Application of anion‐exchange imidazolium silica for the multiphase dispersive extraction of phenolic acids

This paper reports the application of a multiphase dispersive extraction method to the extraction, separation, and determination of the phenolic acids from Salicornia herbacea L. using silica‐confined ionic liquids as sorbents. A suitable sorbent for phenolic acid extraction and separation was first identified based on the adsorption behavior of the phenolic acids on different silica‐confined ionic liquids. The sample was then mixed with the optimized sorbent and solvent to achieve multiphase dispersive extraction. The sample/sorbent ratio was optimized using theoretical calculations from the adsorption isotherm and experiments. After transferring the supernatant to an empty cartridge, an SPE process was used to separate the three phenolic acids from the other interference. Through systematic optimization, the optimal conditions produced high recovery rates of protocatechuic acid (91.20%), caffeic acid (94.03%), and ferulic acid (91.33%). Overall, the proposed method is expected to have wide applicability.     

Combined Application of Ionic Liquid and Hybrid Poly (Ionic Liquid)-Bonded Silica: An Alternative Method for Extraction,Separation and Determination of Flavonoids from Plants

Hybrid poly (ionic liquid)-bonded silica was combined with an ionic liquid solution for the extraction, separation, and determination of flavonoids from natural plants by using a multi-phase dispersive extraction (MPDE) method. The hybrid material was synthesized using a facile method. A suitable sorbent was identified based on the adsorption behaviors of flavonoids on different poly (ionic liquid)-bonded silicas. In contrast to traditional matrix solid-phase dispersion (MSPD) method, the target analytes were first extracted by three-phase (sample-solvent-sorbent) dispersive extraction with ionic liquid (1-oxyl-3-methylimidazolium bromide) solutions as the solvent, and then cleaned up after removal from the sample matrix, called MPDE. This process combines the advantages of ionic liquids, ionic liquid-based sorbent, and MPDE. The recovery rates were achieved by MPDE of the flavonoids from Chamaecyparis obtusa: 76.4% for myricetin and 90.3% for amentoflavone. The proposed method may be used to extract and separate other flavonoids or even polyphenolic compounds from complex samples.     

Solid phase extraction of lactic acid from fermentation broth by anion-exchangeable silica confined ionic liquids

Three anion-exchangeable, silica-confined ionic liquids were synthesized for solid phase extraction of lactic acid from fermentation broth, followed by high-performance liquid chromatography coupled to ultraviolet detection. By comparing the adsorption isotherms of lactic acid on different silica-confined ionic liquids, interactions between the lactic acid and sorbents were investigated. The adsorbed amounts were then fitted into different adsorption isotherm equations; finally, the Langmuir equation was selected. Then the imidazolium silica with the highest adsorption capacity of lactic acid was packed into a cartridge for solid phase extraction. The loading volume of the cartridge was optimized by the Langmuir equation and geometry. After washing with distilled water and eluting with 0.25 mol L⁻¹ of an HCl solution, the lactic acid was separated from interference with a recovery yield of 91.9%. Furthermore, this kind of anion-exchangeable material exhibited potential for industrial applications and separation of other anionic bioactive compounds.     

Molecularly imprinted polymer based on magnetic ionic liquid for solid-phase extraction of phenolic acids

In this study, 1-allyl-3-octylimidazolium tetrachloroferrate ionic liquid was first synthesized. Molecularly imprinted polymer was prepared by suspension polymerization using 1-allyl-3-octylimidazolium tetrachloroferrate as functional monomer and chlorogenic acid as template molecule. The polymer was characterized by Fourier transformed infrared spectroscopy and scanning electron microscopy. Thermal stability of the polymer was investigated. The solid-phase extraction method based on magnetic molecularly imprinted polymer was developed for gallic acid, protocatechuic acid, caffeic acid, chlorogenic acid, p-coumaric acid, and ferulic acid. The sample pH, the type and volume of stripping solution, sorbent amount, and extraction time were optimized for phenolic acids. The analysis of phenolic acids after extraction was carried out using high-performance liquid chromatography with UV detection. Limit of detection, limit of quantification, linear range, correlation coefficient, and reproducibilities of within-day and between-day for phenolic acids were determined. The residues of phenolic acids in apple samples were successfully detected by the developed method. Recovery of standard spiked apple samples was ≥81 for all the phenolic acids.     

