Cloud point extraction and determination of trace trichlorfon by high performance liquid chromatography with ultraviolet-detection based on its catalytic effect on benzidine oxidizing

4-Amino-4′-nitrobiphenyl, which is formed by catalytic effect of trichlorfon on sodium perborate oxidizing benzidine, is extracted with a cloud point extraction method and then detected using a high performance liquid chromatography with ultraviolet detection (HPLC-UV). Under the optimum experimental conditions, there was a linear relationship between trichlorfon in the concentration range of 0.01-0.2 mg L⁻¹ and the peak areas of 4-amino-4′-nitrobiphenyl (r = 0.996). Limit of detection was 2.0 μg L⁻¹, recoveries of spiked water and cabbage samples ranged between 95.4-103 and 85.2-91.2%, respectively. It was proved that the cloud point extraction (CPE) method was simple, cheap, and environment friendly than extraction with organic solvents and had more effective extraction yield.     

Determination of Doxepin in human plasma using cloud‐point extraction with high‐performance liquid chromatography and ultraviolet detection

A new straightforward method based on cloud‐point extraction has been developed, optimized, and validated for the determination of doxepin in human plasma by high‐performance liquid chromatography separation and UV detection. The nonionic surfactant Triton X‐114 was chosen as the extraction solvent. Chromatography separation was performed on a μBondapak^R C₁₈ column (4.6 mm id × 300 mm, 3 μm particle size), which was used for isocratic elution at a detection wavelength of 289 nm. Under the optimum conditions, the linear range of doxepin in human plasma was 0.1–0.9 μg/mL. Also, the detection limit, preconcentration factor, and enrichment factor were 0.08 μg/mL, 50, and 49.0, respectively.     

Micellar extraction and high performance liquid chromatography-ultra violet determination of some explosives in water samples

An analytical method based on the cloud point extraction combined with high performance liquid chromatography is used for the extraction, separation and determination of four explosives; octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazine (HMX), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT) and pentaerythritol tetranitrate (PETN). These compounds are extracted by using of Triton X-114 and cetyl-trimethyl ammonium bromide (CTAB). After extraction, the samples were analyzed using a HPLC-UV system. The parameters affecting extraction efficiency (such as Triton X-114 and CTAB concentrations, amount of Na₂SO₄, temperature, incubation and centrifuge times) were evaluated and optimized. Under the optimum conditions, the preconcentration factor was 40 and the improvement factors of 34, 29, 61 and 42 with detection limits of 0.09, 0.14, 0.08 and 0.40 (μg L⁻¹) were obtained for HMX, RDX, TNT and PETN, respectively. The proposed method was successfully applied to the determination of these compounds in water samples and showed recovery percentages of 97-102% with RSD values of 2.13-4.92%.     

Micelle-mediated cloud point extraction and spectrophotometric determination of rhodamine B using Triton X-100

A new micelle-mediated cloud point extraction method is described for sensitive and selective determination of trace amounts of rhodamine B by spectrophotometry. The method is based on the cloud point extraction of rhodamine B from aqueous solution using Triton X-100 in acidic media. The extracted surfactant rich phase is diluted with water and its absorbance is measured at 563 nm by a spectophotometer. The effects of different operating parameters such as concentration of surfactant and salt, temperature and pH on the cloud point extraction of rhodamine B were studied in details and a set of optimum conditions were obtained. Under optimum conditions a linear calibration graph in the range of 5-550 ng mL⁻¹ of rhodamine B in the initial solution with r = 0.9991 (n = 15) was obtained. Detection limit based on three times the standard deviation of the blank (3S_b) was 1.3 ng mL⁻¹ (n = 10) and the relative standard deviation (R.S.D.) for 50 and 350 ng mL⁻¹ of rhodamine B was 2.40 and 0.87% (n = 10), respectively. The method was applied for the determination of rhodamine B in soft pastel, hand washing liquid soap, matches tip and textile dyes mixture samples.     

