浊点萃取-紫外可见分光光度法测定痕量钴

浊点萃取(Cloud-Point Extraction,简称CPE)是近年来出现的一种新兴的液-液萃取技术,该法以表面活性剂胶束水溶液的溶解性和浊点现象为基础,通过改变实验参数如溶液pH值、离子强度、温度等引发相分离,将疏水性物质与亲水性物质分离,同时起到富集的作用.     

浊点萃取分光光度法测定水样中的痕量锌(Ⅱ)

为建立浊点萃取预富集测定水样中痕量锌的新方法,在表面活性剂TritonX-114存在下,利用5-Br-PADAP与锌(Ⅱ)产生显色反应的性能,采用分光光度法测定了水样中的痕量锌。结果表明,在pH8.5的NH3-NH4Cl缓冲体系中,锌(Ⅱ)与5-Br-PADAP形成紫红配合物,其最大吸收波长为λ=555 nm,摩尔吸光系数为ε=1.284×105L.mol-1.cm-1,检测限为0.003 7μg.mL-1.锌含量在0~1.2μg.mL-1范围内服从比尔定律。该法有较好的选择性,具有低毒、高效、安全、简便等特点,直接用于水样中痕量锌的测定,结果满意,重复6次测定相对标准偏差为2.18%。     

浊点萃取-分光光度法测定水样中痕量结晶紫

提出了浊点萃取-分光光度法测定水样中结晶紫的新方法,研究了非离子表面活性剂Triton X-114浊点萃取的最佳条件,如pH、试剂用量、平衡时间和温度等。结晶紫的最大吸收波长为579 nm,标准曲线的线性范围是32～700 ng/mL,检出限是9.8 ng/mL,富集倍率为20。结晶紫的浓度在0.2和0.5μg/mL时的相对标准偏差分别为2.5%和1.7%(n=8)。应用本方法测定水样中的痕量结晶紫,平均回收率95.2%～98.1%。     

浊点萃取-分光光度法测定自来水及酒类样品中的痕量铁

利用非离子表面活性剂TritonX-100在温度高于其浊点时形成相分离行为,建立了浊点萃取-分光光度法测定痕量铁的新方法,探讨优化了以KSCN为显色剂,TritonX-100浊点萃取富集痕量铁的实验条件.研究发现:加入正辛醇可使TritonX-100的浊点降低约30℃,有利于萃取实验的进行;同时,加入的正辛醇与TritonX-100对痕量铁起到了协同萃取作用.在优化了的实验条件下,进行了痕量铁的分析,检出限为0.02mg·L-1,加标回收率为97.4%～101.6%,应用于自来水及酒类样品中痕量铁的测定,结果满意.     

浊点萃取-分光光度法测定痕量NO2-

建立了浊点萃取-分光光度法测定痕量NO2-根的方法.以对氨基苯磺酸和α-萘胺为络合剂,非离子型表面活性剂TritonX-100为萃取剂,富集、分离水样中痕量NO2-,采用可见吸收光谱法进行检测.研究了溶液的酸度、试剂用量、平衡时间、平衡温度、干扰离子对浊点萃取效果的影响,并得到最佳实验条件:5％的TritonX-100用量2.0mL、平衡温度85℃、平衡时间10min、对氨基苯磺酸和α-萘胺均为0.3mL、0.1mol/LH2SO4溶液0.5mL.在最佳实验条件下,对氨基苯磺酸、α-萘胺和NO2-生成的络合物被萃取到TritonX-100表面活性剂相并与水相分开.该方法适用于环境水样中痕量NO2-的测定.     

ABTT浊点萃取分光光度法测定水样中镉

利用非离子表面活性剂Triton X-114在温度高于其浊点时形成相分离行为,建立了浊点萃取-分光光度法测定水样中痕量镉的新方法,优化了以1-偶氮苯-3-噻唑-三氮烯(ABTT)为显色剂,Triton X-114浊点萃取富集痕量镉的实验条件.在最大吸收波长λ=520 nm,其表观摩尔吸光系数为6.84×105L·mol...     

