液相色谱法测定地表水中氯酚类化合物

采用单滴液相微萃取-高效液相色谱法测定水中的4-氯酚、2,6-二氯酚、2,4-二氯酚和2,4,6-三氯酚。色谱条件为:Diamonsil C18柱(250×4.6mm i.d.,5μm),柱温:室温,流速1.0mL/min,以甲醇∶水∶甲酸(体积比70∶30∶0.2)为流动相,225nm紫外检测。考察了萃取溶剂种类、萃取时间、萃取温度、搅拌速度和pH值对萃取效率的影响。4-氯酚、2,6-二氯酚、2,4-二氯酚在1.5~100mg/L和2,4,6-三氯酚在2.5~100mg/L范围内有良好线性,相关系数不低于0.9996,回收率在74.9%~84.4%之间,相对标准偏差低于4.9%。     

固相萃取/高效液相色谱法同时测定化妆品中9种卤代酚残留

建立了固相萃取/高效液相色谱(SPE/HPLC)测定化妆品中9种卤代酚(2,6-二氯酚、2,3-二氯酚、2,5-二氯酚、2,4-二氯酚、3,4-二氯酚、3,5-二氯酚、2,4,6-三氯苯酚、五氯苯酚和硫氯酚)含量的分析方法。试样经饱和氯化钠溶液分散,乙腈超声提取,HLB柱净化后,以甲醇-乙腈-乙酸铵缓冲溶液为流动相,经C8柱分离后进行HPLC检测。结果显示,9种卤代酚在1.0～50.0 mg/L范围内呈良好的线性关系,相关系数均大于0.999,检出限为0.3～0.6 mg/kg。在2.0、4.0、20.0 mg/kg 3个加标浓度水平下,9种卤代酚的平均回收率为92%～105%,相对标准偏差(RSD,n=6)为0.89%～3.1%。该方法灵敏度高、重现性好、定量准确。     

[Bmim]BF4-NaH2PO4双水相萃取-高效液相色谱法测定水中痕量氯酚类内分泌干扰物

利用离子液体双水相萃取-高效液相色谱(HPLC)法测定了水中痕量氯酚类内分泌干扰物.以2,4-二氯酚(2,4-DCP)、2,6-二氯酚(2,6-DCP)和对氯苯酚(4-CP)为目标分析物,考察了影响离子液体双水相萃取率的主要因素,如分相盐的浓度、水相pH值、萃取时间及离子液体加人量.当NaH2PO4的浓度为0.5 g/...     

分散液液微萃取-高效液相色谱法测定环境水样中2,4-二氯酚

建立了简便、快速、有效的分散液液微萃取-高效液相色谱法测定环境水样中2,4-二氯酚的分析方法。对萃取剂、分散剂的种类和体积、萃取时间、离心时间、盐浓度等影响萃取效率的因素进行了优化。方法的线性范围为1～500μg/L(r=0.9997),相对标准偏差(RSD)为3.8%(n=6),检出限为0.19μg/L。该法适用于环境水样中的痕量2,4-二氯酚的检测。     

氮掺杂Bi2O3光催化剂可见光催化降解2,4-二氯酚

采用自制的Bi2O3及氮掺杂Bi2O3(N-Bi2O3)光催化剂,以卤钨灯为光源,在可见光下对2,4-二氯酚进行光催化降解.结果表明,N-Bi2O3较Bi2O3具有更高的可见光催化活性.当N-Bi2O3光催化剂投加量为2.0 g/L、2,4-二氯酚初始浓度为20 mg/L和pH =7时,光催化反应320 min,2,4-二氯酚的降解率最高可达到91.5％.2,4-二氯酚的光催化反应初活性与其浓度之间的关系符合Langmuir-Hinshelwood动力学速率模型.对降解过程中总有机碳及Cl-测试结果表明,N-Bi2O3光催化剂能较好地完成对2,4-二氯酚的深度矿化及脱氯.     

改进的五氟苄基溴衍生化反应测定水中酚类化合物

建立了气相色谱-质谱法测定水中6种酚类化合物(2,6-二氯酚、2,4-二氯酚、2,4,6-三氯酚、2,4,5-三氯酚、2,3,4,6-四氯酚和五氯酚)的方法。样品经二氯甲烷-乙酸乙酯混合溶剂萃取后,用旋转蒸发浓缩至1 mL,加入五氟苄基溴进行改进版衍生化反应,产物用DB-5 mS毛细管柱分离,采用选择离子监测模式测定。酚类化合物的检出限在0.05~0.13μg/L之间。目标物在0.05~1 mg/L范围内线性关系良好,相关系数R²为0.9972~0.9983。以地下水水样为基体,加入3个浓度水平的标准溶液进行加标回收实验,加标回收率在60.4%~109.6%,相对标准偏差在0.1%~12%之间。     

