液液萃取处理样品-气相色谱法测定水中22种有机氯农药

采用正己烷作萃取溶剂提取并富集水样中有机氯农药(OCP),所得提取液经浓缩并定容为1.0mL后,用气相色谱法-电子捕获检测器测定22种有机氯农药。采用Rtx-CLPⅡ和Rtx-1701双柱法根据与标准物质的保留时间相比较进行定性;采用Rtx-CLPⅡ柱对被测组分按外标法进行定量。结果表明:各种农药质量浓度在1～80μg·L~(-1)范围内与峰面积呈线性关系。22种有机氯农药的方法检出限(3S/N)在1.5～5.6ng·L~(-1)之间。用标准加入法测得其回收率在73.3%～107.9%之间,相对标准偏差(n=7)在2.9%～14.8%之间。     

液液萃取分离-气相色谱-串联质谱法同时测定水中12种有机氯农药

采用液液萃取分离-气相色谱-串联质谱法同时测定水中12种有机氯农药的含量。样品经正己烷提取,在气相色谱分离中用DB-5MS色谱柱为固定相,在质谱分析中采用多反应监测模式。12种有机氯农药在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限在0.002~0.032μg·L~(-1)之间,测定下限在0.008~0.128μg·L~(-1)之间。以空白样品为基体进行加标回收试验,所得回收率在99.1%~126%之间,测定值的相对标准偏差(n=7)在2.3%~9.3%之间。     

液液萃取-气相色谱-质谱联用法测定饮用水中19种农药残留量

提出了液液萃取富集-气质联用法测定饮用水中19种农药的残留量。样品用二氯甲烷萃取3次(20,10,10mL),萃取液合并后旋转蒸发至1.0mL,分取1.0μL进样,进行气相色谱-质谱分析。用HP-5MS毛细管柱分离及电子轰击离子源,用离子检测扫描模式做质谱测定。用菲-d_(10)作内标,峰面积定量。19种农药在一定浓度范围内呈线性,检出限(3S/N)为0.002～0.10mg·L~(-1)之间,回收率在81.1%～103.0%之间,相对标准偏差(n=6)为0.25%～7.7%。     

分散液液微萃取-气相色谱-质谱法测定水中环氧七氯

向已加入100mg氯化钠的5.0mL水样中加入由20.0μL四氯乙烯、1.0mL丙酮混合而成的分散微萃取溶液,采用气相色谱-质谱法测定萃取相中环氧七氯的含量。在气相色谱分离中采用DB-5ms石英毛细管色谱柱,在质谱分析中采用选择离子监测模式。环氧七氯的质量浓度在0.5～200μg·L~(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)为0.1μg·L~(-1)。以空白样品为基体进行加标回收试验,所得回收率为81.6%～97.4%,测定值的相对标准偏差(n=5)为4.6%～7.2%。     

分散液相微萃取-气相色谱法快速测定党参中10种有机氯类农药残留

将党参样品粉碎后过0.250 mm筛,称取1.000g,加入20 mL正己烷,超声提取20min,过滤后,移取50μL滤液,加入950μL水制成1.0mL的样品溶液,迅速加入60μL邻二氯苯与200μL甲醇的混合溶液,涡旋30s,使之成为乳浊液体系,在3 500r·min~(-1)下离心5min,取下层沉积相用N2吹干,加50μL甲醇复溶后,采用气相色谱法测定其中10种有机氯类农药。在最佳试验条件下,10种有机氯农药在0.50～20.0μg·L~(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)在0.5～3.0μg·kg~(-1)之间,富集倍数在11.2～25.5之间。加标回收率在90.1%～109%之间,测定值的相对标准偏差(n=5)在1.6%～6.2%之间。     