紫外可见分光光度法快速测定苯硫酚

设计合成一种全新的苯硫酚检测探针。以试卤灵钠为主要原料,在三乙胺催化下与2,4-二硝基氯苯合成了7-(2’,4’-二硝基苯氧基)-3H-吩噁嗪-3-酮,产率为41.7%。在p H 7.4的磷酸盐缓冲溶液中,该化合物能与苯硫酚发生亲核取代反应,反应体系在可见光区λ=580 nm处有强吸收。该探针测定苯硫酚的线性范围为0.1~20μmol/L,检出限为8.9×10–8 mol/L,精密度为3.7%(n=8),回收率为106%。该方法可快速检测环境及生物体中的苯硫酚。     

浊点萃取-分光光度法测定粉煤灰中痕量Ni(Ⅱ)

利用非离子表面活性剂Triton X-114在温度高于其浊点时形成相分离行为,建立了浊点萃取富集痕量Ni(Ⅱ)的新方法.在pH9.5的Na2B4O7-NaOH缓冲溶液中,Ni(Ⅱ)与1-(4-硝基苯基)-3-(5,6-二甲基-1,2,4三氮唑)-三氮烯(NPDMTT)反应生成稳定的络合物,在475 nm处出现正吸收峰,...     

在薄层扫描仪上进行紫外／可见分光光度法测定的研究

薄层扫描仪是用于进行薄层扫描定量分析的仪器。虽然它的操作方法、设备等在其30多年的历史中已有许多改进,但整个应用过程是不连续的,且较为复杂,每个操作步骤都会影响定量的准确性。因此,它的使用范围受到一定限制。相比之下,分光光度计的使用要简单得多,它可对液体样品直接分析,具有较好的分析灵敏度和精密度,可测元素较多,操作快速简单。鉴于薄层扫描仪与UV/VIS分光光度     

紫外可见分光光度法测定田七花中总黄酮含量

建立了分光光度法测定田七花中黄酮含量的方法.采用分光光度法,以芦丁为对照品,在波长510nm处对样品中的总黄酮进行含量测定.样品总黄酮在浓度0～50μg/mL范围内线性关系良好,其回归方程为A=11.069C-7.143×10-4;R=0.9993.该方法可作为田七花中总黄酮含量的测定的方法之一.     

Cloud point extraction procedure for flame atomic absorption spectrometric determination of lead(II) in sediment and water samples

The conditions for cloud point extraction of lead(II) from aqueous solutions were investigated and optimized. The procedure is based on the separation of Pb(II) – brillant cresyl blue (BCB) complexes into the micellar media by adding the surfactant Triton X-114. After phase separation, the surfactant-rich phase was dissolved with 1 mol L⁻¹ HNO₃ in ethanol and diluted with 1 mol L⁻¹ HNO₃ solution before lead was determined by flame atomic absorption spectrometry. Optimization of the pH, ligand and surfactant quantities, incubation time, temperature, viscosity, sample volume, and interfering ions was performed. The effects of the matrix ions were also examined. The detection limits for three times the standard deviations of the blank for lead were 7.5 μg L⁻¹ for water samples and 0.33 μg g⁻¹ for sediment samples. The validity of cloud point extraction was checked by employing certified reference samples of Lake Sediment IAEA-SL-1 and Sewage Sludge BCR-CRM 144R. The procedure was applied to natural waters and sediment samples with satisfactory results (recoveries >95%, relative standard deviations <6.4%).     

Cloud point extraction for ultra-trace Cd determination in microwave-digested biological samples by ETAAS

