Electromembrane extraction of highly polar bases from biological samples - Deeper insight into bis(2-ethylhexyl) phosphate as ionic carrier.

Similarly to many other sample extraction techniques, efficient extraction of very polar compounds with electromembrane extraction (EME) is difficult. To date, the best known strategy to improve the mass transfer of these compounds is the addition of an ionic carrier, often bis(2-ethylhexyl) phosphate (DEHP) to the supported liquid membrane (SLM). DEHP is known to work by providing ionic interactions with basic compounds, to improve the partitioning into the SLM. In this work, the behavior of DEHP during extractions was studied for the first time. Interestingly, substantial amounts of DEHP was found to leak from the SLM into the aqueous sample at pH > 4. Due to this leakage, the ion-pair formation between analytes and DEHP was moved from the sample/SLM interface (interfacial complexation) to the bulk of the sample solution (bulk-sample complexation), which improved the mass transfer of polar bases considerably. Based on this, an extraction procedure for eight polar bases with log P values from +0.7 to -5.9 was developed and optimized. The optimization demonstrated that extraction of more polar analytes was favored by bulk-sample complexation. With optimized conditions, extraction from biological samples such as urine, protein-precipitated plasma, and raw plasma were performed with recoveries >40%, except for a few analytes. In addition, the extraction system could be operated under robust conditions with relatively low current (<70 µA for plasma), and provided low variability (<16% RSD), as well as good clean-up efficiency. These findings are an important step in further scientific anchoring of EME, and development of the technique towards selective extraction of very polar substances from complex biological matrices.

Magnetic restricted-access carbon nanotubes for dispersive solid phase extraction of organophosphates pesticides from bovine milk samples.

Magnetic restricted-access carbon nanotubes (M-RACNTs) were synthesised and used for dispersive solid phase extraction of organophosphates (chlorpyriphos, malathion, disulfoton, pirimiphos) from commercial bovine raw milk samples. Due to their magnetic susceptibility, M-RACNTs were easily separated from the samples/solvents using a neodymium magnet, and the extracted organophosphates were analysed by gas chromatography-mass spectrometry. The protein exclusion capacity was about 100%. Kinetic and isotherm data (for M-RACNTs - malathion interaction) were adequately adjusted to the pseudo-second order and Sips models, respectively, and the maximum adsorption capacity was about 0.55 mg g-1. The method presented linear ranges from 5.0 to 40.0 µg L-1 for all analytes, with determination coefficients from 0.9902 to 0.9963. The intra-assay precisions (as relative standard deviation) and accuracies (as relative error) ranged from 10.47 to 19.85% and from -0.18 to -18.80%, respectively, whereas the inter-assay precisions ranged from 6.48 to 18.76% and from -0.22 to 19.49%, respectively for 5.0, 20.0 and 40.0 µg L-1 organophosphates levels. The organophosphates were not stable at 4 and 24 h (relative errors ranged from -39.30 to 72.07% and -69.64 to 75.95%, respectively). Limits of detection ranged from 0.36 to 0.95 µg L-1, and 5 µg L-1 was defined as the limit of quantification for all the analytes. The proposed method was applied in the determination of organophosphates in five commercial milk samples, and no pesticides were detected.

Multivariate response surface methodology assisted modified QuEChERS extraction method for the evaluation of organophosphate pesticides in fruits and vegetables cultivated in Nilgiris, South India.

An effective, simple and sensitive analytical method has been developed employing liquid chromatography coupled with tandem mass spectrometry and validated for estimation of five organophosphate pesticides at trace levels in six fruits and twelve vegetables. Plackett-Burman design and central composite design was used to screen and optimize the significant factors in modified QuEChERS (quick, easy, cheap, effective, rugged and safe) extraction method. The method evaluation was done by matrix-matched calibration with linearity ranging from 5 to 500 µg/L with a correlation coefficient more than 0.990. The detection and quantification limit ranged from 0.1 to 1.0 µg/kg and 0.5 to 5 µg/kg, respectively. The mean recoveries were in the range of 76.89-110.30 % with the relative standard deviation less than 13.26% for all pesticides. Further, the method developed was applied to analyze real samples cultivated in the hill areas of Nilgiris, South India.

