High-performance Liquid Chromatography Detection Research Articles

Review of the Analytical Methods Based on HPLC-Electrochemical Detection Coupling for the Evaluation of Organic Compounds of Nutritional and Environmental Interest

This review would like to show the state of the art regarding the coupling of High-Performance Liquid Chromatography (HPLC) with Electrochemical Detection (ED). Since a universal detector for HPLC is not available, the electrochemical detection methods, thanks to their versatility and specificity, are competitive with respect to the detectors currently used. The papers present in literature on HPLC-ED technique are analyzed and discussed: for example, they regard the development of analytical determinations of resveratrol, rosmarinic acid, aromatic heterocyclic amines and glyphosate in food matrices such as meat, aromatic plants, vegetables, fruit and tomato juices. These papers show that electrochemical sensors used as detectors for HPLC can offer better sensitivity values than other detectors. Furthermore, the use of specific working potentials allows avoid matrix interferences to be avoided by almost exclusively determining the analytes of interest. It should be underlined that HPLC-ED methods have a selectivity that allows for limitation of the sample preparation and clean-up procedures to a minimum, making them quick and easy to apply. In addition, these methods offer advantages such as the possibility of direct analysis, that derivatization is often not necessary, the cost-effectiveness of the instrumentation and the possibility of regenerating the electrodes which allows numerous analyses in succession.

Bisphenol and Phthalate Migration Test from Mexican Meat Packaging Using HPLC-DAD Technique

The objective of this work was to analyze the bisphenols’ and phthalates’ (PAEs) migration from meat packages (of sausages, Winnies, and ham found in Mexican markets) to a water simulant. The determination of these compounds was realized by high performance liquid chromatography (HPLC) and diode array detection (DAD) at a wavelength of 254 nm. The mobile phase utilized was a mixture of acetonitrile:H2O (70 : 30). Elution was performed isocratically at a temperature of 25°C and at a flow rate of 1 mL min−1. The LOQs obtained for BPA, DEP, BADGE, DBP, BisDMA, DHP, DOP, and PA in µg mL−1 were 0.53, 2.09, 0.85, 1.45, 5.81, 1.03, 3.12, and 29.6, respectively. Calibration curves exhibited an adequate determination coefficient for all compounds (R2 >0.999). Excellent accuracy and precision in measurements (% RSD) were achieved. The recovery study showed good applicability of the method (percentage recovery 80% to 106%). The BPA, BADGE, DBP, and DOP concentrations found in samples exceeded the simulant migration limits (SMLs) established by the European Union. The contribution of the current investigation was to provide information related to the presence of bisphenols and PAEs in the package of meat products, highlighting the health risks associated with their exposure.

High-performance liquid chromatographic detection of selected phenolic acidsin wine

The aim of this study was to develop a method for identification and quantification of phenolic acids in different wine samples. The simple reversed-phase HPLC-UV method for simultaneous determination of p-coumaric and ferulic acid was developed. The method was validated and working range, linearity, repeatability, accuracy, limit of quantitation LOQ and limit of detection LOD were determined. The linearity of the method was tested in concentration ranges 0.1-1 mg L-1 and 1-10 mg L-1. The correlation coefficients (r2) were greater than 0.996 and quality coefficients (QC) ≤ 5%. Detection limit for both compounds was 0.01 mg L-1. The method is precise (RSD

Method Validation and Rapid Determination of Monosodium Glutamate in Various Food Products by HPLC-Fluorescence Detection and Method Optimization of HPLC-Evaporative Light Scattering Detection Approach without Derivatization.

