dimension, useful complementary information on the sample could be obtained.     

QuEChERS/液相色谱-串联质谱法同时测定鱼肉中30种激素类及氯霉素类药物残留

建立了鱼肉中8种雌激素、5种雄激素、6种孕激素、8种糖皮质激素及3种氯霉素类药物多残留的QuEChERS/液相色谱-串联质谱(LC - MS/MS)同时测定方法.均质样品用水分散后加乙腈提取,经分散固相萃取净化后,采用ZORBAX Extend-C18色谱柱(100 mm ×2.1 mm,3.5 μm)分离,分别在电喷...     

液相色谱-串联质谱法快速测定婴幼儿配方奶粉中39种激素残留量

建立了液相色谱-串联四极杆质谱同时测定婴幼儿配方奶粉中17种糖皮质激素、11种孕激素、3种雄性激素和8种雌激素残留的快速确证方法。采用乙腈提取奶粉中待测组分,提取液经冷冻离心与正己烷除脂、亲水-亲脂平衡固相萃取柱净化、甲醇洗脱。分别在正、负电喷雾离子化多反应监测模式下检测39种激素。正离子模式下的流动相为乙腈-0.1%甲酸,色谱柱为普通硅胶基质的C18柱;负离子模式下的流动相为乙腈-0.1%氨水,色谱柱为能耐受宽pH范围的超高效C18柱。在该优化条件下,39种激素定量限(S/N≥10)为0.02～5 μg/kg,方法回收率为59.5%～117.9%,相对标准偏差(RSD)为6.4%～16.3%。经测定多种市售婴幼儿配方奶粉,表明该方法操作简单、测定结果准确,可用于婴幼儿配方奶粉中多种内源性与化学合成类激素残留的快速测定。