Monitoring of organophosphate and pyrethroid metabolites in human urine samples by an automated method (TurboFlow™) coupled to ultra-high performance liquid chromatography-Orbitrap mass spectrometry.

There is a growing concern to pesticide exposure in humans, being the organophosphate (OP), carbamate and pyrethroid the most commonly used insecticides. Therefore, a fast, simple and automated screening method based on ultra-high performance liquid chromatography coupled to Orbitrap high resolution mass spectrometry (UHPLC-Orbitrap-MS) has been developed to determine six OPs metabolites (3,5,6-trichloro-2-pyridinol "TCPy", 2-isopropyl-6-methyl-4-pyrimidinol "IMPY", 4-nitrophenol "PNP", 4-nitrophenol-d4 "PNP-d4″, 3-chloro-7-hydroxy-4-methylcoumarin "CMHC" and 2-diethylamino-6-methylpyrimidin-4ol "DEAMPY") and three pyrethroid metabolites (3-phenoxybenzoic acid "3-PBA", 4-fluoro-3-phenoxybenzoic acid "4-F-3-PBA" and 3-(2,2-dichlorovinyl)-2,2-dimethyl-1-cyclopropanecarboxylic acid "cis/trans-DCCA") in human urine samples. Off-line solid phase extraction (SPE), on-line SPE and turbulent flow chromatography (TurboFlow™) extraction methodologies were compared, obtaining better results when TurboFlow™ was applied, achieving a total analysis time of 13.83 min. Several validation parameters were tested, obtaining suitable results for all studied compounds. Recoveries ranged from 70 to 116%, meanwhile repeatability and reproducibility were lower than or equal to 7% and 13%, respectively. The limits of quantification (LOQs) were set in the range from 1 µg/L to 5 µg/L (except for DCCA at 10 µg/L). Finally, thirty seven urine samples from women and men living near the agricultural areas of Almeria (Spain) were analyzed to know and control the contamination on the human health. PNP, DEAMPY and IMPY were detected in six urine samples at trace levels except IMPY, which was detected at 3.44 µg/L in one of the samples. Additionally, a post-targeted and untargeted analysis were carried out in the samples, identifying eleven insecticides such as bensulide or cinerin II, one insecticide metabolite, fipronil sulfone, one drug metabolite, carboxyibuprofen and two nicotine metabolites, cotinine and 2-(1-pyrrolidinyl)isonicotinic acid, in several samples.

Synthesis of a zinc-based metal-organic framework with histamine as an organic linker for the dispersive solid-phase extraction of organophosphorus pesticides in water and fruit juice samples.

As a highly efficient adsorbent, the zinc-based metal-organic framework has been successfully synthesized from zinc as the metal ion and histamine as an organic linker under solvothermal conditions. The structure of nanocomposite was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analysis. The synthesized sorbent was applied for dispersive solid-phase extraction (DSPE) of organophosphorus pesticides (OPPs) in fruit juice and water samples. The gas chromatography-flame ionization detector (GC-FID) was used as instrument detection. The main experimental factors affecting the extraction efficiency such as the desorption conditions, sorbent amount and extraction time were evaluated and optimized. Good linearity exhibited for all of the target analytes in the 0.1-100 ng mL-1 concentration range. The enrichment factors (EFs) ranged from 803 to 914. The limits of detection (LODs) for the established DSPE-GC-FID method were found to be 0.03-0.21 ng mL-1. The DSPE-GC-FID method can be used for the analysis of OPPs in water and fruit juice samples with recoveries of the analytes in the range of 91.9% to 99.5%.

Cotton functionalized with nanostructured TiO2-Ag-AgBr layer for solar photocatalytic degradation of dyes and toxic organophosphates.