In this study, an effective, simple and rapid high-performance liquid chromatography (HPLC) using fluorescence (FLD) method was developed and validated for the determination of monosodium glutamate (MSG) in 57 various food samples. Besides, HPLC-Evaporate Light Scattering Detection (ELSD) method was carried out for determination of MSG without derivatization. MSG analysis was performed by derivatization with dansyl chloride at excitation 328, emission 530nm with fluorescence detector. HPLC-FLD method was carried out by using C18 (150mm, 4.6mm, 2.7μm) column with the mobile phase consisting of (Water: Methanol:Glacial Acetic Acid)/(54:45:1,v/v/v). The column temperature was set at 25°C and the flow rate was set at 0.5mLmin-1 with an injection volume 20μL. The results were linear (R2 = 0.9999) with very low quantification limits. The applied method was optimized and the validated parameters such as LOD, LOQ, accuracy, precision, linearity and robustness were calculated. The obtained results were statistically compared with each other. The validated HPLC-FLD method was successfully applied for the analysis of MSG in all of the food samples. Moreover, HPLC-ELSD method was optimized and successfully demonstrated for detect the MSG without derivatization.

Improved quantification of N-methylcarbamates combining supramolecular post-column derivatization-fluorescence detection-high performance liquid chromatography and partial least squares analysis

A strategy to improve the simultaneous quantification of N-methyl-carbamate pesticides was performed. It takes advantage of the supramolecular interactions between the analytes and hydroxypropyl-β-cyclodextrin (HPCD) in the post-column reactor to increase the high-performance liquid chromatography-fluorescence sensitivity and use the partial least squares algorithm for the data analysis to identify strong overlap signals. The use of HPCD in the derivatization reactor generated a 50% of improvement in the limit of detection of Aminocarb (11.29 ng/ mL), Carbofuran (CF) (19.58 ng/mL) and, Bendiocarb (BC) (0.27 mg/mL). It practically was the same for Carbaryl (2.35 ng/mL), but with a precise identification between CF and BC. The methods developed for these analytes were exactly on the elliptic joint confidence region. The recoveries in domiciliary water indicate the accuracy of the methodologies developed with values between 97% and 103% at the maximum concentration levels allow by international recommendations..

Nutrient content in ora-pro-nóbis (Pereskia aculeata Mill.): unconventional vegetable of the Brazilian Atlantic Forest

Abstract Ora-pro-nobis (Pereskia aculeata Mill.) is an unconventional vegetable found in the Brazilian Atlantic Forest and consumed, mainly by the rural population who lives in this biome. The present study investigated the nutritional value and contribution potential this species to the recommendations of daily nutrient intake for adults. Moisture and ash content were determined by gravimetry after oven drying and muffle incineration, respectively. Proteins were determined by the micro-Kjeldhal method; lipids by gravimetric lipids using soxhlet extractor; Total dietary fiber (TDF) by non-enzymatic gravimetry; Carotenoids and vitamin C by High Performance Liquid Chromatography (HPLC) with Diodes Array Detector; Vitamin E by HPLC and fluorescence detection; and minerals by inductively coupled plasma atomic emission spectrometry (ICP-AES). Ora-pro-nobis presented concentrations of TDF (3.73 g 100 g-1), ash (0.96 g 100 g-1), lipids (1.45 g 100 g-1), protein (1.27 g 100 g-1), carotenoids (3.15 mg 100 g-1), total vitamin E (438.68 µg 100 g-1), Ca (427.08 mg 100 g-1), Mg (88.84 mg 100 g-1), Mn (3.46 mg 100 g-1), Fe (13.89 mg 100 g-1) and K (689.41 mg 100 g-1). The species was considered a source of TDF, a good source of Mg, Cu and K, and an excellent source of vitamin A, Ca, Mn, Fe and Se.

In Vivo Monitoring of Acetylcholine Release from Nerve Endings in Salivary Gland.

