Determination of phthalate esters in water samples using Nylon6 nanofibers mat-based solid-phase extraction coupled to liquid chromatography

A new method was developed for simultaneous determination of five phthalate esters by a combination of mat-based solid-phase extraction (SPE) with high-performance liquid chromatography. The mat is composed of Nylon6 nanofibers. Dimethyl phthalate (DMP), diethl phthalate (DEP), di-n-butyl phthalate (DBP), di-(2-ethylhexyl) phthalate (DEHP) and dioctyl phthalate (DOP) were successfully separated on a RP-C18 column. Under optimized conditions, the detection limits found for DMP, DEP, DBP, DEHP and DOP were 3, 2, 6, 10 and 33 pg mL^?1, respectively. The method was applied to the analysis of various water samples. Spiked samples gave recoveries in the range from 86.9 to 101.9%, with relative standard deviations below 7.0%. A comparison of Nylon6 nanofibers mat as sorbents, and C18 cartridges and other kinds of SPE sorbents was carried out with respect to recovery, sensitivity, and reproducibility. The results indicated that the Nylon mat is a viable material for the enrichment and determination of phthalate esters in environmental water samples.     

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%.     

Determination of phthalate esters from environmental water samples by micro‐solid‐phase extraction using TiO2 nanotube arrays before high‐performance liquid chromatography

We describe a highly sensitive micro‐solid‐phase extraction method for the pre‐concentration of six phthalate esters utilizing a TiO₂ nanotube array coupled to high‐performance liquid chromatography with a variable‐wavelength ultraviolet visible detector. The selected phthalate esters included dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, bis(2‐ethylhexyl)phthalate and dioctyl phthalate. The factors that would affect the enrichment, such as desorption solvent, sample pH, salting‐out effect, extraction time and desorption time, were optimized. Under the optimum conditions, the linear range of the proposed method was 0.3–200 μg/L. The limits of detection were 0.04–0.2 μg/L (S/N = 3). The proposed method was successfully applied to the determination of six phthalate esters in water samples and satisfied spiked recoveries were achieved. These results indicated that the proposed method was appropriate for the determination of trace phthalate esters in environmental water samples.     

Mesoporous Silica‐coated Magnetic Nanoparticles for Mixed Hemimicelles Solid‐phase Extraction of Phthalate Esters in Environmental Water Samples with Liquid Chromatographic Analysis

To extract, preconcentrate and determine the trace level of environmental contaminants, a novel mixed hemimicelles solid‐phase extraction (MHSPE) method based on mesoporous silica‐coated magnetic nanoparticles (Fe₃O₄/meso‐SiO₂ NPs) as adsorbent was developed for extraction of phthalate esters from water samples. The Fe₃O₄/meso‐SiO₂ NPs were synthesized by using a combination of hydrothermal method and sol‐gel method. The obtained Fe₃O₄/meso‐SiO₂ NPs possessed a large surface area (570 m²/g), superparamagnetism, and uniform mesopores (2.8 nm). MHSPE parameters, such as the amount of surfactant, pH of sample, shaking and separation time, eluent and breakthrough volume that may influence the extraction of analytes greatly, were further investigated. Under the optimized conditions, the extraction was completed in 20 min and a concentration factor of 500 was achieved by extracting 250 mL water sample. Detection limits obtained of butyl‐benzyl phthalate (BBP), di‐n‐butyl phthalate (DnBP), di‐(2‐ethylhexyl) phthalate (DEHP) and di‐n‐cotyl phthalate (DnOP) were 12, 21, 12, and 32 ng/L, respectively. The proposed method exhibited high extraction efficiency and relatively short time for extracting the target compounds.     