用快速分离柱高效液相色谱法测定烟草中的几种酚

研究了用快速分离柱高效液相色谱法测定烟草样品中的苯酚、苯二酚和甲基苯酚. 烟草样品中的酚经水蒸汽蒸馏分离后用Waters Sep-Pak-C18固相萃取小柱富集, 以ZORBAX Stable Bound (4.6 mm i.d.×20 mm, 1.8 μm) 快速分离柱为固定相, 0.05 mol/L KH2PO4缓冲溶液-甲醇梯度为流动相, 几种主要酚在2.0 min 内可达到基线分离;该方法的相对标准偏差为2.1%～3.6%, 标准加入的回收率为88%～97%, 已用于几种烟草样品测定.     

整体柱固相萃取-高效液相色谱法在线分析水果中的氯吡脲

建立了整体柱固相萃取-高效液相色谱/紫外检测在线联用方法并用于水果中氯吡脲的分析测定。考察了萃取溶剂的pH值及其流速、溶剂解吸时间及其流速等因素对氯吡脲萃取率的影响。在优化的条件下,该方法对氯吡脲的富集倍数为214倍,方法的线性范围为0.01~50.00 μg/L,检出限为25 ng/L,相对标准偏差（RSD）为3.9%。黑葡萄、猕猴桃和西瓜等水果中氯吡脲的加标回收率为87.0%~120.7%,RSD为0.6%~9.2%。结果表明该方法快速、灵敏,能满足水果中痕量氯吡脲残留分析的要求。     

Spectrophtometric determination of malachite green in fish farming water samples after cloud point extraction using nonionic surfactant Triton X-100

A novel and sensitive cloud point extraction procedure for the determination of trace amounts of malachite green by spectrophotometry was developed. Malachite green was extracted at pH 2.5 mediated by micelles of nonionic surfactant Triton X-100. The extracted surfactant-rich phase was diluted with ethanol and its absorbance was measured at 630 nm. The effect of different variables such as pH, Triton X-100 concentration, cloud point temperature and time and diverse ions was investigated and optimum conditions were established. The calibration graph was linear in the range of 4-500 ng mL⁻¹ of malachite green in the initial solution with r = 0.9996 (n = 10). Detection limit based on three times the standard deviation of the blank (3S_b) was 1.2 ng mL⁻¹ and the relative standard deviation (R.S.D.) for 20 and 300 ng mL⁻¹ of malachite green was 1.48 and 1.13% (n = 8), respectively. The method was applied to the determination of malachite green in different fish farming and river water samples.     

Carrier-mediated liquid phase microextraction coupled with high performance liquid chromatography for determination of illicit drugs in human urine

A new method was developed for the analysis of illicit drugs in human urine by coupling carrier-mediated liquid phase microextraction (LPME) to high performance liquid chromatography (HPLC). By adding an appropriate carrier in organic phase, simultaneous extraction and enrichment of hydrophilic (morphine and ephedrine) and hydrophobic (pethidine) drugs were achieved. Effects of the types of organic solvents and carriers, the carrier concentration in the organic phase, the HCl concentration in the acceptor solution, the stirring rate, and the extraction time on the enrichment factor of analytes were investigated. Under the optimal experimental conditions, high enrichment factors (202-515) were obtained. The linear detection ranges were 0.1-10 mg L⁻¹ for the studied drugs. The limits of detection (LOD) at signal-to-noise ratio of 3 were 0.05 mg L⁻¹ for both morphine and ephedrine, and 0.02 mg L⁻¹ for pethidine. This method was successfully applied to analysis of ephedrine in real urine specimens, revealing that the determination of illicit drugs in urine was feasible.     

Flow method based on cloud point extraction for fluorometric determination of epinephrine in human urine

A novel stepwise injection fluorometric method for the determination of epinephrine in human urine has been developed. In the current study, the stepwise injection analysis (SWIA) was successfully combined with on-line in-syringe cloud point extraction (CPE) and fluorometric detection. The procedure was based on the epinephrine derivatization in the presence of o-phenylenediamine followed by the preconcentration stage based on the CPE with the nonionic surfactant Triton X-114. After the phase separation into a syringe of the flow system, the micellar phase containing the epinephrine derivative was transported to a fluorometric detector. The excitation and emission wavelengths were set at 447 nm and 550 nm, respectively. The conditions of epinephrine derivatization and CPE have been studied. The calibration plot constructed using the developed procedure was linear in the range of 1·10⁻¹¹–5·10⁻⁷ mol L⁻¹. The limit of detection, calculated as 3 σ of a blank test (n = 10), was found to be 3·10⁻¹² mol L⁻¹. The proposed method was successfully applied for the determination of epinephrine in human urine samples.     