The functionalization of cotton fabric with photoactive TiO2-Ag-AgBr nanostructured layer has been successfully developed using a low temperature non-aqueous sol-gel route and aqueous suspension of AgBr. Evidence for the growth of TiO2 layer and the immobilization of AgBr nanoparticles have been confirmed by Raman, XRD and XPS. GSDR analysis revealed a strong absorption in the visible region brought by surface Plasmon resonance (SPR) of Ag nanocrystals generated at the surface of AgBr. The XPS evidenced the presence of Ag+, Ag0 and bromine, suggesting that Ag0 formed a shell around the deposited AgBr. The immobilized TiO2-Ag-AgBr heterostructured layer imparts a strong photocatalytic activity under visible light for the degradation of dyes in aqueous solution as well as of dimethyl methylphosphonate (DMMP), a chemical warfare agent simulant. These new catalytically active functionalized fabrics, with self-detoxification properties, have great potential for application in chemical protective clothes and might offer new opportunities for the design of functional materials for toxic chemical protection.

Stir bar sorptive-dispersive microextraction for trace determination of triphenyl and diphenyl phosphate in urine of nail polish users.

This work describes a new analytical method useful for monitoring the human exposure to the endocrine-disrupting plasticizer triphenyl phosphate (TPP) via nail polish use. The method allows trace determination of this parent compound and its main metabolite, namely diphenyl phosphate (DPP), in urine samples of nail polish users. The method is based on a novel microextraction technique termed stir bar sorptive-dispersive microextraction (SBSDME) using a magnetic composite made of CoFe2O4 magnetic nanoparticles embedded into a mixed-mode weak anion exchange polymer (Strata™-X-AW), followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The main parameters involved in the extraction procedure were evaluated and optimized. Under the optimized conditions, the method was successfully validated showing good linearity (at least up to 100 ng mL-1) and enrichment factors (17 and 30), limits of detection and quantification in the low ng L-1 range (1.9-17.1 ng L-1 and 6.3-57.1 ng L-1, respectively) and good intra- and inter-day precision (RSD < 8%). Excellent recoveries (81-112 %) were achieved by using matrix-matched calibration for quantification. Finally, the method was applied to the determination of both the parent compound and the metabolite in human urine samples from volunteers who applied themselves a nail polish containing TPP. Detectable amounts of the parent compound were found just in the first urination, whereas quantifiable amounts of DPP were found in the low ng mL-1 range even 24 h after application of the nail polish, thus suggesting a rapid biotransformation and a low excretion, and showing DPP as excellent biomarker of human exposure to TPP. This work expands the analytical potential of the novel SBSDME, and the proposed methodology contributes to the study of the absorption/excretion levels of endocrine disruptors present in cosmetic products.

Rapid Separation of Organophosphate Pesticides using Micellar Electrokinetic Chromatography and Short-end Injection.

Organophosphate (OP) pesticides are highly toxic substances and are frequently represented as poisons. In order to qualify and quantify the selected OP pesticides (methyl paraoxon, ethyl paraoxon, methyl parathion, fenitrothion, and ethyl parathion), micellar electrokinetic chromatography and short-end injection were investigated. This is the first time that this combination has been used to separate OP pesticides. A capillary with 8.5 cm effective length was used, and the analytes were separated within 2.1 min. Separation conditions including buffer (type, pH, and concentration), sodium dodecyl sulfate concentration, and separation voltage were optimized. The limit of detection (LOD) was estimated in the range of 10-20 µM. The OP pesticides spiked in artificial saliva and drinking water gave superior peak profiles, and good average recoveries 95.6% and 62.3%, respectively. Overall, a rapid method with excellent resolution and efficiency was developed and successfully applied in the analysis of potential sample matrixes.

Organophosphate flame retardants in leachates from six municipal landfills across China.

