MultiSimplex optimization of the dispersive solid-phase microextraction and determination of fenitrothion by magnetic molecularly imprinted polymer and high-performance liquid chromatography

A magnetic molecularly imprinted polymer (MMIP) was fabricated and used as the sorbent for the MMIP-dispersive solid-phase microextraction of fenitrothion prior its determination by high-performance liquid chromatography equipped with an ultraviolet detector. The MMIP was prepared using functionalized Fe₃O₄ nanoparticles as the magnetic supporter. Methacrylic acid, ethylene glycol dimethacrylate and fenitrothion were used as the functional monomer, the cross-linker and the template, respectively. The properties of the resultant MMIP were evaluated using X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. The sorbent exhibited high selectivity and affinity toward fenitrothion compared to other organophosphate pesticides with the maximum adsorption capacity of 31.5 mg g^?1. The effective variables on the extraction were optimized by univariable and MultiSimplex methods. The calibration curve exhibited linearity over the concentration range of 0.3–50.0 μg L^?1 with the limit of detection of 0.1 μg L^?1. The relative standard deviations at 10.0 μg L^?1 level of FNT (n = 5) for intra- and inter-day assays were 1.6 and 3.1%, respectively. The proposed method was successfully used for the determination of trace amounts of FNT in food and water samples.     

Magnetic molecularly imprinted polymer nanoparticles for the solid-phase extraction of paracetamol from plasma samples,followed its determination by HPLC

We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were prepared from magnetite (Fe₃O₄) as the magnetic component, paracetamol as the template, methacrylic acid as a functional monomer, and 2-(methacrylamido) ethyl methacrylate as a cross-linker. The m-MIPs were then characterized by transmission electron microscopy, FT-IR spectroscopy, X-ray diffraction and vibrating sample magnetometry. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples. Following its elution from the column loaded with the m-MIPs with an acetonitrile-buffer (9:1) mixture, it was submitted to HPLC analysis. Paracetamol can be quantified by this method in the 1 μg L^?1 to 300 μg L^?1 concentration range. The limit of detection and limit of quantification in plasma samples are 0.17 and 0.4 μg L^?1. The preconcentration factor of the m-MIPs is 40. The HPLC method shows good precision (4.5 % at 50 μg L^?1 levels) and recoveries (between 83 and 91 %) from spiked plasma samples. Figure

We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples     

Flow Injection Chemiluminescence Sensor with Novel Rhodanine Ramification for Determination of Fenfluramine Based on Molecularly Imprinted Polymer

Abstract

Flow injection chemiluminescence (FI-CL) with molecularly imprinted polymer (MIP) was applied to determine fenfluramine. The fenfluramine-imprinted polymer was prepared with acrylamide (AM) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker. Methyl and sulfonic group were introduced to rhodanine matrix, and a novel rhodanine ramification 3MORASP was synthesized by the author, and it was used as chemiluminescence reagent. 3-(3′-Methoxyphenyl)-5(2′-sulfonylphenylazo)-rhodanine (3MORASP), first synthesized by the authors, was used as chemiluminescence (CL) reagent. The novel flow path of FI-CL was designed, which made three merged streams of reactants injected into MIP column move through different pathways simultaneously. Fenfluramine was detected based on the reaction of fenfluramine, 3MORASP, and potassium permanganate in an acidic medium. The CL intensity was correlated linearly with the concentration of fenfluramine over the range of 1.0 × 10^?7 to 5.0 × 10^?6 g · mL^?1, and the detection limit was 9.48 × 10^?9 g · mL^?1. The relative standard deviation (RSD) was 2.4% for determination of 1.0 × 10^?6 g · mL^?1 fenfluramine (n = 11). This method was successfully applied to the determination of fenfluramine in weight-reducing tonic.     

