顶空固相微萃取气相色谱法测定浓海水中的氯酚

建立浓海水中氯酚的顶空固相微萃取气相色谱法检测方法。采用顶空固相微萃取对海水淡化排放的浓海水样品中2,4,6-三氯酚(2,4,6-TCP)和五氯酚(PCP)进行分离富集,气相色谱-电子捕获检测器(μECD)测定浓海水样品中2,4,6-TCP和PCP的含量。讨论了萃取时间、萃取温度、水样盐度等实验条件对富集效率的影响,确定了萃取时间为40 min,萃取温度为60℃。2,4,6-TCP,PCP的质量浓度在0.500~20.0μg/L范围内与其色谱峰面积呈良好的线性关系,线性相关系数均大于0.999,2,4,6-TCP和PCP的检出限(2S/N)分别为0.055,0.128μg/L,测定结果的相对标准偏差为3.65%~11.4%(n=6),加标回收率为73.5%~119.0%。该方法快速,灵敏度高,适合于浓海水中氯酚的分析。     

离子色谱法同时测定面粉中9种无机阴离子含量

面粉样品经简单的超声波萃取,离心分离,上清液过C18固相萃取小柱后,采用电导抑制离子色谱法测定了面粉中氟、氯、溴、碘、亚硝酸根、硝酸根、硫酸根、磷酸根、溴酸根9种阴离子的含量。测定结果的相对标准偏差均小于8％,平均加标回收率在87．5％-96．0％之间。方法快速、简单,可满足面粉中9种阴离子的同时测定。     

DDTC阴离子交换树脂对痕量铜(Ⅱ)的预浓缩及光度测定

近年来,用强碱性阴离子交换树脂制备螯合型树脂柱已愈益为人们所重视。但均存在柱流速慢(<5mL/min)、洗脱剂用量大、预处理时间长及富集系数小等缺点。曾有人用十八烷基键合玻璃微珠预浓缩并用PADAP分光光度法测定钴。特点是洗脱剂用量少、浓缩倍数高(500倍),但水样需经预处理。我们综合上述两类层析柱优点,将铜试剂(二乙胺二硫代甲酸钠,NaDDTC)中的螯合集团交换在强碱性阴离子树脂上,制备了螯合型树脂柱。初步实验证明,含铜水样流经DDTC阴离子交换树脂柱后形成的中性铜螯合物被键合在树脂上,用氯仿洗脱,可浓缩万倍,水样毋需预处理,检出下限10~(-11)g/mL。     

阴离子交换色谱-积分脉冲安培检测法测定寿胎丸中游离氨基酸

建立了阴离子交换色谱-积分脉冲安培检测法测定寿胎丸煎煮液中游离氨基酸的分析方法。实验考察了18种氨基酸的梯度洗脱条件,优化了固相萃取条件,最终选用SSDBX型固相萃取小柱净化煎煮液。在优化实验条件下,进行了加标回收实验,回收率在71.2%~120.9%之间,相对标准偏差为0.8%~10.4%。18种氨基酸的检测限为0.07~5.00μg/L。方法能满足寿胎丸煎煮液中氨基酸的检测要求。     

环境中除草剂扑草净残留分析方法的研究

建立了高效液相色谱(HPLC)法测定环境中土壤、水和小麦中除草剂扑草净残留量的分析方法。采用丙酮超声提取,硅胶柱层析净化,测定土壤中扑草净残留量;水样直接用LC-18固相萃取小柱分离、净化和富集;采用超声提取,甲醇∶水=1∶1(V/V)为提取剂,LC-18固相萃取小柱分离、净化,测定小麦样品中扑草净的残留。结果表明:HPLC法检测扑草净的线性范围为0.5～16 mg.L-1,相关系数R2=0.9999,方法的检出限为0.0125 mg.L-1。土壤的加标回收率为88.2%～102.4%,相对标准偏差为6.3%～6.4%;水样的加标回收率为81.7%～102.5%,相对标准偏差为4.5%～4.6%;小麦的加标回收率为88.4%～101.7%,相对标准偏差为3.6%～5.5%。     

