Determination of estrone and 17α‐ethinylestradiol in digested sludge by ultrasonic liquid extraction and high‐performance liquid chromatography with fluorescence detection

Estrone, 17β‐estradiol and 17α‐ethinylestradiol are increasingly recognised as important micropollutants to be monitored in wastewater treatment plants. These estrogens are retained onto sludge due to their high adsorption and since they are largely used in land applications, the monitoring of these chemicals in sludge samples is of great importance. This study describes a method for the determination of estrone and 17α‐ethinylestradiol in fresh sludge samples. After spiking fresh digested sludge with estrone and 17α‐ethinylestradiol and maintaining in contact during 5, 30 and 60 min, the freeze‐dried samples were subjected to ultrasonic liquid extraction, with methanol and acetone, and analysed by high‐performance liquid chromatography with fluorescence detection. The average recoveries obtained for estrone and 17α‐ethinylestradiol using the different contact times were 103 ± 3 and 97 ± 4%, respectively. Fresh sludge samples from one waste water treatment plant located in Portugal were analysed and estrone was detected in primary fresh sludge, anaerobic digested sludge and dehydrated sludge at a concentration in the range of 1–4.8 μg/g. The method here developed does not require any sample clean‐up, being fast and simple, reliable and inexpensive, making possible its application for monitoring the contamination of sludge with these estrogens.     

Bulk derivatization and direct injection of human cerebrospinal fluid for trace‐level quantification of endogenous estrogens using trap‐and‐elute liquid chromatography with tandem mass spectrometry

Although there are existing methods for determining estrogen in human bodily fluids including blood plasma and serum, very little information is available regarding estrogen levels in human cerebrospinal fluid (CSF), which is critical to assess in studies of neuroprotective functions and diffusion of neuroprotective estrogens across the blood–brain barrier. To address this problem, a liquid chromatography with tandem mass spectrometry method for the simultaneous quantification of four endogenous estrogens (estrone, 17α‐estradiol, 17β‐estradiol, and estriol) in human CSF was developed. An aliquot (300 μL) of human CSF was bulk derivatized using dansyl chloride in the sample and 10 μL was directly injected onto a restricted‐access media trap column for protein removal. No off‐line sample extraction or cleanup was needed. The limits of detection of estrone, 17α‐estradiol, 17β‐estradiol, and estriol were 17, 28, 13, and 30 pg/mL, respectively, which is in the parts‐per‐trillion regime. The method was then applied to human CSF collected from ischemic trauma patients. Endogenous estrogens were detected and quantified, demonstrating the effectiveness of this method.     

Isolation and determination of estrogens in water samples by solid‐phase extraction using molecularly imprinted polymers and HPLC

Advanced SPE with molecularly imprinted polymers (MIP) was used in this study. A noncovalent imprinting approach was applied to separate 17β‐estradiol, estriol, and estrone from water samples. Polymer material was prepared by bulk polymerization with methacrylic acid as a functional monomer, divinylbenzene and ethyleneglycol dimethacrylate as crosslinkers, and acetonitrile, acetonitrile/toluene (3:1, v/v) or isooctane/toluene (1:99, v/v) as a porogen. We also prepared an MIP film on a silica gel surface with methacrylic acid and ethyleneglycol dimethacrylate as monomers and acetonitrile as a solvent. Qualitative and quantitative hormone analyses were carried out by HPLC with various detection techniques, including UV/visible spectroscopic detection (diode array detection) and electrochemical detection (CoulArray). The results of the study indicate that MIP technology is an excellent method for the quality control of estrogens in environmental analyses with a low quantification limit for 17β‐estradiol of around 26 (diode array detection) and 0.25 ng/mL (electrochemical detection). The proposed method was found to be suitable for routine determinations of the analyzed compound in environmental laboratories.     