Application of magnetized MOF‐74 to phthalate esters extraction from Chinese liquor

In this study, magnetized MOF‐74 (Ni) was prepared using an ultrasound‐assisted synthesis method. This novel functional magnetic adsorbent was characterized using various techniques. Using the prepared material as adsorbents, a magnetic solid‐phase extraction method coupled with high‐performance liquid chromatography was proposed for determining four phthalate esters in Chinese liquor samples. The extraction parameters, including solution pH, adsorbent amount, extraction time, and eluent type and volume, were optimized. Under the optimized conditions, proposed method showed good linearity within the range of 1.53–200 μg/L for diphenyl phthalate, 2.03–200 μg/L for butyl benzyl phthalate, 7.02–200 μg/L for diamyl phthalate, and 6.03–200 μg/L for dicyclohexyl phthalate, with correlation coefficients > 0.9944, low limits of detection (0.46–2.10 μg/L, S/N = 3), and good extraction repeatability (relative standard deviations of 3.7%, n = 6). This method was successfully used to analyze phthalate esters in Chinese liquor samples with recoveries of 74.4–104.8%. Two phthalate esters were detected in two samples, both at concentrations that satisfied the Chinese national standard, indicating this method has practical application prospects. The extraction efficiency of this method was also compared with conventional solid‐phase extraction using commercial C₁₈ cartridges. The results demonstrated that the proposed magnetic solid‐phase extraction is a simple, time‐saving, efficient, and low‐cost method.     

Application of magnetic graphitic carbon nitride nanocomposites for the solid‐phase extraction of phthalate esters in water samples

Magnetic graphitic carbon nitride nanocomposites were successfully prepared in situ and used to develop a highly sensitive magnetic solid‐phase extraction method for the preconcentration of phthalate esters such as di‐n‐butyl phthalate, butyl phthalate, dihexyl phthalate, and di‐(2‐ethyl hexyl) phthalate from water. The adsorption and desorption of the phthalate esters on magnetic graphitic carbon nitride nanocomposites were investigated and the parameters affecting the partition of the phthalate esters, such as adsorption, desorption, recovery, were assessed. Under the optimized conditions, the proposed method showed excellent sensitivity with limits of detection (S/N = 3) in the range of 0.05–0.1 μg/L and precision in the range of 1.1–2.6% (n = 5). This method was successfully applied to the analysis of real water samples, and good spiked recoveries over the range of 79.4–99.4% were obtained. This research provides a possibility to apply this nanocomposite for adsorption, preconcentration, or even removal of various carbon‐based ring or hydrophobic pollutants.     

Solid‐phase extraction based on chloromethylated polystyrene magnetic nanospheres followed by gas chromatography with mass spectrometry to determine phthalate esters in beverages

An ultrasound‐assisted magnetic solid‐phase extraction procedure with chloromethylated polystyrene‐coated Fe₃O₄ nanospheres as magnetic adsorbents has been developed to determine eight phthalate esters (bis(4‐methyl‐2‐pentyl) phthalate, dipentyl phthalate, dihexyl phthalate, benzyl butyl phthalate, bis(2‐butoxyethyl) phthalate, dicyclohexyl phthalate, di‐n‐octyl phthalate, and dinonyl phthalate) simultaneously in beverage samples, in combination with gas chromatography coupled to tandem mass spectrometry for the first time. Several factors related to magnetic solid‐phase extraction efficiencies, such as amount of adsorbent, extracting time, ionic strength, and desorption conditions were investigated. The enrichment factors of the method for the eight analytes were over 2482. A good linearity was observed in the range of 10–500 ng/L for bis(2‐butoxyethyl) phthalate and 2–500 ng/L for the other phthalate esters with correlation coefficients ranging from 0.9980 to 0.9998. The limits of detection and quantification for the eight phthalate esters were in the range of 0.20–2.90 and 0.67–9.67 ng/L, respectively. The mean recoveries at three spiked levels were 75.8–117.7%, the coefficients of variations were <11.6%. The proposed method was demonstrated to be a simple and efficient technique for the trace analysis of the phthalate esters in beverage samples.     

A porous carbon derived from amino‐functionalized material of Institut Lavoisier as a solid‐phase microextraction fiber coating for the extraction of phthalate esters from tea