离子交换净化辐照三烷基氧化膦中脂肪酸

本文研究了用大孔阴离子交换树脂D301R从乏萃取剂30%TRPO-煤油溶液中净化去除脂肪酸的方法,探讨了该法用于乏萃取剂净化的可行性。     

磺酰脲类除草剂在水、土壤及小麦中残留分析的前处理方法研究

分别采用不同的前处理方法处理水、土壤和小麦样品。水样采用C18固相萃取小柱净化和富集;土壤样品以二氯甲烷为提取剂,超声波提取,液-液分配净化;小麦样品经二氯甲烷超声波提取,氟罗里硅土柱净化、富集。样品中磺酰脲除草剂甲磺隆、氯磺隆、苄嘧磺隆的残留量采用高效液相色谱-紫外检测器同时测定。三种磺酰脲除草剂在0.1～4.0mg·mL-1范围内线性良好,相关系数在0.9996～0.9997之间。水样、土壤样品和小麦样品的平均加标回收率分别为82.0%～107.0%、84.5%～100.6%、80.0%～98.5%,相对标准偏差在0.7%～11.2%之间。     

固相萃取-GC/MS法测定水样中20种有机氯农药

建立了用固相萃取小柱提取和净化、GC/MS定性定量同时测定水样中20种有机氯农药的方法。方法采用OasisHLB固相萃取小柱萃取富集水样,二氯甲烷洗脱,加入菲-d₁₀作为内标,利用GC/MS进行定性定量,步骤简便,线性响应良好,干扰小,方法检出限为0.21～0.72 ng/L（按水样1L计）,加标回收率为64.8%～122%,RSD为1.2%～11.0 %。成功利用该方法对广西实际河水样品进行了检测。结果表明方法可以同时满足环境水样中20种痕量有机氯农药的测定。     

高效液相色谱-质谱法分析测定水中氨基甲酸酯

采用固相萃取-高效液相色谱-质谱法（LC／MS）检测研究了水中氨基甲酸酯农药残留。水样用固相萃取富集净化,环己烷＋乙酸乙酯（1＋1）洗脱;以甲醇-10mmol／L乙酸铵为梯度流动相,Symmetry C18柱高效液相色谱分离。电喷雾正离子模式,选择质子化氨基甲酸酯分子离子[M＋H]^＋为定量离子进行MS测定。结果表明,6种氨基甲酸酯组分的平均加标回收率为73．5％～89．8％;相对标准偏差为4．50％～12．6％;水样浓缩至1／2500后的检出限为0．8～3．2ng／L。本法具有非常高的选择性、灵敏度和准确度,完全能满足水中痕量氨基甲酸酯农残的高灵敏分析。     

阴离子交换树脂分离富集水中痕量镉

先用草酸处理水样中的镉离子,生成的[Cd(C2O4)2]2-络阴离子通过强碱性阴离子交换树脂分离富集,最后用火焰原子吸收分光光度法测定了水样中的痕量镉。该法简便,选择性好,富集倍数高,应用于实际水样的检测,回收率为98%~102%,结果令人满意。     

Application of liquid-liquid-liquid microextraction and ion-pair liquid chromatography coupled with photodiode array detection for the determination of chlorophenols in water

A method termed as liquid-liquid-liquid microextraction was utilized to extract chlorophenols from water. The extracted chlorophenols, present in anionic form, were then separated, identified, and quantitated by ion-pair high-performance liquid chromatography with photodiode array detection (HPLC/DAD). For trace chlorophenol determination using HPLC/DAD, the chlorophenolate anion provides a better ultraviolet spectrum for quantitative and qualitative analyses than does uncharged chlorophenol. This is due to the auxochromic effect of the phenolate anion. In the study, experimental conditions such as organic phase identity, acceptor phase volume, sample agitation, extraction time, acceptor phase NaOH concentration, donor phase HCl concentration, salt addition, and UV absorption wavelength were optimized. Relative standard deviations (RSD, 2.3-5.4%), coefficients of determination (r2 0.9994-0.9999), and detection limits (0.049-0.081 ng mL(-1)) of the proposed method were investigated under the selected conditions. The method was successfully applied to analyses of reservoir and tap water samples, and the relative recoveries of chlorophenols from the spiked reservoir and tap water samples were 94.1-100.4% and 87.8-101.2%, respectively. The proposed method is capable of identifying and quantitating each analyte to 0.5 ng mL(-1), confirming the HPLC/DAD technique to be quite robust for monitoring trace levels of chlorophenols in water samples.     

The determination of chlorophenols in waste water by capillary zone electrophoresis with an organic modifier

Summary Acapillary zone electrophoretic method has been optimized to improve selectivity and resolution in the analysis of chlorophenols in waste water. Use of a buffer system containing organic solvent dramatically improved the separation of chlorophenols. It was shown that selectivity was strongly affected by electrolyte pH and the presence of organic modifiers. The results show that the determination of all seventeen chlorinated derivatives of phenol in water can be achieved by use of a single organic modifier. For example, with acetone as organic modifier all 17 chlorophenols could be separated and determined within 20 min. The standard deviation of migration times and peak areas of the chlorophenols were in the ranges 0.48–0.67% and 3.9–5.1% respectively. Detection linear ranges covered two orders of magnitude of concentration with correlation coefficients of 0.998–1.000, except for 4-chlorophenol. Quantitative aspects of capillary zone electrophoresis are also discussed. It was concluded that capillary zone electrophoresis is a potential method for determination of chlorophenol pollutants in waste water.     

