Air-assisted Liquid-liquid Microextraction Research Articles

A sensitive and efficient method for trace analysis of some phenolic compounds using simultaneous derivatization and air-assisted liquid-liquid microextraction from human urine and plasma samples followed by gas chromatography-nitrogen phosphorous detection.

In present study, a simultaneous derivatization and air-assisted liquid-liquid microextraction method combined with gas chromatography-nitrogen phosphorous detection has been developed for the determination of some phenolic compounds in biological samples. The analytes are derivatized and extracted simultaneously by a fast reaction with 1-flouro-2,4-dinitrobenzene under mild conditions. Under optimal conditions low limits of detection in the range of 0.05-0.34 ng mL(-1) are achievable. The obtained extraction recoveries are between 84 and 97% and the relative standard deviations are less than 7.2% for intraday (n = 6) and interday (n = 4) precisions. The proposed method was demonstrated to be a simple and efficient method for the analysis of phenols in biological samples.

Determination of triazole pesticide residues in edible oils using air-assisted liquid-liquid microextraction followed by gas chromatography with flame ionization detection.

In the present study, a rapid, simple, and highly efficient sample preparation method based on air-assisted liquid-liquid microextraction followed by gas chromatography with flame ionization detection was developed for the extraction, preconcentration, and determination of five triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole, and triticonazole) in edible oils. Initially, the oil samples were diluted with hexane and a few microliter of a less soluble organic solvent (extraction solvent) in hexane was added. To form fine and dispersed extraction solvent droplets, the mixture of oil sample solution and extraction solvent is repeatedly aspirated and dispersed with a syringe. Under the optimum extraction conditions, the method showed low limits of detection and quantification between 2.2-6.1 and 7.3-20 μg/L, respectively. Enrichment factors and extraction recoveries were in the ranges of 71-96 and 71-96%, respectively. The relative standard deviations for the extraction of 100 and 250 μg/L of each pesticide were less than 5% for intraday (n = 6) and interday (n = 3) precisions. Finally edible oil samples were successfully analyzed using the proposed method, and hexaconazole was found in grape seed oil.

Air-Assisted Liquid Liquid-Microextraction for the Analysis of Fungicides from Environmental Water and Juice Samples.

In this work, a rapid method based on air-assisted liquid liquid microextraction (AALLME) was developed for the determination of three fungicides (azoxystrobin, diethofencarb and pyrimethanil) in water and juice samples. A narrow-neck glass tube was made to facilitate collection of the low-density extractant. The mixture of extractant and sample solution is rapidly sucked into a 5-mL glass syringe and then is injected into the narrow-neck glass tube and the procedure is repeated six times. A homogeneous solution was formed and then with the continuous injection of air by a 20-mL glass syringe, phase separation happened and the extractant was collected on the top of the sample solution. No centrifugation separation step was involved. It took only 90 s to complete the pretreatment process. The influence of main factors on the extraction efficiency is studied. Under optimal conditions, enrichment factors for the three fungicides varied from 145 to 178. The limits of detection for azoxystrobin, diethofencarb and pyrimethanil were 0.08, 0.16 and 0.25 µg L(-1), respectively. Reasonable relative recoveries were varied from 72.3 to 108.0%. And satisfactory intra-assay (5.3-6.2%, n = 6) and inter-assay (6.8-9.3%, n = 6) precision illustrated good performance of the analytical procedure.

Extraction and enrichment of triazole and triazine pesticides from honey using air-assisted liquid-liquid microextraction.

In the present work, an easy, fast, and effective approach is developed for the extraction and enrichment of triazole and triazine pesticides in honey by air-assisted liquid-liquid microextraction coupled with gas chromatography-flame ionization detection. Initially, honey is dissolved in an acetonitrile: water mixture and after that a few microliter of a less soluble organic solvent in aqueous phase is added. In order to form a cloudy solution, the extractant mixed with aqueous phase is repeatedly sucked and expelled by a syringe needle into a glass tube. After centrifugation, the sedimented phase (1 mL) is removed with a syringe and injected into de-ionized water. By this action, the settled phase volume is reduced to 10 μL and the analytes are concentrated, too. Under optimum extraction conditions, limits of detection and quantitation for the studied pesticides are in the ranges of 2 to 5 and 6 to 17 ng/g, respectively. Extraction recoveries and enrichment factors are from 61% to 95% and 61 to 95, respectively. The proposed approach can be applied for determination of pesticide in honey and may be developed to other complex matrices.