Cloud point extraction (CPE) has been used for the preconcentration of cadmium, after the formation of a complex with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (5-Br-PADAP), and further determination by graphite furnace atomic absorption spectrometry (ETAAS) using polyethyleneglicolmono-p-nonyphenylether (PONPE 7.5) as surfactant. The chemical variables that affect the cloud point extraction were optimized. The separation of the two phases was easily accomplished by cooling the mixture in order to make more viscous the surfactant-rich phase. In order to establish the optimum conditions for the determination of Cd by ETAAS, Pd + Mg, Pt, Ir, Rh and Ru were studied as chemical modifiers. The best thermal stabilization was obtained with Pd + Mg, with a maximum pyrolysis temperature of 1100 °C. Under the optimum conditions i.e., pH 9.0, [5-Br-PADAP] = 2.0 × 10⁻⁵ mol L⁻¹, [PONPE 7.5] = 0.02% (w/v), an enhancement factor of 22-fold was reached. The lower limit of detection (LOD) obtained under the optimal conditions was 0.008 μg L⁻¹. The precision for 10 replicate determinations at 0.2 μg L⁻¹ Cd was 3.5% relative standard deviation (R.S.D.). The calibration graph using the preconcentration method was linear with a correlation coefficient of 0.9984 at levels close to the detection limit up to at least 1.0 μg L⁻¹. The method was successfully applied to the determination of cadmium in urine samples and in a water standard reference material.     

浊点萃取-火焰原子吸收光谱法测定淡水鱼中痕量铅

采用以双硫腙为络合剂、Triton X-100为表面活性剂的新型浊点萃取体系富集淡水鱼中的痕量铅,并用火焰原子吸收光谱法对其进行测定。探讨了溶液pH、表面活性剂浓度、络合剂用量、平衡温度、平衡时间等对浊点萃取及测定灵敏度的影响,优化了实验条件。在最佳条件下测得铅的检出限为0.090μg/L,校准曲线相关系数为0.9999。该方法已用于淡水鱼中痕量铅的测定。     

A novel fiber optic spectrophotometric determination of nitrite using Safranin O and cloud point extraction

A novel fiber optic spectrophotometric method for nitrite determination in different samples is suggested, based on the reaction of nitrite with Safranin O in acidic medium to form a diazo-safranin, which is subsequently coupled with pyrogallol in alkaline medium to form a highly stable, red azo dye, followed by cloud point extraction (CPE) using a mixed micelle of a nonionic surfactant, Triton X-114, with an anionic surfactant, sodium dodecyl sulphate (SDS). The reaction and extraction conditions (e.g., acidity for diazotization and alkalinity for pyrogallol coupling, and other reagent concentrations, time, and tolerance to other ions) were optimized. Linearity was obeyed in a concentration range up to 230 μg L⁻¹, and the detection limit of the method is 0.5 μg L⁻¹ of nitrite ion. The molar absorptivity for nitrite of the Safranin-diazonium salt (?_610 nm = 4 × 10³ L mol⁻¹ cm⁻¹) existing in literature was greatly enhanced by pyrogallol coupling and CPE enrichment (?_592 nm = 1.39 × 10⁵ L mol⁻¹ cm⁻¹). The method was applied to the determination of nitrite in tap water, lake water and milk samples with an optimal preconcentration factor of 20.     

Determination of estrogens in water by HPLC-UV using cloud point extraction

A method based on cloud point extraction was developed to determine four kinds of estrogens: estriol (E3), estradiol (E2), estrone (E1), and progesterone (P) in water by high performance liquid chromatography separation and ultraviolet detection (HPLC-UV). The non-ionic surfactant Triton X-114 was chosen as extractant solvent. The parameters affecting extraction efficiency, such as concentrations of Triton X-114 and Na₂SO₄, equilibration temperature, equilibration time and centrifugation time were evaluated and optimized. Under the optimum conditions, preconcentration factors of 99 for E3, 73 for E2, 152 for E1 and 86 for P were obtained for 10 mL water sample. The detection of limitation was 0.23 ng mL⁻¹ for E3, 0.32 ng mL⁻¹ for E2, 0.25 ng mL⁻¹ for E1 and 5.0 ng mL⁻¹ for P. The proposed method was successfully applied to the determination of trace amount of estrogens in wastewater treatment plant (WWTP) effluent water and exposure water with 10 ng mL⁻¹ E2 for toxicological study in our lab. For the case of WWTP effluent water samples, no estrogen was found. The accuracy of the proposed method was tested by recovery measurements of spiked samples and good recoveries of 81.2-99.5% were obtained.     