Trace Enrichment and HPLC Analysis of Chlorophenols in Environmental Samples,Using Precolumn Sample Preconcentration and Electrochemical Detection

Abstract

A HPLC method has been developed for trace analysis of chlorophenols in the 0.2–2 ppb range from spiked water samples. Simple liquid-liquid extraction followed by on-line preconcentration of total mono- and dichlorophenols has been performed using a divinylbenzene-styrene copolymeric sorbent (PRP₁) as packing material for the precolumn. The chlorophenols have been eluted from the precolumn on an analytical column (5μm LiChrosorb RP-18, 12.5 cm × 4 mm) by use of a switching valve system followed by separation. Detection was carried out with an electrochemical detector. The linearity of the detector response has been proved over two orders of magnitude. The detection limit of chlorophenols by means of the electrochemical method is in the lower picogram range. The recoveries of the isomeric chlorophenols from spiked river water samples having initial concentrations of 2ppb are usually 70–90%. The procedure has been applied to drinking water and river water.     

On-line trace enrichment of phenolic compounds from water using a pyrrole-based polymer as the solid-phase extraction sorbent coupled with high-performance liquid chromatography

A pyrrole-based conductive polymer was prepared and applied as new sorbent for on-line solid-phase extraction (SPE) of phenol and chlorophenols from water samples. Polypyrrole (PPy) was synthesized by chemical oxidation of the monomer in non-aqueous solution. The efficiency of this polymer for extraction of phenol and chlorophenols was evaluated using 35 mg of PPy as the sorbent in an on-line SPE system coupled to reversed-phase liquid chromatography with UV detection. The mobile phase were mixture of phosphate buffer-acetonitrile and compounds were eluted by the mobile phase using a six-port switching valve. High volumes of water, up to 160 ml, could be preconcentrated without the loss of phenols, except for the more polar ones. The R.S.D. for a river water sample spiked with phenol and chlorophenols at sub-ppb level was lower than 7% (n=5) and detection limits of 15-100 and 35-150 ng l⁻¹ for tap and river water were obtained, respectively.     

Stir membrane liquid-liquid microextraction

In this article, a novel liquid phase microextraction technique, called stir membrane liquid-liquid microextraction (SM-LLME), is presented. The new approach combines the advantages of liquid phase microextraction and stirring in the same unit allowing the isolation and preconcentration of the analytes in a simple and efficient way. In the construction of the unit, a polymeric membrane is employed to protect the small volume of the extractant phase. The extraction technique is characterized for the resolution of a model analytical problem: the determination of five selected chlorophenols in water. A two-phase extraction mode is used for the extraction of the analytes with an organic solvent in which an in situ derivatization reaction takes place. The analytes are finally analyzed by gas chromatography/mass spectrometry. All the variables involved in the extraction process have been clearly identified and optimized. The new extraction mode allows the determination of chlorophenols with limits of detection in the range from 14.8 ng/L (for 2,4,5-trichlorophenol) to 22.9 ng/L (for 3-chlorophenol) with a relative standard deviation lower than 8.7% (for 2,6-dichlorophenol).     

Preconcentration of chlorophenols in water samples using threedimensional graphene-based magnetic nanocomposite as absorbent

In this paper, a novel magnetic solid-phase extraction method using three-dimensional graphene-based magnetic nanocomposite as adsorbent for the preconcentration of several chlorophenols from water samples prior to high-performance liquid chromatography analysis was developed. Various experimental parameters were investigated. Under the optimum conditions, the enrichment factors of the method were in the range of 186–312, and the limit of detection(S/N = 3) was 0.10 ng/mL. The recoveries of the method were in the range between 85.1% and 101.2%. The developed method has been successfully applied to the determination of chlorophenols in environmental water samples.     