Simple SummaryStimulation of the parasympathetic nervous system results in the secretion of saliva. Previous studies have demonstrated acetylcholine content in homogenate obtained from salivary glands. Acetylcholine in homogenate, however, includes that stored in the cells, as well as that released in the interstitial fluid. The activity of the parasympathetic nervous system is mainly determined by the amount of acetylcholine released. We established an in vivo microdialysis method for monitoring the acetylcholine released from nerve endings in the salivary glands in rats. The results of the present study demonstrated that acetylcholine levels in the dialysate reflect acetylcholine levels in the interstitial fluid of the submandibular gland, and that an increase in the acetylcholine level in the dialysate depends predominantly on the release of acetylcholine from the parasympathetic nerve endings.A microdialysis technique was used to monitor acetylcholine levels in the local interstitial fluid in rat submandibular glands, with the aim of determining parasympathetic nerve activity in vivo. The dialysis probe housed a 10 × 0.22 mm semipermeable membrane (molecular weight cutoffs: 50,000 Da). When the probe was perfused at 2 μL/min in vitro, the mean relative recovery of acetylcholine was 41.7% ± 2.5%. The dialysis probes were implanted in the submandibular glands of anesthetized rats and perfusion with Ringer’s solution, at 2 μL/min, was performed. Acetylcholine concentrations in the dialysate were measured by high-performance liquid chromatography and electrochemical detection. The results revealed the following: (1) that mixing Eserine with Ringer’s solution allowed acetylcholine in the salivary glands to be quantified; (2) that acetylcholine concentrations in the dialysate were highly variable and unstable over the first 120 min after probe implantation, but reached a nearly stable level (4.8 ± 2.7 nM) thereafter in the presence of 100 µM of Eserine; and (3) that electrical stimulation of the chorda tympani nerve, or perfusion with high potassium Ringer’s solution, significantly increased acetylcholine concentrations in the dialysate. These results indicate that the present microdialysis technique offers a powerful tool for detecting changes in parasympathetic activity within the salivary glands.

Lipid hydroperoxides in nutrition, health, and diseases.

Research on lipid peroxidation in food degradation, oil and fat nutrition, and age-related diseases has gained significant international attention for the view of improvement of societal health and longevity. In order to promote basic studies on these topics, a chemiluminescence detection-high performance liquid chromatography instrument using a high-sensitivity single photon counter as a detector was developed. This instrument enabled us to selectively detect and quantify lipid hydroperoxides, a primary product of lipid peroxidation reactions, as hydroperoxide groups at the lipid class level. Furthermore, an analytical method using liquid chromatography–tandem mass spectrometry has been established to discriminate the position and stereoisomerization of hydroperoxide groups in lipid hydroperoxides. Using these two methods, the reaction mechanisms of lipid peroxidation in food and in the body have been confirmed.

Selective Extraction and Determination of Citrinin in Rye Samples by a Molecularly Imprinted Polymer (MIP) Using Reversible Addition Fragmentation Chain Transfer Precipitation Polymerization (RAFTPP) with High-Performance Liquid Chromatography (HPLC) Detection

Citrinin (CIT) is a mycotoxin naturally in many foods that causes carcinogenic and mutagenic effects in the human body. A novel method was developed for the selective quantification of citrinin in rye samples. Citrinin-imprinted spheres were fabricated through reversible addition fragmentation chain transfer (RAFT) precipitation polymerization (RAFTPP) in the presence of 2-hydroxymethacrylate (HEMA, functional monomer), ethylene glycol dimethacrylate (EGDMA, cross-linker), citrinin (template), 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid (CTA, RAFT agent), azobisisobutyronitrile (AIBN, initiator), and acetonitrile (ACN, porogen). The imprinted polymers were shown to be spherical with a high surface area and a porous structure. The rebinding properties of citrinin to the imprinted spheres were also examined in detail. The maximum adsorption capacity, equilibration time, and imprinting factor were 38.6 mg g−1, 90 min, and 3.89, respectively. In addition, the citrinin-imprinted spheres were regenerated at least 10 times without change in the adsorption capacity. The citrinin-imprinted particles were used to selectively remove and determine the analyte in rye extract. The calibration relationship was linear between 1 and 100 µg kg−1 with a limit of detection of 0.35 µg kg−1. The method also had high recoveries (98 to 100.0%) and low relative standard deviations (less than 4.1%). Therefore, the imprinted spheres are suitable for the selective determination of citrinin in rye extracts.