In this work, a porous carbon derived from amino‐functionalized material of Institut Lavoisier (C‐NH₂‐MIL‐125) was prepared and coated onto a stainless‐steel wire through sol–gel technique. The coated fiber was used for the solid‐phase microextraction of trace levels of phthalate esters (diallyl phthalate, di‐iso‐butyl ortho‐phthalate, di‐n‐butyl ortho‐phthalate, benzyl‐n‐butyl ortho‐phthalate, and bis(2‐ethylhexy) ortho‐phthalate) from tea beverage samples before gas chromatography with mass spectrometric analysis. Several experimental parameters that could influence the extraction efficiency such as extraction time, extraction temperature, sample pH, sample salinity, stirring rate, desorption temperature and desorption time, were investigated. Under the optimal conditions, the linearity existed in the range of 0.05–30.00 μg/L for green jasmine tea beverage samples, and 0.10–30.00 μg/L for honey jasmine tea beverage samples, with the correlation coefficients (r) ranging from 0.9939 to 0.9981. The limits of detection of the analytes for the method were 2.0–3.0 ng/L for green jasmine tea beverage sample, and 4.0–5.0 ng/L for honey jasmine tea beverage sample, depending on the compounds. The recoveries of the analytes for the spiked samples were in the range of 82.0–106.0%, and the precision, expressed as the relative standard deviations, was less than 11.1%.     

基于PA6纳米纤维膜固相萃取-液相色谱法检测牛奶中的邻苯二甲酸酯

采用静电纺丝法制备了聚酰胺6(PA6)纳米纤维膜, 结合固相萃取技术-液相色谱法(HPLC-UV)检测了市售牛奶样品中的6种邻苯二甲酸酯(PAEs)的含量. 对影响实验的各种因素, 如提取溶剂的种类及用量、超声时间、洗脱溶剂的种类及用量、纳米纤维膜的用量、pH及过样速度等进行了考察. 在最优化条件下, 邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸丁基苄酯(BBP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二(2-乙基己)酯(DEHP)和邻苯二甲酸二正辛酯(DOP)的检出限分别为0.02, 0.01, 0.05, 0.05, 0.10和0.25 ng/mL. 将该方法应用于不同品牌不同包装牛奶样品的检测, 只需2.5 mg PA6纳米纤维膜, 即可完全萃取样品中的PAEs, 相对标准偏差(RSD)小于5.82%, 回收率为93.40%~104.83%. 该方法测定牛奶中PAEs环境雌激素, 检出限低, 灵敏度高, 结果准确可靠, 重现性好.     

Simultaneous determination of 22 phthalate esters in polystyrene food‐contact materials by ultra‐performance convergence chromatography with tandem mass spectrometry

A method for the determination of 22 phthalate esters in polystyrene food‐contact materials has been established using ultraperformance convergence chromatography with tandem mass spectrometry. In this method, 22 phthalate esters were analyzed in <3.5 min on an ACQUITY Tours 1‐AA column by gradient elution. The mobile phase, the compensation solvent, the flow rate of mobile phase, column temperature, and automatic back pressure regulator pressure were optimized, respectively. There was a good linearity of 20 phthalate esters with a range of 0.05–10 mg/L, diisodecyl phthalate and diisononyl phthalate were 0.25–10 mg/L, and the correlation coefficients of all phthalates were higher than 0.99 and those of 16 phthalates were higher than 0.999. The limits of detection and the limits of quantification of 15 phthalates were 0.02 and 0.05 mg/kg, meanwhile diallyl phthalate, diisobutyl phthalate, dimethyl phthalate, di‐n‐butyl phthalate, and di(2‐ethylhexyl) phthalate were 0.05 and 0.10 mg/kg, and diisodecyl phthalate and diisononyl phthalate were 0.10 and 0.25 mg/kg. The spiked recoveries were in the range of 76.26–107.76%, and the relative standard deviations were in the range of 1.78–12.10%. Results support this method as an efficient alternative to apply for the simultaneous determination of 22 phthalate esters in common polystyrene food‐contact materials.     

Simultaneous determination of seven phthalic acid esters in beverages using ultrasound and vortex‐assisted dispersive liquid–liquid microextraction followed by high‐performance liquid chromatography

