高效液相色谱法测定烟草中二甲基二硫代氨基甲酸酯类杀菌剂

建立了高效液相色谱法测定烟草中二甲基二硫代氨基甲酸酯类农药方法,优化了烟草样品的前处理方法、样品提取溶剂和提取时间等参数。利用三氯甲烷可提取出烟草中的福美双,福美锌和福美铁通过碱性乙二胺四乙酸二钠盐提取后经碘甲烷衍生化后直接高效液相色谱分析,高效液相色谱流动相比例为甲醇:水=48:52(V/V),紫外检测波长为235 nm和270 nm。方法的平均回收率范围为80%~97%,相对标准偏差范围为1.1%~6.4%,福美双的检出限为10 ng/g,福美锌和福美铁的检出限为1 ng/g。方法适合烟草中二甲基二硫代氨基甲酸酯类杀菌剂的定性和定量分析。     

高效液相色谱-二极管阵列法测定小麦粉中苯甲羟肟酸

基于目标化合物的弱酸性及小麦粉基质的特点,通过对不同提取剂、流动相组成、梯度条件及色谱柱的选择及优化,建立了高效液相色谱-二极管阵列检测器(HPLC-PDA)测定小麦粉中苯甲羟肟酸的分析方法。样品中的苯甲羟肟酸采用甲醇提取,无需净化,以甲醇-磷酸盐(p H 3.7)为流动相,Waters Xbridge C18色谱柱完成了对目标物及特定干扰物的完全分离,高效液相色谱-二极管阵列检测器检测,外标法定量。该方法在0.1～10μg/mL范围内线性关系系数(r~2)大于0.999;方法检出限为0.1 mg/kg,定量限为0.5 mg/kg;在定量限(LOQ),2 LOQ和10 LOQ 3个添加水平下重复测定6次的回收率为93.7%～102.7%,相对标准偏差(RSD)为1.1%～3.8%。该方法适用于小麦粉中苯甲羟肟酸的测定。     

一锅合成异硫氰酸酯

以N,N-二乙基乙胺(Et₃N)为碱,甲苯为溶剂,伯胺和CS₂为原料,叔丁基碳酸二乙基磷酸酐(3)为脱硫试剂,在n(伯胺):n(CS₂):n(Et₃N):n(3)=1:1.1:3.3:1.1,二硫代甲酸盐合成段反应温度为室温,脱硫反应段为-5 ℃至室温的实验条件下,两步一锅合成了系列烷基、芳基和双功能基异硫氰酸酯化合物,收率77%96%。 本方法底物适用范围广,操作简单,对胺的各种保护基团耐受,不引起消旋化副反应。 脱硫剂3作为一种新的脱硫试剂,商业易得,安全有效。     

CS2对完全液相法制备的 Cu-Zn-Al催化剂上合成气制DME反应性能的影响

实验以CS₂为硫源,考察硫对完全液相法制备Cu-Zn-Al催化剂活性的影响,并用X射线粉末衍射(XRD)、氢气程序升温吸附(H₂-TPR)、氨气程序升温脱附(NH₃-TPD)等方法对催化剂性能进行了表征。结果表明,对完全液相法制备的Cu-Zn-Al催化剂而言,加入小于4mg/L 的CS₂对催化剂的活性影响不大;催化剂的活性随着加入硫含量的增加,下降程度增大。     

高效液相色谱法对水果中多菌灵与福美双残留的同时测定

建立了高效液相色谱同时测定水果中多菌灵和福美双残留量的方法。样品经二氯甲烷提取,OasisHLB固相萃取柱净化后,经C18色谱柱分离,甲醇-0.05 mol/L甲酸铵溶液(60∶40,体积比)洗脱,紫外检测器进行检测。结果表明,多菌灵、福美双的的线性范围分别为0.01~10.0、0.05~10.0 mg/kg,相关系数分别为1.0、0.9999,检出限分别为0.005、0.03 mg/kg,平均加标回收率为80%~109%。该方法成功用于市售水果样品的测定。     

固相萃取-高效液相色谱法测定蔬菜水果中的氨基甲酸酯杀虫剂及其代谢物残留

采用乙腈提取-固相萃取浓缩 高效液相色谱分离 柱后衍生-荧光检测法测定了蔬菜 水果中8种氨基甲酸酯类杀虫剂及其代谢物残留量。采用加标法(添加水平为0.10,0.50mg/kg)测定了氨基甲酸酯杀虫剂及其代谢物的回收率,其平均回收率为70%-120%,相对标准偏差(RSD)小于20%(n=3),最低检出限范围为0.0042-0.0106 mg/kg。该方法的测定结果满足多残留农残的检测要求。     