Development of ultrasound-assisted centrifugal extraction and online solvent concentration coupled with parallel countercurrent chromatography for the preparation of purified phytochemicals: Application to Lycium ruthenicum

To improve the preparation efficiency of natural products, new techniques for extraction and concentration of natural products have been established. Based on this, an on-line technology to improve the yield and preparation efficiency of natural products have been established. In this study, a novel method to extract natural products from crops and plants, termed ultrasound-assisted centrifugal extraction (UACE), was developed as a supplement to a new online solvent concentration (OSC) technique. These techniques were coupled with parallel countercurrent chromatography (PCCC) and evaluated in the automated preparation of phytochemicals from Lycium ruthenicum. The UACE device comprises an extraction chamber and a solution separation chamber and offers the advantages of higher extraction efficiency, fewer impurities, and conduciveness to sample processing. The OSC device comprises a spray nozzle, concentrating cylinder, and hot-blast air nozzle. The mechanical parameters of the UACE and OSC were optimized, and the operation mode of online UACE combined with OSC and PCCC was described. Raw plant materials were extracted with a two-phase extractant comprising petroleum ether‒ethyl acetate‒ethanol‒water (2:2:1:6, v/v/v/v), and the aqueous and organic phases were then concentrated by OSC. After extraction and online concentration, the concentrate was separated. During PCCC separation, the on-line extraction, and concentration were still conducted. When the first cycle of the UACE/OSC/PCCC was completed, the second cycle was initiated, and so on. As a result, six target compounds with purities exceeding 97.03 % (high performance liquid chromatography detection at 250 nm) were successfully separated using the countercurrent chromatography solvent systems comprising n-heptane‒ethyl acetate‒acetonitrile‒water (20:4:17:1, v/v/v/v) and n-butanol–ethyl acetate–water (55:21:70, v/v/v). Compared with conventional extraction methods, the proposed method offers the advantages of efficiency, automation, high-purity separation of the analytes, and systematic preparation of natural products from crops.

The influence of anesthetics on neurotransmitters in the nervous system of Sepia pharaonis

Anesthesia is a stress mitigation technique widely used during transportation and short-term human manipulation, such as labeling and measurement of body parameters of aquatic animals. This is because anesthetics affect the content of neurotransmitters, exerting various effects on the body. This study determined optimal anesthetic concentration for cuttlefish by measuring the anesthetic and recovery duration of Sepia pharaonis. This was assessed with Nuclear magnetic resonance (NMR) combined with high performance liquid chromatography (HPLC) detection of nervous system metabolites and specific changes in the content of six neurotransmitters. Successful anesthetization of cuttlefish was observed with ethanol concentration (10–30 mL L−1). The cuttlefish recovered after anesthesia, with the longest exposure time being 60 min at a concentration of 10 mL L−1 ethanol. Likewise, the cuttlefish also reached a sedative state at a concentration below 5 mL L−1 ethanol, but with a maximum exposure time of 270 min. We concluded that the action of ethanol attributed to the 10–20% increase of glycine and tyrosine using NMR and HPLC analysis. We postulate the anesthetic role of ethanol in cuttlefish led to increased inhibitory neurotransmitters gamma-Aminobutyric acid, (GABA) and Glycine (Gly) while it reduced the levels of excitatory neurotransmitters acetylcholine (Ach), dopamine (DA) and 5-hydroxytryptamine (5-HT).However, cuttlefish recovery from anesthesia was probably due to rising Ach and Glutamate (Glu) levels.

HPLC Detection and Antioxidant Capacity Determination of Brown, Red and Green Algal Pigments in Seaweed Extracts.

