Green Microextraction Method Research Articles

Multivariate optimisation of a novel green microextraction method for Fe (III) determination in environmental samples by FAAS

ABSTRACT Industrial development has led to increased heavy metal pollution in bodies of water all over the world. Numerous methods are being developed with the aim of detecting and subsequently removing heavy metal ions from water with hopes of reversing pollution. Here, we present a novel and ecological switchable solvent-based liquid phase microextraction (SS-LPME) method that detects Fe (III) in water samples before they can be tested on flame atomic adsorption spectrometry. In this method, 2-(5-Bromo-2-pyridylazo)-5-(diethylamino) phenol was selected as a complexing agent and switchable polarity solvent was formulated with N, N-dimethyl-n-octylamine. Box–Behnken response surface design was used to investigate and optimise factors associated with the extraction recovery. When the optimal conditions were reached, a linear calibration curve was achieved at 0.05–400 µg L−1. The preconcentration factor was 200, the detection limit was 0.015 µg L−1 with the relative standard deviation (RSD) of 2.2% (at 30 µg L−1; n = 8). Water samples and wastewater reference material (SPSWW1) were used to test the applicability and success of the method.

An efficient green microextraction method of Co and Cu in environmental samples prior to their flame atomic absorption spectrometric detection

ABSTRACT A dispersive liquid-liquid microextraction procedure (DLLME) was developed and validated for the determination of cobalt and copper in environmental samples by flame atomic absorption spectrometry. The optimisation parameters of DLLME procedure including amount of chelating reagent (0.05 mg dithizone), pH (6), extraction type and volume (250 µL chloroform) and dispersive solvent (1000 µL acetone), matrix effect was investigated. Several validation variables, such as limit of detection and quantification, linearity, recovery, precision and trueness were also tested. The quantification limits of Co and Cu were found to be 9.01 and 6.14 µg L−1, respectively. The enrichment factor was 20. The trueness of the method was tested by analysis of certificated reference material (BCR-715) for Cu and calculated less than −1.11% with the relative error. The presented green microextraction method was profitably applied to real samples and the spiked recoveries calculated were more than 95% with the relative standard deviation less than 8.4%.

A new green microextraction method for traces Brown HT (E155) by using deep eutectic solvents prior to its spectrophotometric determination

ABSTRACT A method for determination of Brown HT with UV-Vis spectrophotometer after separation and preconcentration by deep eutectic solvent-based liquid phase microextraction was developed. Tetrabutylammonium bromide and decanoic acid were used to get deep eutectic solvent. Important analytical parameters effective on the method were optimised such parameters are deep eutectic solvent type and volume, sample volume, matrix effects and tetrahydrofuran volume. Brown HT in the model solution was quantitatively extracted at the pH 4.0 to the deep eutectic solvent phase. In this study, the limit of detection (LOD) value and preconcentration factor were found to be 0.23 μg mL−1 and 37.5, respectively. The method was applied to the determination of Brown HT content of cake, artificial urine and water samples.

A green microextraction method for determination of sodium dodecyl sulfate in washing liquid samples based on continuous sample drop flow-based microextraction

A novel and improved version of continuous-flow microextraction known as continuous sample drop flow-based microextraction has been utilized for the first time in extraction and preconcentration of sodium dodecyl sulfate (SDS) from detergent samples prior to spectrophotometric determination. In this paper, some effective parameters for determination of SDS, such as the needle diameter, flow rate, concentration of the methylene blue and pH, were optimized. Under optimized conditions, a good linearity for SDS was obtained in the range of 30–400 ng mL−1 with R2 = 0.999. A practical detection limit of 8.2 ng mL−1 was calculated according to a signal-to-noise ratio of three. The enrichment factor of the method was 122.2. The method was employed for determination of total anionic surfactants in shampoo, hand washing liquid and clothes washing liquid. Satisfactory recoveries in the range of 97.9–100.8% for real samples confirmed the good accuracy and applicability of the present method. Afterward, the samples were analyzed by standard method as well and there was no any difference between the standard and the proposed method.

Modified dispersive solid-liquid microextraction coupled to HPLC and application of experimental design methodology to determine the trace amount of levothyroxine in human real samples

A simple, efficient and green microextraction method namely ultrasound assisted-dispersive solid-liquid microextraction based on solidification of floating organic droplet (UA-DSLME-SFOD) coupled to HPLC and UV detector was developed for preconcentration and determination of levothyroxine in human urine and serum samples. The effects of different variables on the extraction efficiency such as pH, volume of extraction solvent, amount of solid disperser, ionic strength and time of ultra-sonication were studied and optimized simultaneously using response surface methodology. For validation of the technique, its accuracy, precision, limit of detection, linearity, and sensitivity were evaluated. The calibration graph of the proposed method was linear in the range of 0.5–2000.0ngmL−1 with the determination coefficient (R2) of 0.9986. The relative standard deviations for 6 replicates were 1.76–3.32% (n=6). This method provided high sensitivity, using of low toxic organic solvents, and simplicity of the extraction processes. The proposed method was successfully applied for determination of levothyroxine in human urine and serum samples.

A green microextraction method in a narrow glass column for copper in artificial saliva extract of smokeless tobacco products

A green non-dispersive ionic liquid based microextraction (ND-ILμE) method was proposed for the preconcentration of trace levels of copper (Cu2+) in artificial saliva extract (ASE) of smokeless tobacco products (SLT). A 100cm long, narrow glass column containing aqueous solution of Cu/ASE was used to increase phase transfer ratio by providing more contact area between two medium, which drastically improve the recovery of Cu-PAN complex into ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6]. At optimum experimental conditions, the detection limit and the enhancement factor were found to be 0.042μgL−1 and 85, respectively. This method was successfully applied to real samples.

Alternative Green Preconcentration Approach Based on Ultrasound-Assisted Surfactant-Enhanced Emulsification Microextraction and HPLC for Determination of Benzimidazole Anthelmintics in Milk Formulae

An alternative green microextraction method based on ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) using a low-density extraction solvent coupled with HPLC has been developed for preconcentration and determination of six benzimidazole anthelmintics, namely, oxfendazole, albendazole, mebendazole, flubendazole, fenbendazole, and niclosamide. The separation was achieved within 12 min, using an Inertsil® C18 column (4.6 × 150 mm, 5.0 µm), with a gradient mobile phase of acetonitrile and 0.1 % (v/v) formic acid. Under the optimum UASEME conditions using Tergitol® TMN-6 and 1-octanol as emulsifier and extraction solvent, respectively, linearity was in the range of 0.5–5,000 μg L−1 with the coefficients of determination (R 2) ranging from 0.9959 to 0.9999. Enrichment factors were obtained up to 89, corresponding to limits of detection ranging from 0.50 to 6.00 µg L−1. Intra-day (n = 8) and inter-day (n = 3 × 3) precisions were obtained with relative standard deviations for retention time and peak area of lower than 2 and 15 %, respectively. The proposed method was successfully applied to determine the target benzimidazoles in milk formulae.