Development of pressurized liquid extraction and solid‐phase microextraction combined with gas chromatography and flame photometric detection for the determination of organophosphate esters in sediments

Organophosphate esters have been extensively used as flame retardants and plasticizers. The analysis of organophosphate esters in the environment is a hot topic because many of them are toxic and persistent. We developed a novel procedure for determining organophosphate esters in sediment. In this work, pressurized liquid extraction and solid‐phase microextraction are used for sample preparation to extract and concentrate the analytes, which are then analyzed by gas chromatography with flame photometric detection. The extraction parameters of pressurized liquid extraction were investigated and optimized by orthogonal design and then evaluated by range analysis and analysis of variance. Under the optimal conditions, the proposed procedure showed wide linear ranges (0.90–100 ng/g) with correlation coefficients ranging from 0.9921 to 0.9990. The detection limits of the method were in the range of 0.009–0.280 ng/g with standard deviations ranging from 2.2 to 9.5%. Recoveries of the proposed method ranged from 82.3 to 108.9% with relative standard deviations <8.4%. The obtained method was applied successfully to the determination of organophosphate esters in real sediments with recoveries varying from 79.8 to 107.3%. The proposed method was proved to be simple, easy, and sensitive for analyzing organophosphate esters in sediment samples.     

固相萃取-气质联用法测定纺织品中的磷酸三酯类阻燃剂

建立了固相萃取-气质联用法同时测定纺织品中的烷基磷酸三酯和芳香基磷酸三酯类阻燃剂的方法.采用乙腈-甲苯(3∶1,Ⅴ/Ⅴ)混合溶液作为提取剂,对纺织品中的磷酸三酯类阻燃剂进行提取;再用ENVI-Carb固相萃取柱对提取液中的目标分析物进行净化处理;氮吹浓缩定容后,用气质联用仪进行定性与定量分析.磷酸三(2,3-二溴丙基)酯在0.050～20 mg/L浓度范围内存在良好的线性关系,相关系数r为0.9859;定量限为0.050 mg/kg (S/N=10).其它目标分析物在0.010～20 mg/L浓度范围内存在良好的线性关系,r为0.9998～1.000;定量限为0.010 mg/kg(S/N=10).本方法成功应用于纺织品中磷酸三酯类阻燃剂的检测,加标回收率在71.4％～102.5％之间;RSD≤4.9(n=6).分析的20个样品中,有一个Ⅰ类样品检出TBP,含量为(62.2±0.3) μg/kg.     

Organophosphate and phthalate esters in standard reference material 2585 organic contaminants in house dust

The levels of 22 phthalate diesters (phthalates) and organophosphate triesters (organophosphates) have been investigated in standard reference material 2585 (SRM 2585) “organic contaminants in house dust.” Ultrasonic-assisted solvent extraction and solid-phase extraction on a Florisil adsorbent were used as the extraction and cleanup steps combined with analysis using gas chromatography–tandem mass spectrometry in positive ion chemical ionization mode. Seven phthalates were detected in the concentration range 1–570 μg/g. Di(2-ethylhexyl) phthalate was the major phthalate present at 570 μg/g. Ten organophosphates were detected in SRM 2585. Tris(2-butoxyethyl) phosphate was the predominant organophosphate at 82 μg/g, and nine organophosphates were determined at concentrations ranging from 0.19 to 2.3 μg/g. Five organophosphates were below the method detection limit, of which two were in level with the procedural blank. The applied extraction and cleanup method was evaluated for the analysis of SRM 2585. The extraction yield was ≥99%, except for tris(2-chloroethyl) phosphate (97%) and diethyl phthalate (98.5%). The problem of calibration curvature is addressed, and it is shown that the use of deuterated standards improves the analysis. The concentrations of ten organophosphate esters were determined in SRM 2585, and seven of these were compared with existing data. To our knowledge, this is the first report of the levels of the seven phthalates esters in SRM 2585 “organic contaminants in house dust.”     