Application of carbon nanotubes as solid-phase extraction sorbent for analysis of chlorophenols in water samples

The aim of this work was to investigate the efficiency of various MWCNTs as SPE materials for the preconcentration of chlorophenols. The COOH-functionalized MWCNTs and MWCNTs were used as SPE sorbents. To evaluate the capability of MWCNTs for the preconcentration of chlorophenols from water samples, 2,4-chlorophenol, 4-chlorophenol, 2,4,6-chlorophenol, 2,6-chlorophenol, 3,4-chlorophenol, and 2-chlorophenol were used as model compounds. Chlorophenols were extracted with acetone, methanol, ethanol, and dichloromethane, and determined by gas chromatography–mass spectrometry. COOH-functionalized MWCNTs <8 nm were found to be the best sorbent for the tested chlorophenols. For COOH-functionalized MWCNTs <8 nm, the recovery rates for all chlorophenols were higher than 50% when acetone or ethanol was used as eluents. In the case of dichloromethane elution, recovery rates for chlorophenols were from 62.0% for 2,6-DCP to 116.8% for 2,4-DCP; only for 2,4,6-TCP was the recovery rate 30.6%. Similar percentage recoveries were achieved with methanol as the eluent.     

Determination of chlorophenols in red wine using ionic liquid countercurrent chromatography as a new pretreatment method followed by high‐performance liquid chromatography

A countercurrent chromatography method for the enrichment and cleanup of chlorophenols from food samples was successfully established by using an ionic‐liquid‐modified two‐phase solvent system composed of dichloromethane containing 2% 1‐butyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide and water. The column was firstly filled with the organic stationary phase, and then a large volume of sample was pumped into the column after it was equilibrated with pure water at the rotation speed. Finally, the trace amounts of chlorophenols extracted and enriched in the stationary phase were eluted out by an alkaline mobile phase and determined by high‐performance liquid chromatography. Under optimized conditions, the enrichment and cleanup of the chlorophenols can be fulfilled online with enrichment factors (34–65) and high recoveries (84.69–95.23%). The method has been applied to the determination of chlorophenols in real red wine samples with the limits of detection in the range of 1.89–4.21 μg/L. The present method is highly suitable for the pretreatment of large volume of aqueous sample for the determination of trace amounts of contaminants in food and environmental samples.     

In-capillary solid-phase extraction-capillary electrophoresis for the determination of chlorophenols in water

A novel CE method combined with SPE in a single capillary was developed for analysis of chlorophenols in water. A frit of 0.5 mm was first made by a sol-gel method, followed by packing a SPE sorbent in the inlet end of the capillary. Two phenol derivatives, 2,4-dichlorophenol and 2,4,5-trichlorophenol, were used as the model compounds. By loading sample solutions into the capillary, the two chlorophenols were extracted into the sorbent. They were desorbed by injecting only about 4 nL of methanol. Finally, the analytes were separated by conventional CE. The technique provided a concentration enhancement factor of over 4000-fold for both chlorophenols. The detection limits (S/N = 3) of 2,4-dichlorophenol and 2,4,5-trichlorophenol were determined to be 0.1 ng/mL and 0.07 ng/mL, respectively. For replicate analyses of 5 ng/mL of 2,4-dichlorophenol, within-day and between-day RSDs of migration time, peak height and peak area were in the range of 1.8-2.0%, 4.0-4.4% and 4.1-4.6%, respectively. The method shows wide linear range, acceptable reproducibility and excellent sensitivity, and it was applied to the analyses of spiked river water samples. The capillary packed with the SPE sorbents can be used for more than 400 runs without performance deterioration.     

Microwave assisted headspace controlled-temperature single drop microextraction for liquid chromatographic determination of chlorophenols in aqueous samples

We report on an efficient one-step sample preconcentration technique by coupling microwave heating and cloud vapor zone (CVZ)-based headspace controlled-temperature single drop microextraction (HS-CT-SDME), and its application to headspace extraction of chlorophenols in aqueous solutions. Microwave irradiation is utilized to accelerate evaporation of analytes into the headspace sampling zone for the direct extraction of aqueous chlorophenols. A microdrop of extractant is suspended at the bottom of a bell-mouthed micropipette tip connected to a microsyringe needle. An external cooling system was adopted to control the formation of the CVZ around the SDME tip in the headspace sampling area. In the CVZ procedure, the warm headspace vapor is quickly cooled near the SDME tip, thus forming a dense cloud of analyte-water vapor; thereby enhancing the partition of the analytes into the SDME solvent. The chlorophenols are then determined by LC-UV detection. Under the optimized experimental conditions, the analytical signal is linearly related to the concentration of the chlorophenols range of 2.5–250?ng?mL^?1. The detection limits vary from 0.3 to 0.7?ng?mL^?1, and the precision (expressed as the relative standard deviation) from 3.7 to 13.3?%. The method was validated with real water samples, and the spiked recovery ranged between 92 and 103.1?% for river water, and between 85.1?% and 98.6?% for lake water. Compared to other methods, microwave assisted HS-CT-SDME is simple, rapid, sensitive, inexpensive and eco-friendly, and requires less sample and organic extractant.