Automated solid‐phase extraction of phenolic acids using layered double hydroxide–alumina–polymer disks

The application of layered double hydroxide–Al₂O₃–polymer mixed‐matrix disks for solid‐phase extraction is reported for the first time. Al₂O₃ is embedded in a polymer matrix followed by an in situ metal‐exchange process to obtain a layered double hydroxide–Al₂O₃–polymer mixed‐matrix disk with excellent flow‐through properties. The extraction performance of the prepared disks is evaluated as a proof of concept for the automated extraction using sequential injection analysis of organic acids (p‐hydroxybenzoic acid, 3,4‐dihydroxybenzoic acid, gallic acid) following an anion‐exchange mechanism. After the solid‐phase extraction, phenolic acids were quantified by reversed‐phase high‐performance liquid chromatography with diode‐array detection using a core–shell silica–C18 stationary phase and isocratic elution (acetonitrile/0.5% acetic acid in pure water, 5:95, v/v). High sensitivity and reproducibility were obtained with limits of detection in the range of 0.12–0.25 μg/L (sample volume, 4 mL), and relative standard deviations between 2.9 and 3.4% (10 μg/L, n = 6). Enrichment factors of 34–39 were obtained. Layered double hydroxide–Al₂O₃–polymer mixed‐matrix disks had an average lifetime of 50 extractions. Analyte recoveries ranged from 93 to 96% for grape juice and nonalcoholic beer samples.     

Detection of L‐phenylalanine using molecularly imprinted solid‐phase extraction and flow injection electrochemiluminescence

A novel flow injection electrochemiluminescence method combined with molecularly imprinted solid‐phase extraction was developed for the determination of L ‐phenylalanine, in which was used as the luminophor and indium tin oxide glass was modified as the working electrode. Molecularly imprinted polymers, synthesized by self‐assembly with functional monomer and crossing linker, were used for the selective extraction of L ‐phenylalanine. In order to overcome the drawbacks of traditional electrochemiluminescence cells such as high IR drop, high over‐potential and so on, a novel electrochemiluminescence cell was developed. The enhanced electrochemiluminescence intensity was linearly related with the concentration of L ‐phenylalanine in the range from 1.0×10^?7 to 5.0×10^?5 g/mL with a detection limit of 2.59×10^?8 g/mL. The relative standard deviation for the determination of 1.0×10^?6 g/mL L ‐phenylalanine was 1.2% (n=11). The method showed higher sensitivity and good repeatability, and was successfully applied for the determination of L ‐phenylalanine in egg white, chicken and serum samples. A possible mechanism for the enhanced electrochemiluminescence response on indium tin oxide glass is proposed.     

Functionalized nanoparticles based solid‐phase membrane micro‐tip extraction and high‐performance liquid chromatography analyses of vitamin B complex in human plasma

Iron nanoparticles were prepared by a green method following functionalization using 1‐butyl‐3‐methylimidazolium bromide. 1‐Butyl‐3‐methylimidazole iron nanoparticles were characterized using FTIR spectroscopy, energy dispersive X‐ray fluorescence, X‐ray diffraction, scanning electron microscopy and transmission electron microscopy. The nanoparticles were used in solid‐phase membrane micro‐tip extraction to separate vitamin B complex from plasma before high‐performance liquid chromatography. The optimum conditions obtained were sorbent (15 mg), agitation time (30 min), pH (9.0), desorbing solvent [water (5 mL) + methanol (5 mL) + sodium hydroxide (0.1 N) + acetic acid (d = 1.05 kg/L, pH 5.5), desorbing volume (10 mL) and desorption time (30 min). The percentage recoveries of all the eight vitamin B complex were from 60 to 83%. A high‐performance liquid chromatography method was developed using a PhE column (250 × 4.6 mm, 5.0 μm) and water/acetonitrile (95:5, v/v; pH 4.0 with 0.1% formic acid) mobile phase. The flow rate was 1.0 mL/min with detection at 270 and 210 nm. The values of the capacity, separation and resolution factor were 0.57–39.47, 1.12–6.00 and 1.84–26.26, respectively. The developed sample preparation and chromatographic methods were fast, selective, inexpensive, economic and reproducible. The developed method can be applied for analyzing these drugs in biological and environmental matrices.     