With the phasing out of brominated flame retardants, organophosphate flame retardants (OPFRs) have been widely used and further detected in multiple environmental media. However, municipal landfill leachates, an important source of contamination of OPFRs to aquatic environment, have not been fully understood, especially in a developing country like China. Thus, the occurrence, aqueous removal efficiency, environmental emission, and risk assessment of 10 OPFRs were investigated in leachates from six municipal landfills across China. The results indicated that except triethyl phosphate (TEP), the remaining 9 OPFRs were detected in both raw and final leachates with different frequencies higher than 33.3%. The range of total concentrations of OPFRs (ΣOPFRs) across China was 29.0-437 and 0.652-32.4 µg L-1 in raw and final leachates, respectively. Tris(2-chloroethyl) phosphate (TCEP) was the dominant species and accounted for 78.5% and 85.8% of average ΣOPFR concentration in raw and final leachates, respectively. This may be because TCEP is the most prevalently used OPFR in China. The overall aqueous removal efficiency of ΣOPFRs across China ranged from 57.7% to 99.8%. Tris(2-butoxyethyl) phosphate was the most removed species (98.8%), whereas TCEP was the least removed species (91.5%). The annual emissions of ΣOPFRs discharged into the aquatic environment from municipal landfills across China were estimated to be between 170 and 7094 g. Further risk assessment based on risk quotient values in the final leachates showed that most OPFRs posed negligible risk except TCEP (medium and high risk) and tributyl phosphate (medium risk).

Determination of organophosphate flame retardants in soil and fish using ultrasound-assisted extraction, solid-phase clean-up, and liquid chromatography with tandem mass spectrometry.

A solid-liquid extraction method in combination with high-performance liquid chromatography and tandem mass spectrometry was developed and optimized for extraction and analysis of organophosphorus flame retardants in soil and fish. Methanol was chosen as the optimum extraction solvent, not only in terms of extraction efficiency, but also for its broader analyte coverage. The subsequent clean-up by solid-phase extraction is required to eliminate matrix coextractives and reduce matrix effects. Recoveries of the optimized method were 50-121% for soil and 47-123% for biota, both with high precision (RSDs <12% in soil and <23% in biota). The method limits of detection ranged from 0.06 to 0.20 ng/g dry weight and between 0.02 and 0.30 ng/g wet weight for soil and biota samples, respectively. However, samples with a high lipid content produce several problems as solid-phase extraction cartridge clogging that increase variability and analysis time. The method was successfully applied for the determination of organophosphorus flame retardants in soil and fish from L'Albufera Natural Park (Valencia, Spain). Target compounds were detected in all soil and fish samples with values varying from 13.8 to 89.7 ng/g dry weight and from 3.3 to 53.0 ng/g wet weight, respectively.

Determination of Organophosphorous Pesticides in Blood Using Microextraction in Packed Sorbent and Gas Chromatography-Tandem Mass Spectrometry.

The aim of our work was to develop a method for the determination of six organophosphorous pesticides (Ops) (azynphos-ethyl (AZP), diazinon (DZN), chlorpyrifos (CLP), chlorfenvinfos (CLF), parathion-ethyl (PRT) and quinalphos (QLP)) in whole blood using microextraction by packed sorbent (MEPS) and analysis by gas chromatography-tandem mass spectrometry (GC-MS/MS). The optimization of the MEPS procedure was performed using a design of experiments (DOE) approach, assessing different factors that significantly affected the extraction efficiency. Ultimately, the number of sample strokes, wash volume, percentage of 2-propanol in the wash solvent and the number of elution strokes were successfully optimized using a response surface methodology (RSM). The developed and optimized method was fully validated according to international guidelines. Linearity was established from 2.5 to 50 µg/mL for AZP and from 0.5 to 50 µg/mL for the remaining compounds, with coefficients of determination (R2) higher than 0.99 in all cases. The lower limit of quantification were 2.5 µg/mL (AZP) and 0.5 µg/mL (remaining compounds). Recoveries ranged from 61% to 77%. Intra- and inter-day precision and accuracy were considered adequate according to the guidelines. This is the first method employing MEPS as a sample preparation procedure for the analysis of these OPs in whole blood.

UV-driven hydroxyl radical oxidation of tris(2-chloroethyl) phosphate: Intermediate products and residual toxicity.