超高效液相色谱-串联质谱法测定橡胶产品中4种秋兰姆类硫化促进剂含量

建立了橡胶产品中4种秋兰姆类硫化促进剂(二硫化四苄基秋兰姆(TBZTD)、二硫化二甲基二苯基秋兰姆(TMD)、福美双-D12(Thiram D12)、二环戊亚甲基二硫化秋兰姆(DPTD))的超高效液相色谱-串联质谱检测方法。橡胶材料中的硫化促进剂经甲醇超声多次提取,提取液离心过滤后以反相C18色谱柱为分离柱,甲醇和水作为流动相进行洗脱,经超高效液相色谱-串联质谱仪测定,外标法定量。研究了不同色谱条件下目标物质的分离情况和不同提取溶剂对提取净化效率的影响。在最优化条件下,TMD和Thiram D12在0.002~1.000 mg/L浓度范围内线性关系良好,其定量下限分别为0.001 0 mg/L和0.001 2 mg/L;TBZTD在0.100~10.000 mg/L浓度范围内线性关系良好,定量下限为0.100 0 mg/L;DPTD在0.020~10.000 mg/L浓度范围内线性关系良好,定量下限为0.020 0 mg/L。空白样品在不同浓度水平的平均加标回收率为82.7%~98.8%,相对标准偏差(RSD)为4.6%~7.0%。该方法简便、快速、灵敏,可满足橡胶产品中TBZTD,TMD,Thiram D12和DPTD的测试要求。     

气相色谱法检测22种基质中的4种二硫代氨基甲酸盐类农药残留

在密闭加热的容器中用SnCl2-HCl溶液酸解二硫代氨基甲酸盐类（DTCs）农药,反应生成的二硫化碳气体被瓶中的正己烷吸收,形成二硫化碳的正己烷溶液;使用气相色谱-火焰光度检测器(硫滤光片)测定有机相中二硫化碳的含量,即得到DTC农药的残留量。采用该方法对苹果、葡萄等22种基质中残留的代森锰锌、代森联、丙森锌和福美双进行了方法确证: 添加水平为0.06～3.0 mg/kg时,平均回收率为72%～110%,相对标准偏差为0.8%～22.0%,采用外标法定量,方法的检出限范围为0.01～0.1 mg/kg(信噪比(S/N)为3),定量限范围为0.02～0.2 mg/kg(S/N=10)。该方法简单、快速、准确、重复性好,适用于不同基质中DTCs农药的残留检测。     

羟基化多壁碳纳米管分散固相萃取-气相色谱-质谱法测定茶叶中21种有机磷农药

建立了用羟基化多壁碳纳米管(MWCNTs-OH)、N-丙基乙二胺键合固相吸附剂(PSA)和MgSO₄作为吸附剂的改进QuEChERS-气相色谱-质谱快速检测茶叶中21种有机磷农药的方法。茶叶中残留的农药经正己烷-丙酮(2 : 1, v/v)混合溶剂提取,以MWCNTs-OH、PSA和MgSO₄去除杂质,离心、过滤后经气相色谱-电子轰击源质谱测定,外标法定量。结果表明,目标化合物在0.01~0.50 mg/kg范围内的线性关系良好。空白茶叶样品在低、中、高3个添加水平下的平均回收率为81.5%~109.4%,相对标准偏差(n=5)为2.3%~10.6%,定量限为0.001~0.040 mg/kg。该方法操作简单、快速、灵敏、成本低,能满足茶叶中常见有机磷农药残留的检测要求。     

离子色谱法测定面制品和面包改良剂中的溴酸盐

用离子色谱法测定面制品和面粉改良剂中的溴酸盐。用30 mL水超声提取样品15 min(脂肪含量高的样品先用正己烷除脂),过HLB柱和银氢柱净化,以AS9–HC色谱柱分离,NaHCO3作为淋洗液,电导检测器检测,实现了复杂基质面制品中溴酸盐的检测。方法线性相关系数大于0.999,最低检测浓度为0.5 mg/kg,加标回收率为78.4%~106.3%。利用建立的方法对面制品和面包改良剂中的溴酸盐进行检测,共检测各类面制品144份,总体合格率为97.2%;检测面包改良剂类产品10份,合格率为40.0%。     

A sensitive spectrophotometric method for the determination of dithiocarbamate fungicide and its application in environmental samples

A sensitive spectrophotometric method based on the evolution of CS₂ and colour development by leuco crystal violet is described for the determination of dithiocarbamate fungicides, e.g. thiram, ziram and zineb. Dithiocarbamate fungicides release CS₂ on acid hydrolysis. This CS₂ is absorbed in ethanolic sodium hydroxide and forms xanthate. The xanthate formed is subsequently treated with potassium iodate and N-chlorosuccinimide, during which free iodine is liberated. Crystal violet dye was formed through selective oxidation of leuco crystal violet by liberated iodine, which has an absorbance maxima at 595 nm. The colour systems obey Beer's law in the range of 0.02–0.20, 0.02–0.24 and 0.04–0.32 ppm for thiram, ziram and zineb respectively. The molar absorptivity of the colour system were found to be 9.6×10⁵, 1.1×10⁶ and 6.8×10⁵±100 l mol⁻¹ cm⁻¹ for thiram, ziram and zineb respectively. The method has been successfully applied to the determination of these dithiocarbamate fungicides in various environmental samples.     