Determination of strobilurin fungicides in cotton seed by combination of acetonitrile extraction and dispersive liquid−liquid microextraction coupled with gas chromatography

The simultaneous determination of four strobilurin fungicides (picoxystrobin, kresoxim‐methyl, trifloxystrobin, and azoxystrobin) in cotton seed by combining acetonitrile extraction and dispersive liquid?liquid microextraction was developed prior to GC with electron capture detection. Several factors, including the type and volume of the extraction and dispersive solvents, extraction condition and time, and salt addition, were optimized. The analytes were extracted with acetonitrile from cotton seed and the clean‐up was carried out by primary secondary amine. Afterwards, 60 μL of n‐hexane/toluene (1:1, v/v) with a lower density than water was mixed with 1 mL of the acetonitrile extract, then the mixture was injected into 7 mL of distilled water. A 0.1 mL pipette was used to collect a few microliters of n‐hexane/toluene from the top of the aqueous solution. The enrichment factors of the analytes ranged from 36 to 67. The LODs were in the range of 0.1 × 10^?3?2 × 10^?3 mg/kg. The relative recoveries varied from 87.7 to 95.2% with RSDs of 4.1?8.5% for the four fungicides. The good performance of the method, compared with the conventional pretreatments, has demonstrated it is suitable for determining low concentrations of strobilurin fungicide residues in cotton seed.     

Determination of estrogens in environmental water samples using 1,3‐dipentylimidazolium hexafluorophosphate ionic liquid as extraction solvent in dispersive liquid–liquid microextraction

In this work, the potential of a symmetric dialkyl‐substituted ionic liquid (IL), 1,3‐dipenthylimidazolium hexafluorophosphate ([PPIm][PF₆]), as extraction solvent in dispersive liquid–liquid microextraction (DLLME) has been studied for the analysis of a group of three natural (estriol, 17β‐estradiol, and 17α‐estradiol) and four synthetic (17α‐ethynylestradiol, diethylstibestrol, dienestrol, and hexestrol) estrogenic compounds as well as one mycotoxin with estrogenic activity (zearalenone) in different types of water samples (Milli‐Q, mineral, and wastewater). Separation, determination, and quantification were developed by HPLC‐DAD and a fluorescence detector (FD) connected in series. Factors influencing the IL‐DLLME procedure (sample pH, amount of IL, type and volume of disperser solvent, ionic strength, and assistance of vortex agitation) were investigated and optimized by means of a step‐by‐step approach. Once the optimum extraction conditions were established (10 mL of water at pH 8, 60 mg of [PPIm][PF₆], 500 μL of ACN as disperser solvent and vortex agitation for 1 min), the calibration curves of the whole method (IL‐DLLME‐HPLC‐DAD/FD) were obtained and precision and accuracy were evaluated. It was demonstrated that the developed methodology was repeatable, accurate, and selective with limits of detection in the 0.30–0.57 μg/L and 13.8–37.1 μg/L range for FD and DAD, respectively. Relative recovery values were higher than 85% for the different types of water samples and the Student's t test demonstrated that there were not significant differences between the added and the found concentration.     

