High-performance Liquid Chromatography Detection Research Articles

Establishment and Optimization of Flavonoid Extraction and Detection System for Hemerocallis

Hemerocallis is a characteristic vegetable with outstanding edible and medicinal value. Flavonoids are important bioactive components of Hemerocallis. To improve the extraction efficiency and detection accuracy of flavonoids from Hemerocallis, we established a high-performance liquid chromatography (HPLC) detection system, which can simultaneously detect multiple flavonoids. In addition to the previously developed organic solvent extraction method, an ultrasonic-assisted extraction technique that uses fewer samples was established to extract flavonoids from Hemerocallis. The extraction conditions of the ultrasonic-assisted extraction were optimized via a single-factor experiment and a response surface experiment. The HPLC system detected and determined the contents of rutin, isoquercetin, myricetin, quercetin, apigenin, and diosmetin from 70 Hemerocallis germplasm resources. In addition, we evaluated the antioxidant activity of flavonoids in Hemerocallis using DPPH free radical scavenging capacity with ascorbic acid (Vc) as a positive control. The results showed that the optimum conditions for the ultrasonic extraction process were as follows: sample weight of 0.25 g, ethanol volume fraction of 72%, ethanol volume of 2.5 mL, and ultrasonic extraction time of 17 min. Under these conditions, flavonoid extraction had a strong scavenging effect on DPPH. With the increase in the sample solutions’ concentrations, its antioxidant capacity was gradually enhanced, and the DPPH scavenging rate reached 70.2%. The optimized ultrasonic-assisted extraction technology can increase the total content of six flavonoids in day lily bud by 59.01%, especially the content of rutin (increased by 64.41%) in Hemerocallis flower buds. Among 70 Hemerocallis plant resources, we selected materials H0087 and H0059 with high and stable flavonoid content, with the total content of six substances being 4390.54 ug/g and 3777.13 ug/g. Thus, this study provides a reference for extracting and determining flavonoid contents in Hemerocallis materials. It also provides a theoretical basis for high-quality individual plant breeding.

Molecularly imprinted polymer membranes based on single template for recognition and extraction of carbamazepine and its structurally analogues

In this work, a novel molecularly imprinted polymer membrane (MIPM) using oxcarbazepine (OXC) as the single template and polyvinylidene difluoride membrane as the subtract was fabricated for recognition and extraction of carbamazepine (CBZ) and its analogues including OXC, carbamazepine-10,11-epoxide (CBZE), and monohydroxy derivative 10, 11-dihydro-10-hydroxy carbamazepine (MHD). The prepared MIPMs were characterized by scanning electron microscope, Fourier transform infrared spectroscopy, Brunaner-emmet-teller measurements and X-ray photoelectron spectroscopy, showing the successful construction of uniform and porous polymers on the surface of membranes. A series of adsorption affinity tests were investigated, indicating the prepared materials had specific recognition capacity and excellent stability as novel sorbents. The maximum static adsorption capacities of MIPMs towards OXC, CBZ, MHD or CBZE was 4.246, 3.621, 2.316, or 4.877 mg·g−1, respectively. The MIPMs showed reusability and reproducibility. The usability of MIPMs was evaluated by combining MIPMs extraction and high performance liquid chromatography detection for the determination of CBZ, CBZE, OXC and MHD in different matrices including methanol, normal saline, phosphate buffer solution, and plasma. The mean recovery of four target compounds in methanol, normal saline and phosphate buffer solution was more than 75 %, while the mean recovery of CBZ and CBZE in plasma was more than 80 %. The results demonstrated that the proposed MIPMs is very suitable for the determination of OXC, CBZ, MHD and/or CBZE in different matrices.