A novel cloud point extraction approach using cationic surfactant for the separation and pre-concentration of chromium species in natural water prior to ICP-DRC-MS determination

A novel cloud point phase separation of cationic surfactant, Aliquat-336 and capabilities of its reactive solubilizing sites for selective extraction of chromium species at ultra trace levels was examined in natural water. The phase separation behavior of Aliquat-336 is studied with various additives. The nonionic surfactant, Triton X-114 was found to induce the cloud point phase separation of Aliquat-336. The separation of anionic Cr(VI) was enabled by the formation of ion associate with quaternary ammonium head group of Aliquat-336 at pH 2, and the recovery of Cr(VI) and Cr(III) were 101.4 ± 1.4% and 2.2 ± 0.4%, respectively at 0.5-1 ng mL⁻¹, Total Cr was pre-concentrated as Cr-APDC species using the hydrophobic tail group at pH 6.5. The Cr(III) concentration was obtained by subtracting Cr(VI) from total Cr. The recovery of total Cr was 99.5 ± 1.2%. Parameters affecting extraction were assessed. The procedure was applied to NIST 1643c and NIST 1643d waters, and the sum of individual species obtained was compared with the certified chromium values. The method was also applied to various natural waters with limits of detection and pre-concentration factor of 0.010 and 0.025 ng mL⁻¹; 10 and 10, respectively, for Cr(VI) and Cr(III)-APDC using ICP-MS operated in DRC mode.     

Cloud point formation based on mixed micelles in the presence of electrolytes for cobalt extraction and preconcentration

A new micelle-mediated phase separation of metal ions, applied for preconcentrating trace levels of cobalt as a prior step to its determination by flame atomic spectroscopy, has been developed. Two methods were proposed employing both Triton X-100 and sodium dodecyl sulfate (SDS) as a mixed micellar system while the phase separation was induced by HCl or NaCl addition. Cobalt was complexed with pyridylazo compounds (PAN, PAR, 5-Br-PADAP) in an aqueous surfactant medium and it was concentrated in the surfactant rich phase after phase separation. The chemical variables affecting the cloud point extraction were evaluated, optimized and successfully applied to cobalt determination in pharmaceutical samples. Under the optimized conditions, the preconcentration system permitted limits of detection as 1.1 and 1.6 μg l⁻¹ cobalt, respectively, when HCl and NaCl were used. Both proposed methods showed linear calibration within a 25-200 μg l⁻¹ cobalt range. The extraction efficiency was investigated at different cobalt concentrations (40-185 μg l⁻¹) and good recoveries (98-102%) were obtained by using NaCl as electrolyte. The results obtained were compared with those observed with ET AAS.     

Fiber optic-linear array detection spectrophotometry in combination with cloud point extraction for simultaneous preconcentration and determination of cobalt and nickel

A new combined method including fiber optic-linear array detection spectrophotometry (FO-LADS) and cloud point extraction (CPE) was developed using a cylindrical micro cell for simultaneous preconcentration and determination of different species. The CPE and FO-LADS methods have good matching conditions for combination because FO-LADS is suitable as a detection technique for the low volume of remained phase obtained after CPE. This combination was carried out using 50 μL cylindrical micro cell and then employed for simultaneous preconcentration and determination of cobalt and nickel.Cloud point extraction method was based on the chromogenic reaction of metal ions and 1-(2-pyridylazo)-2-naphthol (PAN) and then preconcentration of formed complexes using octylphenoxypolyethoxyethanol (Triton X-114). The remained phase after CPE was transferred into cylindrical micro cell and located at the cell holder of FO-LADS. The spectra of cobalt and nickel complexes were collected by FO-LADS and processed for ordinary and first derivative spectrophotometry.Optimization of different parameters was evaluated. Under optimum conditions, calibration curves were linear in the range of 0.6-30.0 and 0.1-15.0 μg L⁻¹ with detection limits of 0.2 and 0.04 μg L⁻¹ for Co and Ni respectively. The relative standard deviations (R.S.D.s) were lower than 4%. The obtained enhancement factors were 198 and 199 for cobalt and nickel, respectively.The proposed method was compared with the other methods and applied to the analysis of several real and spiked samples.