高效液相色谱-串联质谱法测定饲料和卧床土中的环境雌激素

建立了饲料和卧床土中雌三醇、雌二醇、雌酮、双酚A和己烯雌酚5种环境雌激素的固相萃取结合高效液相色谱-串联质谱(HPLC-MS/MS)测定方法。对色谱流动相、质谱条件、固相萃取柱等影响因素进行了优化,得到的最优化条件为:样品经乙腈提取后,用固相萃取柱(NH₂-SPE)进行富集,采用Acquity UPLC^TM HSS T₃色谱柱分离,以乙腈-甲醇(4:1, v/v)与0.01%氨水为流动相,采用梯度洗脱,在负离子模式下进行MS/MS测定。在该优化条件下,5种环境雌激素的检出限(以信噪比为3计)为0.06~0.22 μg/kg,回收率为81.70%~102.20%,相对标准偏差小于10.00%。该方法用于饲料和卧床土中的5种环境雌激素残留量的测定具有简便、快速、灵敏的特点。     

Quantitative determination of risperidone,paliperidone and olanzapine in human serum by liquid chromatography–tandem mass spectrometry coupled with on‐line solid‐phase extraction

A recent guideline recommends therapeutic drug monitoring for risperidone, paliperidone and olanzapine, which are frequently used second‐generation antipsychotics. We developed a simple high‐performance liquid chromatography–tandem mass spectrometry coupled with an online solid‐phase extraction method that can be used to measure risperidone, paliperidone and olanzapine using small (40 μL) samples. The analytes were extracted from serum samples automatically pre‐concentrated and purified by C₈ (5 μm, 2.1 × 30 mm) solid‐phase extraction cartridges, then chromatographed on an Xbidge™ C₁₈ column (3.5 μm, 100 × 2.1 mm) thermostatted at 30°C with a mobile phase consisting of 70% acetonitrile and 30% ammonium hydroxide 1% solution at an isocratic flow rate of 0.3 mL/min, and detected with tandem mass spectrometry. The assay was validated in the concentration range from 2.5 to 160 ng/mL. Intra‐ and inter‐day precision for all analytes was between 1.1 and 8.2%; method accuracy was between 6.6 and 7.6%. The risperidone and paliperidone assay was compared with a high‐performance liquid chromatography‐ultraviolet assay currently used in our hospital for risperidone and paliperidone therapeutic drug monitoring, and the results of weighted Deming regression analysis showed good agreement. For the olanzapine assay, we compared 20 samples in separate re‐assays on different days; all the relative errors were within the 20% recommended limit.     

Automatic on‐line solid‐phase extraction with ultra‐high performance liquid chromatography and tandem mass spectrometry for the determination of ten antipsychotics in human plasma

An automatic on‐line solid‐phase extraction with ultra‐high performance liquid chromatography and tandem mass spectrometry method was developed for the simultaneous determination of ten antipsychotics in human plasma. The plasma sample after filtration was injected directly into the system without any pretreatment. A Shim‐pack MAYI‐C₈ (G) column was used as a solid‐phase extraction column, and all the analytes were separated on a Shim‐pack XR‐ODS III column with a mobile phase consisting of 0.1% v/v formic acid in water with 5 mM ammonium acetate and acetonitrile. The method features were systematically investigated, including extraction conditions, desorption conditions, the equilibration solution, the valve switching time, and the dilution for column‐head stacking. Under the optimized conditions, the whole analysis procedure took only 10 min. The limits of quantitation were in the range of 0.00321–2.75 μg/L and the recoveries ranged from 75.9 to 122%. Compared with the off‐line ultra‐high performance liquid chromatography and the reported methods, this validated on‐line method showed significant advantages such as minimal pretreatment, shortest analysis time, and highest sensitivity. The results indicated that this automatic on‐line method was rapid, sensitive, and reliable for the determination of antipsychotics in plasma and could be extended to other target analytes in biological samples.     