Simultaneous cloud point extraction and spectrophotometric determination of carmoisine and brilliant blue FCF in food samples

A novel simultaneous cloud point extraction method for the determination of carmoisine and brilliant blue FCF by spectrophotometry has been developed. The method is based on the cloud point extraction of carmoisine and brilliant blue FCF from aqueous solution using Triton X-100, diluting the extracted surfactant rich phase with water and measuring the absorbance at 522 and 640 nm for carmoisine and brilliant blue FCF, respectively. The effects of different parameters such as pH, concentration of surfactant and temperature on the cloud point extraction of both dyes were investigated and optimum conditions were established. Linear calibration curves were obtained in the range of 0.02-3.50 μg mL⁻¹ for carmoisine and 0.05-3.50 μg mL⁻¹ for brilliant blue FCF under optimum conditions. Detection limit based on three times the standard deviation of the blank (3S_b) was 0.017 and 0.016 μg mL⁻¹ (n = 10) for carmoisine and brilliant blue FCF, respectively. The relative standard deviation (RSD) for 0.1 μg mL⁻¹ was 4.14 and 3.30% (n = 10), for carmoisine and brilliant blue FCF, respectively. The method was applied to the simultaneous determination of the dyes in different food samples.     

A cloud point extraction approach using Triton X-100 for the separation and preconcentration of Sudan dyes in chilli powder

A CPE-HPLC (UV) method was developed for the determination of Sudan (I-IV) dyes, non-ionic surfactant Triton X-100 was used to extract and preconcentrate Sudan dyes from chilli powder prior to their determination by HPLC-UV. The separation and determination of Sudan dyes was then carried out in the HPLC-UV system with isocratic elution, and the detector was set at 500 nm. The parameters and variables that affect the extraction were investigated. Under optimum conditions: 3% of Triton X-100 (W/V), 10% of Na₂CO₃ (W/V), heat-assisted at 70 °C for 30 min. Recoveries of the Sudan dyes ranged from 80.70% to 85.45% in chilli powder by CPE method, with all the relative standard deviations of less than 3%. Limit of detection (LOD) and limit of quantification (LOQ) were in the range of 2.0-4.0 and 7.0-12.0 μg kg⁻¹ in chilli powder, respectively.     

基于整体柱的固相萃取-高效液相色谱法测定尿液中4种羟基多环芳烃

建立了基于聚合物整体柱的固相萃取-高效液相色谱测定尿液中4种羟基多环芳烃（OH-PAHs）的分析方法。在注射器管中合成聚（甲基丙烯酸丁酯-乙二醇二甲基丙烯酸酯）整体柱（poly （BMA-co-EDMA））,并将其用于尿液中4种羟基多环芳烃的前处理,同时考察了上样浓度、淋洗液、洗脱液和洗脱体积对萃取效率的影响。结合高效液相色谱-荧光分析,4种羟基多环芳烃在各自的范围内线性关系良好（r≥0.9991）;方法的检出限和定量限分别为0.06~0.09 ng/mL和0.20~0.30 ng/mL;日内（n=5）和日间（n=3）精密度分别为1.4%~5.3%和2.6%~7.3%。对焦炉工人尿液样品进行加标（3 ng/mL）回收试验,回收率为78.2%~117.0%。该固相萃取柱能够有效萃取和净化尿液中4种羟基多环芳烃,并且可以重复使用。该法简单、准确,可应用于尿液中羟基多环芳烃的分析。     

固相萃取-高效液相色谱法同时测定水中的对二氯苯与六氯苯

采用国产新型D4020 大孔吸附树脂作固定相,用自制的玻璃富集柱研究了柱长、上样速度、样品溶液的pH、盐度等因素对对二氯苯与六氯苯吸附率的影响,确定了最佳固相萃取条件,建立了固相萃取-高效液相色谱同时测定水中痕量对二氯苯与六氯苯的分析方法;不同加标水平的对二氯苯与六氯苯的回收率为86.4%～93.9%,RSD≤4.2%,检出限分别为0.85和0.10 ng/mL;方法已用于实际水样分析.     