Spectrophotometric Determination of Bromate in Water Using Multisyringe Flow Injection Analysis

A multisyringe flow injection system for the spectrophotometric determination of bromate in water is proposed, based on the oxidation of phenothiazine compounds by bromate in acidic medium. Several phenothiazines were tested, including chlorpromazine, trifluoperazine, and thioridazine. Higher sensitivity and lower LOD were attained for chlorpromazine. Interference from nitrite, hypochlorite, and chlorite was eliminated in-line, without any changes in the manifold. The automatic methodology using chlorpromazine allowed the determination of bromate between 25 and 750 µg L^?1, with LOD of 6 µg L^?1, good precision (RSD < 1.6%, n = 10), and determination frequency of 35 h^?1.     

Use of ionic liquid based chitosan as sorbent for preconcentration of fluoroquinolones in milk,egg, fish,bovine, and chicken meat samples by solid phase extraction prior to HPLC determination

The possibility of using ionic liquid based chitosan sorbent for the separation and preconcentration of fluoroquinolone antibiotics (marbofloxacin, enoxacin, ofloxacin, ciprofloxacin, and enrofloxacin) has been studied. For this reason, different ionic liquids were prepared and coated on the chitosan sorbent. The conditions of the preconcentration of fluoroquinolones on a microcolumn have been optimized and the extraction efficiencies of the prepared sorbents have been compared. The compounds were eluted with 5 mL of 20% NH₃ (v/v, MeOH) solution and determined by HPLC with diode array and fluorescence detector. The limits of detection were found as 4.23 µ g L^?1 for marbofloxacin, and 1.09 µg L^?1 for enoxacin; 3.23 × 10^?3 µg L^?1 for ofloxacin; 8.39 × 10^?3 µg L^?1 for ciprofloxacin; and 19.50 × 10^?3 µg L^?1 for enrofloxacin. The developed method was applied for the analysis of fluoroquinolone in milk, egg, fish, bovine, and chicken samples and the recoveries were obtained in the range 70–100%.     

Determination of ultratrace amounts of plutonium in high saline groundwater by inductively coupled plasma mass spectrometry

For determination of ultratrace amounts of plutonium in high saline groundwater, large-volume sampling and preconcentration are necessary. However, traditional co-precipitation methods, such as Fe(OH)₃, Ca(OH)₂–Mg(OH)₂ and hydroxide-carbonate co-precipitation, are unable to meet the requirements of preconcentration of the ultratrace plutonium in high saline groundwater. In this paper, the ultratrace plutonium in high saline groundwater was concentrated by sequential co-precipitation with MnO₂ and Fe(OH)₃, and purified by two-stage anion-exchange separation on Dowex1 × 4 resin column. Quadrupole ICP-MS was employed for the determination of ²³⁹Pu with ²⁴²Pu spiked. After co-precipitation and purification, the major matrix elements were significantly decreased to μg mL^?1 level and decontamination factor of uranium is better than 10⁶. The detection limit for ²³⁹Pu in 50 L high saline water is 2.1 × 10^?16 g L^?1. Three high saline fountain samples (total dissolved solids more than 20 g L^?1) from Dunhuang region of China were analyzed using this method. The concentrations of ²³⁹Pu in these samples were 0.48 ± 0.2 × 10^?15, 1.40 ± 0.10 × 10^?15 and 2.13 ± 0.21 × 10^?15 g L^?1 respectively. The recovery obtained for 7 pg of ²⁴²Pu spiked into real high saline-water samples was all above 70 %.     