Smartphone as a fluorescence detector for high-performance liquid chromatography

BackgroundFluorescence detection is employed in high-performance liquid chromatography (HPLC) due to its high specificity and sensitivity. However, it is often limited by expensive components and bulkiness. Recently, advances in technology and electronics have led to the development of smartphones that can serve as portable recording, analysis, and monitoring tools. Smartphone-based detection provides advantages of cost effectiveness, rapid signal/data processing, and the display of results on a handhold monitor. The combination of smartphone-based detection with HPLC can offer unique features that are beneficial in overcoming limitations of commercial fluorescence detectors. (90) ResultsA miniaturized and low-cost HPLC fluorescence detector based on a smartphone is introduced for the detection of six fluorescent molecules. The smartphone is able to capture emitted fluorescence in video format while MATLAB code is used for data processing to provide chromatograms based on different detection channels. A custom designed double-channel flow cell was utilized to enable simultaneous detection of fluorescent compounds with different excitation wavelengths. The detector consists of a lab-made flow cell, monochromatic LEDs as the light source, 3D printed housing and connector box, fiber optic cables, and a smartphone. The effects of flow cell geometry, channel width and light slit diameter, as well as a comparison of different flow cell manufacturing techniques, are studied and discussed. The validated system was successfully applied to samples from diverse water sources, yielding spiking recoveries within the range of 91.7% and 109.7%. (141) SignificanceThis study introduces the first smartphone-based fluorescence detector for HPLC with cost-effective and customizable flow cells, allowing for the simultaneous detection of fluorescent compounds with different excitation wavelengths and offering a potential solution for the analysis of co-eluting compounds. Beyond its user-friendly interface and low-cost, smartphone detection in HPLC provides tremendous opportunities in further miniaturizing chromatographic instrumentation while offering high sensitivity and can be expanded to other mechanisms of detection. (70)

Advances in Extraction Techniques for Beer Flavor Compounds

Owing to the unique chemical properties exhibited by beer flavor compounds, different extraction methods have been utilized to extract these compounds from the sample matrix. Carbonyl compounds, which significantly contribute to flavor instability in beer, pose challenges in detection due to their low concentrations and reactivity. Consequently, the analysis of beer flavor compounds has focused on improving sensitivity and specificity through techniques that minimize sample preparation requirements and reduce interactions between factors involved in the analysis. Notably, extraction techniques such as headspace solid-phase microextraction (HS-SPME), stir bar sorptive extraction (SBSE), and gas diffusion microextraction (GDME) have been successfully applied to the analysis of carbonyl compounds in alcoholic beverages, including beer. Derivatization agents like 2,4-dinitrophenylhydrazine (DNPH) and O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) enhance the volatility and stability of analytes, facilitating their separation and detection in gas chromatography and high-performance liquid chromatography. Chromatographic separation methods, particularly gas chromatography and liquid chromatography, are extensively employed to identify and quantify aroma/flavor compounds in various foodstuffs, including beer. This review provides a comprehensive overview of extraction techniques and chromatographic methods used in the analysis of beer compounds.

Synthesis of novel hydroxyl-functionalized hyper-crosslinked polymer for extraction of phenylurea herbicides from environmental waters

Water resources are frequently contaminated by organic micropollutants (OMPs), which present a significant peril to ecosystem and well-being of the people. Phenylurea herbicides (PUHs) are an important class of OMPs since they are widely used in modern agriculture. However, efficient extraction of PUHs from water is of challenge because of their high water affinity. Therefore, the synthesis of novel adsorbent capable of effectively extracting PUHs from water is urgently needed. Here, three novel hydroxyl-functional hyper-crosslinked polymers (HCPs) were synthesized through Friedel-Crafts reaction by using the brominated β-cyclodextrin, i.e., heptakis(6-bromo-6-deoxy)-β-CD) [(CD-(Br)7)], as the building unit. Among them, PQ-CD-HCP, which was synthesized by using p-quaterphenyl (PQ) and CD-(Br)7, had the best adsorption capability for the PUHs. Finally, the quantitative determination of the PUHs for environmental waters was realized by using the PQ-CD-HCP as the solid-phase adsorbent in conjunction with high-performance liquid chromatographic detection. Under the optimal conditions, the limits of detection for environmental water samples were 0.02–0.05 ng mL−1. The method recoveries were 86.0%-116.5% with the relative standard deviations ≤ 7.8%. The PQ-CD-HCP also showed good adsorption performance for other OMPs such as triazine herbicides, chlorophenols, polycyclic aromatic hydrocarbons, endocrine disruptors, nitroimidazoles and benzoylureas insecticides, indicating its good application prospect. The adsorption experiments show that the PQ-CD-HCP extracts the analytes by encapsulation, π-stacking, hydrophobic and hydrogen bonding interactions.