Multi-walled carbon nanotube-based dispersive solid phase extraction with following back-extraction for HPLC/UV determination of Rosmarinic acid in lemon balm and Rosemary plant samples

In this paper, dispersive solid phase extraction with following back-extraction and HPLC/UV determination of Rosmarinic acid have been investigated. Multi-walled carbon nanotubes were used as sorbent in the suggested method. The effectiveness of some parameters such as extraction time, sorbent dosage, pH and ionic strength of the aqueous solution on Rosmarinic acid adsorption were studied. The extraction time of 5.0 min, adsorbent weight of 5.0 mg, and pH of 2.5 were obtained as the optimum experimental parameters. Adsorption of Rosmarinic acid molecules was almost independent from ionic strength. For back-extraction purpose a basic solution containing methanol was brought into contact with sorbent to desorb Rosmarinic acid molecules from sorbent containing adsorbed Rosmarinic acid molecules. Linear range of HPLC method for Rosmarinic acid quantification was 1.80–21.62 mg/L (R² = 0.998). The relative standard deviation, limit of detection, and limit of quantification for the suggested method were 0.81%, 0.68 mg/L, and 2.86 mg/L, respectively. The proposed method was applied for extraction and HPLC/UV determination of Rosmarinic acid in Lemon balm and Rosemary plant samples. Comparison between obtained chromatograms before adsorption and after desorption processes showed that suggested extraction/back-extraction process has good selectivity and efficiency for separation of Rosmarinic acid molecules from interfering molecules existing in the plant extracts. The proposed method is efficient, low cost, fast, and simple for separation, extraction, and determination of Rosmarinic acid.     

酸功能化-温控型三元杂多酸离子液体的合成、表征及其酯催化性能

采用酸化-乙醚萃取法制备了不同钒取代数目的 Keggin结构的磷钨钒杂多酸,并进一步通过离子交换法合成了磺酸功能化的杂多酸离子液体催化剂,采用核磁、元素分析、红外、紫外、X射线衍射、热重-差示扫描、电位滴定等分析手段对所得样品进行了表征,考察了所得样品对氯乙酸和正戊醇的酯化反应性能和重复使用性能。结果表明,所制备的杂多酸离子液体是一种具有温度响应特性的无定型结构化合物,仍保留Keggin结构和较高的酸强度,该催化剂在反应温度下与反应物形成一相,而反应结束温度降低后,催化剂和产物又形成两相,通过简单的倾倒法就可以快速分离催化剂和反应产物。与杂多酸以及未磺酸化的杂多酸离子液体相比,磺酸功能化的杂多酸离子液体具有更高的酯催化活性。在优化的反应条件下,[PyPS]4PW11VO40(PyPS为1-(3-磺酸基)丙基吡啶)对氯乙酸的转化率可达到97.6%,重复使用4次后转化率为91.9%,而催化剂的结构未有明显变化。     

Separation of phenolic acids from sugarcane rind by online solid‐phase extraction with high‐speed counter‐current chromatography

Sugarcane rind contains some functional phenolic acids. The separation of these compounds from sugarcane rind is able to realize the integrated utilization of the crop and reduce environment pollution. In this paper, a novel protocol based on interfacing online solid‐phase extraction with high‐speed counter‐current chromatography (HSCCC) was established, aiming at improving and simplifying the process of phenolic acids separation from sugarcane rind. The conditions of online solid‐phase extraction with HSCCC involving solvent system, flow rate of mobile phase as well as saturated extent of absorption of solid‐phase extraction were optimized to improve extraction efficiency and reduce separation time. The separation of phenolic acids was performed with a two‐phase solvent system composed of butanol/acetic acid/water at a volume ratio of 4:1:5, and the developed online solid‐phase extraction with HSCCC method was validated and successfully applied for sugarcane rind, and three phenolic acids including 6.73 mg of gallic acid, 10.85 mg of p‐coumaric acid, and 2.78 mg of ferulic acid with purities of 60.2, 95.4, and 84%, respectively, were obtained from 150 mg sugarcane rind crude extracts. In addition, the three different elution methods of phenolic acids purification including HSCCC, elution–extrusion counter‐current chromatography and back‐extrusion counter‐current chromatography were compared.     