固相萃取-高效液相色谱法测定枸杞中的类胡萝卜素

研究了固相萃取富集和预分离,高效液相色谱测定枸杞中的类胡萝卜素的方法;枸杞中的类胡萝卜素用WatersXterraTMRP18固相萃取小柱预分离,以WatersXterraTMRP18(3.9×150mm,5μm)液相色谱柱为固定相,甲醇 四氢呋喃(4 1)为流动相分离,用二极管矩阵检测器检测,检测波长为450nm。方法标准回收率为95%～103%。用该方法测定了几种枸杞样品中的类胡萝卜素。     

Molecularly imprinted solid-phase extraction for determination of tilmicosin in feed using high performance liquid chromatography

A simple, sensitive and reproducible molecularly imprinted solid-phase extraction (MISPE) coupled with high performance liquid chromatographic method was developed for monitoring tilmicosin in feeds. The polymers were prepared using tylosin as mimic template molecule, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linking monomer, and chloroform as a solvent by bulk polymerization. Under the optimum MISPE conditions, the novel polymer sorbent can selectively extract and enrich tilmicosin from variety of feeds. The MISPE cartridge was better than non-imprinted, C₁₈ and HLB cartridges in terms of both recovery and precision. Mean recoveries of tilmicosin from five kinds of feeds spiked at 1, 10 and 50 mg kg⁻¹ ranged from 76.9% to 95.6%, with intra-day and inter-day relative standard deviation less than 7.6%. The linearity was ranged from 1.0 to 100 mg L⁻¹ for matrix standard solution (r = 0.9990). The limit of detection was approximately 0.35 mg kg⁻¹ and the limit of quantification was approximately 0.98 mg kg⁻¹. There was cleaner chromatogram by using MISPE than C₁₈ and HLB SPE.     

Cloud-point extraction and reversed-phase high-performance liquid chromatography for the determination of carbamate insecticide residues in fruits

A cloud-point extraction (CPE) method using Triton X-114 non-ionic surfactant was developed for the extraction and preconcentration of carbamate insecticide residues (i.e., methomyl, propoxur, carbofuran, carbaryl, isoprocarb, and promecarb) in fruit samples. The optimum conditions of CPE were 1.5% (w/v) Triton X-114, 7.0% (w/v) NaCl and 20 min equilibrated at 45 °C. The surfactant-rich phase was then analyzed by reversed-phase high-performance liquid chromatography with ultraviolet detection at 270 nm, under gradient separation using methanol and 0.1% (v/v) acetic acid. Under the study conditions, six carbamate insecticides were successfully separated within 27 min. Good reproducibility was obtained with the relative standard deviation of <3% for retention time and <9% for peak area. Limits of detection in the studied fruit samples were in the range of 0.1–1.0 mg kg⁻¹. No carbamate insecticides were detected in the studied fruit samples. The high recoveries of the spiked fruit samples were obtained in the range 80.0–107%. The CPE method has been shown to be a potential useful methodology for the preconcentration of the target analytes, with a preconcentration factor of 14. Moreover, the method is simple, has high sensitivity, consumes much less solvent than traditional methods, and is environmental friendly.     