Molecular Imprinting-Chemiluminescence Sensor for the Determination of Amoxicillin

The amoxicillin-imprinted polymer was synthesized with methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross-linker. The binding characteristic of the imprinted polymer to amoxicillin was evaluated by equilibrium binding experiments. Using the imprinted polymer as recognition material, 3-(3′-nitrophenyl)-5(2′-sulfonylphenylazo)-rhodanine (4NRASP) was synthesized by the authors and was used as chemiluminescence (CL) reagent. A novel chemiluminescence (CL) sensor for the determination of amoxicillin was developed based on the CL reaction of amoxicillin with potassium permanganate in an acidic medium. The sensor displayed excellent selectivity and high sensitivity. The linear response range of the sensor was from 5.0 × 10^?9 to 1.0 × 10^?6 g · mL^?1 (r = 0.9985) and the detection limit was 1.3 × 10^?9 g · mL^?1. The relative standard deviation for the determination of 1.0 × 10^?7 g · mL^?1 amoxicillin solution was 1.7% (n = 11). The sensor was applied to the determination of amoxicillin in urine samples with satisfactory results.     

Molecularly imprinted stir bar sorptive extraction coupled with high-performance liquid chromatography for trace analysis of naphthalene sulfonates in seawater

In this paper, a novel molecularly imprinted polymer coated stir bar has been used to selectively extract naphthalene sulfonates (NS_s) directly from seawater sample. 1-Naphthalene sulfonic acid (1-NS) was used as template molecule. The effects of different parameters were optimized on the extraction efficiency and the optimum conditions were established as: the absorption and desorption times were fixed, respectively, at 10 and 15 min, stirring speed was 700 rpm, pH was adjusted to 4.1, amount of NaCl was 1 mol L^?1 and extraction process was performed at a temperature of 50 °C. The linear ranges were 2–250 µg L^?1 for 3,6-NDS-1-OH (1-naphthol-3,6-disulfonic acid), 4–250 µg L^?1 for 2-NS (2-naphthalene sulfonate) and 3–250 µg L^?1 for 1-NS. The detection limits were within the range of 0.32–0.95 µg L^?1. Under optimum conditions, the detection limits of the NSs were 0.84, 0.95 and 0.32 µg L^?1 with the enrichment factor of 117-, 41- and 77-fold for 2-NS, 1-NS, and 6-NDS-1-OH, respectively. The repeatability of the method was satisfactory (0.53 ≤ RSD ≤6.0 %, n = 10). The method has been successfully applied for the analysis of trace amounts of three naphthalene sulfonates in seawater of Chabahar Bay.     

Preparation and Performance Research on Glutathione Molecularly Imprinted Polymers

Methacrylic acid and ethylene glycol dimethacrylate were respectively used as functional monomer and cross-linker to synthesize molecularly imprinted polymers (MIPs), for adsorption of glutathione (GSH), named GSH-MIPs. Evaluation of various polymers by static experiment indicated the optimum ratio of template to functional monomer was 1:4; the optimal concentration and pH of loading buffer were 5.00?C6.50 mmol L^?1 and 5.0, respectively. By Scatchard analysis, the GSH binding site was found in GSH-MIPs, with K _d and Q _max of 1.96 mmol L^?1 and 47.19 ??mol g^?1, respectively. The method validated the extraction of GSH from yeast cells samples with the enrichment rate of 76%.     

Magnetic molecularly imprinted polymer nanoparticles for the solid-phase extraction of paracetamol from plasma samples,followed its determination by HPLC

We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were prepared from magnetite (Fe₃O₄) as the magnetic component, paracetamol as the template, methacrylic acid as a functional monomer, and 2-(methacrylamido) ethyl methacrylate as a cross-linker. The m-MIPs were then characterized by transmission electron microscopy, FT-IR spectroscopy, X-ray diffraction and vibrating sample magnetometry. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples. Following its elution from the column loaded with the m-MIPs with an acetonitrile-buffer (9:1) mixture, it was submitted to HPLC analysis. Paracetamol can be quantified by this method in the 1 μg L⁻¹ to 300 μg L⁻¹ concentration range. The limit of detection and limit of quantification in plasma samples are 0.17 and 0.4 μg L⁻¹. The preconcentration factor of the m-MIPs is 40. The HPLC method shows good precision (4.5 % at 50 μg L⁻¹ levels) and recoveries (between 83 and 91 %) from spiked plasma samples.