Green construction of hydroxyl-functionalized magnetic porous organic framework for effective extraction of triazine herbicides from environmental water and watermelon juice samples

Triazine herbicides have been widely detected in water resources and food, which poses a potential hazard to both ecosystem and human health. Due to their high polarity, conventional adsorbents have limitations for their extractions. Herein, for the effective magnetic extraction of triazine herbicides, a novel and effective magnetic adsorbent was prepared with a satisfactory extraction performance. In the experiments, five porous organic frameworks (POFs) with hydroxyl functional groups were synthesized by diazo-coupling reactions in aqueous solution with β-cyclodextrin (β-CD) as a green monomer. After evaluation of the five POFs, the DDM-CD-POF, which was synthesized with 4′4-diaminodiphenylmethane (DDM) and β-CD, showed the largest specific surface area and the best adsorption capacity for the five triazine herbicides. Then, it was magnetized by introducing Fe3O4@SiO2 into it to prepare a magnetic adsorbent (M-DDM-CD-POF) to facilitate separation and recycling. Finally, the M-DDM-CD-POF-based magnetic solid-phase extraction in combination with high performance liquid chromatographic detection method was established for the quantitative determination of the triazine herbicides in environmental water and watermelon juice samples. The current strategy showed low limits of detection of 0.03–0.11 ng mL−1 for environmental water and 0.07–0.22 ng mL−1 for watermelon juice sample. The method recoveries for spiked samples ranged from 84.0% to 113.0% with the relative standard deviations ≤8.8%. This work provides a new approach for the detection of the triazine herbicides with good application prospect.

Preparation and evaluation of molecularly imprinted polymers based on magnetic graphene oxide for selective extraction and determination of quercetin in red wine

In this work, a high selectivity molecularly imprinted polymer (Fe3O4/GO@MIP) for quercetin was successfully synthesized by combination of surface molecular imprinting technology and magnetic graphene oxide (Fe3O4/GO). Several characterization methods were adopted to verify the successful synthesis of Fe3O4/GO@MIPs. The resultant Fe3O4/GO@MIPs exhibited outstanding adsorption capacity (18.24 mg g−1), remarkable regeneration ability and excellent selectivity toward quercetin. The results indicated that the Fe3O4/GO@MIPs had higher adsorption capacity and better selectivity for quercetin compared with non-imprinted polymers (Fe3O4/GO@NIPs). The wide linearity of the proposed method was achieved within the concentration of quercetin from 0.1 to 200 μg mL−1 with R2 > 0.999, and the limit of detection (LOD) was calculated as 0.03 μg mL−1. Under the optimum conditions, the satisfactory recoveries for quercetin in the spiked red wine samples were in the range of 96.8%–101.4% with the relative standard deviation (RSD) less than 5%. Furthermore, the obtained Fe3O4/GO@MIPs were further employed as promising adsorbents for the separation and detection of quercetin in red wine combined with high performance liquid chromatography (HPLC) detection.

Thoughtful design of a covalent organic framework with tailor-made polarity and pore size for the enrichment of bisphenols and their derivatives: Extraction performance, adsorption mechanism and toxicity evaluation

A stable, reusable and cost-effective covalent organic framework (COF) with medium polarity was successfully decorated on Fe3O4. The Fe3O4@COF contained tailor-made polarity and pore size that fitted well with bisphenols and their derivatives (BPs). When coupling magnetic solid-phase extraction (MSPE) with high-performance liquid chromatography (HPLC) detection, the Fe3O4@COF featured efficient recognition and enrichment for BPs due to π-π stacking, C–H⋯π interactions, pore-filling effect, dispersion force and hydrophobic interactions. Under optimized conditions, calibration plots exhibited good linearity (5–1000 ng mL−1), and limits of detection (LOD) ranged from 0.15 to 0.39 ng mL−1. The method was successfully employed in quantifying BPs in authentic lake and river water samples with satisfactory recoveries ranging from 81.4% to 120%. Molecular dynamics simulation revealed extraction mechanisms, and a microscopic behavior related to the clustering property of the emerging brominated compounds was first discovered. Ecotoxicological assessments of target pollutants were conducted from multiple aspects, highlighting the harmfulness of the chemicals and the significance of the analytical method. The proposed methodology offered sensitive detection and quantification, which was beneficial for the timely tracking of the concentration, transportation and distribution of BPs to better explore their environmental behavior and tackle contamination problems in complex environmental matrices.

