Determination of phthalic acid esters in Chinese white spirit using dispersive liquid–liquid microextraction coupled with sweeping β‐cyclodextrin‐modified micellar electrokinetic chromatography

A simple method that consumes low organic solvent is proposed for the analysis of phthalic acid esters in Chinese white spirit using dispersive liquid–liquid microextraction coupled with sweeping‐micellar electrokinetic chromatography. Tetrachloromethane and white‐spirit‐containing ethanol were used as the extraction and dispersing solvents, respectively. The electrophoresis separation buffer was composed of 5 mM β‐cyclodextrin, 50 mM sodium dodecyl sulfate and 25 mM borate buffer (pH 9.2) with 9% acetonitrile, enabling the baseline resolution of the analytes within 13 min. Under the optimum conditions, satisfactory linearities (5–1000 ng/mL, r ≥ 0.9909), good reproducibility (RSD ≤ 6.7% for peak area, and RSD ≤ 2.8% for migration time), low detection limits (0.4–0.8 ng/mL) and acceptable recovery rates (89.6–105.7%) were obtained. The proposed method was successfully applied to 22 Chinese white spirits, and the content of dibutyl phthalate in 55% of the samples exceeded the Specific Migration Limit of 0.3 mg/kg established by the domestic and international regulations.     

Green methodology based on dispersive liquid–liquid microextraction and micellar electrokinetic chromatography for 5‐nitroimidazole analysis in water samples

Dispersive liquid–liquid microextraction has been proposed as an extraction technique combined with micellar electrokinetic chromatography (MEKC) for the analysis of eight 5‐nitroimidazole compounds, including some metabolites, in water samples. Determination has been carried out using a diode array detector, employing 20 mM sodium phosphate and 150 mM SDS as separation buffer. Separation has taken place under a voltage of 25 kV and a temperature of 20°C. Samples were prepared in a buffer without micelles and they were hydrodynamically injected at 50 mbar for 25 s, producing a sweeping effect on the analytes for increasing sensitivity. Different factors involved in the dispersive liquid–liquid microextraction procedure were optimized, such as sample pH, nature, and volume of extraction and dispersive solvents in the mixture, percentage of NaCl added to sample and shaking time after the injection of the extraction and dispersive solvents. The method was characterized for water samples, achieving detection limits lower than 2.4 μg/L. Trueness was checked in river, tap, and bottled water. Dispersive liquid–liquid microextraction combined with MEKC constitutes an easy, cheap, and green alternative for 5‐nitroimidazole analysis in environmental water samples.     

Preconcentration and determination of ceftazidime in real samples using dispersive liquid–liquid microextraction and high‐performance liquid chromatography with the aid of experimental design

A rapid and simple method for the extraction and preconcentration of ceftazidime in aqueous samples has been developed using dispersive liquid–liquid microextraction followed by high‐performance liquid chromatography analysis. The extraction parameters, such as the volume of extraction solvent and disperser solvent, salt effect, sample volume, centrifuge rate, centrifuge time, extraction time, and temperature in the dispersive liquid–liquid microextraction process, were studied and optimized with the experimental design methods. Firstly, for the preliminary screening of the parameters the taguchi design was used and then, the fractional factorial design was used for significant factors optimization. At the optimum conditions, the calibration curves for ceftazidime indicated good linearity over the range of 0.001–10 μg/mL with correlation coefficients higher than the 0.98, and the limits of detection were 0.13 and 0.17 ng/mL, for water and urine samples, respectively. The proposed method successfully employed to determine ceftazidime in water and urine samples and good agreement between the experimental data and predictive values has been achieved.     

Optimization of alcohol‐assisted dispersive liquid–liquid microextraction by experimental design for the rapid determination of fluoxetine in biological samples

A sensitive and rapid method based on alcohol‐assisted dispersive liquid–liquid microextraction followed by high‐performance liquid chromatography for the determination of fluoxetine in human plasma and urine samples was developed. The effects of six parameters on the extraction recovery were investigated and optimized utilizing Plackett–Burman design and Box–Benken design, respectively. According to the Plackett–Burman design results, the volume of disperser solvent, extraction time, and stirring speed had no effect on the recovery of fluoxetine. The optimized conditions included a mixture of 172 μL of 1‐octanol as extraction solvent and 400 μL of methanol as disperser solvent, pH of 11.3 and 0% w/v of salt in the sample solution. Replicating the experiment in optimized condition for five times, gave the average extraction recoveries equal to 90.15%. The detection limit of fluoxetine in human plasma was obtained 3 ng/mL, and the linearity was in the range of 10–1200 ng/mL. The corresponding values for human urine were 4.2 ng/mL with the linearity range from 10 to 2000 ng/mL. Relative standard deviations for intra and inter day extraction of fluoxetine were less than 7% in five measurements. The developed method was successfully applied for the determination of fluoxetine in human plasma and urine samples.     