We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples

     

Sensitive Analysis of Wilforidine in Human Plasma by LC-APCI-MS/MS

Wilforidine is a potentially efficient medicine to cure autoimmune diseases. In this paper, a sensitive and selective liquid chromatographic method coupled with atmospheric -pressure chemical ionization mass spectrometry (LC–APCI–MS/MS) has been developed for quantification of wilforidine in human plasma. Samples were deproteinized with acetonitrile and cleaned by solid-phase extraction. The chromatographic separation was performed on an analytical RRHD C₁₈ column (50 × 2.1 mm) using ammonium acetate solution (10.0 mmol L^?1)/acetonitrile (30/70, v/v) as the mobile phase at a flow rate of 0.7 mL min^?1. Detection was carried out by the positive multiple reaction monitoring mode with transitions of m/z 780 → 684 for wilforidine, and 646 → 586 for aconitine (internal standard), respectively. The calibration curve was linear (r = 0.9991) in the concentration range of 0.5–100.0 μg L^?1 with a lower limit of quantification of 0.5 μg L^?1 in plasma. Intra- and inter-day relative standard deviations were less than 6.8 and 13.1 %, respectively, and the recoveries were between 88.0 and 96.0 %. This accurate and highly specific assay provides a useful method for evaluating the pharmacokinetics of wilforidine in human plasma.     

LC Determination of Ketorolac in Human Plasma and Urine for Application to Pharmacokinetic Studies

A simple, specific and sensitive liquid chromatographic method has been developed for the assay of ketorolac in human plasma and urine. The clean-up of plasma and urine samples were carried out by protein precipitation procedure and liquid–liquid extraction, respectively. Separation was performed by a Waters sunfire C₁₈ reversed-phase column maintained at 35 °C. The mobile phase was a mixture of 0.02 M phosphate buffer (pH adjusted to 4.5 for plasma samples and to 3.5 for urine samples) and acetonitrile (70:30, v/v) at a flow rate of 1.0 mL min^?1. The UV detector was set at 315 nm. Nevirapine was used as an internal standard in the assay of urine sample. The method was validated over the concentration range of 0.05–8 and 0.1–10 μg mL^?1 for ketorolac in human plasma and urine, respectively. The limits of detection were 0.02 and 0.04 μg mL^?1 for plasma and urine estimation at a signal-to-noise ratio of 3. The limits of quantification were 0.05 and 0.1 μg mL^?1 for plasma and urine, respectively. The extraction recoveries were found to be 99.3 ± 4.2 and 80.3 ± 3.7% for plasma and urine, respectively. The intra-day and inter-day standard deviations were less than 0.5. The method indicated good performance in terms of specificity, linearity, detection and quantification limits, precision and accuracy. This assay demonstrated to be applicable for clinical pharmacokinetic studies.     

Multivariate Analysis for the Classification Differentiation of Brazilian Sugarcane Spirits by Analysis of Organic and Inorganic Compounds

Abstract

Brazilian sugarcane spirits were analyzed to elucidate similarities and dissimilarities by principal component analysis. Nine aldehydes, six alcohols, and six metal cations were identified and quantified. Isobutanol (LD 202.9 µg L^?1), butiraldehyde (0.08–0.5 µg L^?1), ethanol (39–47% v/v), and copper (371–6068 µg L^?1) showed marked similarities, but the concentration levels of n-butanol (1.6–7.3 µg L^?1), sec-butanol (LD 89 µg L^?1), formaldehyde (0.1–0.74 µg L^?1), valeraldehyde (0.04–0.31 µg L^?1), iron (8.6–139.1 µg L^?1), and magnesium (LD 1149 µg L^?1) exhibited differences from samples.     

