Determination of phthalates and adipate in bottled water by headspace solid-phase microextraction and gas chromatography/mass spectrometry

The performance of three fibres for the headspace solid-phase microextraction (SPME) of di-2-ethylhexyl adipate (DEHA) and eight phthalates in water was investigated systematically under different extraction conditions. Good responses on the 65 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) SPME fibre were observed for DEHA and all phthalates. The polydimethylsiloxane (PDMS) SPME fibre had very poor responses for the lighter and slightly polar phthalates, dimethyl phthalate (DMP) and diethyl phthalate (DEP), while the divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fibre had very poor responses for the heavier and non-polar adipate and phthalates. The salt (NaCl) was found to increase the partitioning of DMP, DEP, diisobutyl phthalate (DiBP), di-n-butyl phthalate, and benzyl butyl phthalate (BBP) from water into the headspace, while partitioning of heavier adipate and phthalates from water into headspace was suppressed when the concentration of NaCl was above 10%. The automated headspace SPME methods were developed and validated under two different salting conditions (30% NaCl for DMP, DEP and BBP, and 10% for DEHA, DiBP, DBP, di-n-hexyl phthalate (DHP), di-2-ethylhexyl phthalate (DEHP), and di-n-octyl phthalate (DOP)). Linearity with R(2) values better than 0.9949 was observed for DEHA and eight phthalates over the range from 0.1 to 20 microg L(-1). Method detection limits ranged from 0.003 microg L(-1) for DOP to 0.085 microg L(-1) for BBP. Good repeatability was observed for DEHA and most phthalates with relative standard deviation (RSD) values less than 10%. The methods were used to analyse bottled water samples for DEHA and eight phthalates. DMP, DHP, BBP, DEHA and DOP were not detected in any samples. Concentrations of the other phthalates were low (around sub-ppb) except for DBP in the water from a polycarbonate bottle at 1.72 microg L(-1).     

Determination of phthalate acid esters plasticizers in plastic by ultrasonic solvent extraction combined with solid-phase microextraction using calix[4]arene fiber

Ultrasonic solvent extraction combined with solid-phase microextraction (SPME) with calix[4]arene/hydroxy-terminated silicone (C[4]/OH-TSO) oil coated fiber was used to extract phthalate acid esters (PAEs) plasticizers in plastic, such as blood bags, transfusion tubing, food packaging bag, and mineral water bottle for analysis by gas chromatography (GC). Both extraction parameters (i.e. extraction time, extraction temperature, ionic strength) and conditions of the thermal desorption in a GC injector were optimized by analysis of eight phthalates. The fiber shows wonderful sensitivity and selectivity to the tested compounds. Owing to its high thermal stability (380 °C), the carryover effect that often encountered when using conventional fibers can be reduced by appropriately enhancing the injector temperature. The method showed linear response over two to four orders of magnitude with correlation coefficients (r) better than 0.996, and limits of detection (LOD) ranged between 0.006 and 0.084 μg l⁻¹. The relative standard deviation values obtained were ≤10%. bis-2-Ethylhexyl phthalate (DEHP) was the sole analyte detected in these plastics and recoveries were in the ranges 95.5-101.4% in all the samples.     

Development of a solid-phase microextraction method for the determination of phthalic acid esters in water

Solid-phase microextraction method (SPME) coupled to GC/ECD has been developed and validated for the determination of phthalic acid esters (dimethyl-, diethyl-, di-n-butyl-, butylbenzyl-, di-2-ethylhexyl- and di-n-octyl phthalate) in water samples. Two types of coatings (PDMS, PA), altogether four different kinds of fibers have been investigated. Both parameters affecting the partition of analytes between a fiber coating and aqueous phase (i.e. extraction time, extraction temperature, agitation) and conditions of the thermal desorption in a GC injector were optimized. The final SPME method employing the polyacrylate fiber, extraction time 20 min, heating and stirring of the sample enabled the determination of all six phthalates in water samples. The method showed linear response over four orders of magnitude and the limits of quantification of the method ranged between 0.001 and 0.050 μg l⁻¹. The repeatability expressed as R.S.D. was in the range 4-10% for the spiking level 7 μg l⁻¹ of each analyte. The applicability of the developed SPME method was demonstrated for real water samples.     