This study was carried out to determine the main pigments in some different selected seaweeds and to reveal their antioxidant potential regarding the ever-increasing demand for utilization of marine pigments in human health and nutrition. The individual amounts of algal pigments were found by reverse phase high-performance liquid chromatography (HPLC) and their total antioxidant capacities (TAC) by two spectrophotometric TAC assays, namely: CUPRAC (CUPric ion Reducing Antioxidant Capacity) and ABTS/TEAC (2,2'-azinobis [3-ethyl benzo thiazoline-6-sulfonate])/(trolox equivalent antioxidant capacity). These two tests gave the same rank order for TAC. The TAC of HPLC-quantified compounds accounted for a relatively much lower percentage of the observed CUPRAC capacities of seaweed extracts, namely ranging from 11 to 68% for brown, from 4 to 41% for red and from 3 to 100% for green species, i.e., some TAC originated from chromatographically unidentified compounds. Fucoxanthin, chlorophyll a, and pheophytin a compounds were major pigments in brown algae. The relative carotenoid contents in red marine algae were generally lower than those of chlorophylls. Overall total quantities were quite low compared with those of brown species. In general, chlorophyll a and chlorophyll b were chiefly present in green algae, but β-carotene, violaxanthin and siphonaxanthin were also detected substantially higher in some species of green algae such as Caulerpa racemosa var. cylindracea and Codium fragile.

Enhancement of functional characteristics of blueberry juice fermented by Lactobacillus plantarum

Lactic acid bacteria with various probiotic functions and excellent fermentation characteristics are widely used in food production, which not only enhance flavor, but also improve functional quality. In this research, Lactobacillus plantarum J26 was selected as the fermented strain in blueberry juice, and the basic indexes, nutritional functional properties, antioxidant capacity and enzyme inhibition were tested to judge the fermentation process influences to blueberry matrix. The results showed that the total amount of phenolic substances increased by 43.42% after fermentation. Four kinds of anthocyanins were found through High Performance Liquid Chromatography (HPLC) detection. Then the scavenging abilities of DPPH, superoxide anion radical and hydroxyl radical were estimated to determine the antioxidant activities of fermented blueberry juice. Moreover, the effect of oxidative damage was also analyzed in the model of Caco-2 cells. Finally, the inhibition of α-glucosidase and α-amylase were both detected in fermented blueberry juice. To sum up, these findings suggested that L. plantarum J26 could be used as fermented strain in the blueberry juice to improve the functional activities.

Comparison of determination of sugar-PMP derivatives by two different stationary phases and two HPLC detectors: C18 vs. amide columns and DAD vs. ELSD

Reducing sugars, especially aldoses with their ring structures, have strong reducibility to react with 1-phenyl-3-methyl-5-pyrazolone (PMP) to form sugar-PMP derivatives detected by ultraviolet (UV) detector at 248 nm. In this study, several carbohydrates and some of their alcohols, including 1). seven main monosaccharides, 2). three common disaccharides, 3). two oligosaccharides, and 4). some sweeteners like sugar alcohols were investigated for their reactivities with PMP. Analytes were separated chromatographically by two common high performance liquid chromatography (HPLC) columns and subsequently detected by two tandem detectors. Results pointed out that C18 column had a stronger capacity to separate the reducing sugar-PMP derivatives rather than the sugar themselves. While amide column could only effectively separate the original sugars. These phenomena demonstrated that polarity of reducing sugars decreased after their PMP derivatization. Moreover, both diode array detector (DAD) and evaporative light scattering detector (ELSD) were able to detect the reducing sugar-PMP derivatives, including the PMP-derivative of the oligosaccharide hydrolysate of chitosan, though the DAD exhibits a higher sensitivity than ELSD. In conclusion, carbohydrates themselves are more likely to be efficiently separated by an amide column and detected by ELSD, while DAD combined with a C18 column has more power to determine carbohydrates derivatives.

