液液萃取-气相色谱法测定缓释尿素中吡唑类硝化抑制剂

建立了一种快速测定缓释尿素中吡唑类硝化抑制剂（DL-1）的方法-液液萃取．气相色谱法。从5种有机溶剂中选出三氯甲烷作为DL-1的萃取剂,并采用盐析的方法将革取率提高。本文采用内标法,通过SE30柱,氢火焰离子化检测器（FID）定量检测三氯甲烷萃取相中DL-1。萃取率为96．08％～98．10％,平均萃取率为97．33％;回收率为87．96％～90．54％;RSD为0．089％～1．6％,本法测定缓释尿素中的DL-1含量快速、灵敏,便于产品的质量监控。     

液相微萃取-气相色谱法测定水样中邻苯二甲酸酯

建立了水试样中5种痕量邻苯二甲酸酯的单液滴液相微萃取-气相色谱检测方法。确定了对单液滴液相微萃取(SDME)的最佳实验条件。DMP、DEP、DBP、DEHP和DOP的方法检出限分别为0.042、0.0037、0.0097、0.045和0.23μg/L。将该方法应用于某江水、湖水、自来水和饮用纯净水试样的检测,相对标准偏差(RSD)在1.4%~14.0%;回收率在90.8%~107.0%。本方法简单、快速并且成本低、可信度高。     

固相微萃取活性炭涂层萃取头的制备及其对卤代烃化合物的萃取

利用自制的有机硅树脂胶粘剂和粉状活性炭制成活性炭涂层萃取头。该萃取头富集能力强,对氯仿、四氯化碳、三氯乙烯、四氯乙烯4种卤代烃化合物的富集率达到13.8~18.7倍;热稳定性好,最高使用温度可达290 ℃;使用寿命长,250 ℃解吸条件下可反复使用140次以上。上述4种化物固相微萃取-气相色谱分析的结果表明,方法的最低检出质量浓度为0.008~0.05 μg/L。采用该萃取头对含有该4种卤代烃化合物的实际水样进行了SPME-GC分析,4种化合物的回收率为95.5%~104.6%。     

微波快速萃取-荧光衍生化HPLC-MS测定不同品种金银花中游离脂肪酸

建立了金银花中游离脂肪酸的微波快速萃取方法,采用柱前荧光衍生化法,测定了金银花中16种长链饱和与不饱和游离脂肪酸的含量。微波萃取功率800 W,溶剂V(氯仿):V(甲醇)=1:1,70℃萃取8 min,萃取率>98.8%。采用酸性乙腈/水流动相在反向C8色谱柱上进行梯度洗脱,HPLC荧光检测波长为505 nm,在线联用质谱辅助鉴定(APCI-MS),提高了检测的准确度。方法检出限在0.366~2.58μg/L之间,回收率88.3%~107.6%。     

中药材中拟除虫菊酯类农药残留的微波萃取/气相色谱检测

研究了采用微波辅助萃取法从中药材中提取拟除虫菊酯类农药的影响因素。拟除虫菊酯类农药用毛细管气相色谱-电子捕获检测器检测。实验结果表明萃取中药材中拟除虫菊酯类农药残留的最佳微波萃取参数设置为:萃取温度80℃;萃取时间10 min;萃取压力808 kPa。在此微波萃取条件下,萃取回收率在80%~108%之间,相对标准偏差介于4.4%~5.8%,方法检出限(S/N=3)为0.04~0.16μg.g-1。     

微波萃取/GC-MS法对电子电气产品中多氯萘的测定

建立了微波萃取/GC-MS法检测电子电气产品中多氯萘的方法。将破碎后的样品以甲苯为溶剂进行微波萃取,萃取液经硅胶小柱净化、平行蒸发定量浓缩后采用气相色谱-质谱法测定多氯萘的含量,外标法定量。优化了样品前处理条件,包括前处理方式、微波萃取溶剂、萃取时间,以及净化小柱的选择。对于8种含不同氯原子数的多氯萘,在1~50 mg/L范围内,线性关系良好,相关系数均大于0.995;方法定量下限为0.2~1.0 mg/kg,相对标准偏差为2.7%~7.2%,回收率为77%~112%。该法操作简便、分析迅速、结果准确,可以满足对电子电气产品中多氯萘的定性确证和定量分析。     