Evaluation of a new method for chemical coating of aluminum wire with molecularly imprinted polymer layer. Application for the fabrication of triazines selective solid-phase microextraction fiber

A new solid-phase microextraction (SPME) fiber is fabricated through ultra violet irradiation polymerization of ametryn-molecularly imprinted polymer on the surface of anodized-silylated aluminum wire. The prepared fiber is durable with very good chemical and thermal stability which can be coupled to GC and GC/MS. The effective parameters on the fabrication and application procedures such as spraying mode, ultra violet irradiation (polymerization) time, number of sprayings and polymerizations, pH and ionic strength of sample and extraction time were optimized. This fiber shows high selectivity with great extraction capacity toward triazines. SPME and GC analysis of ametryn, prometryn, terbutryn, atrazine, simazine, propazine and cyanazine using the fabricated fiber result in the detection limits of 9, 32, 27, 43, 51, 74 and 85 ng mL⁻¹, respectively. The reliability of the prepared fiber in real samples has been investigated and proved by using spiked tap water, rice, maize and onion samples.     

Headspace solid-phase microextraction of oil matrices heated at high temperature and phthalate esters determination by gas chromatography multistage mass spectrometry

A solvent-free analytical approach based on headspace solid-phase microextraction (SPME) of oil matrices heated at high temperatures coupled to gas chromatography with mass spectrometry detector (GC-ion trap) has been developed for the determination of phthalic acid esters (PAEs) in oil matrices without sample manipulation. For this study, three fibers, i.e., 85 μm-polyacrylate (PA), 50/30 μm-divinylbenzene-carboxen-polydimethylsiloxane (DVB/CAR/PDMS) and 100 μm-polydimethylsiloxane (PDMS) were tested. Variables affecting the SPME headspace composition such as incubation sample temperature, sample incubation time and fiber exposition time were optimized. The optimal values found were 250 °C for sample incubation temperature and 30 min for incubation and extraction time. PA fiber was not suitable for the lightest polar phthalates which showed poor extraction and repeatability values. PDMS fiber had very poor response for some of the heavier and non-polar phthalates, whereas DVB/CAR/PDMS fiber showed the best response and repeatability values for the majority of the phthalates studied. The main benefit of the analytical method proposed is the absence of sample manipulation and hence avoidance of possible contamination coming from glassware, environment, solvents and samples.     

Selective solid-phase extraction of dibutyl phthalate from soybean milk using molecular imprinted polymers

An analysis method is reported for dibutyl phthalate and related compounds with high selectivity and sensitivity by using the selective molecularly imprinted solid-phase extraction (MISPE) technique. In this report, dibutyl phthalate (DBP) is employed as the template molecule, and the molecularly imprinted polymers (MIPs) are synthesized through the bulk polymerization of methacrylic acid (MAA). The Scatchard plot suggests that the template-polymer system has two-site binding behavior with the dissociation constants of 0.5187 and 0.01898 mmol L⁻¹, respectively. The rebinding test, based on the MISPE column technique, shows the recoveries of soybean milk samples spiked with 5 phthalates are in the range of 75.8-107.5% with the relative standard deviations of 1.80-10.08%, indicating the feasibility of the prepared MIPs for phthalates extraction. Finally, the method is used to analyze the trace level of phthalates in commercial soybean milk.     

Headspace solid-phase microextraction of phthalic acid esters from vegetable oil employing solvent based matrix modification