Organophosphorus esters (OPEs) are emerging contaminants widely applied as annexing agents in a variety of industrial products, and they are robust against conventional wastewater treatments. Ultraviolet-driven (UV) radical-based advanced oxidation processes have a potential to become cost-effective treatment technologies for the removal of OPEs in water matrix, but residual and newly generated toxicities of degradation products are a concern. This study is a comprehensive attempt to evaluate UV/H2O2 for the degradation of a water dissolved OPE, tris(2-chloroethyl) phosphate (TCEP). In ultrapure water, a pseudo-first order reaction was observed, and the degradation rate constant reached 0.155 min-1 for 3.5 µM TCEP using 7.0 mW cm-2 UV irradiation with 44.0 µM H2O2. Hydroxyl radicals were involved in the oxidative degradation of TCEP, as demonstrated by the quenching of the degradation reaction in the presences of tertiary butanol or ethanol. High resolution mass spectroscopy data showed a partial transformation of TCEP to a series of hydroxylated and dechlorinated products e.g., C4H9Cl2O4P, C6H13Cl2O5P and C2H6ClO4P. Based on proteomics data at molecular and metabolic network levels, the toxicity of TCEP products was reduced obviously as the reaction proceeded, which was confirmed by the up-regulated tricarboxylic acid cycle, fatty acid metabolism and amino acid metabolism in Escherichia coli cells exposed to degradation products mixture. In conclusion, incomplete hydroxylation and dechlorination of TCEP likewise are effective for its detoxification, indicating that UV/H2O2 can be a promising treatment method for OPEs removal.

Development and validation of an ultra-performance liquid chromatography method for the determination of bis(2,4-di-tert-butylphenyl)phosphate and related extractable compounds from single-use plastic films.

A UPLC-UV method is described for the detection of bDtBPP and related breakdown compounds of Irgafos 168 from single-use bioprocessing bag films using a CSH (charged surface hybrid) fluoro phenyl column and UV detection at 220nm. The method limits of detection were between 16µgL-1 and 60µgL-1, repeatability was %RSD≤1.8 and linearity was R2≥0.9992. The method was applied to an extractables and leachables test of three single-use bioprocessing bag films. bDtBPP and oxidised Irgafos were detected from all three films in the extractables study, but not in the leachables study. A comparison of whole bag and small scale film extractions demonstrated that the small scale extractions were more suitable for finding concentration per area of film and/or estimating total load of extractables in the entire bag. The feasibility of upstream monitoring of extractable and leachable compounds with the Waters PATROL UPLC System via a Flownamics® sampling probe was also tested with cell growth medium spiked with bDtBPP. bDtBPP was only detected in at-line injections or online injections when the probe membrane was removed indicating that with the current sampling interface, monitoring of extractables and/or leachables is limited to at-line sampling.

Carbon quantum dots as fluorescence resonance energy transfer sensors for organophosphate pesticides determination.

Carbon quantum dots (CQDs) obtained from natural organics attract significant attention due to the abundance of carbon sources, varieties of heteroatom doping (such as N, S, P) and good biocompatibility of precursor. In this study, tunable fluorescence emission CQDs originated from chlorophyll were synthesized and characterized. The fluorescence emission can be effectively quenched by gold nanoparticles (Au NPs) via fluorescence resonance energy transfer (FRET). Thiocholine, which was produced from acetylthiocholine (ATC) by the hydrolysis of butyrylcholinesterase (BChE), could cause the aggregation of Au NPs and the corresponding recovery of FRET-quenched fluorescence emission. The catalytic activity of BChE could be irreversibly inhibited by organophosphorus pesticides (OPs), thus, the recovery effect was reduced. By evaluating the fluorescence emission intensity of CQDs, a FRET-based sensing platform for OPs determination was established. Paraoxon was studied as an example of OPs. The sensing platform displayed a linear relationship with the logarithm of the paraoxon concentrations in the range of 0.05-50µgL-1 and the limit of detection (LOD) was 0.05µgL-1. Real sample study in tap and river water revealed that this sensing platform was repeatable and accurate. The results indicate that the OP sensor is promising for applications in food safety and environmental monitoring.

Process-relevant concentrations of the leachable bDtBPP impact negatively on CHO cell production characteristics.