新型吸附剂-固相萃取-超高效液相色谱-串联质谱法测定鱼塘水中21种常见农药

取鱼塘水样4L于5 000mL烧瓶中,加入混合内标溶液[含0.5mg·L~(-1)普罗迪芬盐酸盐(SKF525A)和2mg·L~(-1)苯巴比妥]100μL。另取由4种常用填料C_8、C_(18)、GDX403及X-5,按1∶2∶1∶8的质量比混合组成的新型吸附剂6g,置于甲醇10mL中浸泡活化并过滤,将经活化的吸附剂加入于上述水样中,于振摇器上振荡1h,经减压过滤,在所收集的固相吸附剂(包括其所吸附的农药)以及滤纸中,加入无水硫酸镁5g和苯及乙酸乙酯各100mL,振荡萃取10min,通过1.0μm滤膜过滤,取滤液并吹氮蒸发至近干,用甲醇溶解残渣并定容其体积为1.0mL。将此溶液通过0.22μm滤膜过滤,取滤液按所选择仪器工作条件进行超高效液相色谱-串联质谱法(UPLC-MS/MS)分析。上述预富集中所用新型吸附剂对所测定的常见农药进行固相萃取富集时,各农药中有11种的回收率大于90.0%,全部试验农药的平均回收率达82.0%。色谱分离中,选用IntertSustain C_(18)柱为固定相,以不同比例的(A)0.1%(体积分数)甲酸的20mmol·L~(-1)乙酸铵溶液,或(A′)不加甲酸的20mmol·L~(-1)乙酸铵溶液,和(B)乙腈或(B′)甲醇的混合液作为流动相,按3种不同的程序进行洗脱。在此条件下,所测定的农药和2种内标的保留时间在0.53～9.81min之间。在质谱分析中,选择正、负离子2种电离模式和多反应监测(MRM)模式进行测定,用内标法定量。所测农药中17种农药的线性范围在0.005～0.5μg·L~(-1)之间,其余4种农药的线性范围在0.01～0.5μg·L~(-1)之间,检出限(3S/N)为1～5ng·L~(-1)之间。以加标方法进行准确度试验,根据测得质量浓度和理论质量浓度的比值得到的结果在92.5%～106%之间,测定值的相对标准偏差(n=6)为1.3%～9.7%(日内)和2.5%～13%之间(日间)。     

加速溶剂提取-气相色谱法测定土壤中3种有机磷和9种有机氯农药

提出了气相色谱法测定土壤中3种有机磷和9种有机氯农药含量的方法。样品经粉碎后用正己烷-丙酮(1+1)混合溶剂经加速溶剂萃取仪在60℃静态萃取10min。采用Rtx-1701色谱柱分离,火焰光度检测器测定3种有机磷农药;采用Rtx-CLPⅡ色谱柱分离,电子捕获检测器测定9种有机氯农药。12种有机农药的质量浓度均在5.0～80μg·L-1范围内呈线性,方法的检出限(3s)在0.02～0.40μg·kg-1之间。以空白石英砂样品为基体,进行加标回收试验,回收率在78.5%～108%之间,相对标准偏差(n=7)在4.2%～9.9%之间。     

气相色谱-质谱法测定陈皮及其制品中的三氯杀螨醇和拟除虫菊酯残留量

样品2.000 0g,加水2mL或4mL浸润,再加入乙酸乙酯-正己烷(1+1)混合液5mL,超声5min,提取2次。合并的提取液吹干,残渣用乙酸乙酯-正己烷(1+1)混合液2mL溶解,经被氧化的改性多壁碳纳米管净化后,其中的三氯杀螨醇和8种拟除虫菊酯农药采用气相色谱-质谱法测定。以Rtx-1701毛细管色谱柱为固定相进行气相色谱分离。质谱分析中采用选择离子监测模式,外标法定量。9种农药的质量浓度在0.010~1.0mg·L~(-1)内与其峰面积呈线性关系,检出限(3S/N)在3.5~6.0μg·kg~(-1)之间。按标准加入法在3个浓度水平上进行回收试验,回收率在84.8%~105%之间,测定值的相对标准偏差(n=6)在3.1%~8.2%之间。     