Solid‐phase extraction assisted dispersive liquid–liquid microextraction based on solidification of floating organic droplet to determine sildenafil and its analogues in dietary supplements

A novel analytical method for the simultaneous determination of the concentration of sildenafil and its five analogues in dietary supplements using solid‐phase extraction assisted reversed‐phase dispersive liquid–liquid microextraction based on solidification of floating organic droplet combined with ion‐pairing liquid chromatography with an ultraviolet detector was developed. Parameters that affect extraction efficiency were systematically investigated, including the type of solid‐phase extraction cartridge, pH of the extraction environment, and the type and volume of extraction and dispersive solvent. The method linearity was in the range of 5.0–100 ng/mL for sildenafil, homosildenafil, udenafil, benzylsildenafil, and thiosildenafil and 10–100 ng/mL for acetildenafil. The coefficients of determination were ≥0.996 for all regression curves. The sensitivity values expressed as limit of detection were between 2.5 and 7.5 ng/mL. Furthermore, intraday and interday precisions expressed as relative standard deviations were less than 5.7 and 9.9%, respectively. The proposed method was successfully applied to the analysis of sildenafil and its five analogues in complex dietary supplements.     

Application of liquid–liquid microextraction for the effective separation and simultaneous determination of 11 pharmaceuticals in wastewater samples using high‐performance liquid chromatography with tandem mass spectrometry

A dispersive liquid–liquid microextraction method for the simultaneous determination of 11 pharmaceuticals has been developed. The method is based on a microextraction procedure applied to wastewater samples from different regions of Hungary followed by high‐performance liquid chromatography with mass spectrometry. The effect of the nature of the extractant, dispersive solvent, different additives, and extraction time were examined on the extraction efficiently of the dispersive liquid–liquid microextraction method. Under optimal conditions, the linearity for determining the pharmaceuticals was in the range of 1–500 ng/mL, with the correlation coefficients ranging from 0.9922 to 0.9995. The limits of detection and limits of quantification were in the range of 0.31–6.65 and 0.93–22.18 ng/mL, respectively.     

Determination of chlorophenols in water using dispersive liquid–liquid microextraction coupled with water‐in‐oil microemulsion electrokinetic chromatography in normal stacking mode

The current routes to couple dispersive liquid–liquid microextraction with capillary electrophoresis are the evaporation of water immiscible extractants and the back‐extraction of analytes. In this study, a new methodology for this combination using water‐in‐oil microemulsion electrokinetic chromatography coupled with normal stacking mode on‐line sample concentration was developed to analyze chlorophenols in water samples. The analytes were extracted with tributyl phosphate and the extractant dilution (3×) was directly injected into an electrophoresis buffer (7.7 cm) containing 5% sodium dodecyl sulfate, 78% 1‐butanol, 2% 1‐heptane, and 15% sodium acetate solution (pH 8.0). This proposed method is very simple and convenient compared to the conventional procedures. The key parameters affecting separation and concentration were systematically optimized. Under the optimized conditions, dispersive liquid–liquid microextraction contributed an enrichment factor of 45–50, and the overall sensitivity improvement was 312–418‐fold. Limits of detection between 1.4 and 3.0 ng/mL and limits of quantification between 4.5 and 10.2 ng/mL were achieved. Acceptable repeatability lower than 3.0% for migration time and 9.0% for peak areas were obtained. The developed method was successfully applied for analysis of the chlorophenols in real water samples.     