Rat liver glutathione S-transferase-catalyzed conjugation of glutathione to the endogenous epoxides of oleic acid and cholesterol

cis-9,10-Epoxy-octadecanoic acid (oleic acid epoxide, OAE) and 5α,6α-epoxy-cholesterol (ChE) are endogenous epoxides. Unlike other epoxides, the oxirane groups of OAE and ChE are relatively stable against nucleophiles. OAE lacks toxicity and mutagenicity, while ChE is considered harmful, mutagenic and cancerogenic to animals. In humans, ChE is associated with cancer. The metabolism of OAE and ChE includes hydrolysis by cytosolic and microsomal hydrolases to their diols and glutathione (GSH) conjugation by GSH S-transferases (GST) to form the GSH conjugates (R-SG; R, residue). The GST-catalyzed GSH conjugation of OAE and ChE is poorly investigated. This article reports on the GSH conjugation of OAE, its methyl ester (OAEMe) and of ChE by rat liver homogenate GST. The GSH conjugates of OAE, OAEMe and ChE, i.e., OAE-SG, OAEMe-SG and ChE-SG, respectively, were determined by pre-column derivatization with o-phthaldialdehyde (OPA)/2-mercaptoethanol, high-performance liquid chromatography (HPLC) and fluorescence detection. Complex biphasic kinetics were observed with substrate inhibition of GST activity by OAE, OAEMe and ChE, an optimum pH of about 8.3 for OAE, and no measurable chemical GSH conjugation, underlying the importance of GST for the biotransformation of these epoxides. The results confirm the substrate concentration-dependent kinetic mechanism of GST isoforms first reported by William B. Jakoby (J. Biol. Chem. 1974) for exogenous electrophiles including the epoxide 1,2-epoxy-3-(p-nitrophenoxy)propane and the organic nitrates. This mechanism allows for maximal GST activity that can be achieved under given concentrations of GSH, epoxides and other electrophiles.

Use of high and ultra-high pressure based-processes for the effective recovery of bioactive compounds from Nannochloropsis oceanica microalgae

In this study, the recovery of different bioactive compounds from Nannochloropsis oceanica biomass is proposed using high and ultra-high pressure-based processes. The effect of different pretreatments to weaken cell wall was evaluated before pressurized liquid extraction (PLE). PLE was optimized using an experimental design with ethanol as extraction solvent. Optimum extraction conditions were found at 57 °C and 3 extraction cycles, providing a total carotenoids content of 115.1 ± 0.6 mg/g extract. Then, the residual biomass was extracted using limonene, and an enriched-lipid fraction was obtained. In parallel, ultra-high pressure extraction (UHPE) was applied directly to dry biomass to simultaneously disrupt the cell wall and extract the valuable compounds. Results showed that UHPE technique did not improve carotenoids extraction compared to PLE, although the recovery of polyunsaturated fatty acids was significantly better. Moreover, extracts were chemically characterized using high-performance liquid chromatography detection and gas chromatography coupled to mass spectrometry detection.

Novel metal-organic framework combining with restricted access molecularly imprinted nanomaterials for solid-phase extraction of gatifloxacin from bovine serum

Novel restricted access molecularly imprinted nanomaterials (RAMIPs) were successfully prepared on the surface of metal-organic frameworks (NH2-MIL-125) by surface-initiated atom transfer radical polymerization (SI-ATRP) technology. Then it was applied as a solid phase extraction (SPE) material in analysis of quinolones in bovine serum by HPLC detection. NH2-MIL-125@RAMIPs was empolyed as a sorbent for gatifloxacin (GTFX) and the resulted material has a good binding amounts (86.1 mg g−1), rapid binding kinetic (36 min). The results indicated that the prepared NH2-MIL-125@RAMIPs possess excellent specific recognition for GTFX. Combined with high-performance liquid chromatography (HPLC), the SPE column filled with NH2-MIL-125@RAMIPs was applied to selectively enrich GTFX antibiotic from bovine serum. The recovery of GTFX is between 96.8% and 105.6%, with relative standard deviations of 1.7–3.2% (n = 3). The research results illustrate that the method is successfully applied to the selective enrichment of GTFX in bovine serum. It provides a simple and efficient method for the direct detection of GTFX in bovine serum.