GC-MS/MS法对焙烤食品及其塑料包装材料中25种磷酸三酯类与邻苯二甲酸酯类化合物的同时测定

建立了气相色谱-质谱/质谱(GC-MS/MS)测定焙烤食品及其塑料包装材料中25种磷酸三酯类及邻苯二甲酸酯类化合物的高通量检测方法。焙烤食品以乙腈-丙酮(8∶2,体积比)超声提取,采用50 mg C18和50 mg PSA混合填料进行Qu ECh ERS净化;塑料包装材料经二氯甲烷-甲醇超声提取后直接检测。样液经DB-5 ms色谱柱分离,选择反应监测(SRM)模式测定。25种化合物在各自线性范围内的相关系数不小于0.997 5,方法检出限为10~500μg/kg,平均回收率为80.2%~119.6%,相对标准偏差(n=6)为1.5%~9.4%。该方法操作简单,净化效果好,可有效消除基质效应,适用于不同焙烤食品及其塑料包装材料中磷酸三酯类及邻苯二甲酸酯类化合物的同时测定。     

Trace determination of organophosphate esters in environmental water samples with an ionogel‐based nanoconfined ionic liquid fiber coating for solid‐phase microextraction with gas chromatography and flame photometric detection

Organophosphate esters, widely used as flame retardants and plasticizers, are regarded as a class of emerging pollutants. In this work, a novel approach was developed for the fabrication of a solid‐phase microextraction fiber by using hybrid silica‐based materials with immobilized ionic liquids with sol–gel technology, and the prepared solid‐phase microextraction fiber was then coupled with gas chromatography and flame photometric detection for the analysis of six organophosphate esters. The high loading of 1‐hexadecyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide was confined within the hybrid network. The developed solid‐phase microextraction fiber possesses a coating thickness of ～35 μm with good thermal stability and long lifetime. The parameters affecting the extraction efficiency such as extraction time, temperature, pH, and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.04?0.95 μg L^?1, and the precision of the method assessed with repeatability and reproducibility of (RSD%) ?13 and ?29%, respectively. The proposed method was successfully applied to determine the six organophosphate esters in three real water samples, with recoveries in the range of 64.8?125.4% at two different spiking concentration levels. As a result, the proposed method demonstrated its potential for application in trace determination of organophosphate esters in actual water samples.     

C_(18)膜萃取/液相色谱-质谱联用法测定极地水体中有机磷酸酯

建立了C_(18)膜萃取/液相色谱-质谱联用技术测定极地水体中10种有机磷酸酯(OPEs)的方法。根据优化后的样品前处理及仪器方法,利用C_(18)膜富集4 L水体中的10种OPEs,经二氯甲烷超声提取,在电喷雾正离子模式下,采用选择反应监测(SRM)模式进行分析,线性相关系数为0.994 4~0.999 9。10种OPEs的加标回收率为64.1%~115%,方法检出限为0.08~0.55 ng/L。该方法适用于极地水体中10种OPEs的分析,利用该方法对北极水体样品中的10种OPEs进行检测,测得冰川融水中∑OPEs的质量浓度为0.64~6.64 ng/L,海水中∑OPEs的质量浓度为0.09~2.03 ng/L。     

Facile synthesis of spherical covalent organic frameworks for enrichment and quantification of aryl organophosphate esters in mouse serum and tissues

Here, an imine-linked-based spherical covalent organic framework (COF) was prepared at room temperature. The as-synthesized spherical COF served as an adsorbent in dispersive solid-phase extraction (dSPE), by its virtue of great surface area (1542.68 m²/g), regular distribution of pore size (2.95 nm), and excellent stability. Therefore, a simple and high-efficiency dispersive solid phase extraction method based on a spherical COF coupled with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established to determine aryl organophosphate esters in biological samples. This approach displayed favorable linearity in the range of 10.0–1000.0 ng/L (r > 0.9989), a high signal enhancement factor (58.8–181.8 folds) with low limits of detection (0.3–3.3 ng/L). Moreover, it could effectively eliminate complex matrix interference to accurately extract seven aryl organophosphate esters from mouse serum and tissue samples with spiked recoveries of 82.0%–117.4%. The as-synthesized spherical COF has been successfully applied in sample preparation. The dSPE-HPLC-MS/MS method based on a spherical COF has potential application to study the pollutants' metabolism in vivo.     