Determination of haloacetic acids in water using layered double hydroxides as a sorbent in dispersive solid‐phase extraction followed by liquid chromatography with tandem mass spectrometry

In the present study, highly efficient and simple dispersive solid‐phase extraction procedure for the determination of haloacetic acids in water samples has been established. Three different types of layered double hydroxides were synthesized and used as a sorbent in dispersive solid‐phase extraction. Due to the interesting behavior of layered double hydroxides in an acidic medium (pH?4), the analyte elution step was not needed; the layered double hydroxides are simply dissolved in acid immediately after extraction to release the analytes which are then directly introduced into a liquid chromatography with tandem mass spectrometry system for analysis. Several dispersive solid‐phase extraction parameters were optimized to increase the extraction efficiency of haloacetic acids such as temperature, extraction time and pH. Under optimum conditions, good linearity was achieved over the concentration range of 0.05–100 μg/L with detection limits in the range of 0.006–0.05 μg/L. The relative standard deviations were 0.33–3.64% (n = 6). The proposed method was applied to different water samples collected from a drinking water plant to determine the concentrations of haloacetic acids.     

Carbon nanotube-based magnetic bucky gels in developing dispersive solid-phase extraction: application in rapid speciation analysis of Cr(VI) and Cr(III) in water samples

In this work, we developed dispersive solid-phase extraction method with the use of carbon nanotube based magnetic bucky gels. The hydrophilic carbon nanotube (CNT)-based magnetic bucky gels (M-BGs) were developed with the features of magnetic susceptibility to permit fast injection of sorbent, rapid retrieval of the sorbent and high dispersion of MWCNT in the aqueous sample. We combined magnetic multi-wall carbon nanotube nanocomposite (MMWCNTs) with hydrophilic ionic liquids in order to prepare highly stable carbon nanotube-based magnetic bucky gels. The hydrophilic ILs act simultaneously as modifier and disperser for MMWCNTs and reduce the agglomeration of sorbent in water .Consequently they enhance the extraction efficiency. We used the unique features of this responsive gel (fluidity, stability, magnetic properties, and strong sorbing ability) in developing a new, fast, sensitive, simple, and environmental-friendly magnetic bucky gel-based dispersive solid-phase extraction method (M-BG-dSPE) combined with fibre optic linear array detection spectrophotometer (FO-LADS) for preconcentration and speciation of Cr(VI) and Cr(III) in water samples. The properties of MMWCNT and magnetic bucky gels were characterised by scanning electron microscopy (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and Fourier transform infrared spectrophotometer (FT-IR). Under the optimised conditions, the enrichment factor of the method was 318, the limit of detection was 0.1 ng mL^?1 and the repeatability of the method, expressed as the relative standard deviation (RSD, n = 5), varies between 3.2% and 2.5% in different concentrations. The proposed procedure has been applied for speciation of Cr(VI) and Cr(III) in water samples with good recoveries in the range from 90 to 105%. Validation of the method was carried out by comparison of the obtained results with results obtained by the ET-AAS and spiking-recovery method.     

Polyethyleneimine‐modified porous aromatic framework and silane coupling agent grafted graphene oxide composite materials for determination of phenolic acids in Chinese Wolfberry drink by HPLC

A simple method for the determination of phenolic acids in Chinese Wolfberry drink based on polyethyleneimine modified porous aromatic framework and graphene oxide composite sorbent for pipette‐tip solid‐phase extraction was developed. Porous aromatic framework and raphene oxide composite materials were grafted by silane coupling agent (3‐Chloropropyl)‐trimethoxysilane. The modified materials were characterized by five kinds of characterization. Experimental results showed that the prepared p‐phenylenediamine, cyanuric chloride, and graphene oxide composite material had a loose structure combined with the framework which improved hydrophobicity, and polyethyleneimine to increase the selectivity with the targets. The parameters of the pipette‐tip solid‐phase extraction procedure including the amount of sorbents, volumes and types of washing solvents and elution solvents were optimized to achieve optimal extraction efficiency. Good linearity of best material was achieved in the range of 0.1–400 µg/mL with correlation coefficient of chlorogenic acid (0.9994), caffeic acid (0.9997), and ferulic acid (0.9998). Recoveries between 93.5 and 102.3% were obtained at three spiked levels with relative standard deviation ≤3.1%. The proposed method was successfully applied for the determination of phenolic acids in Chinese Wolfberry drink sample.     