固相萃取-原子荧光光谱法测定大米中无机硒的含量

建立了固相萃取-原子荧光光谱法测定大米中无机硒含量的方法。大米粉样品0.5 g用水20 mL提取,离心后上清液中加入5 g·L~(-1)氢氧化钠溶液,调至pH 4～7,过滤即得提取液。将提取液上SAX强阴离子交换柱进行固相萃取,收集洗脱液10 mL以分离无机硒,再采用原子荧光光谱法测定大米中无机硒的含量。结果表明:无机硒的质量浓度在10μg·L~(-1)以内与其对应的荧光强度呈线性关系,检出限(3s)为2.52μg·kg~(-1)。按标准加入法进行回收试验,回收率为90.3%～98.2%,测定值的相对标准偏差(n=6)为9.9%～19%。     

涡旋辅助分散液液微萃取-气相色谱法测定饮用水中11种氯苯类化合物

移取饮用水样品10.0mL,加入0.5g氯化钠和100μL二硫化碳,以2 500r·min~(-1)转速离心5min,静置5min后,移取离心管底部的沉积相(约65μL),采用气相色谱法测定其中11种氯苯类化合物的含量。11种氯苯类化合物用Agilent JW DB-WAX毛细管色谱柱分离,电子俘获检测器检测。11种氯苯类化合物的质量浓度在一定范围内与其对应的峰面积呈线性关系,方法的检出限(3S/N)为0.032～0.97μg·L~(-1)。以空白样品为基体进行加标回收试验,所得回收率为86.7%～101%,测定值的相对标准偏差(n=6)为1.2%～3.3%。     

毛细管气相色谱法测定烟草及烟气中有机氯农药残留量

烟草样品或从卷烟烟气中收集到的固态悬浮颗粒样品以正己烷在索氏提取器中提取,提取液用弗罗里硅土固相萃取净化,所得溶液经蒸缩至5mL后,供气相色谱法测定。采用DB-5弹性石英毛细管柱分离样品,电子捕获检测器检测,共测定了17种有机氯农药(OCP′s),其检出限(3S/N)在0.02～0.10μg.g-1范围内。平均加标回收率为86%～92%,相对标准偏差(n=7)为3.0%～4.1%。     

气相色谱-质谱法测定塑料玩具中多环芳烃

提出了气相色谱-质谱法测定塑料玩具中16种多环芳烃(PAH′s)含量的方法。样品经正己烷超声提取30min后,40℃水浴氮气吹干。用水、甲醇和正己烷-二氯甲烷(3+2)混合溶剂各5mL溶解残渣,过C18固相萃取柱净化,用正己烷-二氯甲烷(3+2)混合溶液洗脱,所得洗脱液过HP-5MS色谱柱分离,电子轰击离子源检测。16种多环芳烃的质量浓度在0.2～4.0mg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.002～0.021mg·kg-1之间。以聚丙乙烯、聚乙烯、聚氯乙烯或丙烯腈-丁二烯-苯乙烯共聚物等4种材质的塑料玩具为基体,进行加标回收试验,回收率在79.6%～95.2%之间。     

Rapid screening of bioactive components from Zingiber cassumunar using elution-extrusion counter-current chromatography