分散液液微萃取-微量分光光度法测定再造烟叶废水中烟碱

基于2,6-二氯靛酚与烟碱的荷移反应生成红色络合物,以氯仿为萃取剂,乙腈为分散剂,建立了分散液液微萃取(DLLME)-微量分光光度法测定烟碱含量的方法,用于再造烟叶废水中烟碱的测定。研究了酸度、萃取剂种类及用量、分散剂种类及用量等条件对测定的影响。在优化条件下,此方法的线性范围为1~100 mg/L(R2=0.9996),检出限为0.42 mg/L。相对标准偏差为1.3%~3.5%(n=6),加标回收率为95.9%~102.1%。该方法可满足再造烟叶废水中烟碱快速测定的要求。     

硼掺杂金刚石薄膜电极上二氯酚的电化学阻抗谱研究

以2,4-二氯酚(2,4-DCP)和2,6-二氯酚(2,6-DCP)为模型污染物,采用循环伏安法和电化学阻抗谱研究了硼掺杂金刚石(BDD)电极上2种氯酚的电催化氧化过程.结果表明,2,4-DCP和2,6-DCP的氧化电位分别为1.55和1.62 V.等效电路拟合结果表明,当极化电位由开路电位提高至1.5 V时,2种氯酚的电荷转移电阻均有明显下降,反应控制步骤为扩散控制步骤.与2,6-DCP相比,2,4-DCP在BDD电极上更容易发生直接电化学氧化.     

类Fenton试剂-罗丹明B-HCI体系动力学荧光法测定环境水样中2，4-二氯酚

在酸性介质中,痕量2,4-二氯酚对类Fenton试剂与罗丹明B的反应具有明显阻抑作用,且其阻抑作用大小与2,4-二氯酚的浓度有关。据此建立了一种动力学荧光法测定痕量2,4-二氯酚的新方法。考察了各种因素对测定方法灵敏度的影响。在最佳条件下,方法的线性范围为0．04～0．8 μg/mL,检出限为0．012 μg／mL。将该方法用于7种环境水样和6种合成样品中2,4-二氯酚的测定,加标回收率为93．5％～108．0％。相对误差为-5．45％～4．60％。     

庚醛改性壳聚糖的制备及其对酚类化合物的吸附性能

在相转移催化剂存在下由庚醛与壳聚糖反应生成Schiff's碱,再用NaBH4 还原制备了N-烷基化壳聚糖衍生物,改性壳聚糖(CTS)产物的结构用FTIR和XRD进行了表征,研究了它对2,4-二氯酚的吸附性能. 考察了吸附时间、溶液pH值、2,4-二氯酚浓度和改性剂用量等因素对吸附的影响. 结果表明,改性CTS具有较好的抗酸碱性能;溶液的pH值对吸附的影响较大,在pH=6.0,吸附2 h时对2,4-二氯酚的吸附量最大,酚浓度对吸附的影响符合Freundlich吸附等温方程;改性壳聚糖对2,4-二氯酚的吸附性能明显优于未改性的CTS,对质量浓度为0.6 g/L的2,4-二氯酚溶液的吸附量分别为70.0和7.7 mg/g.     

Development of a novel ultrasound-assisted headspace liquid-phase microextraction and its application to the analysis of chlorophenols in real aqueous samples

A new sample pretreatment technique, ultrasound-assisted headspace liquid-phase microextraction was developed as mentioned in this paper. In the technique, the volatile analytes were headspace extracted into a small drop of solvent, which suspended on the bottom of a cone-shaped PCR tube instead of the needle tip of a microsyringe. More solvent could be suspended in the PCR tube than microsyringe due to the larger interfacial tension, thus the analysis sensitivity was significantly improved with the increase of the extractant volume. Moreover, ultrasound-assisted extraction and independent controlling temperature of the extractant and the sample were performed to enhance the extraction efficiency. Following the extraction, the solvent-loaded sample was analyzed by high-performance liquid chromatography. Chlorophenols (2-chlorophenol, 2,4-dichlorophenol and 2,6-dichlorophenol) were chosen as model analytes to investigate the feasibility of the method. The experimental conditions related to the extraction efficiency were systematically studied. Under the optimum experimental conditions, the detection limit (S/N=3), intra- and inter-day RSD were 6 ng mL(-1), 4.6%, 3.9% for 2-chlorophenol, 12 ng mL(-1), 2.4%, 8.8% for 2,4-dichlorophenol and 23 ng mL(-1), 3.3%, 5.3% for 2,6-dichlorophenol, respectively. The proposed method was successfully applied to determine chlorophenols in real aqueous samples. Good recoveries ranging from 84.6% to 100.7% were obtained. In addition, the extraction efficiency of our method and the conventional headspace liquid-phase microextraction were compared; the extraction efficiency of the former was about 21 times higher than that of the latter. The results demonstrated that the proposed method is a promising sample pretreatment approach, its advantages over the conventional headspace liquid-phase microextraction include simple setup, ease of operation, rapidness, sensitivity, precision and no cross-contamination. The method is very suitable for the analysis of trace volatile and semivolatile pollutants in real aqueous sample.     