克菌丹和灭菌丹的气相和液相色谱分析方法

采用气相色谱法和高效液相色谱法两种方法分别对克菌丹和灭菌丹进行定性定量分析。气相色谱法均以邻苯二甲酸二戊酯为内标物,色谱柱采用3%OV-101 chromosorb AW DMCS 150~177μm,1 m×3 mm玻璃柱,柱温为195℃,汽化温和检测温均为230℃,克菌丹和灭菌丹的回收率分别为99.2%~100.7%和98.8%~99.9%;方法相对标准偏差分别为0.46%和0.59%。高效液相色谱法中使用Nova-PaK C18250 mm×4.6 mm色谱柱,以V(甲醇)∶V(水)=85∶15为流动相,检测波长为225 nm。克菌丹和灭菌丹的回收率分别为99.5%~100.6%和98.9%~99.7%;方法相对标准偏差分别为0.68%和0.51%。     

药物中水合肼残留量的气相色谱分析

建立了用气相色谱-氮磷检测器(GC-NPD)测定药物中水合肼的新方法。其萃取和衍生采用同一种试剂-丙酮,一步完成,可简单快速地定量检测药物中水合肼的残留量,其检出限为41.0μg/kg;相对标准偏差小于4.1%;回收率在101.5%~107.8%。已用于药物中水合肼的残留量分析。     

气相色谱法测定饮用水中碘代消毒副产物碘代三卤甲烷的研究

对比研究了吹扫捕集/气相色谱-质谱法(PT/GC-MS)和液液萃取-气相色谱/电子捕获检测器(LLE-GC/ECD)检测饮用水中碘代三卤甲烷(I-THMs)的分析方法。结果表明,采用甲基叔丁基醚(MTBE)作为萃取剂直接液液萃取,LLE-GC/ECD检测更适于I-THMs的分析。在选定条件下,内标法定量,6种ITHMs在0.5~1 000μg/L范围内线性关系良好,相关系数均大于0.99,相对标准偏差(RSD,n=7)为3.9%~6.4%,方法检出限为0.05~0.11μg/L。0.5,2.0,10.0μg/L加标水平下,分别对某地表水、水厂滤后水和自来水进行I-THMs的加标回收实验,平均回收率为81.2%~108.6%,RSD为2.6%~7.7%。结果表明,该方法简便、快速、灵敏,适用于饮用水中新兴消毒副产物I-THMs的检测。     

GC-MS法测定木质食品接触材料中10种多氯苯酚

建立了气相色谱-质谱法(GC-MS)同时测定木质食品接触材料中10种多氯苯酚化合物含量的检测方法。样品中10种多氯苯酚化合物经甲醇萃取,提取液在K_2CO_3溶液环境中经乙酸酐乙酰化后以正己烷萃取,经DB-5MS型毛细管气相色谱柱分离,质谱定量。结果表明:10种多氯苯酚化合物含量在1.0~200μg/m L范围内呈良好的线性关系,线性相关系数R~20.9996;检出限均低于1.0 mg/kg;回收率为88.4%~103.6%,相对标准偏差(n=6)为2.1%~4.6%。方法能够满足对木质食品接触材料中10种多氯苯酚化合物的分析要求。     

Efficient Extractive Desulfurization of Fuel Oils Using N‐Pyrrolidone/Alkylphosphate‐Based Ionic Liquids