High-throughput dynamic microwave-assisted extraction on-line coupled with solid-phase extraction for analysis of nicotine in mushroom

A simple and low-cost high-throughput dynamic microwave-assisted extraction (HTDMAE) device was firstly assembled and validated by the extraction of nicotine in mushroom samples. In this device, a household microwave oven was applied to provide the microwave energy; a vacuum pump was used to deliver the solvent. Compared with traditional dynamic microwave-assisted extraction method, the sample throughput and microwave energy utilization were improved by the HTDMAE, up to 20 samples could be treated simultaneously in 9 min. Taking extraction of nicotine in mushroom sample as an example, a method was established with extraction, separation and enrichment of nicotine in a single step by the device on-line coupled with solid-phase extraction (SPE). Nicotine was first extracted from the mushroom samples with water under the action of microwave energy, and then directly introduced into the SPE column which was packed with cation-exchange resins. Subsequently, the nicotine trapped on the resins was eluted with methanol-ammonia (95:5, v/v) and determined by high-performance liquid chromatography. The limit of detection of nicotine obtained is 5.6 μg kg(-1) in fresh mushroom sample. The recovery of nicotine in mushroom samples is in the range of 87.4-104.0%. The proposed method which significantly reduced the overall analysis time and increased sample throughput should be favored for routine analyse of complex solid sample.     

气相色谱-串联质谱法测定婴儿奶粉中16种邻苯二甲酸酯类化合物

建立了气相色谱-串联质谱（GC-MS/MS）测定复杂基体婴儿奶粉中16种邻苯二甲酸酯类塑化剂的分析方法。奶粉样品以水溶解均质,乙腈提取,乙二胺-N-丙基硅烷（PSA）类型玻璃固相萃取柱净化,DB-5 MS UI气相色谱柱（30 m×0.25 mm×0.25 μm）分离,同位素稀释质谱法（IDMS）定量。比较了氧化铝/PSA和PSA两种固相萃取柱在不同洗脱条件下萃取16种塑化剂的回收率。最终选择PSA固相萃取柱,以正己烷-丙酮（60：40,v/v）作为洗脱溶剂,实现奶粉基体中16种塑化剂的净化。采用基质匹配同位素内标法定量,16种塑化剂在0.01~2.0 mg/kg范围内线性良好,线性相关系数（R²）大于0.9996,检出限和定量限分别是0.15~2.50 μg/kg和0.50~8.33 μg/kg,加标回收率为96.1%~104.0%,相对标准偏差（RSD）小于3.3%（n=5）,该方法灵敏度好、精密度高,适用于婴儿奶粉基体中16种塑化剂的痕量分析。     

Electrochemical preparation of zinc oxide/polypyrrole nanocomposite coating for the highly effective solid‐phase microextraction of phthalate esters

In this work, zinc oxide/polypyrrole nanocomposite coating was fabricated on stainless steel and evaluated as a novel headspace solid‐phase microextraction fiber coating for extraction of ultra‐trace amounts of environmental pollutants, namely, phthalate esters, in water samples. The fiber nanocomposite were prepared by a two‐step process including the electrochemical deposition of polypyrrole on the surface of stainless steel in the first step, and electrochemical deposition of zinc oxide nanosheets in the second step. Porous structure together with zinc oxide nanosheets with the average diameter of 30 nm were observed on the surface by using scanning electron microscopy. The effective parameters on extraction of phthalate esters (i.e., extraction temperature, extraction time, desorption temperature, desorption time, salt concentration, and stirring rate) were investigated and optimized by one‐variable‐at‐a‐time method. Under optimized conditions (extraction temperature, 90°C; extraction time, 40 min; desorption temperature, 270°C; desorption time, 5 min; salt concentration, 25% w/v; and stirring rate, 1000 rpm), the limits of detection were in the range of 0.05–0.8 μg/L, and the repeatability and fiber‐to‐fiber reproducibility were in the ranges of 6.1–7.3% and 8.7–10.2%, respectively.     