Application of dispersive liquid–liquid microextraction for the preconcentration of eight parabens in real samples and their determination by high‐performance liquid chromatography

A simple and sensitive method for the simultaneous determination of eight parabens in human plasma and urine samples was developed. The samples were preconcentrated using dispersive liquid–liquid microextraction based on the solidification of floating organic drops and determined by high‐performance liquid chromatography with ultraviolet detection. The influence of variables affecting the extraction efficiency was investigated and optimized using Placket–Burman design and Box–Behnken design. The optimized values were: 58 μL of 1‐decanol (as extraction solvent), 0.65 mL methanol (as disperser solvent), 1.5% w/v NaCl in 5.0 mL of sample solution, pH 10.6, and 4.0 min centrifugation at 4000 rpm. The extract was injected into the high‐performance liquid chromatography system for analysis. Under the optimum conditions, the linear ranges for eight parabens in plasma and urine were 1.0–1000 ng/mL, with correlation coefficients above 0.994. The limit of detection was 0.2–0.4 and 0.1–0.4 ng/mL for plasma and urine samples, respectively. Relative recoveries were between 80.3 and 110.7%, while relative standard deviations were less than 5.4%. Finally, the method was applied to analyze the parabens in 98 patients of primary breast cancer. Results showed that parabens existed widely, at least one paraben detected in 96.9% (95/98) of plasma samples and 98.0% (96/98) of urine samples.     

Sensitive determination of methadone in human serum and urine by dispersive liquid–liquid microextraction based on the solidification of a floating organic droplet followed by HPLC–UV

Dispersive liquid–liquid microextraction based on solidification of floating organic droplet was developed for the extraction of methadone and determination by high‐performance liquid chromatography with UV detection. In this method, no microsyringe or fiber is required to support the organic microdrop due to the usage of an organic solvent with a low density and appropriate melting point. Furthermore, the extractant droplet can be collected easily by solidifying it at low temperature. 1‐Undecanol and methanol were chosen as extraction and disperser solvents, respectively. Parameters that influence extraction efficiency, i.e. volumes of extracting and dispersing solvents, pH, and salt effect, were optimized by using response surface methodology. Under optimal conditions, enrichment factor for methadone was 134 and 160 in serum and urine samples, respectively. The limit of detection was 3.34 ng/mmL in serum and 1.67 ng/mL in urine samples. Compared with the traditional dispersive liquid–liquid microextraction, the proposed method obtained lower limit of detection. Moreover, the solidification of floating organic solvent facilitated the phase transfer. And most importantly, it avoided using high‐density and toxic solvents of traditional dispersive liquid–liquid microextraction method. The proposed method was successfully applied to the determination of methadone in serum and urine samples of an addicted individual under methadone therapy.     

Double dispersant‐assisted ionic liquid dispersive liquid–liquid microextraction coupled with capillary electrophoresis for the determination of benzophenone‐type ultraviolet filters in sunscreen cosmetic product

In this work, double dispersant‐assisted ionic liquid dispersive liquid–liquid microextraction coupled with micellar electrokinetic chromatography was developed to determine four UV filters (benzophenone, 4‐hydroxybenzophenone, 2,4‐dihydroxybenzophenone, and 2‐hydroxy‐4‐methoxybenzophenone). 1‐Hexyl‐3‐methylimidazolium hexafluorophosphate was used as the extraction solvent. The main novelty of the present work was that acetonitrile‐Triton X‐114 was used as double disperser solvent. Parameters affected the extraction efficiency were investigated and optimized. Under the optimum conditions, enrichment factors were in the range of 25.3?40.5. The limits of detection and quantitation, calculated at a S/N of three and ten, were 3.9?6.7 ng/mL and 13.0?22.3 ng/mL. The linearity of the method was in the range of 0.02?2 μg/mL for 2, 4‐dihydroxybenzophenone and 4‐hydroxybenzophenone, 0.01?2 μg/mL for benzophenone and 2‐hydroxy‐4‐methoxybenzophenone, with correlation coefficient (R²) of 0.9984?0.9991. The proposed method was successfully applied to the determination of four benzophenone‐type UV filters in six kinds of sunscreen cosmetic products, with yielded relative recoveries ranging from 80.2 to 117.7%.     

In situ ionic‐liquid‐dispersive liquid–liquid microextraction of Sudan dyes from liquid samples

In situ ionic‐liquid‐dispersive liquid–liquid microextraction was introduced for extracting Sudan dyes from different liquid samples followed by detection using ultrafast liquid chromatography. The extraction and metathesis reaction can be performed simultaneously, the extraction time was shortened notably and higher enrichment factors can be obtained compared with traditional dispersive liquid–liquid microextraction. When the extraction was coupled with ultrafast liquid chromatography, a green, convenient, cheap, and efficient method for the determination of Sudan dyes was developed. The effects of various experimental factors, including type of extraction solvent, amount of 1‐hexyl‐3‐methylimidazolium chloride, ratio of ammonium hexafluorophosphate to 1‐hexyl‐3‐methylimidazolium chloride, pH value, salt concentration in sample solution, extraction time and centrifugation time were investigated and optimized for the extraction of four kinds of Sudan dyes. The limits of detection for Sudan I, II, III, and IV were 0.324, 0.299, 0.390, and 0.655 ng/mL, respectively. Recoveries obtained by analyzing the seven spiked samples were between 65.95 and 112.82%. The consumption of organic solvent (120 μL acetonitrile per sample) was very low, so it could be considered as a green analytical method.     