Determination of Organotin Compounds in Wine by Microwave-Assisted Extraction and High Performance Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry

A new analytical procedure for the determination of five organotin compounds in several matrix wine samples is reported. The organotin compounds were extracted by microwave-assisted extraction with n-hexane. Extraction conditions, such as volume of n-hexane required, extraction temperature, and extraction time, were investigated and optimized by an orthogonal array experimental design. The determination of organotin compounds in the final extracts was carried out by liquid chromatography–inductively coupled plasma mass spectrometry. The procedure showed limits of detection between 0.029–0.049 µg · L^?1. The linearity was in the range of 0.5 to 100 µg · L^?1. The precision expressed as relative standard deviation (RSD) was below 9.43%. The developed method was successfully employed to analyze different matrix wine samples, and some analytes were detected at the level of 0.053 to 1.14 µg · L^?1.     

Optimized solid phase extraction based on diethyldithiocarbamate-coated Fe3O4 magnetic nanoparticles followed by ICP-OES for determination of Cd(II) and Ni(II) in rice and water samples

In the present study, application of Fe₃O₄ magnetic nanoparticles (MNPs) coated with diethyldithiocarbamate as a solid-phase sorbent for extraction of trace amounts of cadmium (Cd²⁺) and nickel (Ni²⁺) ions by the aid of ultrasound was investigated. The analytes were determined by inductively coupled plasma-optical emission spectroscopy. Fe₃O₄ MNPs were prepared by solvothermal method and characterized with dynamic light scattering, scanning electron microscope and X-ray diffraction. Response surface methodology was used for optimization of the extraction process and modeling the data. The optimal conditions obtained were as follows: chelating agent, 1.2 g L^?1; pH, 6.13; sonication time, 13 min and Fe₃O₄ MNPs, 10.3 mg. The calibration curves were linear over the concentration range of 1–1,000 μg L^?1 for Cd²⁺ and 2.5–1,000 for Ni²⁺ with the determination coefficients (R ²) of 0.9997 and 0.9995, respectively. The limits of detection were 0.27 μg L^?1 for Cd²⁺ and 0.76 μg L^?1 for Ni²⁺. The relative standard deviations (n = 7, C = 200 μg L^?1) for determination of Cd²⁺ and Ni²⁺ were 2.0 and 2.7 %, respectively. The relative recoveries of the analytes from tap, river and lagoon waters and rice samples at the spiking level of 10 μg L^?1 were obtained in the range of 95–105 %.     

Ion Chromatography with Post-column Reaction and Serial Conductivity and Spectrophotometric Detection Method Development for Quantification of Transition Metal Dissolution in Lithium Ion Battery Electrolytes

We present a method for the separation and determination of transition metals in electrolytes based on ion chromatography (IC) with post-column reaction (PCR) and serial conductivity and spectrophotometric detection. Three IC columns [Metrosep C4—250/4.0 (column A), Metrosep C6—250/4.0 (column B), and Nucleosil 100-5SA—250/4.6 (column C)] with different capacities, and stationary phases were used and compared with each other for method development. All spectrophotometric measurements were carried out with 4-(2-pyridylazo)resorcinol (PAR) as PCR reagent at a wavelength of 500 nm. To characterize the precision of the separation, the selectivity for the analysis of transition metals (nickel, cobalt, copper, and manganese) in the presence of large amounts of lithium and the resolution of the peaks were determined and compared with one another. Furthermore, the limits of detection (LOD) and quantification (LOQ) were determined for the transition metals. The LODs and LOQs determined by column C were as follows: cobalt (LOD/LOQ): 9.4 µg L^?1/31.3 µg L^?1, manganese (LOD/LOQ): 7.0 µg L^?1/23.5 µg L^?1, and nickel (LOD/LOQ): 6.3 µg L^?1/21.1 µg L^?1. Finally, the concentration of transition metal dissolution of the cathode material Li₁Ni_1/3Co_1/3Mn_1/3O₂ (NCM) was investigated for different charge cut-off voltages by the developed IC method.     