The biopharmaceutical industry has invested considerably in the implementation of single-use disposable bioreactors in place of or in addition to their stainless steel-counterparts. This new wave of construction materials for disposable bioprocess containers encompass a plethora of uncharacterized secondary compounds that, when in contact with the culture media, can leach, contaminating the bioprocess. One such cytotoxic leachable already receiving attention is bis(2,4-di-tert-butylphenyl)-phosphate (bDtBPP), a breakdown product of the secondary antioxidant Irgafos 168 in polyethylene-film based bags. This compound has been demonstrated to inhibit cell growth at concentrations ranging from 0.12 to 0.73 mg/L across an array of cell lines. Here we demonstrate that a further two CHO cell lines exhibit sensitivity to bDtBPP exposure at concentrations lower than that previously reported (0.035-0.1 mg/L). Furthermore, these inhibitory concentrations reflect bDtBPP levels found to leach early into the bioprocess, exposing reactor inoculums to serious risk. Quantitative label-free LC-MS/MS revealed that irrespective of cell line or concentration of bDtBPP, 8 proteins were found to be commonly differentially expressed in response to exposure to the compound highlighting biological processes related to cellular stress. Although the glycoprofile of the recombinant antibody remains primarily unchanged, we demonstrate that this compound when spiked at meaningful concentrations 72 h into culture considerably reduces the maximum cell density achieved. Studies like this reinforce the requirement for the complete characterization of all potential leachable compounds from disposable materials to assess their risk not only to the patient but also to the production pipeline itself. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1547-1558, 2016.

Zirconium(IV) functionalized magnetic nanocomposites for extraction of organophosphorus pesticides from environmental water samples.

The widespread use of organophosphate pesticides (OPPs) in agriculture leads to residue accumulation in the environment which is dangerous to human health and disrupts the ecological balance. In this work, one nanocomposite immobilized zirconium (Zr, IV) was prepared and used as the affinity probes to quickly and selectively extract organophosphorus pesticides (OPPs) from water samples. The Fe3O4-ethylenediamine tetraacetic acid (EDTA)@Zr(IV) nanocomposites (NPs) were prepared by simply mixing Zr(IV) ions with Fe3O4-EDTA NPs synthesized by one-pot chemical co-precipitation method. The immobilized Zr(IV) ions were further utilized to capture OPPs based on their high affinity for the phosphate moiety in OPPs. Coupled with GC-MS, four OPPs were used as models to demonstrate the feasibility of this approach. Under the optimum conditions, the limits of detection for target OPPs were in the range of 0.10-10.30ngmL(-1) with relative standard deviations (RSDs) of 0.61-4.40% (n=3), respectively. The linear ranges were over three orders of magnitudes (correlation coefficients, R(2)>0.9995). The Fe3O4-EDTA@Zr(IV) NPs were successfully applied to extract OPPs samples with recoveries of 86.95-112.60% and RSDs of 1.20-10.42% (n=3) from two spiked real water. By the proposed method, the matrix interference could be effectively eliminated. We hope our finding can provide a promising alternative for the fast extraction of OPPs from complex real samples.

Recovery of Palm Oil and Valuable Material from Oil Palm Empty Fruit Bunch by Sub-critical Water.

Oil palm empty fruit bunch (EFB) is one of the solid wastes produced in huge volume by palm oil mill. Whilst it still contains valuable oil, approximately 22.6 million tons is generated annually and treated as solid waste. In this work, sub-critical water (sub-cw) was used to extract oil, sugar and tar from spikelet of EFB. The spikelet was treated with sub-cw between 180-280°C and a reaction time of 2 and 5 minutes. The highest yield of oil was 0.075 g-oil/g-dry EFB, obtained at 240°C and reaction time of 5 minutes. Astonishingly, oil that was extracted through this method was 84.5% of that obtained through Soxhlet method using hexane. Yield of oil extracted was strongly affected by the reaction temperature and time. Higher reaction temperature induces the dielectric constant of water towards the non-polar properties of solvent; thus increases the oil extraction capability. Meanwhile, the highest yield of sugar was 0.20 g-sugar/g-dry EFB obtained at 220°C. At this temperature, the ion product of water is high enough to enable maximum sub-critical water hydrolysis reaction. This study showed that oil and other valuable material can be recovered using water at sub-critical condition, and most attractive without the use of harmful organic solvent.

Tris(pentafluoroethyl)trifluorophosphate-basd ionic liquids as advantageous solid-phase micro-extraction coatings for the extraction of organophosphate esters in environmental waters.

