In-process prepared deep eutectic solvent based homogeneous liquid-liquid microextraction for the determination of irgaphos 168 and irganox 1010 in polypropylene packed drinks

In situ synthesis of a deep eutectic solvent and homogeneous liquid-liquid microextraction performed in a narrow bore tube was developed for efficient extraction of irgaphos 168 and irganox 1010 in doogh and water samples packed in polypropylene packages. First, pH of the aqueous sample solutions containing the analytes is adjusted at 9. Then a hydrogen bond acceptor (choline chloride) and a hydrogen bond donor (oleic acid) are dissolved in the solution and vortexed to obtain a homogeneous solution. The solution is filled into a narrow bore tube, in which its bottom was clogged by a septum. Then hydrochloric acid solution is injected into the solution by a syringe. The tube is placed in an ultrasonic bath. During this step, the droplets of choline chloride:oleic acid deep eutectic solvent are produced. The method indicated high enrichment factor (435 for irgaphos 168 and 488 for irganox 1010), low limits of detection (0.03 and 0.09 ng/mL for irgaphos 168 and irganox 1010, respectively) and quantification (0.13 and 0.29 ng/mL for irgaphos 168 and irganox 1010), good recovery (74 and 83% for irgaphos 168 and irganox 1010, respectively), and satisfactory repeatabilities (relative standard deviations ≤12%) can be obtained using the developed method.

Synthesis and characterization of phosphocholine chloride-based three-component deep eutectic solvent: application in dispersive liquid-liquid microextraction for determination of organothiophosphate pesticides

BACKGROUND

A new type of deep eutectic solvent based on three components using phosphate salts has been synthesized, characterized, and applied in the extraction of eight organothiophosphate pesticides from honey samples. In this study, the deep eutectic solvent was prepared from phosphocholine choline chloride as a hydrogen bond acceptor and dichloroacetic acid and decanoic acid as hydrogen bond donors. The method consisted of two steps in which initially the analytes were extracted from the samples into a water-miscible organic solvent. In the second step, the extracted phase was mixed with the prepared deep eutectic solvent and the mixture was used in the following dispersive liquid-liquid microextraction method.

RESULTS

The method was validated under optimal conditions, and it was found that it has low limits of detection (0.05-0.10 ng g^-1 ) and quantification (0.19-0.36 ng g^-1 ), good linearity (r²  ≥ 0.994), broad linearity (0.36-1000 ng g^-1 ), and satisfactory repeatability (relative standard deviation ≤10% for intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 2 ng g^-1 of each analyte).

CONCLUSION

The proposed method was applied in different honey samples, and malathion was found at a concentration of 29 ng g^-1 in one sample. © 2019 Society of Chemical Industry.

Preparation of a new three-component deep eutectic solvent and its use as an extraction solvent in dispersive liquid-liquid microextraction of pesticides in green tea and herbal distillates

BACKGROUND

A new solvent, deep eutectic solvent, in which there is growing interest, has been prepared and used as an extraction solvent in the dispersive liquid-liquid method of microextraction. To prepare the solvent, dichloroacetic acid, l-menthol, and n-butanol are mixed at a molar ratio of 4:1:1 and the deep eutectic solvent is formed after heating. Then a dispersive liquid-liquid microextraction method using the prepared solvent is used for the extraction and preconcentration of some pesticides from an aqueous sample. To carry out the procedure, the deep eutectic solvent is mixed with methanol and rapidly injected by a syringe into the aqueous sample containing the analytes. After centrifuging, an aliquot of the sedimented phase is injected into the gas chromatograph. The influence of several variables on the extraction efficiency was investigated and optimized.

RESULTS

Extraction recoveries and enrichment factors were obtained in the ranges of 53-86% and 1760-2853, respectively. The intra- (n = 6) and inter-day (n = 5) precision of the method was satisfactory, with relative standard deviations ≤ 7% obtained at two concentrations of 10 and 50 μg L^-1 of each analyte. Moreover, detection and quantification limits for the target analytes were obtained in the ranges of 0.11-0.23 and 0.38-0.74 μg L^-1 , respectively.

CONCLUSION

Different samples, including green tea, rose water, lemon balm, mint, and pussy willow distillates were analyzed successfully using the method that was developed, and chlorpyrifos was found in rose water at a concentration of 17 ± 1 μg L^-1 (n = 3). © 2019 Society of Chemical Industry.