A sensitive, rapid, and simple high‐performance liquid chromatography with UV detection method was developed for the simultaneous determination of seven phthalic acid esters (dimethyl phthalate, dipropyl phthalate, di‐n‐butyl phthalate, benzyl butyl phthalate, dicyclohexyl phthalate, di‐(2‐ethylhexyl) phthalate, and di‐n‐octyl phthalate) in several kinds of beverage samples. Ultrasound and vortex‐assisted dispersive liquid–liquid microextraction method was used. The separation was performed using an Intersil ODS‐3 column (C₁₈, 250 × 4.6 mm, 5.0 μm) and a gradient elution with a mobile phase consisting of MeOH/ACN (50:50) and 0.2 M KH₂PO₄ buffer. Analytes were detected by a UV detector at 230 nm. The developed method was validated in terms of linearity, limit of detection, limit of quantification, repeatability, accuracy, and recovery. Calibration equations and correlation coefficients (> 0.99) were calculated by least squares method with weighting factor. The limit of detection and quantification were in the range of 0.019–0.208 and 0.072–0.483 μg/L. The repeatability and intermediate precision were determined in terms of relative standard deviation to be within 0.03–3.93 and 0.02–4.74%, respectively. The accuracy was found to be in the range of –14.55 to 15.57% in terms of relative error. Seventeen different beverage samples in plastic bottles were successfully analyzed, and ten of them were found to be contaminated by different phthalic acid esters.     

Determination of phthalate esters in soil by microemulsion electrokinetic chromatography coupled with accelerated solvent extraction

A novel method using microemulsion electrokinetic chromatography combining accelerated solvent extraction was developed for quantitative analysis of six phthalate esters (PAEs) including dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate, as well as dioctyl phthalate. The effect of each individual component within the microemulsions, i.e. oil phase, surfactant and co-surfactant on resolution of the analytes was systematically studied. Baseline separation of six PAEs was achieved within 26?min by using the microemulsion buffer containing a 60?mmol/L borate buffer at pH 9.0, 0.5% v/v n-octane as oil droplets, 100?mmol/L sodium cholate as surfactant and 5.0% v/v 1-butanol as co-surfactant. The purposed accelerated solvent extraction-microemulsion electrokinetic chromatography method was successfully applied to the determination of trace amount of PAEs in soil samples collected from three different fields in areas of Fujian Province and the contents of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate and dioctyl phthalate were 0.63-0.68, 0.32-0.63, 2.53-3.96, 0-1.75, 7.32-11.7 and 0-3.46mg/kg, respectively. It was validated that the results were consistent with those obtained by GC-MS method.     

Determination of phthalates in beverages using multiwalled carbon nanotubes dispersive solid‐phase extraction before HPLC–MS

A microdispersive solid‐phase extraction method has been developed using multiwalled carbon nanotubes of 110–170 nm diameter and 5–9 μm length for the extraction of a group of nine phthalic acid esters (i.e., bis(2‐methoxyethyl) phthalate, bis‐2‐ethoxyethyl phthalate, dipropyl phthalate, butylbenzyl phthalate, bis‐2‐n‐butoxyethyl phthalate, bis‐isopentyl phthalate, bis‐n‐pentyl phthalate, dicyclohexyl phthalate, and di‐n‐octyl phthalate) from tap water as well as from different beverages commercialized in plastic bottles (mineral water, lemon‐ and apple‐flavored mineral water, and an isotonic drink). Determination was carried out by high‐performance liquid chromatography coupled to mass spectrometry. The extraction procedure was optimized following a step‐by‐step approach, being the optimum extraction conditions: 50 mL of each sample at pH 6.0, 80 mg of sorbent, and 25 mL of acetonitrile as elution solvent. To validate the methodology, matrix‐matched calibration and a recovery study were developed, obtaining determination coefficients >0.9906 and absolute recovery values between 70 and 117% (with relative standard deviations < 17%) in all cases. The limits of quantification of the method were between 0.173 and 1.45 μg/L. After the evaluation of the matrix effects, real samples were also analyzed, finding butylbenzyl phthalate in all samples (except in apple‐flavored mineral water), though at concentrations below its limit of quantification of the method.     