A new solvent-free analytical procedure based on headspace solid-phase microextraction (SPME) coupled to gas chromatography employing an electron capture detector (GC/ECD) or alternatively a mass spectrometric detector (GC/MSD) has been developed for the determination of phthalic acid esters (dimethyl-[DMP], diethyl-[DEP], di-n-butyl-[DnBP], butylbenzyl-[BBP], di-2-ethylhexyl-[DEHP] and di-n-octyl [DnOP] phthalate) in vegetable oils. Four different fiber coatings were evaluated, among them polydimethylsiloxane with a thickness of 100 μm appeared to be the best choice for allowing extraction of the whole group of analytes. Various solvents were tested as sample matrix modification agents with the aim to facilitate the transfer of esters with low vapour pressure (DEHP and DnOP) from oil matrix into the headspace. The addition of methanol resulted in optimal set-up applicable for all phthalate esters. Temperature control and the way of sample stirring were recognized as critical points of the whole procedure. Primarily, because shaking rather than stirring of the sample is carried out using a CombiPal multipurpose sampler, the automation of the SPME method employing this instrument was found to be not fully suitable for efficient stripping of phthalates from the oil matrix into the sample headspace. Nevertheless, the optimized manual SPME method, encompassing GC/ECD or GC/MSD for the separation and detection of target analytes, offers a unique solution and showed acceptable performance characteristics: linear response in the range of 0.5-2 mg kg⁻¹ and repeatability expressed as R.S.D. between 14 and 23% at the spiking level of 2 mg kg⁻¹.     

Multivariate optimization of a solid-phase microextraction method for the analysis of phthalate esters in environmental waters

A solid-phase microextraction method (SPME) coupled to gas chromatography-mass spectrometry (GC-MS) has been developed for the determination of the six phthalate esters included in the US Environmental Protection Agency (EPA) Priority Pollutants list in water samples. These compounds are dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBP), di-2-ethylhexyl phthalate (DEHP) and di-n-octyl phthalate (DOP). Detailed discussion of the different parameters, which could affect the extraction process, is presented. Main factors have been studied and optimized by means of a multifactor categorical design. Different commercial fibers, polydimethylsiloxane (PDMS), polydimethylsiloxane-divinylbenzene (PDMS-DVB), polyacrylate (PA), Carboxen-polydimethylsiloxane (CAR-PDMS) and Carbowax-divinylbenzene (CW-DVB), have been investigated, as well as the extraction mode, exposing the fiber directly into the sample (DSPME) or into the headspace over the sample (HS-SPME), and different extraction temperatures. The use of this experimental design allowed for the evaluation of interactions between factors. Extraction kinetics has also been studied. The optimized microextraction method showed linear response and good precision for all target analytes. Detection limits were estimated considering the contamination problems associated to phthalate analysis. They were in the low pg mL(-1), excluding DEHP (100 pg mL(-1)). The applicability of the developed SPME method was demonstrated for several real water samples including mineral, river, industrial port and sewage water samples. All the target analytes were found in real samples. Levels of DEP and DEHP were over 1 ng mL(-1) in some of the samples.     

固相萃取-气相色谱/质谱法同时测定化妆品中的邻苯二甲酸酯和对羟基苯甲酸酯

采用超声协助甲醇提取、固相萃取净化、气相色谱/选择离子质谱联用法,同时测定化妆品中8种邻苯二甲酸酯和4种对羟基苯甲酸酯。该方法线性范围广、重现性好、快速简便、干扰小。样品的加标回收率为80%～100%;含量检测的相对标准偏差小于10%;方法的检出限为0.1~5.0 μg/kg。用该方法对15种实际样品中的12种残留物进行定量检测,结果表明除了一种样品中不含待测物外,其余样品均检测到3~7种待测物。其中以对羟基苯甲酸甲酯、对羟基苯甲酸丙酯、邻苯二甲酸丙酯、邻苯二甲酸环己酯和邻苯二甲酸乙基庚基酯为主。     

Preparation and evaluation of propranolol molecularly imprinted solid-phase microextraction fiber for trace analysis of β-blockers in urine and plasma samples

An improved multiple co-polymerization technique was developed to prepare a novel molecularly imprinted polymer (MIP)-coated solid-phase microextraction (SPME) fiber with propranolol as template. Investigation was performed for the characteristics and application of the fibers. The MIP coating was highly crosslinked and porous with the average thickness of only 25.0 μm. Consequently, the adsorption and desorption of β-blockers within the MIP coating could be achieved quickly. The specific selectivity was discovered with the MIP-coated fibers to propranolol and its structural analogues such as atenolol, pindolol, and alprenolol. In contrast, only non-specific adsorption could be shown with the non-imprinted polymer (NIP)-coated fibers, and the extraction efficiencies of propranolol and pindolol with the MIP-coated fibers were higher markedly than that with the commercial SPME fibers. A MIP-coated SPME coupled with high-performance liquid chromatography (HPLC) method for propranolol and pindolol determination was developed under the optimized extraction conditions. Linear ranges for propranolol and pindolol were 20–1000 μg L⁻¹ and detection limits were 3.8 and 6.9 μg L⁻¹, respectively. Propranolol and pindolol in the spiked human urine and plasma samples, extracted with organic solvent firstly, could be simultaneous monitored with satisfactory recoveries through this method.     