Air-assisted liquid–liquid microextraction for simultaneous derivatization, extraction, and preconcentration of some phenolic compounds

In this study, an air-assisted liquid–liquid microextraction (AALLME) method has been developed for simultaneous derivatization, extraction, and preconcentration of some phenolic pollutants in aqueous samples before their determination by gas chromatography-flame ionization detection (GC-FID). In order to improve the chromatographic behavior of phenolic compounds, the analytes were derivatized with butyl chloroformate (BCF) and extracted simultaneously into 1,1,1-trichlorethane. The effects of different parameters influencing the extraction efficiency including extraction solvent type and its volume, ionic strength, volume of derivatization agent, and extraction numbers were investigated and optimized for the simultaneous derivatization/microextraction procedure. Under the optimum extraction conditions, the method showed wide linear ranges (LRs) between 1–2000 μg L−1. The other analytical parameters were obtained in the following ranges: enrichment factors (EFs) 2020–2761, enhancement factors (EnFs) 2225–3807, extraction recoveries (ERs) 65–88%, and limits of detection (LODs) 0.1–0.4 μg L−1. Relative standard deviations (RSDs) for the extraction of 100 and 200 μg L−1 of each selected phenol (n = 6) were obtained in the ranges of 2–4% and 1–4%, respectively. Finally, the target phenols were determined in different samples such as tap water, river water, petrochemical wastewater, refinery wastewater, and municipality wastewater by the proposed AALLME-GC-FID method.

Development and validation of a rapid and sensitive gas chromatographic method for the analysis of some phenolic compounds in vegetable oils

A new method based on simultaneous derivatization and air-assisted liquid–liquid microextraction (AALLME) is developed for the determination of some phenolic compounds in different oils. In this method, the analytes are extracted from the oil samples by NaOH solution, then a few μL of butyl chloroformate and carbon tetrachloride are injected into the NaOH solution containing the extracted analytes, and the resulting mixture is sucked into a syringe and injected several times into a test tube with a conical base. After centrifugation of the resulting cloudy solution, the fine droplets of the organic phase containing the derivatized phenols are precipitated at the bottom of the tube. Then, 1 μL of the settled phase is injected into a gas chromatograph with flame ionization detection (GC-FID). The effects of extraction solvent type, derivatization agent and extraction solvent volumes, number of extractions and reaction time on the extraction efficiency were investigated. Under the optimum conditions, the enrichment factors (EF), extraction recoveries (ER), and enhancement factors (EnF) were high and ranged between 572–991, 60–109%, and 497–1471, respectively. The calibration graphs were linear in the concentration range of 3–10 000 μg L−1. Relative standard deviations (RSD, %) for the extraction of each of the selected phenols were in the ranges of 2–4% for intra-day (n = 6) and 3–5% (n = 5) for inter-day precision for a concentration of 200 μg L−1 of each analyte. Limits of detection (LOD) were in the range of 1–2 μg L−1. Various oil samples, including olive oil, virgin olive oil, sunflower oil, and colza oil, were successfully analyzed by the proposed method.

Simultaneous derivatization and air-assisted liquid-liquid microextraction of some parabens in personal care products and their determination by GC with flame ionization detection

A simultaneous derivatization/air-assisted liquid-liquid microextraction technique has been developed for the sample pretreatment of some parabens in aqueous samples. The analytes were derivatized and extracted simultaneously by a fast reaction/extraction with butylchloroformate (derivatization agent/extraction solvent) from the aqueous samples and then analyzed by GC with flame ionization detection. The effect of catalyst type and volume, derivatization agent/extraction solvent volume, ionic strength of aqueous solution, pH, numbers of extraction, aqueous sample volume, etc. on the method efficiency was investigated. Calibration graphs were linear in the range of 2-5000 μg/L with squared correlation coefficients >0.990. Enhancement factors and enrichment factors ranged from 1535 to 1941 and 268 to 343, respectively. Detection limits were obtained in the range of 0.41-0.62 μg/L. The RSDs for the extraction and determination of 250 μg/L of each paraben were <4.9% (n = 6). In this method, the derivatization agent and extraction solvent were the same and there is no need for a dispersive solvent, which is common in a traditional dispersive liquid-liquid microextraction technique. Furthermore, the sample preparation time is very short.

Air-assisted liquid–liquid microextraction used for the rapid determination of organophosphorus pesticides in juice samples

A novel and simple air-assisted liquid–liquid microextraction (AALLME) is introduced to analyze the organophosphorus pesticide (OPP) residues in fruit juice samples, using the gas chromatography-flame photometric detection (GC-FPD). In this method, fine extraction solvent drops are rapidly formed and dispersed into the aqueous samples, by using a syringe to withdraw and push-out the mixture of aqueous sample solution and extraction solvent several times. The parameters affecting the extraction efficiency were investigated including the type and volume of the extraction solvent, salt addition, extraction times, and pH. Under optimized conditions, the method showed good linearities with the correlation coefficients (γ) higher than 0.9988, and the sensitivity with the limits of detection (LODs) between 0.02μgL−1 and 0.6μgL−1. The method was applied to determine the OPP residues in juice samples and the recoveries were ranged from 79% to 113% with relative standard deviations (RSDs) of 0.4–9.9%. The feasibility of the method in real samples was proved.