Four BrØsted acid ionic liquids (ILS) [MMP][DMP], [MEP][DEP], [HMP][DMP] and [HEP][DEP] were synthesized and used as extractants for desulfurization of aromatic sulfur compounds in model oil. The mutual solubility of four ILs were investigated. The extraction equilibrium of four ILs could be reached in as soon as 5 min and the extraction capability followed the order [MMP][DMP]>[MEP][DEP]>[HEP][DEP]>[HMP][DMP]. The S extraction showed the highest efficiency under the conditions of 30°C, 30 min and 1:1 (V/V) IL:oil. Under the optimal condition, 70.9% of thiophene (TS), 76.9% of benzothiophene (BT) and 87.5% of dibenzothiophene (DBT) in n‐octane could be efficiently removed by [MMP][DMP]. The multiple extraction and regeneration performance of [MMP][DMP] for TS was also investigated and the results were satisfying. These results suggest that [MMP][DMP] has the best extraction capability and can serve as a promising solvent for extractive desulfurization of fuel oils.     

超声辅助分散液液微萃取-高效液相色谱测定水样中的4种邻苯二甲酸酯类增塑剂

建立了采用超声辅助分散液液微萃取技术结合高效液相色谱法(UA-DLLME-HPLC)对4种邻苯二甲酸酯(PAEs)进行富集、检测的方法,并成功应用于实际水样分析。实验中采用富集因子来评价萃取效率,考察并优化了影响萃取效率的主要因素,包括萃取剂类型和用量、分散剂类型和用量、超声时间、离子强度、萃取时间和pH值等。结果表明: 在最佳萃取条件下,该法对4种PAEs（邻苯二甲酸二甲酯、邻苯二甲酸二乙酯、邻苯二甲酸二丁酯和邻苯二甲酸二正辛酯）具有较高的富集能力,富集因子分别为71、144、169和159;检出限分别为3.78、1.77、3.07和3.30 μg/L。对实验室自来水、某品牌矿泉水以及湖水分别加标50、200及500 μg/L的回收率为82.99%～114.47%,相对标准偏差为1.93%～8.31%。该法简便、快速、环保,可以用于测定实际水样中的PAEs类增塑剂。     

Stir bar sorptive extraction coupled to thermodesorption-gas chromatography-mass spectrometry for the determination of insect repelling substances in water samples

Stir bar sorptive extraction (SBSE) in combination with thermodesorption-gas chromatography-mass spectrometry (TD-GC-MS) was applied for the determination of eight insect repellents and synergists in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 20 mL of water sample with 4 g NaCl and stirred at 1000 rpm for 180 min. Then, the stir bar was subjected to TD-GC-MS. SBSE parameters (ionic strength, presence of organic solvent and time) were optimised. Blank contamination and carryover problems were also studied. The method affords detection limits between 0.5 and 30 ng/L, except for dimethyl phthalate (DMP) (150 ng/L) due to blank contamination problems. It shows good linearity with correlation coefficients over 0.997 and reproducibility (RSD) below 20%. The extraction efficiencies were between 29% for DMP and 80% for di-n-propyl isocinchomeronate (R-326). The feasibility of the method was tested by analysing real samples such as lake water, river water and wastewater.     

A novel method to prepare monolithic molecular imprinted polymer fiber for solid‐phase microextraction by microwave irradiation†

In this paper, a new approach to prepare monolithic molecularly imprinted polymer (MIP) fibers for solid‐phase microextraction is proposed with the help of microwave irradiation. Imprinting polymerization was carried out within silica capillaries in 4.5 min, using dimethyl phthalate (DMP) as a template molecular, α‐methacrylic acid as a functional monomer and ethylene dimethacrylate as a crosslinker, acetonitrile as the porogenic solvent. The synthesis was optimized by varying the ratio of template/monomer and different volume of porogen. The resulted MIP fibers were obtained after silica being etched away with a controlled length of 1 cm, and subsequently characterized by SEM. In order to increase the selective extraction of DMP, factors affecting the extraction including extraction time, salt concentration, desorption time, and desorption solvents were investigated for solid‐phase microextraction procedures in detail. The selectivity coefficients, defined as the extraction amount ratio of MIP to its nonimprinting fiber, were 5.6, 2.6, and 1.4 for DMP and its counterpart including dibutyl phthalate and di‐n‐octylo‐phthalate, respectively. The resulted fibers were also applied to detect DMP, dibutyl phthalate, and di‐n‐octylo‐phthalate in bottled beverage samples coupled to HPLC and resulted in relative recoveries of up to 73.8–98.5%, respectively.     