A UFLC–MS/MS method for the simultaneous determination of eight bioactive constituents from red wine and dealcoholized red wine in rat plasma: Application to a comparative pharmacokinetic study

To explore whether alcohol has an effect on the pharmacokinetic behavior of phenolic acids, the main bioactive constituents in red wine, a highly sensitive and simple ultra‐fast liquid chromatography coupled with triple quadrupole mass spectrometry (UFLC–MS/MS) method was developed for simultaneous quantitation of eight phenolic acids in plasma samples. Plasma samples were extracted by liquid–liquid extraction and the chromatographic separation was achieved on a Zorbax SB‐C₁₈ column within 7.0 min. Results of the validated method revealed that all of the calibration curves displayed good linear regression (r > 0.99). The intra‐ and inter‐day precisions of the analytes were <14.0% and accuracies ranged from ?8.5 to 7.3%. The extraction recoveries of the analytes were from 71.2 to 110.2% and the matrix effects ranged from 86.2 to 105.5%. The stability of these compounds under various conditions satisfied the requirements of biological sample measurement. The method was successfully applied to a comparative pharmacokinetic study of phenolic acids in rat plasma. For gallic acid and gentisic acid, the parameters AUC_0–t and AUC_0–∞ increased remarkably (p < 0.05) after oral administration of red wine, which suggested that alcohol might enhance their absorption. This is the first report to compare the pharmacokinetic behavior of phenolic acids in red wine and dealcoholized red wine.     

Ionic liquid‐based dispersive liquid–liquid microextraction followed by RP‐HPLC determination of saquinavir in rat serum: application to pharmacokinetics

An ionic liquid‐based dispersive liquid–liquid microextraction followed by RP‐HPLC determination of the most commonly prescribed protease inhibitor, saquinavir, in rat plasma was developed and validated. The effects of different ionic liquids, dispersive solvents, extractant/disperser ratio and salt concentration on sample recovery and enrichment were studied. Among the ionic liquids investigated, 1‐butyl‐3‐methylimidazolium hexafluorophosphate was found to be most effective for extraction of saquinavir from rat serum. The recovery was found to be 95% at an extractant/disperser ratio of 0.43 using 1‐butyl‐3‐methylimidazolium hexafluorophosphate and methanol as extraction and dispersive solvents. The recovery was further enhanced to 99.5% by addition of 5.0% NaCl. A threefold enhancement in detection and quantification limits was achieved, at 0.01 and 0.03 µg/mL, compared with the conventional protein precipitation method. A linear relationship was observed in the range of 0.035–10.0 µg/mL with a correlation coefficient (r²) of 0.9996. The method was validated and applied to study pharmacokinetics of saquinavir in rat serum. Copyright © 2014 John Wiley & Sons, Ltd.     

Extraction of phenolic compounds from water samples by dispersive micro‐solid‐phase extraction

In this article, the use of magnetically separable sorbent polyaniline/silica‐coated nickel nanoparticles is evaluated under a dispersive micro‐solid‐phase extraction approach for the extraction of phenolic compounds from water samples. The sorbent was prepared by in situ chemical polymerization of aniline on the surface of silica‐modified nickel nanoparticles and was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, X‐ray powder diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectrometry, and vibrating sample magnetometry. Effective variables such as amount of sorbent (milligrams), pH and ionic strength of sample solution, volume of eluent solvent (microliters), vortex, and ultrasonic times (minutes) were investigated by fractional factorial design. The significant variables optimized by a Box–Behnken design were combined by a desirability function. Under the optimized conditions, the calibration graphs of analytes were linear in a concentration range of 0.02–100 μg/mL, and with correlation coefficients more than 0.999. The limits of detection and quantification were in the ranges of 10–23 and 33–77 μg/L, respectively. This procedure was successfully employed in the determination of target analytes in spiked water samples; the relative mean recoveries ranged from 96 to 105%.     