Control of Organophosphorus Pesticides Residues in Honey Samples Using a Miniaturized Tandem Preconcentration Technique Coupled with High Performance Liquid Chromatography

Background : In the present work, a miniaturized sample preparation method based on combination of dispersive solid phase extraction and temperature–induced homogenous liquid–liquid microextraction has been proposed for the extraction and preconcentration of some organophosphorus pesticides (parathion–methyl, triazophos, parathion, diazinon, and phoxim) from honey samples prior to their analysis by high performance liquid chromatography–ultraviolet detection. Methods: In this method, initially the analytes were adsorbed onto a sorbent (C18) and then desorbed by the use of cyclohexyl amine as an eluent. In the next step, the eluent was mixed with water thermostated at 0 °C to obtain a homogenous solution. By increasing the temperature, the solubility of cyclohexyl amine in water was decreased and led to formation of dispersed fine droplets in the whole of solution. These droplets go up through the solution and collected on top of the solution. Finally, an aliquot of the organic phase was sucked in a microsyringe and injected into the separation system for analysis. Results: Under the optimum experimental conditions, limits of detection and quantification were calculated to be in the ranges of 0.90–1.75 and 3.0–5.8 ng g–1 in honey samples, respectively. Enrichment factors and extraction recoveries were in the ranges of 148–183 and 59–73%, respectively. The relative standard deviations varied from 2–4% and 4–5% for intra– (n = 6) and inter–day (n = 4) precisions, respectively. Conclusion: The suggested approach was satisfactorily utilized to the analysis of 21 honey samples. The proposed miniaturized tandem sample pretreatment method enhanced the sensitivity of the instrumental analysis.

Magnetic solid-phase extraction method for extraction of some pesticides in vegetable and fruit juices

A new version of magnetic solid-phase extraction performed in a narrow-bore tube has been proposed for the extraction and preconcentration of different pesticides from various vegetable and fruit juices followed by gas chromatography. A few milligrams of C₈ @SiO₂ @Fe₃ O₄ nanoparticles are added into an aqueous sample solution placed in a narrow-bore tube. The sorbent particles move down through the tube under gravity and are collected at the end of the tube by applying an external magnetic field. The end of the tube is narrower and it is connected to a stopcock. After a predetermined time, the stopcock is opened and the solution is passed through the bed of the sorbent maintained by the magnet. Then the adsorbed analytes are desorbed using an elution solvent. To achieve high enrichment factors, a dispersive liquid-liquid microextraction method is carried out. The nanoparticles were characterized by scanning electron microscopy, X-ray diffraction, and FTIR spectroscopy. Under the optimum extraction conditions, limits of detection and quantification were in the ranges of 0.1-0.3 and 0.3-0.9 μg/L, respectively. High enrichment factors (1166-1605) and good extraction recoveries (58-80%) were obtained.

Application of a clean-up procedure using a ternary liquid phase system combined with pre-concentration by microextraction in the analysis of seven pesticides from soya milk

BACKGROUND

A method has been developed based on a three-phase system, followed by dispersive liquid-liquid microextraction for the extraction of seven pesticides from soya milk prior to analysis by gas chromatography-flame ionization detection. The base of this method is the different extraction capability of the components of soya milk according to each of the phases involved. In this procedure, a homogeneous solution consisting of soya milk and a water-miscible solvent (acetonitrile) is separated into two phases in the presence of Na₂ SO₄ and the analytes are extracted into the produced acetonitrile droplets. The acetonitrile phase is mixed with a pre-concentration solvent to perform the next microextraction procedure for further enrichment of the analytes.

RESULTS

Limits of detection and quantification were reached in the ranges of 0.11-0.35 and 0.35-1.20 µg L^-1 , respectively. Enrichment factors and extraction recoveries were in the ranges of 562-933 and 56-93%, respectively. Relative standard deviations were ≤7% for intra- (n = 6) and inter-day (n = 5) precisions at two concentrations of 10 and 50 µg L^-1 of each analyte.

CONCLUSION

The proposed method was applied to the analysis of pesticides in soya milk samples at µg L^-1 concentrations. © 2019 Society of Chemical Industry.