固相萃取-微乳液相色谱法测定环境水体中的3种酚类化合物

建立了固相萃取-微乳液相色谱法同时测定环境水体中的苯酚、双酚A (BPA)、2,4-二氯苯酚3种酚类化合物的检测方法。水样加酸酸化后,经C18固相萃取小柱富集净化,用微乳液相色谱法测定3种目标物的含量。在Inertsil C18色谱柱(150 mm×4.6 mm, 5 μm)上以微乳(3.0%十二烷基硫酸钠(SDS)-6.0%正丁醇-0.8%正庚烷-90.2%(水+0.5%HAc))和乙腈作为流动相进行梯度洗脱,流速1.0 mL/min,检测波长280 nm。结果表明,苯酚、双酚A、2,4-二氯苯酚的检出限(S/N=3)依次为0.74、8.0、8.0 μg/L,线性范围在0.1~10 mg/L范围内,相关系数(r)均大于0.999。将3种酚类化合物定量加到空白水样中,苯酚、双酚A、2,4-二氯苯酚的加标回收率分别为82.7%、87.8%、82.6%,其RSD均小于5%(n=6)。对环境水样的酚类化合物分析也取得了良好的加标回收率,其值均在85.7%~113.2%之间。结果表明,该方法准确可靠、灵敏度高,适用于环境水体中酚类化合物的检测。     

Optimizing Separation Conditions for Chlorophenoxycarboxylic Acid Herbicides in Natural and Potable Water Using Capillary Zone Electrophoresis

Chlorophenoxycarboxylic acid herbicides were separated and determined by capillary electrophoresis. An analysis of a six-component mixture containing 2,4-dichlorophenoxybutyric (2,4-DB), 2,4-dichlorophenoxypropionic (2,4-DP), 2,4,5-trichlorophenoxyacetic (2,4,5-T), 2,4-dichlorophenoxyacetic (2,4-D), and phenoxyacetic (PA) acids and 2,4-dichlorophenol (2,4-DCP), the product of their degradation in aqueous media, took no longer than 15 min. Solid-phase extraction on Diapak C-16 cartridges was used for sample preparation. The detection limits for herbicides in water samples with account for preconcentration (K = 250) were found to be 0.0005 mg/L for 2,4-DB, 2,4-DP, 2,4,5-T, and 2,4-D and 0.001 mg/L for PA. It was shown that humic acids (< 50 mg/L) do not interfere with the determination of chlorophenoxycarboxylic acids.     

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet followed by high-performance liquid chromatography with ultraviolet detection and liquid chromatography-tandem mass spectrometry for the determination of triclosan and 2,4-dichlorophenol in water samples

A novel, simple and efficient dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) technique coupled with high-performance liquid chromatography with ultraviolet detection (HPLC-UV) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of triclosan and its degradation product 2,4-dichlorophenol in real water samples. The extraction solvent used in this work is of low density, low volatility, low toxicity and proper melting point around room temperature. The extractant droplets can be collected easily by solidifying it at a lower temperature. Parameters that affect the extraction efficiency, including type and volume of extraction solvent and dispersive solvent, salt effect, pH and extraction time, were investigated and optimized in a 5 mL sample system by HPLC-UV. Under the optimum conditions (extraction solvent: 12 μL of 1-dodecanol; dispersive solvent: 300 of μL acetonitrile; sample pH: 6.0; extraction time: 1 min), the limits of detection (LODs) of the pretreatment method combined with LC-MS/MS were in the range of 0.002-0.02 μg L(-1) which are lower than or comparable with other reported approaches applied to the determination of the same compounds. Wide linearities, good precisions and satisfactory relative recoveries were also obtained. The proposed technique was successfully applied to determine triclosan and 2,4-dichlorophenol in real water samples.     