A new effective on chip electromembrane extraction coupled with high performance liquid chromatography for enhancement of extraction efficiency

In the present research, an effective on chip electromembrane extraction (CEME) coupled with high performance liquid chromatography was presented for analysis of nortriptyline (NOR) and amitriptyline (AMI) as basic model analytes from urine samples. The chip consists of two polymethyl methacrylate (PMMA) parts with two craved microfluidic channels in each part. These channels were used as flow path for the sample solution and a thin compartment for the acceptor phase. A porous polypropylene sheet membrane impregnated with an organic solvent was placed between two parts of chip device to separate the channels. Two platinum electrodes were mounted at the bottom of these channels that were connected to a power supply providing the electrical driving force for migration of ionized analytes from sample solution through the porous sheet membrane into the acceptor phase. This new setup provides effective and reproducible extractions with low volume of sample solution. Efficient parameters on CEME of the model analytes were optimized using one variable at a time method. Under the optimized conditions, the calibration curve was linear in the range of 10.0–500 μg L⁻¹ with coefficient of determination (r²) more than 0.9902. The relative standard deviations (RSDs %) for extraction and determination of the analytes were less than 6.8% based on six replicate measurements. LODs less than 4.0 μg L⁻¹ were obtained for both of the model analytes. The preconcentration factors higher than 17.0-fold were obtained. The results demonstrated that CEME would be used efficiently for extraction and determination of AMI and NOR from urine samples.     

Preparation and evaluation of a molecularly imprinted sol-gel material for on-line solid-phase extraction coupled with high performance liquid chromatography for the determination of trace pentachlorophenol in water samples

A highly selective imprinted amino-functionalized silica gel sorbent was prepared by combining a surface molecular imprinting technique with a sol-gel process for on-line solid-phase extraction-HPLC determination of trace pentachlorophenol (PCP) in water samples. The PCP-imprinted amino-functionalized silica sorbent was characterized by FT-IR, SEM, nitrogen adsorption and the static adsorption experiments. The imprinted functionalized silica gel sorbent exhibited high selectivity and offered a fast kinetics for the adsorption and desorption of PCP. The prepared sorbent was shown to be promising for on-line solid-phase extraction for HPLC determination of trace levels of PCP in environmental samples. With a sample loading flow rate of 5 ml min(-1) for 2 min, an enhancement factor of 670 and a detection limit (S/N = 3) of 6 ng l(-1) were achieved at a sample throughput of five samples h(-1). The precision (RSD) for nine replicate on-line sorbent extractions of 10 microgl(-1) PCP was 3.8%. The sorbent also offered good linearity (r = 0.9997) for on-line solid-phase extraction of trace levels of PCP. The method was applied to the determination of PCP in local lake water, river water and wastewater samples.     

Development of a cloud point extraction and preconcentration method for silver prior to flame atomic absorption spectrometry

The possibility was investigated of using 2-mercaptobenzothiazole (MBT) for Ag(I) concentration by micellar extraction at cloud point (CP) temperature and subsequent determination by flame atomic absorption spectrometry (FAAS). The method is based on the complexation of Ag(I) with 2-mercaptobenzothiazole (MBT) in the presence of non-ionic micelles of Triton X-114. The effect of experimental conditions such as pH, concentration of chelating agent and surfactant, equilibration temperature and time on cloud point extraction was studied. Under the optimum conditions, the preconcentration of 10 mL of water sample in the presence of 0.1% Triton X-114 and 2 × 10⁻⁴ mol L⁻¹ 2-mercaptobenzothiazole permitted the detection of 2.2 ng mL⁻¹ silver. The calibration graph was linear in the range of 10–200 ng mL⁻¹, and the recovery of more than 99% was achieved. The proposed method was used in FAAS determination of Ag(I) in water samples.     

多功能柱净化-高效液相色谱法检测谷物中的玉米赤霉烯酮

建立了玉米和小麦中玉米赤霉烯酮（ZEN）的多功能柱净化-高效液相色谱检测方法。样品经乙腈-水混合溶剂（V（乙腈）：V（水）=84：16）提取,通过多功能净化柱（MFC）进行一次性净化,以Symmetry^R C18柱为分离柱,甲醇-水（V（甲醇）：V（水）=68：32）为流动相进行高效液相色谱分离和检测。玉米赤霉烯酮的质量浓度在0．01～4．0μg／mL范围内呈良好线性,相关系数为0．9996。检出限为0．04μg／g,在0、04—5．0mg／kg添加范围内的回收率为87．5％～98．6％,相对标准偏差为1．5％～8．3％。