Synthesis of spherical amine-functionalized silica molecular sieve and application as selective adsorbents for aromatic hydrocarbons analysis

In this work, spherical amine-functionalized mesoporous silica (Sp-Amino-Si) molecular sieve was fabricated by an acid hydrothermal method using 3-aminopropyltriethoxysilane as a modifier and toluene as the solvent. The results of scanning electron microscopy, Barrett-Joyner-Halenda pore size distribution, Fourier transform-infrared spectroscopy, and low-angle X-ray diffraction patterns revealed that the Sp-Amino-Si was monodispersed microspheres with uniform and controllable pore sizes sharing two-dimensional hexagonal P6mm symmetry and a large number of amino groups. The Sp-Amino-Si molecular sieve was verified to be suitable for the selective separation of aromatic hydrocarbons (AMHs) containing two fused benzene rings among other compounds from environmental water matrix. Under the optimized conditions, the Sp-Amino-Si exhibited much higher adsorption efficiency for AMHs (above 88.19%), comparing to the original SBA-15 (below 44.52%). The maximum adsorption capacities for naphthalene, methyl naphthalene, 2-methyl naphthalene, and acenaphthene were 477.1, 1006.5, 893.3, and 1253.2 µg·g−1, respectively. The high selectivity of Sp-Amino-Si for the four AMHs attributed to the size sieving and p-π interactions between the lone pair electrons of amine groups and the π-electrons in AMHs molecules. The Sp-Amino-Si based solid-phase extraction coupled with high performance liquid chromatography detection method was constructed for the analysis of the four AMHs, and the recoveries of spiked AMHs ranged from 89.67% to 112.74% with a relative standard deviation lower than 5.75%. This study provides some inspiration and a reliable method for AMHs separation, removal, and analysis.

Effect of Soil Composition on Secondary Metabolites of Moroccan Saffron (Crocus sativus L.)

Climate and soil are important factors that affect the quality of saffron. Saffron quality is determined by the marked content of secondary metabolites. The objective of this work was to study the effect of soil physicochemical properties on the secondary metabolites of saffron. Our study concerned the analysis of saffron samples by high-performance liquid chromatography-detection by diode array (HPLC-DAD). Soil samples were analyzed by physicochemical methods, ED-XRF fluorescence and X-ray diffraction to determine the different types of clays. Saffron samples grown in loam-clay-sand soils contained high values of crocins and kaempferol 3-sophoroside 7-glucoside but low values of safranal. In addition, saffron samples grown in soils rich in organic matter, phosphorus and potassium contained high values of crocins and kaempferol 3-sophoroside 7-glucoside but low values of safranal. This original approach was carried out for the first time in our study, both by ED-XRF fluorescence and by X-ray diffraction, to determine what elements affect the quality of saffron. Thus, we concluded that clays containing low amounts of iron could have a positive effect on the coloring strength of saffron.

One-Step Synthesis of Polydopamine-Coated Dummy Molecularly Imprinted Polymers on the Surface of Fe3O4 for Selective Extraction and Enrichment of Aflatoxin B in Foods Prior to High-Performance Liquid Chromatography Detection

One-Step Synthesis of Polydopamine-Coated Dummy Molecularly Imprinted Polymers on the Surface of Fe3O4 for Selective Extraction and Enrichment of Aflatoxin B in Foods Prior to High-Performance Liquid Chromatography Detection

Preparation and anti-tumor effects of mesoporous silica nanoparticles loaded with trifluoperazine.