Isolation of free phenolic compounds from arboreal leaves by use of the Florisil/C<Subscript>18</Subscript> system

In studies of the phenolic compounds present in leaves and needles, GC and GC–MS have so far been applied only sporadically. This is probably because of the greater difficulties encountered in preparing the samples for this method than those used for liquid chromatography. When preparing a sample for gas chromatography the analyst is faced with two difficult stages—separation of the compound from the matrix without losses (stage 1) so that the final sample can be derivatized to make it suitable for analysis on a non-polar capillary column of the gas chromatograph (stage 2). This paper presents a procedure for extraction of phenolic compounds from the matrix by means of a Florisil/C₁₈ sorbent system and their analysis by GC. After passage through the adsorbents the recovery ranges from 32% for ferulic acid to 88% for gentisic acid. It was found that this extraction method and the GC analysis are very precise (particularly for samples of a mass <1 g) and can be used for quantification. The high-precision quantification of 15 phenolic acids, shikimic acid, and six other compounds present in pine needles has been achieved. The conditions used for GC analysis and construction of calibration curves for quantitative determination are given.     

Application of solid-phase extraction for determination of phenolic compounds in barrique wines

A fast, selective and sensitive chromatographic method has been developed for determination of gallic, protocatechuic, p-hydroxybenzoic, vanillic, caffeic, syringic, p-coumaric, benzoic, ferulic, sinapic, cinnamic, and ellagic acids and p-hydroxybenzaldehyde, vanillin, syringaldehyde, 2-furfural, 5-methylfurfural, and 5-methoxyfurfural. The compounds from untreated wine samples were pre-concentrated and cleaned using solid-phase extraction on RP-105 polymeric sorbent. The cartridge was conditioned with methanol and water. Co-extracted ballast substances were rinsed from the sorbent with 0.1 mol L^–1 hydrochloric acid–methanol, 1:4 (v/v). Retained phenolic compounds were selectively eluted with diethyl ether. A linear mobile phase gradient containing 0.3% acetic acid and methanol was used for final baseline chromatographic separation on a Hypersil BDS C18 column. Limits of detection (LOD=3s_bl) in the range 5.2 to 181.2 g L^–1, resolution (R) better than 1.7, and repeatability of 2.7–5.1% (RSD for real samples) were achieved. The method was applied for quantification of individual phenolic compounds in barrique wines.     

Using magnetic core‐shell nanoparticles coated with an ionic liquid dispersion assisted by effervescence powder for the micro‐solid‐phase extraction of four beta blockers from human plasma by ultra high performance liquid chromatography with mass spectrometry detection

In this work, a novel, efficient, and green sorbent, SiO₂@Fe₃O₄ has been created and functionalized with 1‐butyl‐3‐methylimidazolium hexafluorophosphate as an ionic liquid. This sorbent was applied for microextraction of four beta blockers, propranolol, metoprolol, atenolol, and alprenolol with bupivacaine as internal standard from human plasma followed by liquid chromatography with mass spectrometric detection. A mixture of sodium bicarbonate and sodium dihydrogen phosphate was used as an extractant dispersive agent (effervescent power) to enhance the interaction between the magnetic sorbent and analytes. Main affecting parameters on microextraction and elution were optimized. Figures of merit for dispersive solid phase extraction with ionic liquid coated magnetic nanoparticles assisted by effervescent powder were calculated under the optimized conditions. The detection limits for propranolol, metoprolol, atenolol, and alprenolol were found at 0.33, 0.62, 0.03, and 0.44 ng/mL, respectively. For all analytes, good linearity was obtained. Intra‐ (n = 5) and interday (n = 10) precision were both under 6.3% while the preconcentration factors were obtained in the range between 15–18. The extraction efficiencies for each analyte ranged from 75 to 91%. The method was successfully applied for determination of trace amounts of the beta blockers in human plasma samples.     

Quantitative determination of trace phenazopyridine in human urine samples by hyphenation of dispersive solid‐phase extraction and liquid‐phase microextraction followed by gas chromatography/mass spectrometry analysis

Magnetic dispersive solid‐phase extraction followed by dispersive liquid?liquid microextraction coupled with gas chromatography/mass spectrometry was applied for the quantitative analysis of phenazopyridine in urinary samples. Magnetic dispersive solid‐phase extraction was carried out using magnetic graphene oxide nanoparticles modified by poly(thiophene‐pyrrole) copolymer. The eluting solvent of this step was used as the disperser solvent for the dispersive liquid?liquid microextraction procedure. To reach the maximum efficiency of the method, effective parameters including sorbent amount, adsorption time, type and volume of disperser and extraction solvents, pH of the sample solution, and ionic strength as well as desorption time, and approach were optimized, separately. Characterization of the synthesized sorbent was studied by utilizing infrared spectroscopy, scanning electron microscopy, and energy‐dispersive X‐ray analysis. Calibration curve was linear in the range of 0.5?250 ng/mL (R² = 0.9988) with limits of detection and quantification of 0.1 and 0.5 ng/mL, respectively. Intra‐ and interday precisions (RSD%, n = 3) of the method were in the range of 4.6?5.4% and 4.0?5.5%, respectively, at three different concentration levels. Under the optimal condition, this method was successfully applied for the determination of phenazopyridine in human urine samples. The relative recoveries were obtained in the range of 85.0?89.0%.     

