Microwave-assisted of dispersive liquid–liquid microextraction and spectrophotometric determination of uranium after optimization based on Box–Behnken design and chemometrics methods

2017

J. Braz. Chem. Soc.

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Dispersive liquid-liquid microextraction (DLLME) and spectrofluorimetry, coupled with chemometrics methods, are proposed in this work for the pre-concentration and determination of ofloxacin concentration in spiked human urine. Chloroform and acetonitrile were selected as the extraction and dispersive solvents by the one-variable-at-a-time process. The Box-Behnken design was used to optimize the other variables, including the volume of extraction and dispersion solvents, solution pH, and ionic strength. A linear calibration curve was obtained in the 5.0-120.0 ng mL -1 range under optimal conditions with a detection limit of 1.61 ng mL -1 and correlation coefficient of 0.9948. A relative standard deviation (RSD) of 1.13% was obtained for seven consecutive replicates. Parallel factor analysis (PARAFAC) and partial least square (PLS) modeling were applied for the multivariate calibration of the spectrofluorimetric data. To pre-process the data matrices and predict the model results, the orthogonal signal correction (OSC) was used, and the analysis results were statistically compared. The methods accuracy values for ofloxacin determination, evaluated by the root mean square errors of prediction (RMSEP) and relative standard error of prediction (RSEP), were 0.82 and 1.12 using OSC-PLS, and 0.31 and 0.42 using OSC-PARAFAC models, respectively. Ofloxacin can be reliably determined in human urine samples through the proposed procedure, according to the results.

Section: Discussionmentioning

confidence: 91%

Application of Response Surface Modeling and Chemometrics Methods for the Determination of Ofloxacin in Human Urine Using Dispersive Liquid-Liquid Microextraction Combined with Spectrofluorimetry

Assadian

2017

J. Braz. Chem. Soc.

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“…7 showed that, there was a significant increase in the extraction recovery from pH 2.0 to 7.0, in which the maximum amounts of complexes were formed and then the progressive decrease in extraction of uranium at pH<7.0 might be due to the competition of proton with the analyte for reaction with PAN, also there was decrease in the recovery at pH larger than 7.0 that might be due to the hydrolysis of the uranium ions. Therefore, a pH of 7.0 was selected as the optimum pH for subsequent work 25) .…”

Section: Effect Of Type and Volume Of Homogeneous Solventmentioning

confidence: 99%

Flotation-Assisted Homogeneous Liquid-Liquid Microextraction for Trace Determination of Uranium in Water Samples by Icp-MS

Veyseh

2017

J. Chil. Chem. Soc.

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In this study, a novel method based on floatation assistance of homogeneous liquid-liquid microextraction (FA-HLLME), combined with inductively coupled plasma-mass spectroscopy (ICP-MS) was proposed, for the determination of trace uranium in environmental water samples. As one of the miniaturized separation and extraction techniques, homogenous liquid-liquid microextraction (HLLME) has been widely applied in the field of environmental monitoring and assessment. 1,2-pyridylazo-2-naphthol (PAN) was used as the complexing agent while toluene and methanol were selected as the extraction and homogeneous solvents, respectively. The factors that influenced the extraction efficiency for uranium determination (including pH, extraction and homogeneous solvents, concentration of PAN and NaCl, extraction time) were studied statistically. Under optimum conditions (pH=7.0, 100 mL toluene, 500 mL methanol, 6.4×10-5 mol L -1 PAN, 1.5 mol L -1 NaCl and 60 sec of extraction time), the linear dynamic range for uranium determination was 1.0-500.0 ng L -1 (R 2 =0.9995), with a corresponding limit of detection (LOD) of was 0.27 ng L , n=9) was 1.13%, with a corresponding enrichment factor of 360 for uranium extraction. The proposed method was successfully applied for the determination of uranium in different water samples.

“…The experimental data was analyzed by multiple regression analysis through the least square method. 12,13 One empirical second-order quadratic model was developed from this study to predict the FA-HLLME efficiency of extraction pesticides from soil.…”

Section: ¹1mentioning

confidence: 99%

“…Since soil is the basis of plant and animal life, it is important to study the presence of exogenous chemicals such as fertilizers, adjuvants, pesticides, and others. 13 Pesticides present in soil are mainly used for crop protection in different manners, such as direct treatments, aerial spraying, or as vegetable waste after harvest. 4,5 As mentioned above, it is necessary to develop and implement reliable methodologies with fast and low environmental impact for the analysis of pesticide residues in soil.…”

mentioning

confidence: 99%

Development of Flotation-assisted Homogeneous Liquid–Liquid Microextraction to Determine Organochlorine Pesticides in Soil by GC-MS

Sarkhosh

2015

Chemistry Letters

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This work describes optimal flotation-assisted homogeneous liquidliquid microextraction with a special homemade extraction cell that was designed to collect the low-density extraction solvent without centrifugation for the extraction of heptachlor, aldrin, trans-chlordane, cis-chlordane, and op-DDD in soil samples. The extraction solvent was transferred to GC-MS for analysis in the selected ion-monitoring mode. To obtain the optimum conditions for extraction, a rotatable face-centered central composite design consisting of three factors at three levels was used. Under optimum conditions, the method performance was studied in term of the linear dynamic range (LDR from 0500¯g kg ¹1 soil), linearity (R 2 > 0.9989), and precision (in the range of 0.0360.062).Soil is a complex and dynamic natural body that occupies much of the earth's surface; it is mainly composed of organic matter, minerals, and organisms. In addition, it serves as a plant growth substrate. Since soil is the basis of plant and animal life, it is important to study the presence of exogenous chemicals such as fertilizers, adjuvants, pesticides, and others. 13 Pesticides present in soil are mainly used for crop protection in different manners, such as direct treatments, aerial spraying, or as vegetable waste after harvest. 4,5 As mentioned above, it is necessary to develop and implement reliable methodologies with fast and low environmental impact for the analysis of pesticide residues in soil. 6 The first part of the study focused on constructing a calibration with the data recorded in single ion monitoring (SIM) mode using the m/z values of the ions selected previously, while the second part is focused on calculating the figures of merit. The procedure designed in this study allows us to develop an analytical method completely with GC-MS data onto external specifications, from selection of identifying ions (m/z ratios), to quantifications and validation.The four organochlorine pesticides used in the present study were obtained from Supelco (PA, USA). Acetone, n-hexane, 1-decanol, xylene, decane, and toluene were obtained from Merck Co. The determination of compounds was carried out using a gas chromatograph (GC, Agilent 7890 N, Agilent Technologies, Palo Alto, CA, USA) equipped with MS (Agilent 5975, Agilent Technologies, Foster City, CA, USA). The SIM modes were used for determination of target compounds. Four or two selection ions of the compounds were studied by 135, 237, 272; aldrin: 66, 79, 91, 263; transchlordane: 207, 375; 373; 176, 199, 235). An ultrasonic water bath, VGT-1740QTD, Taiwan, was used. Stock standard solutions of each pesticide of 200¯g L ¹1 were prepared in isooctane. For the soil analyses, an intermediate standard solution of 50¯g L ¹1 of each analyte was prepared in acetone. A sieved (through a 500-¯m sieve) soil sample (nonpolluted) was collected from Tehran (Iran). For preparing the soil sample, 500 g was accurately weighed and an appropriate amount of the standard stock solution was added. Three real soil samples were an...