Ultra‐trace analysis of furanic compounds in transformer/rectifier oils with water extraction and high‐performance liquid chromatography

A novel approach for the determination of parts‐per‐billion level of 5‐hydroxymethyl‐2‐furaldehyde, furfuryl alcohol, furfural, 2‐furyl methyl ketone, and 5‐methylfurfural in transformer or rectifier oils has been successfully innovated and implemented. Various extraction methods including solid‐phase extraction, liquid–liquid extraction using methanol, acetonitrile, and water were studied. Water was by far the most efficient solvent for use as an extraction medium. Separation of the analytes was conducted using a 4.6 mm × 250 mm × 3.5 μm Agilent Zorbax column while detection and quantitation were conducted with a variable wavelength UV detector. Detection limits of all furans were at 1 ppb v/v with linear ranges range from 5 to 1000 ppb v/v with correlation coefficients of 0.997 or better. A relative standard deviation of at most 2.4% at 1000 ppb v/v and 7.3% at 5 ppb v/v and a recovery from 43% to 90% depending on the analyte monitored were obtained. The method was purposely designed to be environmental friendly with water as an extraction medium. Also, the method uses 80% water and 20% acetonitrile with a mere 0.2 mL/min of acetonitrile in an acetonitrile/water mixture as mobile phase. The analytical technique has been demonstrated to be highly reliable with low cost of ownership, suitable for deployment in quality control labs or in regions where available analytical resources and solvents are difficult to procure.     

Optimization and development of a high‐performance liquid chromatography method for the simultaneous determination of vitamin E and carotenoids in tomato fruits

A simple and reliable high‐performance liquid chromatography method was developed and validated for the simultaneous determination of lipophilic antioxidants in tomato fruits using C₃₀ column operated at 15°C and a gradient mobile phase based on acetonitrile/methanol/dichloromethane in a total run time of 30 min. Diode array and fluorescence detectors were used respectively for the detection of carotenoids (lutein, zeaxanthin, cryptoxanthin, lycopene, and β‐carotene) and vitamin E analogs (α‐, β‐, γ‐, and δ‐tocopherols, and tocotrienols). The best extraction yield of analytes in tomato fruits was achieved by employing ethyl acetate/hexane (1:1, v/v) after several treatments with various solvents. In addition, low extraction yields were obtained for carotenoids compared to tocopherols by adopting solid‐phase extraction as a second clean‐up step. The method was validated on the basis of recovery, precision, linearity, and limit of detection and quantification using spiked tomato samples. The method was applied to cherry and medium‐sized tomato fruits. Lycopene was found to be present in largest amount in tomato pulp, followed by β‐carotene and lutein. Due to its simplicity, rapidity, and efficiency, the method is suitable for routine analysis of lipophilic antioxidants in tomato fruits, and may also be applied to other vegetables of similar phytochemical profiles.     

High‐performance liquid chromatography with solid‐phase extraction for the quantitative determination of nilotinib in human plasma

A simple, rapid and sensitive high‐performance liquid chromatography (HPLC)‐based method with ultraviolet detection was developed for the quantitation of nilotinib, a tyrosine kinase inhibitor, in human plasma. Nilotinib and the internal standard dasatinib were separated using a mobile phase of 0.5% KH₂PO₄ (pH2.5)–acetonitrile–methanol (55:25:20, v/v/v) on a Capcell Pak MG II column (250 × 4.6 mm) at a flow rate of 0.5 mL/min and optical measurement at 250 nm. Analysis required only 100 μL of plasma and involved a rapid and simple solid‐phase extraction with an Oasis HLB cartridge, which gave recoveries from 72 to 78% for nilotinib and from 74 to 76% for dasatinib. The lower limit of quantification for nilotinib was 10 ng/mL. The linear range of this assay was between 10 and 5000 ng/mL (r² > 0.9992 for the regression line). Intra‐ and inter‐day coefficients of variation were less than 10.0% and accuracies were within 10.4% over the linear range. Our results indicate that this method is applicable to the monitoring of plasma levels of nilotinib in a clinical setting. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of rifampicin in human plasma by high‐performance liquid chromatography coupled with ultraviolet detection after automatized solid–liquid extraction