Sensitive determination of three aconitum alkaloids and their metabolites in human plasma by matrix solid‐phase dispersion with vortex‐assisted dispersive liquid–liquid microextraction and HPLC with diode array detection

A simple and sensitive method for determination of three aconitum alkaloids and their metabolites in human plasma was developed using matrix solid‐phase dispersion combined with vortex‐assisted dispersive liquid–liquid microextraction and high‐performance liquid chromatography with diode array detection. The plasma sample was directly purified by matrix solid‐phase dispersion and the eluate obtained was concentrated and further clarified by vortex‐assisted dispersive liquid–liquid microextraction. Some important parameters affecting the extraction efficiency, such as type and amount of dispersing sorbent, type and volume of elution solvent, type and volume of extraction solvent, salt concentration as well as sample solution pH, were investigated in detail. Under optimal conditions, the proposed method has good repeatability and reproducibility with intraday and interday relative standard deviations lower than 5.44 and 5.75%, respectively. The recoveries of the aconitum alkaloids ranged from 73.81 to 101.82%, and the detection limits were achieved within the range of 1.6–2.1 ng/mL. The proposed method offered the advantages of good applicability, sensitivity, simplicity, and feasibility, which makes it suitable for the determination of trace amounts of aconitum alkaloids in human plasma samples.     

Preconcentration and determination of 2‐mercaptobenzimidazole by dispersive liquid–liquid microextraction and experimental design

A method was developed to determine 2‐mercaptobenzimidazole in water and urine samples using dispersive liquid–liquid microextraction technique coupled with ultraviolet–visible spectrophotometry. It was essential to peruse the effect of all parameters that can likely influence the performance of extraction. The influence of parameters, such as dispersive and extraction solvent volume and sample volume, on dispersive liquid–liquid microextraction was studied. The optimization was carried out by the central composite design method. The central composite design optimization method resulted in 1.10 mL dispersive solvent, 138.46 μL extraction solvent, and 4.46 mL sample volume. Under the optimal terms, the calibration curve was linear over the range of 0.003–0.18 and 0.007–0.18 μg/mL in water and urine samples, respectively. The limit of detection and quantification of the proposed approach for 2‐mercaptobenzimidazole were 0.013 and 0.044 μg/mL in water samples and 0.016 and 0.052 μg/mL in urine samples, respectively. The method was successfully applied to determination of 2‐mercaptobenzimidazole in urine and water samples.     

Ionic‐liquid‐based dispersive liquid–liquid microextraction combined with magnetic solid‐phase extraction for the determination of aflatoxins B1, B2, G1, and G2 in animal feeds by high‐performance liquid chromatography with fluorescence detection

A novel two‐step extraction technique combining ionic‐liquid‐based dispersive liquid–liquid microextraction with magnetic solid‐phase extraction was developed for the preconcentration and separation of aflatoxins in animal feedstuffs before high‐performance liquid chromatography coupled with fluorescence detection. In this work, ionic liquid 1‐octyl‐3‐methylimidazolium hexafluorophosphate was used as the extractant in dispersive liquid–liquid microextraction, and hydrophobic pelargonic acid modified Fe₃O₄ magnetic nanoparticles as an efficient adsorbent were applied to retrieve the aflatoxins‐containing ionic liquid. Notably, the target of magnetic nanoparticles was the ionic liquid rather than the aflatoxins. Because of the rapid mass transfer associated with the dispersive liquid–liquid microextraction and magnetic solid phase steps, fast extraction could be achieved. The main parameters affecting the extraction recoveries of aflatoxins were investigated and optimized. Under the optimum conditions, vortexing at 2500 rpm for 1 min in the dispersive liquid–liquid microextraction and magnetic solid‐phase extraction and then desorption by sonication for 2 min with acetonitrile as eluent. The recoveries were 90.3–103.7% with relative standard deviations of 3.2–6.4%. Good linearity was observed with correlation coefficients ranged from 0.9986 to 0.9995. The detection limits were 0.632, 0.087, 0.422 and 0.146 ng/mL for aflatoxins B₁, B2, G1, and G2, respectively. The results were also compared with the pretreatment method carried out by conventional immunoaffinity columns.     