超高效液相色谱法测定香型中性笔墨水中10种PAEs

建立超高效液相色谱–二极管阵列检测器测定香型中性笔墨水中邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二正丙酯(DPP)、邻苯二甲酸丁基苄酯(BBP)、邻苯二甲酸二正丁酯(DBP)、邻苯二甲酸二正戊酯(DAP)、邻苯二甲酸二环己酯(DCHP)、邻苯二甲酸二正己酯(DHP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)和邻苯二甲酸二正辛酯(DNOP)10种邻苯二甲酸酯(PAEs)的方法。样品采用甲醇涡旋超声提取,色谱柱为Waters ACQUITY UPLC BEH C_(18)柱(100 mm×2.1 mm,1.7μm),以乙腈–水为流动相进行梯度洗脱,用PDA检测器检测,10 min内完成10种邻苯二甲酸酯的检测。10种邻苯二甲酸酯的质量浓度在5.0~200.0 mg/L范围内与其色谱峰面积呈良好的线性关系,线性相关系数均大于0.999,检出限为3.2~4.0 mg/kg;在高低两个添加水平下,10种邻苯二甲酸酯的回收率为96.3%~104.1%,测定结果相对标准偏差为0.1%~2.9%(n=6)。该方法样品处理简单,提取效率高,分离效果好,且灵敏度高,能快速准确测定香型中性笔墨水中10种邻苯二甲酸酯。     

Determination of Phthalate Esters in Textiles by Solid Phase Extraction and Gas Chromatography–Mass Spectrometry

A sensitive and rapid method was developed for the determination of seven phthalate esters in baby waterproof fabrics, decorated waterproof tarpaulins, and printed textiles by solid phase extraction followed by gas chromatography–mass spectrometry. The method showed good linearity with correlation coefficients between 0.9958 and 0.9999 and limits of quantification and detection from 23 to 274 micrograms per liter and 7 to 82 micrograms per liter, respectively. The maximum recoveries were between 96.2 and 100.9 percent with relative standard deviations from 1.06 to 6.87 percent. The protocol was applied to the determination of phthalate esters in textiles: the samples contained more than 0.1 percent phthalate esters, which exceed relevant standards.     

Nanostructured gemini‐based supramolecular solvent coupled with ultrasound‐assisted back extraction as a preconcentration step before GC–MS

Liquid‐phase microextraction based on gemini‐based supramolecular solvent was successfully applied as a preconcentration step before gas chromatography with mass spectrometry. To eliminate the interferences of gemini surfactant, the analytes were back‐extracted into an immiscible organic solvent in the presence of ultrasonic sound waves. Three phthalate esters (di‐n‐butyl‐, butylbenzyl‐, bis(2‐ethylhexyl)‐, and di‐n‐octyl phthalatic esters) were used as target analytes. The effective parameters on extraction efficiency of the target analytes (i.e., the amount of surfactant and volume of propanol as major components making up the supramolecular solvent, ionic strength, hexane volume, and ultrasound time) were investigated and optimized by a one‐variable‐at‐a‐time method. Under the optimum conditions, the preconcentration factors of the analytes were in the range of 95–182. The linear dynamic range of 0.05–200.00 μg/L with a correlation of determination of (R ²) ≥ 0.9935 was obtained. The proposed method had an excellent limit of detection (S/N = 3) of 0.01 for di‐n‐octyl and 0.02 μg/L for butylbenzyl‐ and di‐n‐butyl‐phthalatic ester. Good relative recoveries in the range of 85.7–105.2% guaranteed the accuracy of the amount of phthalates distinguished in the nonspiked samples.     

Simultaneous determination of 17 phthalate esters in edible vegetable oils by GC‐MS with silica/PSA‐mixed solid‐phase extraction

A quantified method for the determination of 17 phthalate esters (PAEs) in edible vegetable oil by GC‐MS with the pretreatment of acetonitrile extraction and silica/N‐(n‐Propyl)ethylenediamine‐mixed SPE column was established. By the quantification of internal standard of D₄‐di(2‐ethylhexyl) phthalate, a good linearity range of related 17 PAEs was observed. The correlation coefficient was ranged at 0.994～1.000, and the standard lowest quantified level was 0.05～0.15 mg/L. The spiking recoveries of 17 PAEs were 78.3～108.9% with the relative standard deviations of 4.3～12.1% (n = 6). The method detection limits were 0.1～0.2 mg/kg. Meanwhile, PAEs were determined in 30 plastic buckets of edible vegetable oil from supermarkets in Hangzhou city of China. The survey of 30 oil samples showed di(2‐ethylhexyl) phthalate (DEHP) had the 100% (30/30) detection rate. The levels of diisobutyl phthalate with 86.7% (26:30), di‐n‐butyl phthalate (DBP) with 70% (21:30) and diethyl phthalate with 10% (3:30) were detected. It was worth note that DBP with 16.7% (5:30) samples and DEHP with 10% (3:30) samples were beyond the regular migrating limit, which indicated that more attention should be paid to the PAEs in oil with plastic package.     