We have developed a targeted nano-drug delivery system that effectively harnesses the anti-tumor properties of trifluoperazine (TFP), while concurrently mitigating its side effects on the central nervous system. The manufacturing process entailed the preparation of mesoporous silica nanoparticles (MSN-NH2), followed by the loading of trifluoperazine into the pores of MSN-NH2 and then surface modification with polyethylene glycol (PEG) and anisamide (AA), resulting in the formation of TFP@MSN@PEG-AA (abbreviated as TMPA) nanoparticles. In vitro and in vivo anti-tumor activity and hemolysis experiments showed that TMPA had an excellent safety profile and a good anti-tumor effect. Importantly, the drug content of the TMPA nanoparticle group was found to be significantly lower than that of the TFP group in the mouse brain tissue as determined by High Performance Liquid Chromatography (HPLC) detection. Therefore, the developed drug delivery system achieved the goal of maintaining TFP's anti-tumor action while avoiding its negative effects on the central nervous system.

Agrobacterium tumefaciens mediated genetic transformation of Tripterygium wilfordii and its application to enhance the accumulation of triptolide

Triptolide, an important representative active compound of Tripterygium wilfordii, is hopeful to be developed into modern drug. However, the content of triptolide in natural plants is very low, which seriously restricts its development in the pharmaceutical industry. As a perennial woody vine, research on the genetic transformation of T. wilfordii is challenging and slow, which limits the process of improving triptolide content through biotechnology. In this study, the concentrations and combinations of growth regulators for T. wilfordii callus induction and regeneration were firstly optimized. The 2,4-dichlorophenoxyacetic acid (1 mg/L) was efficient to induce callus formation from leaf explants, while 2.0 mg/L 6-benzylaminopurine with 0.1 mg/L α-naphthaleneacetic acid had the best effect on regeneration from callus. Subsequently, the effect of different concentrations of screening agent (kanamycin or hygromycin B) on callus induction rate was determined. Then, Agrobacterium tumefaciens mediated genetic transformation was established and validated by two different plant expression vectors, pCambia1301 and pJCV53, corresponding to β-glucuronidase histochemical assay and monomeric red fluorescent protein fluorescence detection, respectively. It took 3–4 months from A. tumefaciens infection to complete transgenic plant regeneration. Based on this transformation system of T. wilfordii, the overexpression of miltiradiene synthase gene (TwMS) was performed. Real-time quantitative PCR analysis indicated that the expression levels of TwMS were highly up regulated in the transgenic plants compared with control line. The detection of high-performance liquid chromatography showed that overexpression of TwMS resulted in a 1.20–1.51-fold increase of triptolide in the transgenic lines. These results indicated that this efficient A. tumefaciens mediated genetic transformation provides a useful tool for future T. wilfordii genetic engineering studies to enhance the accumulation of triptolide in this economically important medicinal plant.

Differential Effects on HbA1c Detection by HPLC and Capillary Electrophoresis in Five Types of Hb Variants in China.

Hemoglobin A1c (HbA1c) can be used to evaluate blood glucose control. Its measurement will be affected by many factors, but Hb variation is the most critical factor. This study aimed to explore the types of variants found in routine work and their impact on test results. Samples with abnormal HbA1c chromatograms found in routine testing were tested with high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) and then further tested with polymerase chain reaction (PCR) and sequencing. Five recessive heterozygous mutations were identified after PCR and sequencing. Hb Riccarton-II (a mutation in the HBA2 gene), Hb E, Hb G-Coushatta, Hb G-Taipei, and Hb North Manchester (a mutation in the HbB gene) were identified. All HbA1c values of these variants detected by HLC-723 G8 (HPLC method) were lower than those of Sebia Capillarys 2 FP (C2FP, CE method) with P < .0001. Five Hb mutations were identified in our routine HbA1c test, and their HPLC detection values were significantly lower than those obtained with the CE method.

Unpruning improvement the quality of tea through increasing the levels of amino acids and reducing contents of flavonoids and caffeine.