Dispersive liquid–liquid microextraction with solidification of floating organic drop combined with high performance liquid chromatography for the determination of phenolic oestrogens from human urine and water samples

A novel, simple and rapid method, termed dispersive liquid–liquid microextraction with solidification of floating organic drop coupled to high performance liquid chromatography, was developed for analysis of three phenolic oestrogens including diethylstilbestrol, dienestrol and hexestrol in human urine and water samples. The parameters of dispersive liquid–liquid microextraction with solidification of floating organic drop procedure including sample pH, type and volume of disperser solvent, and type and volume of extraction solvent were optimised. High performance liquid chromatography was applied for the phenolic oestrogens’ analysis. Under the optimum extraction and detection conditions, excellent analytical performances were attained. Good linear relationships (r ≥ 0.998) between peak area and concentration for diethylstilbestrol and dienestrol were optimised from 0.1 to 20 µg/mL, for hexestrol from 2 to 50 µg/mL. Method detection limits of 28.6–666.7 ng/mL were achieved. Satisfactory relative recoveries ranging from 72% to 122% were determined for urine, lake and tap water samples, with relative standard deviations (RSDs, n = 6) of 1.5–9.8%. The developed dispersive liquid–liquid microextraction with solidification of floating organic drop-high performance liquid chromatography method has a great potential in routine residual analysis of trace phenolic oestrogens in biological and water samples.     

Ionic‐liquid‐based dispersive liquid–liquid microextraction coupled with high‐performance liquid chromatography for the forensic determination of methamphetamine in human urine

Determination of methamphetamine in forensic laboratories is a major issue due to its health and social harm. In this work, a simple, sensitive, and environmentally friendly method based on ionic liquid dispersive liquid–liquid microextraction combined with high‐performance liquid chromatography was established for the analysis of methamphetamine in human urine. 1‐Octyl‐3‐methylimidazolium hexafluorophosphate with the help of disperser solvent methanol was selected as the microextraction solvent in this process. Various parameters affecting the extraction efficiency of methamphetamine were investigated systemically, including extraction solvent and its volume, disperser solvent and its volume, sample pH, extraction temperature, and centrifugal time. Under the optimized conditions, a good linearity was obtained in the concentration range of 10–1000 ng/mL with determination coefficient >0.99. The limit of detection calculated at a signal‐to‐noise ratio of 3 was 1.7 ng/mL and the relative standard deviations for six replicate experiments at three different concentration levels of 100, 500, and 1000 ng/mL were 6.4, 4.5, and 4.7%, respectively. Meanwhile, up to 220‐fold enrichment factor of methamphetamine and acceptable extraction recovery (>80.0%) could be achieved. Furthermore, this method has been successfully employed for the sensitive detection of a urine sample from a suspected drug abuser.     

Using dispersive liquid-liquid microextraction and liquid chromatography for determination of guaifenesin enantiomers in human urine

A simple, rapid, and efficient method, dispersive liquid–liquid microextraction (DLLME) coupled with high‐performance liquid chromatography‐fluorescence detector, has been developed for the determination of guaifenesin (GUA) enantiomers in human urine samples after an oral dose administration of its syrup formulation. Urine samples were collected during the time intervals 0–2, 2–4, and 4–6 h and concentration and ratio of two enantiomers was determined. The ratio of R‐(?) to S‐(+) enantiomer concentrations in urine showed an increase with time, with R/S ratios of 0.66 at 2 h and 2.23 at 6 h. For microextraction process, a mixture of extraction solvent (dichloromethane, 100 μL) and dispersive solvent (THF, 1 mL) was rapidly injected into 5.0 mL diluted urine sample for the formation of cloudy solution and extraction of enantiomers into the fine droplets of CH₂Cl₂. After optimization of HPLC enantioselective conditions, some important parameters, such as the kind and volume of extraction and dispersive solvents, extraction time, temperature, pH, and salt effect were optimized for dispersive liquid–liquid microextraction process. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 10 to 2000 ng/mL for target analytes. LOD was 3.00 ng/mL for both of the enantiomers.     