Air-assisted liquid–liquid microextraction-gas chromatography-flame ionisation detection: A fast and simple method for the assessment of triazole pesticides residues in surface water, cucumber, tomato and grape juices samples

A recently reported microextraction technique namely air-assisted liquid–liquid microextraction (AALLME) has been described for the extraction/preconcentration of some triazole pesticides from different samples prior to gas chromatography-flame ionisation detection (GC-FID). This technique is similar to dispersive liquid–liquid microextraction (DLLME) but in this method there is no need to use a disperser solvent and also volume of the used extraction solvent is less than DLLME. In this study, toluene with a density lower than that of water was used as an extraction solvent. Under the optimum extraction conditions, the method showed wide linear ranges with R2>0.996 and low limits of detection and quantification between 0.53–1.13 and 1.76–3.77ngmL−1, respectively. Enrichment factors (EFs) and extraction recoveries (ERs) were in the ranges of 713–808 and 100–113%, respectively. Relative standard deviations (RSDs) for the extraction of 25 and 250ngmL−1 of each selected triazole pesticide were less than 7% for intra-day (n=6) and inter-days (n=5) precision. The method was successfully used for analytes determination in different surface water, grape juice, cucumber, and tomato samples.

Simultaneous derivatization and air-assisted liquid–liquid microextraction of some aliphatic amines in different aqueous samples followed by gas chromatography-flame ionization detection

The paper presents a new method based on simultaneous derivatization and air-assisted liquid–liquid microextraction (AALLME) for the extraction and preconcentration of some aliphatic amines prior to gas chromatography-flame ionization detection (GC-FID). Primary aliphatic amines are derivatized and extracted simultaneously by a fast reaction with butylchloroformate (derivatization agent/extraction solvent) under mild conditions. The mixture of butylchloroformate and aqueous sample solution is rapidly sucked into a 10-mL glass syringe and then is injected into a test tube with conical bottom and the procedure is repeated seven times. After centrifuging the resulted cloudy solution, the derivatized analytes in the sedimented phase are determined by GC-FID. The influence of main factors on the efficiency of derivatization/extraction procedure is studied. Under the optimal conditions, the enrichment factors (EFs) for aliphatic amines are obtained in the range of 248–360 and limits of detection (LODs) are between 0.30 and 2.6μgL−1. The obtained extraction recoveries ranged from 50 to 72% and the relative standard deviation (RSD) was less than 4.8% for intra-day (n=6) and inter-days (n=4) precision. The method is successfully applied to determine some aliphatic amines in environmental water samples.

Air-assisted liquid–liquid microextraction method as a novel microextraction technique; Application in extraction and preconcentration of phthalate esters in aqueous sample followed by gas chromatography–flame ionization detection

A novel microextraction technique, air-assisted liquid–liquid microextraction (AALLME), which is a new version of dispersive liquid–liquid microextraction (DLLME) method has been developed for extraction and preconcentration of phthalate esters, dimethyl phthalate (DMP), diethyl phthalate (DEP), di-iso-butyl phthalate (DIBP), di-n-butyl phthalate (DNBP), and di-2-ethylhexyl phthalate (DEHP), from aqueous samples prior to gas chromatography–flame ionization detection (GC–FID) analysis. In this method, much less volume of an organic solvent is used as extraction solvent in the absence of a disperser solvent. Fine organic droplets were formed by sucking and injecting of the mixture of aqueous sample solution and extraction solvent with a syringe for several times in a conical test tube. After extraction, phase separation was performed by centrifugation and the enriched analytes in the sedimented phase were determined by GC–FID. Under the optimum extraction conditions, the method showed low limits of detection and quantification between 0.12–1.15 and 0.85–4ngmL−1, respectively. Enrichment factors (EFs) and extraction recoveries (ERs) were in the ranges of 889–1022 and 89–102%, respectively. The relative standard deviations (RSDs) for the extraction of 100ngmL−1 and 500ngmL−1 of each phthalate ester were less than 4% for intra-day (n=6) and inter-days (n=4) precision. Finally some aqueous samples were successfully analyzed using the proposed method and three analytes, DIBP, DNBP and DEHP, were determined in them at ngmL−1 level.