A precise and accurate high‐performance liquid chromatography (HPLC) quantification method of rifampicin in human plasma was developed and validated using ultraviolet detection after an automatized solid‐phase extraction. The method was validated with respect to selectivity, extraction recovery, linearity, intra‐ and inter‐day precision, accuracy, lower limit of quantification and stability. Chromatographic separation was performed on a Chromolith RP₈ column using a mixture of 0.05 m acetate buffer pH 5.7–acetonitrile (35:65, v/v) as mobile phase. The compounds were detected at a wavelength of 335 nm with a lower limit of quantification of 0.05 mg/L in human plasma. Retention times for rifampicin and 6,7‐dimethyl‐2,3‐di(2‐pyridyl) quinoxaline used as internal standard were respectively 3.77 and 4.81 min. This robust and exact method was successfully applied in routine for therapeutic drug monitoring in patients treated with rifampicin.     

Simultaneous determination of 4‐hydroxyphenyl lactic acid, 4‐hydroxyphenyl acetic acid,and 3,4‐hydroxyphenyl propionic acid in human urine by ultra‐high performance liquid chromatography with fluorescence detection

A simple and reliable method was established for simultaneous determination of 4‐hydroxyphenyl acetic acid, 4‐hydroxyphenyl lactic acid, and 3,4‐hydroxyphenyl propionic acid in human urine by high‐performance liquid chromatography with fluorescence detection. Solid‐phase extraction was used to eliminate the interferences in urine. The separation of three analytes was achieved using a C₁₈ column and a mobile phase formed by a 95:5 v/v mixture of 50 mmol/L ammonium acetate buffer at pH 6.8 that contained 5 mmol/L tetrabutyl ammonium bromide and acetonitrile. Under the optimized conditions, the detection limits of 4‐hydroxyphenyl acetic acid, 4‐hydroxyphenyl lactic acid, and 3,4‐hydroxyphenyl propionic acid were 4.8 × 10⁻³, 8.80 × 10⁻³, and 9.00 × 10⁻³ mg/L, respectively, and the recoveries were in the range of 85.0–120.0% with relative standard deviations of 1.5–3.1%. This method was used to analyze urine samples from breast cancer patients, healthy people and post‐surgery breast cancer patients. Significant differences in urinary levels of 4‐hydroxyphenyl acetic acid and 4‐hydroxyphenyl lactic acid could be found between the breast cancer patients group and other two groups. No effect of age and sex was observed on the urinary levels of 4‐hydroxyphenyl acetic acid and 4‐hydroxyphenyl lactic acid. This method might be helpful for cancer biomarkers discovery in urine.     

Stacking and simultaneous determination of estrogens in water samples by CE with electrochemical detection

A rapid and sensitive method based on transient ITP and field enhancement in CE with electrochemical detection at copper disk electrode was developed for the simultaneous separation and determination of three estrogens: estrone, 17β‐estradiol, and estriol. The effects of several important factors that influence the separation and detection were investigated. Under the optimum conditions, the estrogens could be separated in 0.06 mol/L sodium hydroxide solution within 14 min. With transient ITP by addition of 0.5% NaCl, a good linear response was obtained for three estrogens from 0.2 to 10 μmol/L, with correlation coefficients higher than 0.9993. The detection limits were 8.9 × 10^?8, 6.7 × 10^?8, and 1.1 × 10^?7 mol/L (S/N = 3) for estriol, 17β‐estradiol, and estrone, respectively. This method was successfully employed to analyze different water samples from waterworks, tap water, fishpond, and river samples with recoveries in the range of 90.8–108.9%, and RSDs < 4.69%. The satisfied results demonstrated that this method was of convenient preparation, high sensitivity, and good repeatability, which could be applied to the rapid determination of environmental water samples.     