离心沉淀气相色谱法测定面粉中过氧化苯甲酰含量的研究

建立了离心沉淀,气相色谱氢火焰离子化检测器测定面粉中过氧化苯甲酰含量的方法。考察了不同提取时间和采用不同工作曲线对过氧化苯甲酰测定的影响。试样在石油醚中被冰乙酸还原成苯甲酸,经HP-5（30m×0．25mm×0．25μm）毛细管气相色谱柱分离,氢火焰离子化检测器测定。方法的线性范围为0．005～0．08g／L（r=0．9992）,检出限（S／N=3）为2mg／kg。在添标水平为0．06、0．18和0．30g／kg时的平均回收率为82．70％～89．46％,相对标准偏差为3．77％～6．93％。该方法仪器设备简单,测定结果灵敏、准确,适合面粉中过氧化苯甲酰的测定。     

基于真菌毒素污染差异的液相色谱-串联质谱法鉴别板栗粉中掺假小麦粉

建立了分散固相萃取-超快速液相色谱-串联质谱法同时测定板栗粉和小麦粉中43种真菌毒素的方法,对48份板栗粉和80份小麦粉样品的污染状况进行调查,筛选出5种专属于小麦粉的标志性真菌毒素.样品采用84％(v/v)乙腈水溶液提取,提取液采用C18结合增强型脂质去除净化剂(EMR-Lipid)净化,采用响应曲面-中心组合设计优...     

基于超高效液相色谱-高分辨质谱的非衍生化法测定面粉和燕麦中草甘膦及氨甲基膦酸残留

建立了固相萃取-超高效液相色谱-高分辨质谱（UPLC-HRMS）快速准确测定面粉和燕麦中残留草甘膦（GLY）及其代谢物氨甲基膦酸（AMPA）的分析方法。面粉和燕麦样品经水涡旋和超声提取,用混合阳离子交换固相萃取（MCX）小柱净化与乙腈沉淀蛋白质后,以5 mmol/L乙酸铵水溶液（pH=10.5）和乙腈溶液作为流动相在Dikma Polyamino HILIC色谱柱（150 mm×2.0 mm,5 μm）上进行梯度洗脱与分离,采用电喷雾电离源、负离子模式和平行反应监测（PRM）模式下,内标法定量分析。系统优化了液相色谱与高分辨质谱等仪器条件和样品前处理条件对GLY及其代谢物AMPA测定的影响,并比对了不同分析方法的基质效应,研究了进样系统残留。实验结果表明,GLY和AMPA在5.0~100.0 μg/L范围内呈现良好的线性关系（线性相关系数R²>0.999）,检出限分别为0.005和0.05 mg/kg;低（0.1 mg/kg）、中（0.5 mg/kg）、高（2.0 mg/kg）3个添加水平下,GLY和AMPA的加标回收率分别为93.8%~115%和89.8%~110%,相对标准偏差均小于10%。基质效应实验结果表明,利用同位素内标物能有效降低方法的基质抑制效应（基质效应参数|η|<3%）;进样系统的残留率小于1.0%。本方法与文献报道的衍生化法方法进行比对,结果表明,两种检测方法与靶值的相对偏差分别为2.19%和3.07%。将该方法用于弗帕斯（FAPAS）能力验证样品的测定（编号为09122,燕麦中GLY的测定）,结果满意,测定值与真值之间的偏离程度（z值）=0.2。FAPAS质控样品（编号为T09119QC,面粉中GLY的测定）检测结果显示本方法的准确度为102.2%。该方法具有快速、简便、灵敏和准确等优点,适合面粉与燕麦样品中GLY及其代谢物AMPA的日常监测。     

Spectrophotometric determination of some dithiocarbamates

A procedure has been developed for the determination of six dithiocarbamates [sodium dimethyldithiocarbamate (dibam), sodium diethyldithiocarbamate (NaDDC), tetramethylthiuram disulphide (thiram), zinc dimethyldithiocarbamate (ziram), sodium N-methylpiperazinecarbodithioate and potassium morpholine-4-carbodithioate] in microgram quantities by converting them into selenium dithiocarbamate complexes, which are then extracted into chloroform and measured at 430 nm against a reagent blank. The method is sensitive and can be used for the determination of dithiocarbamates in commercial samples and synthetic mixtures.     