Tea tree [Camellia sinensis var. sinensis or assamica (L.) O. Kuntze], an important crop worldwide, is usually pruned to heights of 70 to 80 cm, forming pruned tea tree (PTT) plantations. Currently, PTTs are transformed into unpruned tea tree (UPTT) plantations in Yunnan, China. This has improved the quality of tea products, but the underlying reasons have not been evaluated scientifically. Here, 12 samples of sun-dried green teas were manufactured using fresh leaves from an UPTT and the corresponding PTT. Using sensory evaluation, it was found that the change reduced the bitterness and astringency, while increasing sweetness and umami. Using high performance liquid chromatography detection showed that the contents of free amino acids (theanine, histidine, isoleucine and phenylalanine) and catechin gallate increased significantly (P < 0.05), whereas the content of alanine decreased significantly (P < 0.05). A liquid chromatography–mass spectrometry-based metabolomics analysis showed that the transformation to UPTT significantly decreased the relative levels of the majority of flavonols and tannins (P < 0.05), as well as γ-aminobutyric acid, caffeine and catechin (epigallocatechin, catechin, epigallocatechin gallate, gallocatechin gallate), while it significantly increased the relative contents of catechins (gallocatechin, epicatechin, epicatechin gallate and catechin gallate), phenolic acids and some amino acids (serine, oxidized glutathione, histidine, aspartic acid, glutamine, lysine, tryptophan, tyramine, pipecolic acid, and theanine) (P < 0.05). In summary, after transforming to UPTT, levels of amino acids, such as theanine increased significantly (P < 0.05), which enhanced the umami and sweetness of tea infusions, while the flavonoids (such as kaempferol, myricetin and glycosylated quercetin), and caffeine contents decreased significantly (P < 0.05), resulting in a reduction in the bitterness and astringency of tea infusions and an increase in tea quality.

Study on microbial community of "green-covering" Tuqu and the effect of fortified autochthonous Monascus purpureus on the flavor components of light-aroma-type Baijiu.

"Green-covering" Tuqu (TQ), as one of Xiaoqu, is a special fermentative starter (also known as Jiuqu in Chinese) that originated in southern China and is characterized by a layer of green mold covering (Aspergillus clavatus) the surface and (sometimes) with a red heart. It plays a vital role in producing light-aroma-type Baijiu (LATB). However, to date, the microbiota that causes red heart of TQ remain largely unexplored, and it is still unclear how these microbiota influence on the quality of LATB. In this study, two types of TQ, one with a red heart (RH) and another with a non-red heart (NRH), were investigated by high throughput sequencing (HTS) and directional screening of culture-dependent methods. The obtained results revealed the differences in the microbial communities of different TQ and led to the isolation of two species of Monascus. Interestingly, the results of high performance liquid chromatography (HPLC) detection showed that citrinin was not detected, indicating that Monascus isolated from TQ was no safety risk, and the contents of gamma-aminobutyric acid in the fermented grains of RH were higher than that of NRH during the fermentation. Selecting the superior autochthonous Monascus (M1) isolated from the TQ to reinoculate into the TQ-making process, established a stable method for producing the experimental "red heart" Tuqu (ERH), which confirmed that the cause of "red heart" was the growth of Monascus strains. After the lab-scale production test, ERH increased ethyl ester production and reduced higher alcohols production. In addition, Monascus had an inhibitory effect on the growth of Saccharomyces and Aspergillus. This study provides the safe, health-beneficial, and superior fermentation strains and strategies for improving the quality of TQ and LATB.

Boronic acid grafted metal-organic framework for selective enrichment of cis-diol-containing compounds

This study constructed boronic acid grafted Zr-MOF (BA-Zr-MOF) by a simple pre-installation strategy through mixed organic ligands. Typically, BA-Zr-MOF was prepared by one-step hydrothermal method used for enrichment of cis-diol-containing nucleosides through pipette tip solid-phase extraction (PT-SPE) followed by detection of high-performance liquid chromatography. It is worth mentioning that BA is well assembled into MOF and cis-diol-containing compounds can be efficiently and selectively enriched by abundant boronic acid groups. Three groups of different types of compounds were used to evaluate their selectivity and the results showed the excellent selectivity to cis-diol-containing compounds of as-prepared adsorbent. The BA-Zr-MOF adsorbent possesses a high adsorption capacity, which can reach 86.40 mg g−1 for adenosine. Under the optimal extraction condition, a PT-SPE-HPLC method based on BA-Zr-MOF for analysis of nucleosides was established. The linear range of the four nucleosides is 0.01 to 50 µg mL−1 with R2 ≥ 0.99 and the detection limits (LODs) are estimated at between 0.005-0.012 µg mL−1. The recoveries in urine were used to test the reliability of the analytical methods, which ranged from 82.8% to 117.1%, with intra-day relative standard deviations (RSDs) ranged from 0.1% to 4.2% and the inter-day RSDs ranged from 0.2% to 6.2%. All the results show that the pre-installation strategy based on dual ligands is an alternative to fabricate MOF composite material and BA-Zr-MOF is a promising material for the analysis of cis-diol-containing biomolecules.