Pre‐concentration of trace amount of bisphenol A in water samples by palm leaf ash and determination with high‐performance liquid chromatography

Palm leaf ash was characterized and used as low‐cost adsorbent for solid‐phase extraction and preconcentration of bisphenol A (BPA) in real water samples. Analysis of BPA was carried out using HPLC involving Eurospher 100–5‐C₁₈ (25 cm × 4.5 mm, particle size 5 μm) column and water–acetonitrile (40:60, v/v) as mobile phase. The adsorption was achieved quantitatively at a pH of 6 with elution by 3 mL acetonitrile. The limits of detection and enrichment factor were 0.02 μg L^?1 and 333, respectively. Under optimum conditions the relative standard deviation (RSD) was 2% (n = 10). Comparison of qualification criteria of presented preconcentration procedure with other research indicated that palm leaf ash adsorbent was better than many of the adsorbents in terms of cost and reusability. Also, the limit of detection, precision and enrichment factor were comparable and even better than the previously reported methods. Finally, the efficiency of method was computed by determination of trace amounts of BPA in sea, river, mineral and tap waters with recoveries of 93.3–105.5% and RSDs of 0.61–3.12%.. Briefly, the developed solid‐phase extraction and Preparative layer chromatography (PLC) methods may be used for bisphenol A monitoring in any environmental water sample. Copyright © 2016 John Wiley & Sons, Ltd.     

Comparison of C18 silica and multi‐walled carbon nanotubes as the adsorbents for the solid‐phase extraction of Chlorpyrifos and Phosalone in water samples using HPLC

A comparison between C₁₈ silica and multi‐walled carbon nanotubes (MWCNTs) in the extraction of Chlorpyrifos and Phosalone in environmental water samples was carried out using HPLC. Parameters affecting the extraction were type and volume of elution solvent, pH and flow rate of sample through the adsorbent. The optimum conditions obtained by C₁₈ cartridge for adsorption of these pesticides were 4 mL dichloromethane as elution solvent, sample pH of 5, flow rate of 1 mL/min, and those for MWCNT cartridge were 3 mL dichloromethane, pH of 5 and flow rate of 10 mL/min, respectively. Optimized mobile phase for separation and determination of these compounds by HPLC was methanol/water (80:20 v/v) with pH=5 (adjusted with phosphate buffer). Under optimal chromatographic and SPE conditions, LOD, linear range and precision (RSD n=8) were 3.03×10^?3, 0.01–5.00 μg/mL and 2.7% for Chlorpyrifos and 4.03×10^?4, 0.01–5.00 μg/mL and 2.3% for Phosalone, in C₁₈ cartridge, respectively. These values for MWCNT were 4.02×10^?6, 0.001–0.500 μg/mL and 1.8% for Chlorpyrifos and 1.02×10^?6, 0.001–0.500 μg/mL and 1.5% for Phosalone, respectively.     

Porous carbon derived from a metal–organic framework as an efficient adsorbent for the solid‐phase extraction of phthalate esters

A porous carbon designated as MOF‐5‐C was prepared by directly carbonizing a metal–organic framework (MOF‐5). The morphology and microstructure of MOF‐5‐C were characterized by scanning electron microscopy, N₂ adsorption, and powder X‐ray diffraction. The MOF‐5‐C retained the original porous structures of MOF‐5, and showed a high Brunauer–Emmett–Teller surface area (1808 m² g^?1) and large pore volume (3.05 cm³ g^?1). To evaluate its adsorption performance, the MOF‐5‐C was used as an adsorbent for the solid‐phase extraction of four phthalate esters from bottled water, peach juice, and soft drink samples followed by high‐performance liquid chromatographic analysis. Several parameters that could affect the extraction efficiencies were investigated. Under the optimum conditions, a good linearity was achieved in the concentration range of 0.1–50.0 ng mL^?1 for bottled water sample and 0.2–50.0 ng mL^?1 for peach juice and soft drink samples. The limits of detection of the method (S/N = 3) were 0.02 ng mL^?1 for bottled water sample, and 0.04–0.05 ng mL^?1 for peach juice and soft drink samples. The results indicated that the MOF‐5‐C exhibited an excellent adsorption capability for trace levels of phthalate esters, and it could be a promising adsorbent for the preconcentration of other organic compounds.