Spectrophotometric determination of ziram (dithiocarbamate fungicide) by thiocyanate and rhodamine 6G method

A sensitive spectrophotometric method has been developed for the determination of ziram in water, vegetables and grains. The method is based on the dissociation of dithiocarbamate complex of zinc with thiocyanate and rhodamine 6G at pH 4 to form a pink coloured complex that is stabilized by gelatin. The method is simple and Beer's law is obeyed over the concentration range of 0.05-1 ppm of ziram. The method is free from interference of similar dithiocarbamate fungicides containing Mn(2+) and Fe(3+) ions.     

HPLC-Electrochemical detection with graphite-poly (tetrafluoroethylene) electrode Determination of the fungicides thiram and disulfiram

The suitability of composite graphite-poly(tetrafluoroethylene) (Teflon) electrodes as amperometric indicator electrodes in HPLC detection is demonstrated. The determination of the fungicides thiram and disulfiram in the presence of ziram has been chosen as an analytical problem. The optimization of working conditions, such as the choice of the organic solvent used in the mobile phase as well as its percentage, the potential applied to the composite electrode, and the time elapsed between mixing the carbamates and the injection, has been accomplished by using the wall-jet flow-cell configuration. The effect of the acetonitrile percentage used in the mobile phase on the retention of thiram, disulfiram, ziram and phenol was evaluated. Resolution up to the baseline can be achieved with 45% acetonitrile. The sensitivity of the determination of thiram and disulfiram in the presence of a constant concentration of ziram is slightly better when using a wall-jet cell; however, the background current is higher, as well as the baseline noise and the time necessary to achieve stabilization of the baseline before the injection. Lower limits of detection for both fungicides, as well as a better repeatability, were obtained when using a thin-layer flow cell configuration. As an application, the determination of thiram in spiked apple samples, at a level of 0.5 mg thiram kg(-1) apple, has been carried out with a mean recovery of 97 +/- 3% for a significance level of 0.05.     

Measurement of water absorption capacity in wheat flour by a headspace gas chromatographic technique

The purpose of this work is to introduce a new method for quantitatively analyzing water absorption capacity in wheat flour by a headspace gas chromatographic technique. This headspace gas chromatographic technique was based on measuring the water vapor released from a series of wheat flour samples with different contents of water addition. According to the different trends between the vapor and wheat flour phase before and after the water absorption capacity in wheat flour, a turning point (corresponding to water absorption capacity in wheat flour) can be obtained by fitting the data of the water gas chromatography peak area from different wheat flour samples. The data showed that the phase equilibrium in the vial can be achieved in 25 min at desired temperature (35°C). The relative standard deviation of the reaction headspace gas chromatographic technique in water absorption capacity determination was within 3.48%, the relative differences has been determined by comparing the water absorption capacity obtained from this new analytical technique with the data from the reference technique (i.e., the filtration method), which are less than 8.92%. The new headspace gas chromatographic method is automated, accurate and be a reliable tool for quantifying water absorption capacity in wheat flour in both laboratory research and mill applications.     

正交实验法在小麦粉中甲醛振荡提取条件的应用研究

小麦粉中甲醛的提取问题是一个比较复杂的多因素问题。采用正交实验法,选用L9(34)正交实验表,在提取试剂、提取温度、提取时间等多个因素和水平中优选小麦粉中甲醛振荡提取的最佳条件。实验中甲醛提取量采用Nash试剂柱前衍生高效液相色谱法测定。结果表明,提取温度是小麦粉中甲醛提取的最主要因素,最佳的提取条件为提取温度30℃、提取液为硫酸钠、提取时间为40min。     

Determination of nickel, chromium and cobalt in wheat flour using slurry sampling electrothermal atomic absorption spectrometry

The slurry technique was applied to the determination of Ni, Cr and Co in wheat flour by electrothermal atomic absorption spectrometry (ETAAS). The influence of the graphite furnace temperature programme was optimized. Optimum sensitivity was obtained by using a mixture of 15% HNO₃–10% H₂O₂ as suspended medium for a 3% w/v slurry in the determination of Ni; lower concentrations of HNO₃ were necessary for the determination of Co and Cr (viz. 5 and 10%). The precision of direct analyses of the slurries was improved by using mechanical agitation between measurements; thus, the RSD of the measurements was ca. 5% for repeatability. The direct slurry sampling (SS) technique is suitable for the determination of Ni and Cr in wheat flour samples at levels of 150–450 and 30–72 ng g⁻¹, respectively, as it provides results similar to those obtained by ashing the sample. However, the typically low level of Co in these samples precluded its determination by the proposed method (the study was made in an SRM spiked wholemeal flour), at least in those samples that were contaminated with elevated concentrations of the metal (viz. more than 90 ng of Co per g of flour). The method provides a relative standard deviation of 6, 8, and 4% for Ni, Cr, and Co, respectively.