Ionic liquid foam floatation coupled with ionic liquid dispersive liquid–liquid microextraction for the separation and determination of estrogens in water samples by high‐performance liquid chromatography with fluorescence detection

An ionic liquid foam floatation coupled with ionic liquid dispersive liquid–liquid microextraction method was proposed for the extraction and concentration of 17‐α‐estradiol, 17‐β‐estradiol‐benzoate, and quinestrol in environmental water samples by high‐performance liquid chromatography with fluorescence detection. 1‐Hexyl‐3‐methylimidazolium tetrafluoroborate was applied as foaming agent in the foam flotation process and dispersive solvent in microextraction. The introduction of the ion‐pairing and salting‐out agent NH₄PF₆ was beneficial to the improvement of recoveries for the hydrophobic ionic liquid phase and analytes. Parameters of the proposed method including concentration of 1‐hexyl‐3‐methylimidazolium tetrafluoroborate, flow rate of carrier gas, floatation time, types and concentration of ionic liquids, salt concentration in samples, extraction time, and centrifugation time were evaluated. The recoveries were between 98 and 105% with relative standard deviations lower than 7% for lake water and well water samples. The isolation of the target compounds from the water was found to be efficient, and the enrichment factors ranged from 4445 to 4632. This developing method is free of volatile organic solvents compared with regular extraction. Based on the unique properties of ionic liquids, the application of foam floatation, and dispersive liquid–liquid microextraction was widened.     

Molecularly imprinted polymer microspheres for solid-phase extraction of protocatechuic acid in Rhizoma homalomenae

Molecularly imprinted polymers (MIPs) had been prepared by precipitation polymerization method using acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, acetonitrile as the porogen solvent and protocatechuic acid (PA), one of phenolic acids, as the template molecule. The MIPs were characterized by scanning electron microscopy and Fourier transform infrared, and their performance relative to non-imprinted polymers was assessed by equilibrium binding experiments. Six structurally similar phenolic acids, including p-hydroxybenzoic acid, gallic acid, salicylic acid, syringic acid, vanillic acid, ferulic acid were selected to assess the selectivity and recognition capability of the MIPs. The MIPs were applied to extract PA from the traditional Chinese medicines as a solid-phase extraction sorbent. The resultant cartridge showed that the MIPs have a good extraction performance and were able to selectively extract almost 82% of PA from the extract of Rhizoma homalomenae. Thus, the proposed molecularly imprinted-solid phase extraction-high performance liquid chromatography method can be successfully used to extract and analyse PA in traditional Chinese medicines.     

New application of chitosan‐grafted polyaniline in dispersive solid‐phase extraction for the separation and determination of phthalate esters in milk using high‐performance liquid chromatography

Chitosan‐grafted polyaniline was synthesized and applied as a sorbent for the preconcentration of phthalate esters in dispersive solid‐phase extraction. By coupling dispersive solid‐phase extraction with high‐performance liquid chromatography and response surface methodology (central composite design), a reliable, sensitive, and cost‐effective method for simultaneous determination of phthalate esters including dimethyl phthalate, di‐n‐butyl phthalate, and di(2‐ethylhexyl)phthalate was developed. The morphology of sorbent had been studied by scanning electron microscopy and its chemical structure confirmed by Fourier transform infrared spectroscopy. Under optimum condition, good linearity was observed in the range of 5.0–5000.0 ng/mL. The limits of detection (S/N = 3) and limits of quantification (S/N = 10) were 0.1–0.3 and 0.3–1 ng/mL, respectively. The relative standard deviations were less than 8.8%. Finally, this procedure was employed for extraction of trace amounts of phthalic acid esters in milk samples, the relative recoveries ranged from 82 to 103%.