Simultaneous determination of five phthalate esters and bisphenol A in milk by packed‐nanofiber solid‐phase extraction coupled with gas chromatography and mass spectrometry

A novel polystyrene/pyridine composite nanofiber was synthesized and utilized as the sorbent material for the solid‐phase extraction of bisphenol A and five common phthalate esters in milk. The method of extraction integrated extraction and preconcentration of target analytes into a single step. Bisphenol A and five common phthalate esters were selected as target compounds for the development and evaluation of the method. The effects of operating parameters for nanofiber‐based solid‐phase extraction, such as selection and amount of sorbent, the volume fraction of perchlorate (precipitate protein), desorption solvent, volume of desorption solvent, and effect of salt addition were optimized. Under optimal conditions, higher extraction recoveries (89.6–118.0%) of the six compounds in milk spiked at three levels were obtained, and the satisfied relative standard deviation were ranged from 0.6 to 10.9%. The detection limits and quantification limits of the method ranged from 0.01 to 0.06 μg/L and 0.05 to 0.53 μg/L, respectively. Matrix effects were also verified and well controlled in the range of 91.3–109.3%. The new method gave better performance metrics than Chinese standard method and other published methods. Thus, the proposed method may be applied to the analysis of the phthalate esters and bisphenol A in complex matrixes.     

Microwave‐assisted preparation of poly(ionic liquids)‐modified polystyrene magnetic nanospheres for phthalate esters extraction from beverages

The fabrication of novel poly(ionic liquids)‐modified polystyrene (PSt) magnetic nanospheres (PILs‐PMNPs) by a one‐pot miniemulsion copolymerization reaction was achieved through an efficient microwave‐assisted synthesis method. The morphology, structure, and magnetic behavior of the as‐prepared magnetic materials were characterized by using transmission electron microscopy, vibrating sample magnetometry, etc. The magnetic materials were utilized as sorbents for the extraction of phthalate esters (PAEs) from beverage samples followed by high‐performance ultrafast liquid chromatography analysis. Significant extraction parameters that could affect the extraction efficiencies were investigated particularly. Under optimum conditions, good linearity was obtained in the concentration range of 0.5–50 (dimethyl phthalate), 0.3–50 (diethyl phthalate), 0.2–50 (butyl benzyl phthalate), and 0.4–50 μg/L (di‐n‐butyl phthalate), with correlation coefficients R ² > 0.9989. Limits of detection were in the range 125–350 pg. The proposed method was successfully applied to determine PAEs from beverage samples with satisfactory recovery ranging from 77.8 to 102.1% and relative standard deviations ranging from 3.7 to 8.4%. Comparisons of extraction efficiency with PSt‐modified MNPs as sorbents were performed. The results demonstrated that PILs‐PMNPs possessed an excellent adsorption capability toward the trace PAE analytes.     

Study on the Solid Phase Extraction of Hg(II)‐ABR Chelate with C18 Disks and its Application to the Determination of Mercury in Tobacco and Tobacco Additives

A highly sensitive, selective and rapid method for the determination of mercury based on the rapid reaction of mercury(II) with 5‐(p‐aminobenzylidene)‐rhodanine (ABR) and the solid phase extraction of the colored chelate with C₁₈ disks has been developed. In the presence of pH = 3.5 sodium acetate‐acetic acid buffer solution and Emulsifier‐OP medium, ABR reacts with mercury(II) to form a red chelate of a molar ratio 1:2 (mercury to ABR). This chelate was enriched by the solid phase extraction with C₁₈ disks and eluted the retained chelate from the disks with dimethyl formamide (DMF). The enrichment factor of 50 was achieved. In the DMF medium, the molar absorptivity of the chelate is 1.16 × 10⁵ L.mol^?1.cm^?1 at 540 nm. Beer's law is obeyed in the range of 0.01?3 μg/mL in the measured solution. The relative standard deviation for eleven replicated samples of 0.01 μg/mL level is 1.83%. This method was applied to the determination of mercury in tobacco and tobacco additives with good results.