Elution-extrusion counter-current chromatography (EECCC) takes full advantages of the liquid nature of the stationary phase. It effectively extends the solute hydrophobicity window that can be studied and renders the CCC technique particularly suitable for rapid analysis of complex samples. In this paper, EECCC was used to screen the crude ethanol extract of Zingiber cassumunar and to isolate milligram-amounts of bioactive components. The two column volume (2V(C)) EECCC method was applied to rapidly optimize the composition of the biphasic liquid system in both reversed- and normal-phase separation mode. With the n-hexane/ethyl acetate/methanol/water 1/1/1/1 (v/v) system, 100mg of crude Z. cassumunar extract were fractionated on a 140 mL-capacity semi-preparative hydrodynamic CCC column and 0.5 g on a 1600 mL column for large-scale preparation. Satisfactory separation efficiency was achieved in both cases, producing milligram-amounts of four phenylbutenoids over 90% pure and of a mixture of diastereoisomers (phenylbutenoid dimers). However, the global throughputs of the two columns were 8 and 11 mg/h, not very different. This is due to the fact that the 1600 mL column could not retain the liquid stationary phase as well as the smaller 140 mL column. It was necessary to work at much lower flow rate than calculated. Methanol was added as a post-column clarifying reagent for stable continuous UV detection. A lipophilic biphasic liquid system composed of n-hexane/acetonitrile/water (5/3/2, v/v) allowed to resolve the pair of diastereoisomers with the larger preparative instrument producing 35 mg of the (+/-)-trans form 99.1% pure and 28 mg of the (+/-)-cis isomer 98.1% pure. Compared with classical elution, the EECCC approach exhibits strong separation efficiency and great potential to be a high-throughput separation technique in the case of complex samples.     

Sensitive determination of n-hexane and cyclohexane in human body fluids by capillary gas chromatography with cryogenic oven trapping

A sensitive method was developed for determination of n-hexane and cyclohexane in human body fluids by headspace capillary gas chromatography (GC) with cryogenic oven trapping. Whole blood and urine samples containing n-hexane and cyclohexane were heated in a 7.5 mL vial at 70 degrees C for 15 min, and 5 mL of the headspace vapor was drawn into a glass syringe. All vapor was introduced through an injection port of a GC instrument in the splitless mode into an Rtx-Volatiles middle-bore capillary column at an oven temperature of -40 degrees C for trapping volatile compounds. The oven temperature was programmed to 180 degrees C for GC with flame ionization detection. These conditions gave sharp peaks for both n-hexane and cyclohexane, a good separation of each peak, and low background impurities for whole blood and urine. The extraction efficiencies of n-hexane and cyclohexane were 13.2-30.3% for whole blood and 12.7-20.7% for urine. The coefficients of within-day variation in terms of extraction efficiency of both compounds were 5.0-9.5% for whole blood and 3.8-10.8% for urine; those of day-to-day variation for the compounds were not greater than 16.6%. The regression equations for n-hexane and cyclohexane showed good linearity in the range of 5-500 ng/0.5 mL for whole blood and urine. The detection limits (signal-to-noise ratio = 3) for both compounds were 1.2 and 0.5 ng/0.5 mL for whole blood and urine, respectively. The data on n-hexane or cyclohexane in rat blood after inhalation of each compound are also presented.     

Establishing an alternative method for the quantitative analysis of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans by comprehensive two dimensional gas chromatography-time-of-flight mass spectrometry for developing countries

Comprehensive Gas Chromatography-Time-of-Flight Mass Spectrometry (GC×GC-TOFMS) methodology has been refined for the analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in samples with different matrices. This is specifically for application in developing countries where access to gas chromatography-high resolution mass spectrometry (GC-HRMS) and highly skilled personnel is limited. The method, using an Rxi-5 Sil MS column in the first dimension ((1)D) coupled with an Rtx-200 column in the second dimension ((2)D), was used to quantify PCDDs and PCDFs in different environmental sample matrices. The results were compared with those obtained using GC-HRMS and good agreement was observed. The limit of detection (LOD) for the method (300fg on column for spiked soil samples) was determined using an Rxi-XLB ((1)D) column coupled with an Rtx-200 column ((2)D). Preliminary South African sample results are also discussed. Isomer specificity for different tetrachloro dibenzo-p-dioxins (TCDDs) and tetrachloro dibenzofurans (TCDFs) was investigated using a commercial standard. Adequate resolution was achieved. The method as described has great attraction for developing countries being both financially and operationally favourable.     