Optimization of ultrasonic-assisted extraction of 3-monochloropropane-1,2-diol (MCPD) and analysis of its esters from edible oils by gas chromatography-mass spectrometry

In this paper, ultrasonic-assisted extraction of 3-chloropropane-1,2-diol and its esters from edible oils was studied with isotope dilution GC-MS. Effects of several experimental parameters, such as types and concentrations of extracting solvent, ratios of liquid to material, extraction temperature, time of ultrasonic treatment on the extraction efficiency of 3-chloropropane-1,2-diol and its esters from edible oils and sample preparation for calibration were compared and optimized. The optimal extraction conditions were suggested as 66 mg oil sample in mixture of 0.5 mL MTBE/ethyl acetate (20% v/v) and 0.5 mL of sulfuric acid/n-propanol (0.3% v/v), being extracted for 30 min at 45°C under ultrasonic irradiation. Good linearity was gained in the range of 0.020-5.000 μg/g with the limit of detection (LOD) of 0.006 μg/g (S/N = 3) and the limit of quantification (LOQ) of 0.020 μg/g (S/N = 10). The recoveries at five spiked concentrations were ranged from 91.9 to 109.3% with RSD less than 9.4%. The method was successfully applied to the determination of 3-chloropropane-1,2-diol and its esters amounts in rapeseed, sesame, peanut, camellia, and soybean oils.     

离子交换固相萃取-气相色谱-质谱联用法测定方便面皮复合包装袋中2,4-二氨基甲苯的迁移量

建立了方便面皮复合包装袋中2,4-二氨基甲苯迁移量的离子交换固相萃取-气相色谱-质谱联用检测方法。样品用4%（v/v）乙酸溶液浸泡,然后采用MCX混合型阳离子交换柱富集净化,以5.0 mL水淋洗小柱,用3.0 mL 5%（v/v）氨化甲醇洗脱样品,洗脱液经过溶剂交换,七氟丁酸酐衍生后,用气相色谱-质谱联用仪对目标物进行检测,外标法定量。2,4-二氨基甲苯在1~50 μg/L范围内,线性相关系数（r）为0.9991,检出限（S/N=3）为0.2 μg/L,定量限（S/N=10）为0.6 μg/L,回收率在89.0%~94.2%之间,相对标准偏差为1.9%~3.6%。该方法的前处理过程无需调节提取液的pH值,也不需要液液萃取,大幅简化了前处理过程,降低了有机溶剂的消耗,具有操作便捷、结果准确的优点,适用于方便面皮复合包装袋中2,4-二氨基甲苯迁移量的检测。     

Hollow-fiber liquid-phase microextraction for the determination of pesticides and metabolites in soils and water samples using HPLC and fluorescence detection

A new and simple method has been developed for the determination of a group of four benzimidazole pesticides (carbendazim/benomyl, thiabendazole, and fuberidazole), a carbamate (carbaryl), and an organophosphate (triazophos), together with two of their main metabolites (2-aminobenzimidazole, metabolite of carbendazim/benomyl, and 1-naphthol, metabolite of carbaryl) in soils. First, an ultrasound-assisted extraction (UAE) was performed, followed by evaporation and reconstitution in water. Then, extraction and preconcentration of the analytes was accomplished by two-phase hollow-fiber liquid-phase microextraction (HF-LPME) using 1-octanol as extraction solvent. Parameters that affect the extraction efficiency in HF-LPME technique (organic solvent, pH of the sample, extraction time, stirring speed, temperature, and ionic strength) were deeply investigated. Optimum HF-LPME conditions involved the use of a 2.0 cm polypropylene fiber filled with 1-octanol to extract 10 mL of an aqueous soil extract at pH 9.0 containing 20% (v/v) of NaCl for 30 min at 1440 rpm. Separation and quantification was achieved by HPLC with fluorescence detection (FD). The proposed optimum UAE-HF-LPME-HPLC-FD methodology provided good calibration, precision, and accuracy results for two soils of different physicochemical properties. LODs were in the range 0.001-6.94 ng/g (S/N = 3). With the aim of extending the validation, the HF-LPME method was also applied to different types of waters (Milli-Q, mineral and run-off), obtaining LODs in the range 0.0002-0.57 μg/L.     