The evaluation of solid phase micro-extraction fibre types for the analysis of organic components in unburned propellant powders

This work describes the evaluation of various solid phase micro-extraction (SPME) fibre types for the detection of compounds originating from particles of unburned propellant powders. These compounds may also be found in association with organic gunshot residues (OGSR). Seven SPME fibres were assessed based on their ability to extract the compounds of interest (diphenylamine (DPA), 4-nitrodiphenylamine (4-NDPA), ethyl centralite (EC), nitroglycerin (NG) and dibutyl phthalate (DBP)) from four ammunition types across three calibres (9 mm, 5.56 mm and 7.62 mm). Extracts were analysed by gas chromatography/mass spectrometry (GC/MS). Results indicated that the 65 μm polydimethylsiloxane/divinylbenzene (PDMS/DVB) was the most suitable fibre type for the extraction of these compounds across the ammunition types tested. Optimal extraction time parameters were also assessed with a 35-min period determined to be suitable. A number of previously unreported considerations for extracting propellant powders and potentially OGSR related materials are discussed.     

Simultaneous screening and determination eight phthalates in plastic products for food use by sonication-assisted extraction/GC-MS methods

Studies on determination of eight kinds of phthalates, e.g. di-ethyl phthalate (DEP), di-propyl phthalate (DPP), di-isobutyl phthalate (DIBP), di-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di-cyclohexyl phthalate (DCHP), di-(2-ethylhexyl) phthalate (DEHP), di-octyl phthalate (DOP), in 25 kinds of plastic products for food use, including packaging bags, packaging film, containers, boxes for microwave oven use, sucking tubes, spoons, cups, plates, etc. by gas chromatography in combination with mass spectrometry detector (GC-MS) in electronic ionisation mode (EI) with selected-ion monitoring (SIM) acquisition method (GC-MS (EI-SIM)) have been carried out. Methods have been developed for both qualitative and quantitative analysis of phthalates. Extraction, clean-up and analysis procedure have been optimized. Determination of samples were performed after frozen in liquid nitrogen and sonication-assisted extraction with hexane, clean-up with LC-C18 SPE and analyzed by GC-MS methods. The base peak (m/z = 149) of all the phthalates was selected for the screening studies. The characteristic ions, 121, 177, 222 for DEP; 191, 209 for DPP; 57, 223 for DIBP; 104 for DBP; 91, 132, 206 for BBP; 55, 167 for DCHP; 113, 167, 279 for DEHP; 279 for DOP were chosen for quantitative studies. These techniques are possible to detect phthalates at the level of 10.0 μg/kg. Overall recoveries were 82-106% with R.S.D. values at 3.8-10.2%. Only one of the 25 examined samples was free from phthalates. The rest 24 samples were found to contain at least three or more of these phthalates. The predominant phthalate detected in the studied samples was DEHP.     

基于杯［6］芳烃萃取头的固相微萃取-气相色谱法测定啤酒中痕量的酞酸酯类化合物

选用自制杯［6］芳烃溶胶-凝胶固相微萃取(SPME)萃取头,建立了顶空SPME与气相色谱联用检测啤酒中8种酞酸酯(PAEs)的方法。采用L25(56)正交设计对萃取条件进行了优化,所得方法检出限为0.003～3.429 μg/L,相对标准偏差不超过13.5%,加标回收率为86.3%～109.3%。采用标准加入法对3种瓶装啤酒中PAEs进行了检测,结果表明邻苯二甲酸二(2-乙基己)酯(DEHP)是啤酒中最主要的酞酸酯类污染物,含量最高达5.24 μg/L。迁移试验表明,瓶装啤酒所用塑料垫圈中高含量的DEHP可能成为酒体中PAEs的一种来源,且延长贮存时间、提高贮存温度和振荡都能加快垫圈中DEHP的迁移。     