液相色谱-质谱联用法测定牛奶中14种青霉素及相应青霉噻唑酸残留量

利用超高效液相色谱-串联质谱法(UPLC-MS/MS)同时测定牛奶中的7种青霉素类抗生素以及7种相应的青霉噻唑酸。样品经乙腈沉淀蛋白,上清液N2吹干后,用水溶解,加入正己烷萃取除去脂肪;提取液经ACQUITY UPLCBEH C18柱分离,乙腈-乙酸铵+甲酸水溶液洗脱。14种物质峰分离良好,定量限范围在5～20μg/kg。在10～50ng/mL质量浓度范围内线性良好,相关系数均大于等于0.999,牛奶中的加标回收率在90%～98%。     

Selectivity equivalence of two poly(methylphenylsiloxane) open-tubular columns prepared with different deactivation techniques for gas chromatography

The solvation parameter model is used to characterize the retention properties of a poly(methylphenylsiloxane) column Rxi-50 over the temperature range 60-240 degrees C. The smooth variation of the system constants with temperature affords a general picture of how the relative importance of the different intermolecular interactions change with temperature. The system constants and retention factors for varied compounds are compared with those for Rtx-50 prepared with a similar stationary phase but using a different surface deactivation technique. The two columns are shown to be nearly selectivity equivalent. The Rtx-50 column is slightly more cohesive, dipolar/polarizable and hydrogen-bond basic than Rxi-50, while Rxi-50 is slightly more electron lone pair attractive and hydrogen-bond acidic. Only the difference in hydrogen-bond acidity can be identified with some certainty as related to the difference in deactivation processes. For compounds with a separation greater than 0.2 retention factor units on Rtx-50, it should be relatively straightforward to achieve an acceptable separation for the same compounds on Rxi-50.     

Analytical procedure for the determination of chlorobenzenes in sediments

This study presents the procedure for the determination of chlorobenzenes in sediment. It consists of solvent extraction (shaking overnight), extract clean-up with the use of a homemade glass column packed with activated silica gel and freshly activated copper, and slow solvent evaporation to a volume of 0.3 mL. Two-microliter extract portions are analyzed by means of gas chromatography with an Rtx-624 capillary column (60 m x 0.32 mm, d(f) = 1.8 microm) coupled with mass spectrometry (in selected ion-monitoring mode). Deuterated 1,2-dibromobenzene is used as the recovery standard. The recovery of this method for all chlorobenzenes is high (ranging from 78% to 107%) with the exception of monochlorobenzene, which is 58%. The method is also characterized by good precision, which is commonly accepted in the analysis of trace organic pollution.     

2-(9-蒽基)-2-甲氧基乙酸乙酯的高效液相色谱手性拆分

以键合在5 μm硅胶上的纤维素-三(二甲基苯基氨基甲酸酯)为色谱柱的手性固定相,采用高效液相色谱(HPLC)法对外消旋的2-(9-蒽基)-2-甲氧基乙酸乙酯进行了手性拆分.对影响2-(9-蒽基)-2-甲氧基乙酸乙酯拆分的三个重要因素:流动相组成、流速、色谱柱温度进行了研究.实验结果表明,在流动相组成为正已烷-异丙醇(94/6,V/V),流速1.0 mL/min,柱温20℃的条件下,2-(9-蒽基)-2-甲氧基乙酸乙酯对映体得到很好的分离,分离度为3.63.     

毛细管柱气相色谱法测定人血清中有机氯农药残留量

提出了毛细管气相色谱测定人血清中有机氯农药残留量的方法。利用正己烷超声提取人血清样品中有机氯农药六六六和滴滴涕,所得萃取液作气相色谱测定,用甲酸及浓硫酸净化、磺化处理后,电子捕获检测器检测。在优化的试验条件下,8种有机氯农药同分异构化合物组分在20 min内能够很好的分离,其质量浓度与色谱峰面积在0.4～10μg·L~(-1)浓度范围内呈线性关系,检出限(3S/N)在0.07～0.30μg·L~(-1)之间。方法的日内的相对标准偏差为2.9%～5.4%,日间的相对标准偏差为4.5%～8.9%。方法的加标回收率在81.5%～117.6%范围。