Ionic liquids (ILs) containing the tris(pentafluoroethyl)trifluorophosphate [FAP] anion and various cations have great potential in sample preparation because of their excellent hydrophobicity, thermostability and low hydrolysity. In the present study, a [FAP]-based IL, 1-hexyl-3-methylimidazolium tris (pentafluoroethyl) trifluoro phosphate ([HMIM][FAP]), was used as coatings of solid-phase microextraction (SPME) for extracting organophosphate esters (OPEs) from environmental water samples. This SPME fiber was fabricated by coating a stainless steel wire substrate with [HMIM][FAP] via a simple direct dip-coating approach, and the extraction was conducted by the direct immersion solid phase microextraction. Coupling to gas chromatography mass spectrometry (GC-MS), the developed SPME method exhibited excellent selectivity and sensitivity towards the extraction of 11 OPEs from aqueous samples. Satisfactory linearity (R(2)≥0.99) of the calibration curves was obtained over the range of 0.05-50.0ngmL(-1) with the limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) ranged from 0.13-7.40ngL(-1) and 0.50-24.0ngL(-1), respectively. The proposed SPME method showed excellent extraction efficiency to OPEs with enrichment factors in the range of 168-2603, and acceptable reproducibility with relative standard deviations (RSDs) ≤15% for single fiber (n=7) and ≤16% for fiber-to-fiber (n=3×3) at a concentration level of 0.5ngmL(-1), respectively. The prepared IL-based fiber was successfully applied to determine eleven common used OPEs in tap water, influent and effluent of sewage treatment plant, with results are comparable to those determined by the reference (UPLC-MS/MS), and spiked recoveries in the range of 84.0-108%, 82.1-123% and 82.8-100%, respectively.

Mesoporous-silica nanofluidic channels for quick enrichment/extraction of trace pesticide molecules.

As nanofluidic channels, uniaxially oriented mesoporous-silica is, for the first time, in-situ self-assembled in a microfluidic chip for quick enrichment/extraction of ng L(-1)(ppt)-level organo-phosphorous (OP) pesticide residue from aqueous solution to ethanol. This micro/nano combined pre-treatment chip is essential for following gas chromatography-mass spectrometry (GC-MS) quantitative analysis. Featuring huge surface area and dense silanol groups at the inwall surface, the mesoporous-silica is uniaxially self-assembled in a micro-reservoir to form a pile of nanofluidic channels (diameter = 2.1 nm). The captured/enriched pesticide molecules in the nanochannels can be efficiently extracted by much smaller volume of ethanol due to its much higher solubility to OP. In our affirming experiment, three mixed OP pesticides of dichlorvos, paraoxon and chlorpyrifos (in water) are captured/enriched by the nano-channels and eluted/extracted by only 0.6 mL ethanol. The whole process only takes 16 min. The GC-MS quantitative results for the extracted three pesticides indicate that the extraction recovery achieves 80%. The achieved limit of quantification (LOQ) and the limit of detection (LOD) are 100 ng L(-1) and 30 ng L(-1), respectively. The nanofluidic-channel pre-treatment technique is promising in various application fields like agriculture and food safety security.

Cation-enhanced capillary electrophoresis separation of atropoisomer anions.

CE was used to study the separation of the atropoisomers of four phosphoric acids and two sulfonic acids and the enantiomers of two phosphoric acids. All solutes are in their anionic forms in aqueous electrolytes. The chiral additives were two hydroxypropyl cyclodextrins (CDs) and cyclofructan 6 (CF6). The CDs were able to separate four solutes and the CF6 additive could separate only one: 1,1'-binaphthyl-2,2'-diyl hydrogenphosphate (BHP). Since CF6 is able to bind with cations, nitrate of alkaline metals, Ba(2+) , and Pb(2+) were added, greatly improving the BHP separation at the expense of longer migration times. There seems to be a link between CF6-cation-binding constants and BHP resolution factors. Cation additions were also performed with CD selectors that are less prone to form complexes with cations. Significant improvements of enantiomer or atropoisomer separations were observed also associated with longer migration times. It is speculated that the anionic solutes associate with the added cations forming larger entities better differentiated by CDs.