Development of an ionic liquid-based dispersive liquid-liquid micro-extraction method for the determination of phthalate esters in water samples

Ionic liquid-based dispersive liquid-liquid micro-extraction (IL-DLLME) was coupled with high-performance liquid chromatography-ultraviolet (HPLC-UV) for the determination of four phthalate esters, including butyl benzyl phthalate, di-n-butyl phthalate, dicyclohexyl phthalate and bis(2-ethylhexyl) phthalate in water samples. The mixture of ionic liquid (IL) and dispersive solvent was rapidly injected into 10 mL aqueous sample. Then, IL phase was separated by centrifugation and was determined by high-performance liquid chromatography-ultraviolet. The factors influencing the extraction efficiency, such as type and volume of IL, disperse solvent, extraction time, centrifuging time and ionic strength, were investigated and optimized. Under the optimized conditions, the extraction recoveries by the proposed ionic liquid-based dispersive liquid-liquid micro-extraction for the four phthalates ranged from 83.0 to 91.7%. The relative standard deviations were between 7.8 and 15%. The limits of quantification for four phthalates were between 10.6 and 28.5 μg/L. The proposed method was successfully applied for the analysis of PAEs in tap, lake and treated wastewater samples.     

Preparation and binding study of solid-phase microextraction fiber on the basis of ametryn-imprinted polymer: Application to the selective extraction of persistent triazine herbicides in tap water,rice, maize and onion

A monolithic ametryn molecular-imprinted polymer based on a simple polymerization method was fabricated for use as new solid-phase microextraction (SPME) fiber, which can be coupled with GC and GC/MS for selective extraction and analysis of triazine herbicides. Methacrylic acid (MAA), ethylene glycol dimethacrylate (EDMA) and ametryn bear role of functional monomer, cross-linker and template, respectively. In the optimized conditions the fabricated fiber showed better molecular recognition abilities for methylthiotriazine herbicides than chloro-triazine herbicides. By use of bi-Langmuir isotherm model the evaluated equilibrium constants for ametryn were 0.01 and 890.69 μM⁻¹, and the numbers of binding sites were 129.98 and 5.82 nmol g⁻¹, respectively. The high extraction efficiency was obtained for ametryn, prometryn, terbutryn, atrazine, simazine, propazine, and cyanazine, yielding the detection limits of 14, 28, 45, 56, 85, 95 and 74 ng mL⁻¹, respectively by GC with flame ionization detection. The reliability of the prepared fiber for extraction of ametryn and other analogues in real samples has been investigated and proved by using spiked samples such as tap water, rice, maize, and onion.     

Molecularly imprinted polymer coated solid-phase microextraction fiber prepared by surface reversible addition–fragmentation chain transfer polymerization for monitoring of Sudan dyes in chilli tomato sauce and chilli pepper samples

Surface reversible addition-fragmentation chain transfer (RAFT) polymerization method was firstly applied to the preparation of molecularly imprinted polymer (MIP) coated silicon solid-phase microextraction (SPME) fibers. With Sudan I as template, an ultra-thin MIP coating with about 0.55-μm thickness was obtained with homogeneous structure and controlled composition, due to the controllable radical growing and chain propagation in surface RAFT polymerization. The MIP-coated fibers were found with enhanced selectivity coefficients (3.0–6.5) to Sudan I–IV dyes in contrast with those reported in our previous work. Furthermore, the ultra-thin thickness of MIP coating was helpful to the effective elution of template and fast adsorption/desorption kinetics, so only about 18 min was needed for MIP-coated SPME operation. The detection limits of 21–55 ng L⁻¹ were achieved for four Sudan dyes, when MIP-coated SPME was coupled with liquid chromatography (LC) and mass spectrometry (MS) detection. The MIP-coated SPME–LC–MS/MS method was tested for the monitoring of ultra trace Sudan dyes in spiked chilli tomato sauce and chilli pepper samples, and high enrichment effect, remarkable matrix peaks-removing capability, and consequent high sensitivities were achieved to four Sudan dyes.     