Utilization of homogeneous liquid–liquid extraction followed by HPLC-UV as a sensitive method for the extraction and determination of phthalate esters in environmental water samples

A simple and sensitive method for the extraction of four phthalate esters including dimethyl phthalate (DMP), diethyl phthalate (DEP), benzyl butyl phthalate (BBP) and di-n-butyl phthalate (DBP) as well as their determination in water samples was developed using homogeneous liquid–liquid extraction (HLLE) and HPLC-UV. The extraction method is based on the phase separation phenomenon by the salt addition to the ternary solvent system. The extraction parameters such as type and volume of extracting and consolute solvent, concentration of salt, pH of sample and extraction time were optimized. Under the optimal conditions (extraction solvent: 100?µL CHCl₃; consolute solvent: 2.0?mL methanol; NaCl 15% (w/v) and pH of sample: 6.5) extraction recovery was in the range of 92–102%. Linearity was observed in the range of 0.5–300?µg?L^?1 for DEP and 0.6–300?µg?L^?1 for DMP, BBP and DBP. Correlation coefficients (r ²), limits of detection (LODs) and relative standard deviations (RSDs) were in the ranges of 0.9976–0.9993, 0.18–0.25 and 1.5–4.8%, respectively. The method was successfully applied for the preconcentration and determination of these phthalate esters in the several environmental water samples.     

Does a diol cyclic urea inhibitor of HIV-1 protease bind tighter than its corresponding alcohol form? A study by free energy perturbation and continuum electrostatics calculations

The cyclic urea inhibitors of HIV-1 protease generally have two hydroxyl groups on the seven-membered ring. In this study, free energy perturbation and continuum electrostatic calculations were used to study the contributions of the two hydroxyl groups to the binding affinity and solubility of a cyclic urea inhibitor DMP323. The results indicated that the inhibitor with one hydroxyl group has better binding affinity and solubility than the inhibitor with two hydroxyl groups. Therefore, removal of one hydroxyl group from DMP323 may help to improve the properties of DMP323. This is also likely to be true for other cyclic urea inhibitors. The study also illustrated the difficulty in accurate modeling of the binding affinities of HIV-1 protease inhibitors, which involves many possible protonation states of the two catalytic aspartic acids in the active site of the enzyme.     

LC Determination of Phthalate Esters in Water Samples Using Continuous-Flow Microextraction

A novel method, continuous-flow microextraction (CFME) combined with liquid chromatography (LC) with variable-wavelength detector (VWD), has been developed for the determination of three phthalate esters (dimethyl phthalate (DMP), diethyl phthalate (DEP), and di-n-butyl phthalate (DnBP)) in water samples. Experimental parameters including extraction solvent, solvent drop volume, flow rate of sample solution, extraction time and ionic strength, which affected the extraction efficiency, were studied and optimized. Under the optimum extraction conditions, the method yields a linear calibration curve in the concentration range of 10–10,000 ng mL^?1 for target analytes. The enrichment factors of this method for DMP, DEP and DnBP reached at 27, 44 and 20, respectively, and the detection limits were 2, 1 and 5 ng mL^?1, respectively. Good repeatability of extraction was obtained with relative standard deviations below 8.6%. The results demonstrated that CFME followed by LC-VWD is a simple and reliable technique for the determination of phthalate esters in water samples.     