Mercury speciation by a high performance liquid chromatography—atomic fluorescence spectrometry hyphenated system with photo-induced chemical vapour generation reagent in the mobile phase

Speciation of mercury was accomplished by using a simple interface with photo-induced chemical vapour generation in a high performance liquid chromatography—atomic fluorescence spectrometry (HPLC-AFS) hyphenated system. Acetic acid and 2-mercaptoethanol in the mobile phase were used as photochemical reagent. The operating parameters were optimized to give limits of detection of 0.53 µg L^?1, 0.22 µg L^?1, 0.18 µg L^?1 and 0.25 µg L^?1 for inorganic mercury, methylmercury, ethylmercury and phenylmercury, respectively. The method was validated with the certified reference material DORM-2 and applied to the analysis of seafood samples. The HPLC-AFS hyphenated system is simple, environmentally friendly, and represents an attractive alternative to the conventional peroxothiosulfate-borohydride method.     

Dispersive Liquid–Liquid Microextraction of Silver Prior to Determination by Microsample Introduction-Flame Atomic Absorption Spectrometry

Abstract

A new simple and sensitive method has been proposed for rapid determination of trace levels of silver in environmental water samples, using dispersive liquid–liquid microextraction (DLLME) prior to its microsample introduction-flame atomic absorption spectrometry. Under the optimum conditions, the linear range was 0.1–7 µg L^?1 and limit of detection was 0.018 µg L^?1. The relative standard deviation for 0.50 and 5.00 µg L^?1 of silver in water sample was 4.0 and 1.7%, respectively. The relative recoveries of silver from tap, well, river, and seawater samples at spiking levels of 1.00 and 5.00 µg L^?1 were in the range of 86.4–98.6%.     

Use of Surfactant as Mobile Phase Additive in LC for Simultaneous Determination of Metal-Pyrrolidine Dithiocarbamate Chelates

Reversed phase liquid chromatography using UV detection was developed for the simultaneous analysis of Hg(II), Pb(II), Cd(II), Ni(II), Fe(III) and V(V) ions after their complexation with pyrrolidine-dithiocarbamate (PDC). Optimum chromatographic conditions were a μ-Bondapak C₁₈ column and an isocratic mobile phase consisting of 40 mmol L^?1 SDS, 34 mmol L^?1 TBABr and 68% acetonitrile in 10 mmol L^?1 phosphate buffer pH 3.5. The separation of six PDC complexes was achieved within 8 min. Analytical performances and method validation were investigated. The detection limits ranged from 0.16 μg L^?1(Fe(III)) to 5.40 μg L^?1(Pb(II)). Recoveries obtained for all the studied samples including tap water, whole blood and vegetables were 72–98%. The results obtained from the proposed method were not significantly different compared to those obtained from atomic absorption spectrometry (P = 0.05).     

LC–MS–MS Quantitative Determination of Ursolic Acid in Human Plasma and Its Application to Pharmacokinetic Studies

A sensitive and specific liquid chromatography–electrospray ionization-tandem mass spectrometry method has been developed and validated for the identification and quantification of ursolic acid in human plasma using glycyrrhetic acid as an internal standard. The method involves extraction with methyl tert-butyl ether. The analyte was separated on a C₁₈ column and analyzed in multiple reaction monitoring mode with a negative electrospray ionization interface using the [M–H]? ions, m/z 455.4 for ursolic acid and m/z 469.5 → m/z 425.5 for glycyrrhetic acid. The method was validated over the concentration range of 0.86–110.0 μg L^?1. The intra- and inter-day precisions were less than 13.53% relative standard deviation (RSD) and the accuracy was within ?4.76% in terms of relative error (RE). The lower limit of quantification was 0.86 μg L^?1 with acceptable precision and accuracy. There were almost no matrix effects. Recovery of ursolic acid from spiked drug-free plasma was higher than 68%. The method was used to study the pharmacokinetic profile of ursolic acid in human plasma after oral administration of Jieyu capsules.