Polyurethane functionalized silica aerogel for in-tube solid-phase microextraction of estrogens prior to high performance liquid chromatography detection

In order to improve the extraction performance and stability of silica aerogel, the polyurethane was used to functionalize silica aerogel. A silica aerogel hybridized with polyurethane was in situ prepared on the surface of basalt fibers for in-tube solid-phase microextraction (IT-SPME). When a polyetheretherketone tube filled with the modified basalt fibers was combined with high performance liquid chromatography (HPLC), an online IT-SPME-HPLC method for the detection of five estrogens in environment samples was developed. This method achieved wide linear ranges (0.1–50.0 μg L−1 and 0.03–100.0 μg L−1), low limits of detection (0.01 μg L−1 and 0.03 μg L−1), high enrichment factors (1178–3102), and acceptable relative standard deviations (n = 5, 2.1–4.9% and 3.7–6.9%) for intra-day and inter-day tests. Compared with other methods, the method exhibited some superiorities including online analysis, better sensitivity and faster test. It has been verified that the method can sensitively determine some estrogens from water samples.

HPLC Analysis of Patulitrin and Patuletin in Flowers of Tagetes Patula L.

The flowers of spreading marigold (Tagetes patula L.) are new interesting view of medicinal plant material. This raw material is one of the valuable sources of flavonoids. The aim of this study was to develop a method for the quantitative determination of the patulitrin (7-O-β-D-glucopyranoside of 3,5,7,3’,4’-pentahydroxy-6-methoxyflavone) and patuletin (3,5,7,3’,4’-pentahydroxy-6-methoxyflavone) content in flowers of spreading marigold by HPLC. The inflorescences of spreading marigold (Tagetes patula L.) variety "Tangerine", collected in August-September 2018 and 2019 in the Botanical Garden of the Samara University. The water-alcohol extracts were obtained from spreading marigold flowers, which were used for qualitative and quantitative analysis, as well as for preparative isolation of individual compounds. There was developed the method of determination of patulitrin and patuletin in the spreading marigold flowers (Tagetes patula L.) using high performance liquid chromatography (HPLC). The content of dominant flavonoid patulitrin in the flowers of T. patula varies from 5.11±0.18% to 5.64±0.17%. The error of single determination of patulitrin in the spreading marigold flowers with confidence probability of 95 % is ±3.32%. The results of the studies carried out indicate the advisability of the standardization of the flowers of the spreading marigold by determining of the content of the main and diagnostically significant flavonoid, patulitrin, using the HPLC method and detection on a UV detector at a wavelength of 360 nm.

Determination of phenolic acids in Rehmannia glutinosa rhizosphere using a new method of microdialysis-HPLC

Microdialysis is an important technology in the field of medicine, and with the popularization and development of microdialysis technology, it has been gradually applied to the field of ecology. In this study, microdialysis-HPLC as a new and environmentally friendly in situ technique was developed and applied for the first time to detect phenolic acid allelochemicals in Rehmannia glutinosa rhizosphere. A response surface analysis (RSM) was used to optimize the microdialysis in situ based on the Box–Behnken design (BBD) experiment. The optimum dialysis conditions were obtained as follows: the perfusion solution was a NaCl solution of 200 mmol/L with pH 4, and the dialysis temperature was 37 °C. Under these conditions, the content of phenolic acids in the rhizosphere 10, 20 and 30 cm away from the root was analyzed using high-performance liquid chromatography (HPLC) detection combined with the standard curve of phenolic acid addition. Compared to traditional methods, microdialysis-HPLC is a simple and environmentally friendly method for the in situ detection of phenolic acids in rhizosphere.