固相萃取结合气相色谱-串联质谱法测定烟草制品中23种酯类香料

利用固相萃取结合气相色谱-串联质谱(SPE-GC-MS/MS)检测技术建立了烟草制品中23种酯类香料的定量分析方法。样品以乙酸乙酯为提取溶剂,经NH₂固相萃取柱(依次用甲醇和水活化)净化,用4 mL乙酸乙酯洗脱,在多反应监测(MRM)模式下进行检测。结果表明,23种香料在20.0~500.0 μ g/L范围内线性关系良好(r² > 0.996),检出限(LOD, S/N=3)及定量限(LOQ, S/N=10)分别为1.9~13.6 μ g/kg及6.3~45.3 μ g/kg,在1、1.5、2倍定量限的加标水平下,平均回收率为62.1%~91.4%,相对标准偏差(RSD)均小于7%。该方法准确可靠、灵敏度好,适用于烟草制品中23种常用酯类香料的快速筛查与定性、定量分析。该方法为烟草中酯类物质的检测开拓了平台。     

Determination of organophosphate esters in water samples by mixed‐mode liquid chromatography and tandem mass spectrometry

A simple and sensitive method for the determination of organophosphate esters in water samples by mixed‐mode liquid chromatography with electrospray ionization tandem mass spectrometry coupled with solid‐phase extraction is developed. Using seven alkyl phosphates, three chlorinated alkyl phosphates, and four aryl phosphates as the targets, the developed method was systematically evaluated on the basis of the influence of the solid‐phase extraction cartridge, eluting solvent, sample‐loading volume, mobile phase condition, and the separation of reversed‐phase chromatography and mixed‐mode liquid chromatography. Under the optimal conditions, these organophosphate esters can be extracted by ENVI‐18 cartridge, eluted by 6 mL of 25% dichloromethane in acetonitrile, and then qualified and quantified by mixed‐mode liquid chromatography with tandem mass spectrometry in the multiple reaction‐monitoring mode. The application of mixed‐mode liquid chromatography endows the separation with reasonable retention for both hydrophilic and hydrophobic organophosphate esters regardless of their polarity, which is hardly achieved by reversed‐phase chromatography. Good linearity (from 0.9877 to 0.9969), low quantification limits (1–35 ng/L after extraction of 100 mL of river water), and acceptable recovery rates (58.6–116.2%, with the relative standard deviation <18.0%) were obtained. Finally, the established method was used for analyzing surface water samples, and the good applicability of this method was demonstrated.     

Method of fast trace microanalysis of the chiral pesticides epoxiconazole and novaluron in soil samples using off-line flow-through extraction and on-column direct large volume injection in reversed-phase high performance liquid chromatography