Combination of liquid-phase hollow fiber membrane microextraction with gas chromatography-negative chemical ionization mass spectrometry for the determination of dichlorophenol isomers in water and urine

A method for the determination of trace amount of dichlorophenol isomers in urine samples using the combination of liquid-phase hollow fiber microextraction (LPME-HF) with gas chromatography-negative chemical ionization mass spectrometry (GC-NCI-MS) has been demonstrated. The method has been optimized with respect to several parameters including the effects of negative chemical ionization (NCI) reagent pressure, the hollow fiber length, extraction time, stirring rate, sample pH and salt concentration for the determination of dichlorophenol isomers in water. The correlation coefficient (r²) of the calibration curves for 2,5-dichlorophenol, 2,3-dichlorophenol, 2,6-dichlorophenol, 3,5-dichlorophenol and 3,4-dichlorophenol were 0.988, 0.981, 0.985, 0.971 and 0.994, respectively. The average recovery rates for 2,5-dichlorophenol, 2,3-dichlorophenol, 2,6-dichlorophenol, 3,5-dichlorophenol and 3,4-dichlorophenol were 0.97, 0.93, 0.96, 0.95 and 0.95, respectively (n = 3 for each dichlorophenol) indicate that the methodology is feasible for the determination of trace amounts of dichlorophenol isomers in water and urine samples. Limits of detection (LOD) have been found to be in the range of 5-20 ng/ml. In addition, differentiation of the five dichlorophenol isomers is an easy task using the current approach of combining LPME-HF with NCI-GC-MS technique since they exhibit different NCI spectra.     

Membrane-assisted solvent extraction of seven phenols combined with large volume injection-gas chromatography-mass spectrometric detection

Membrane-assisted solvent extraction (MASE) was applied for the determination of seven phenols (phenol, 2-chlorophenol, 2,4-dimethylphenol, 2,4-dichlorophenol, 4-chloro-3-methylphenol, 2,4,6-trichlorophenol and pentachlorophenol) with log Kow (octanol-water-partition-coefficient) between 1.46 (phenol) and 5.12 (pentachlorophenol) in water. The extraction solvents cyclohexane, ethyl acetate and chloroform were tested and ethyl acetate proved to be the best choice. The optimisation of extraction conditions showed the necessity of adding 5 g of sodium chloride to each aqueous sample to give a saturated solution (333 g/L). The pH-value of the sample was adjusted to 2 in order to convert all compounds into their neutral form. An extraction time of 60 min was found to be optimal. Under these conditions the recovery of phenol, the most polar compound, was 11%. The recoveries of the other analytes ranged between 42% (2-chlorophenol) and 98% (2,4-dichlorophenol). Calibration was performed using large volume injection (100 microL injection volume). At optimised conditions the limits of detection were between 0.01 and 0.6 microg/L and the relative standard deviation (n = 3) was on average about 10%. After the method optimisation with reagent water membrane-assisted solvent extraction was applied to two contaminated ground water samples from the region of Bitterfeld in Saxony-Anhalt, Germany. The results demonstrate the good applicability of membrane-assisted solvent extraction for polar analytes like phenols, without the necessity of derivatisation or a difficult and time-consuming sample preparation.     

Polypyrrole/graphene composite-coated fiber for the solid-phase microextraction of phenols

A polypyrrole (Ppy)/graphene (G) composite was developed and applied as a novel coating for use in solid-phase microextraction (SPME) coupled with gas chromatography (GC). The Ppy/G-coated fiber was prepared by electrochemically polymerizing pyrrole and G on a stainless-steel wire. The extraction efficiency of Ppy/G-coated fiber for five phenols was the highest compared with the fibers coated with either Ppy or Ppy/graphene oxide (GO) using the same method preparation. Significantly, compared with various commercial fibers, the extraction efficiency of Ppy/G-coated fiber is better than or comparable to 85 μm CAR/PDMS fiber (best extraction efficiency of phenol, o-cresol, and m-cresol in commercial fibers) and 85 μm polyacrylate (PA) fiber (best extraction efficiency of 2,4-dichlorophenol and p-bromophenol in commercial fibers). The effects of extraction and desorption parameters such as extraction time, stirring rate, and desorption temperature and time on the extraction/desorption efficiency were investigated and optimized. The calibration curves were linear from 10 to 1000 μg/L for o-cresol, m-cresol, p-bromophenol, and 2,4-dichlorophenol, and from 50 to 1000 μg/L for phenol. The detection limits were within the range 0.34-3.4 μg/L. The single fiber and fiber-to-fiber reproducibilities were <8.3 (n=7) and 13.3% (n=4), respectively. The recovery of the phenols spiked in natural water samples at 200 μg/L ranged from 74.1 to 103.9% and the relative standard deviations were <3.7%.     

Detection and determination of chlorophenols and chlorophenoxyacetic acids by instrumental analysis

A quantitative method for the determination of chlorophenols and chlorophenoxyacetic acids in aqueous solutions is described. The samples investigated contained 2-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol, 2,4,6-trichlorophenol and their phenoxyacetic acid derivatives. The total amount of chlorophenols is determined by spectrophotometry, the ratio of individual chlorophenols by gas chromatography and the total quantity of phenoxyacetic acids by acidimetric titration. The determinations are carried out after extraction with diethyl ether, carbon tetrachloride and petroleum ether, respectively.