Surfactant‐assisted dispersive liquid–liquid microextraction combined with field‐amplified sample stacking in capillary electrophoresis for the determination of mexiletine and lidocaine

A sensitive method for the determination of mexiletine and lidocaine using surfactant‐assisted dispersive liquid–liquid microextraction coupled with capillary electrophoresis was developed. Triton X‐100 and dichloromethane were used as the dispersive agent and extraction solvent, respectively. After the extraction, mexiletine and lidocaine were analyzed using capillary electrophoresis with ultraviolet detection. The detection sensitivity was further enhanced through the use of field‐amplified sample stacking. Under optimal extraction and stacking conditions, the calibration curves were linear over a concentration range of 0.05–1.00 μM for mexiletine and 0.03–1.00 μM for lidocaine. The limits of detection (signal‐to‐noise ratio of 3) were 0.01 and 0.01 μM for mexiletine and lidocaine, respectively. An approximately 1141‐ to 1250‐fold improvement in sensitivity was observed for the two analytes compared with the injection of a standard solution without the surfactant‐assisted dispersive liquid–liquid microextraction and field‐amplified sample stacking procedures. This developed method was successfully applied to the determination of mexiletine and lidocaine in human urine and serum samples. Both precision and accuracy for urine and serum samples were less than 8.7 and 6.7%, respectively. The recoveries of the two analytes from urine and serum samples were 54.7–64.9% and 16.1–56.5%, respectively.     

Trace determination of five triazole fungicide residues in traditional Chinese medicine samples by dispersive solid‐phase extraction combined with ultrasound‐assisted dispersive liquid–liquid microextraction and UHPLC–MS/MS

A novel and reliable method for determination of five triazole fungicide residues (triadimenol, tebuconazole, diniconazole, flutriafol, and hexaconazol) in traditional Chinese medicine samples was developed using dispersive solid‐phase extraction combined with ultrasound‐assisted dispersive liquid–liquid microextraction before ultra‐high performance liquid chromatography with tandem mass spectrometry. The clean up of the extract was conducted using dispersive solid‐phase extraction by directly adding sorbents into the extraction solution, followed by shaking and centrifugation. After that, a mixture of 400 μL trichloromethane (extraction solvent) and 0.5 mL of the above supernatant was injected rapidly into water for the dispersive liquid–liquid microextraction procedure. The factors affecting the extraction efficiency were optimized. Under the optimum conditions, the calibration curves showed good linearity in the range of 2.0–400 (tebuconazole, diniconazole, and hexaconazole) and 4.0–800 ng/g (triadimenol and flutriafol) with the regression coefficients higher than 0.9958. The limit of detection and limit of quantification for the present method were 0.5–1.1 and 1.8–4.0 ng/g, respectively. The recoveries of the target analytes ranged from 80.2 to 103.2%. The proposed method has been successfully applied to the analysis of five triazole fungicides in traditional Chinese medicine samples, and satisfactory results were obtained.     

Ultrapreconcentration and determination of organophosphorus pesticides in water by solid‐phase extraction combined with dispersive liquid–liquid microextraction and high‐performance liquid chromatography

Solid‐phase extraction coupled with dispersive liquid–liquid microextraction was developed as an ultra‐preconcentration method for the determination of four organophosphorus pesticides (isocarbophos, parathion‐methyl, triazophos and fenitrothion) in water samples. The analytes considered in this study were rapidly extracted and concentrated from large volumes of aqueous solutions (100 mL) by solid‐phase extraction coupled with dispersive liquid–liquid microextraction and then analyzed using high performance liquid chromatography. Experimental variables including type and volume of elution solvent, volume and flow rate of sample solution, salt concentration, type and volume of extraction solvent and sample solution pH were investigated for the solid‐phase extraction coupled with dispersive liquid–liquid microextraction with these analytes, and the best results were obtained using methanol as eluent and ethylene chloride as extraction solvent. Under the optimal conditions, an exhaustive extraction for four analytes (recoveries >86.9%) and high enrichment factors were attained. The limits of detection were between 0.021 and 0.15 μg/L. The relative standard deviations for 0.5 μg/L of the pesticides in water were in the range of 1.9–6.8% (n = 5). The proposed strategy offered the advantages of simple operation, high enrichment factor and sensitivity and was successfully applied to the determination of four organophosphorus pesticides in water samples.