Optimization of Modern Analytical SPME and SPDE Methods for Determination of <Emphasis Type="Italic">Trans</Emphasis>-2-nonenal in Barley,Malt and Beer

Trans-2-nonenal is an aldehyde contributing to an unpleasant off-flavor and odor of rancid butter in stored beer. The automated solid-phase microextraction technique (SPME) coupled with gas chromatography (GC) and solid-phase dynamic extraction (SPDE) coupled with gas chromatography were optimized and introduced to determine trans-2-nonenal in barley, malt and beer. Five types of SPME fibers coated with different stationary phases (100 μm PDMS, 65 μm PDMS/DVB, 85 μm CAR/PDMS, 50/30 μm DVB/CAR/PDMS, 85 μm PA) and two needles (PDMS, PDMS/AC) were compared and tested for their efficiencies in the headspace (HS) SPME and SPDE determination of trans-2-nonenal in barley, malt and beer. The highest extraction efficiency of HS-SPME was achieved with the PDMS/DVB fiber, and addition of 1.5 g of NaCl, extraction time was 20 min at 60 °C. The highest extraction efficiency of HS-SPDE was obtained with the PDMS needle, 15 extraction strokes at 60 °C and addition of 1.5 g of NaCl. Trans-2-nonenal was identified with the method of HS-SPME coupled gas chromatography-mass spectrometry (GC–MS); the samples were analyzed using the HS-SPME-GC-coupled gas chromatography-flame ionization detector (GC-FID) technique.     

Determination of phthalates in milk and milk products by liquid chromatography/tandem mass spectrometry

A liquid chromatographic/tandem mass spectrometric method using pneumatically assisted electrospray ionisation (LC/ESI-MS/MS) was developed for determination of dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), di-2-ethylhexyl phthalate (DEHP), di-'isononyl' phthalate (DINP) and di-'isodecyl' phthalate (DIDP) in milk and milk products including infant formulas. The phthalates were extracted by a mixture of tert-butyl methyl ether and hexane from liquid samples. DBP, BBP and DEHP were removed from fats by liquid/liquid extraction into acetonitrile while DINP and DIDP were cleaned up on deactivated silica. The phthalates were detected in positive ion mode after separation on a reversed-phase C5 analytical column. Two transition products were monitored for each compound. The detection limits related to the transition products of lowest abundance were in the range 5-9 microg/kg.     

Application of head-space solid-phase microextraction coupled to comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry for the determination of multiple pesticide residues in tea samples

A new method has been developed to detect 36 pesticides that may contaminate tea samples (green, black and fruit tea). The hyphenation of solid-phase microextraction in head-space mode with a comprehensive two-dimensional gas chromatography coupled with high-speed time-of-flight mass spectrometry (HS-SPME-GC × GC/TOF MS) proved to be a quick alternative to conventional GC/MS methodology which employs solvent-based extraction. The key parameters for controlling HS-SPME performance were optimized, including fiber coating type, temperature and absorption time settings and tea matrix modification by adding water. Quantification was carried out using matrix-matched calibration. The repeatability of measurements, expressed as relative standard deviation (R.S.D.), was less than 24% for all analytes. The limits of quantification ranged from 1 to 28 μg kg⁻¹. The optimized method was applied to analyze real life samples obtained from a retail market. Results generated by the new SPME procedure and those obtained by using a conventional one involving ethyl acetate extraction and high-performance gel permeation chromatography (HPGPC) clean up agreed with each other for positive (containing residue) samples.     

自制固相微萃取装置对水中5种农药残留量的分析

合成了一种丙烯酸酯聚合物,并将其作为固相微萃取涂层,使用自制的SPME装置和气质联用仪对水样中5种农药残留量进行分析,该装置制作简单、价格低廉.对影响分析灵敏度的各种实验因素进行了优化,在优化条件下分析5种农药标准样品质量浓度在1～1000 μg/L内与色谱峰面积呈良好的线性关系(r=0.995～0.999),检出限为0.391～1.170 ng/L.将自制涂层与商品涂层(PA)进行了比较,自制涂层对5种农药具有优良的吸附特性,较低的检出限.