An analytical method combining off-line flow-through extraction of a soil micro-sample (mass around 100 mg, packed into a short HPLC glass column) and direct on-column large-volume injection (LVI up to 1.00 mL) of a methanol-water soil extract onto a conventional C18 RP HPLC column enabled fast (within 3.5 minutes) trace micro-analysis of the relatively new chiral pesticides epoxiconazole (E) and novaluron (N), respectively. Linear calibration curves were evaluated from UV detection (230 nm) data in the range from 0.1 to 5 mg/kg in three most abundant Slovak agricultural soils. LOD (confidence band) at the levels 0.08-0.11 mg/kg and LOQ 0.4-0.6 mg/kg and LOD (S/N = 3) at the levels 0.007-0.018 mg/kg and LOQ (S/N = 10) 0.024-0.060 mg/kg, respectively, of dry soil were achieved. Recovery of pesticides in the overall LVI method including flow-through 130-200 mg soil micro-sample extraction was: for epoxiconazole from 74 to 85% and from 56% to 90% for novaluron with reproducibility within +/- 6% RSD. This fast (30 min) and simple method consists of just three steps which are short column filling with a solid micro-sample; flow-through liquid extraction and direct large-volume injection RP HPLC DAD analysis. The method is prepared for automation and further analysis of enantiomers of both investigated pesticides by achiral-chiral column switching techniques.     

Determination of acephate in human urine

Acephate is a commonly used organophosphate insecticide applied on agricultural crops and in residential communities. Because very little acephate is metabolized prior to excretion, the parent pesticide compound can be measured in human urine. The residue method must be sensitive enough to determine human exposure and potential health risk for both agricultural workers and their families who may be exposed by pesticide drift or by inadvertent carry-home residues. A reliable and sensitive method was developed to measure acephate concentrations in human urine. Urine was diluted with water and acetone, adjusted to a neutral pH, and partitioned twice in acetone-methylene chloride (1 + 1, v/v), with NaCl added to aid separation. The solvent-reduced organic phase extracts were clarified by activated charcoal solid-phase extraction and then adjusted to a final volume with the addition of a D-xylose analyte protectant solution to reduce matrix enhancement effects. Acephate concentrations in urine were determined by gas chromatography using pulsed flame photometric detection. The method limit of detection was established at 2 microg/L, with a method limit of quantitation of 10 microg/L. The average recovery from urine fortified with 10-500 microg/L was 102 +/- 12% (n = 32).     

Application of single-drop microextraction to the determination of dialkyl phthalate esters in food simulants

A fast and simple method, using static single-drop microextraction (SDME), has been developed to facilitate the identification and quantification of seven dialkyl phthalate esters in the three aqueous food simulants. The simulants were: A, distilled water; B, 3% (w/v) acetic acid/water; and C, 15% (v/v) ethanol/water. The extraction is performed by simply suspending a drop of organic solvent in the aqueous sample using a conventional gas chromatography (GC) microsyringe. Following extraction, the organic phase is withdrawn into the syringe and analyzed by gas chromatography and flame ionization detection (FID). The optimized method yields a linear calibration curve over three orders of magnitude for all the simulants, and method detection limits (MDLs) allowing detection of all the studied compounds at concentrations below migration limits established by the European Union. The accuracy of the SDME method was tested and compared to that of solid-phase microextraction (SPME) by recovery experiments using spiked samples, with results ranging from 85 to 115% in most cases.     

自制混合型小柱净化-高效液相色谱-串联质谱法同时测定尿液中有机磷酸酯代谢物和8-羟基-2'-脱氧鸟苷

建立了基于自制混合型小柱的样品净化-高效液相色谱-串联质谱同时测定7种有机磷酸酯（OPEs）主要代谢产物及生物标志物8-羟基-2'-脱氧鸟苷（8-OHdG）的分析方法。样品经乙腈提取后用自制小柱富集净化,以乙腈-0.2%（v/v）氨水溶液作为流动相进行梯度洗脱,在多反应监测模式下进行定性和定量分析。结果显示,8种目标物在0.1~200 μg/L范围内呈良好的线性关系,7种OPEs代谢物的回收率为52.36%~114.56%,8-OHdG回收率为88.63%~97.72%。将该方法应用于人体尿液实际样品中,7种OPEs代谢物和8-OHdG的检出范围分别为6.24~46.07 μg/L和5.90~16.71 μg/L,8-OHdG与7种OPEs代谢物总含量之间存在显著相关性。该方法操作简单、灵敏度高、准确性好、重现性强,可为更全面地评价人体内OPEs暴露水平及机体损伤提供可靠的技术支持。