Determination of Dextromethorphan and its Metabolite Dextrorphan in Human Hair by Gas Chromatography–Mass Spectrometry

An analytical method has been developed for determination of dextromethorphan (DMP) and dextrorphan (DRP) in human hair by gas chromatography–mass spectrometry (GC–MS). Hair samples (30 mg) were washed with distilled water and acetone and cut into small fragments (<1 mm) before extraction with methanol. The extracts were evaporated to dryness and then derivatized by use of BSTFA containing 1% TMCS, for preparation of the trimethylsilyl (TMS) derivative of DRP. The extract (1 μL) was then injected into the GC–MS. Recoveries of DMP and DRP at 7.0 and 22.5 ng mg^?1 were in the range 90.6–97.2% with intra-assay and inter-assay precision of less than 5.7% and 4.7%, respectively. LOD and LOQ were, respectively, 0.67 and 2.13 ng mg^?1 for DMP and 0.14 and 0.47 ng mg^?1 for DRP. The responses were linear with correlation coefficients (r > 0.9995) for the drugs studied. The applicability of the method was proven by analysis of authentic hair samples.     

Determination of phthalate esters in water samples using Nylon6 nanofibers mat-based solid-phase extraction coupled to liquid chromatography

A new method was developed for simultaneous determination of five phthalate esters by a combination of mat-based solid-phase extraction (SPE) with high-performance liquid chromatography. The mat is composed of Nylon6 nanofibers. Dimethyl phthalate (DMP), diethl phthalate (DEP), di-n-butyl phthalate (DBP), di-(2-ethylhexyl) phthalate (DEHP) and dioctyl phthalate (DOP) were successfully separated on a RP-C18 column. Under optimized conditions, the detection limits found for DMP, DEP, DBP, DEHP and DOP were 3, 2, 6, 10 and 33 pg mL^?1, respectively. The method was applied to the analysis of various water samples. Spiked samples gave recoveries in the range from 86.9 to 101.9%, with relative standard deviations below 7.0%. A comparison of Nylon6 nanofibers mat as sorbents, and C18 cartridges and other kinds of SPE sorbents was carried out with respect to recovery, sensitivity, and reproducibility. The results indicated that the Nylon mat is a viable material for the enrichment and determination of phthalate esters in environmental water samples.     

A novel liquid-phase microextraction method combined with high performance liquid chromatography for analysis of phthalate esters in landfill leachates

A novel liquid-phase microextraction (LPME) method was presented in this paper. The most attractive feature of this method is using a polychloroprene rubber tube (PCR tube) instead of a microsyringe to load organic solvent. The PCR tube and sample vial were horizontally placed so that the selection of organic solvent was not affected by the density of extractant. Therefore, the stability of organic solvent increased and the available organic solvent was extended greatly. In this work, three phthalate esters (PAEs) (dimethyl phthalate (DMP), diethyl phthalate (DEP), and di-n-butyl phthalate (DnBP)) were chosen as model analytes to testify the feasibility of the new method. A series of extraction parameters have been investigated systematically. Under the optimized condition, the method showed linear response over four orders of magnitude, ranged from 0.005 mg L⁻¹ to 50 mg L⁻¹. The correlation coefficients (r) were better than 0.997 and the limits of detection (LOD) were 0.0012 mg L⁻¹ for DMP, 0.0014 mg L⁻¹ for DEP and 0.0022 mg L⁻¹ for DnBP. Good reproducibility of extraction was acquired, the inter-day and intra-day relative standard deviation (R.S.D.) were below 7.9% and 7.4%, respectively. Recoveries that ranged from 82.7% to 116.9% were gained when the new method was used to determine three phthalate esters in landfill leachates. The enrichment factors were 5–26 for the three PAEs. The novel LPME is promising to be an alternative sample preparation method for extracting target analytes in complex sample matrices because of the simplicity, low cost and short sample preparation time.