Hybridization of Metal-Organic Frameworks with attapulgite for magnetic solid phase extraction and determination of benzoylurea insecticides in environmental water samples

A magnetic Metal-Organic Frameworks composite material modified with attapulgite was prepared via in situ growth method and characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, N2 adsorption-desorption and vibration sample magnetometer analysis. It was applied as an efficient adsorbent for the magnetic solid-phase extraction of seven benzoylurea insecticides from environmental water samples couple with high-performance liquid chromatography detection. Under the optimized experimental conditions, the established procedure exhibited low limit of detection ranging from 0.75 to 1.5 µg L−1 and good linear response ranging from 2.5 to 500 µg L−1 with coefficients of determination >0.99. The method recoveries of spiked analytes at the concentrations of 20, 100 and 200 µg L−1 in real water samples were 73.56–99.63% with the relative standard deviations <7.53%. Moreover, the hybrid materials showed excellent reusability and there was no loss observed for the extraction efficiency within five cycles. This study highlighted the potential of functional Metal-Organic Frameworks as efficient adsorbents in sample pretreatment.

Hydrophilic magnetic molecularly imprinted nanobeads for efficient enrichment and high performance liquid chromatographic detection of 17beta-estradiol in environmental water samples

Novel magnetic molecularly imprinted nanobeads for 17β-estradiol (E2), namely, E2-MMINs, were synthesized by molecularly imprinted polymers on the surface of magnetic nanobeads in aqueous solvents. The hydrophilic nanobeads were set up by adopting carboxyl group-functionalized Fe3O4 nanoparticles as carriers, E2 as template molecule, and dopamine as functional monomer. The synthesized E2-MMINs were investigated in different aspects including synthesis conditions, physical and chemical properties, and adsorption conditions. The experimental results show that the E2-MMINs present not only thin imprinting layers, stable crystal form, and fast magnetic separation ability, but also rapid kinetics (20 min), high binding amount (41.48 mg g−1), satisfactory specificity (imprinting factor = 8.07), and favorable reusability (adsorption efficiency > 94.8% after reusing for 10 times). Moreover, the method employing E2-MMINs combined with high performance liquid chromatography for the specific enrichment and determination of trace E2 has been developed with the low LOD (0.008 μg L−1), and the application in environmental water samples has been proved. This work demonstrates that the proposed synthetic strategy is highly promising to the synthesis of hydrophilic nanobeads for efficient enrichment and detection of target molecule E2.

Preparation of poly (KH570-co-DVB) microspheres and application in HPLC for separation of benzene and benzene homologs

High-performance liquid chromatography (HPLC) is one of the most widely used separations and analysis methods, which has become an indispensable part of the separation and detection of mixtures, qualitative and quantitative analysis and other scientific research and social production fields. Because of the decisive effect of the chromatographic column on analysis and separation, it has become the core of research in the chromatographic system. In the past decades, the research and development of new chromatographic column stationary phase have been highly concerned. Monodisperse polymer microsphere, because of its special large pore structure, has good permeability and high specific surface area, which can be used as special materials in various fields, such as adsorption materials in the separation process, HPLC column packing, catalyst carrier, preparation template of nanomaterials and nuclear fusion targeting materials. When it is used in HPLC, because of the good permeability of microspheres, it can effectively improve the separation efficiency and performance. In this article, based on the previous work, a number of new polymer microspheres were prepared, and the prepared microspheres were used for the separation and detection of HPLC, and their physical and chemical properties were studied.