Chromatographic Peak Areas Research Articles

Factors affecting untargeted detection of doping agents in biological samples.

Doping control is essential for sports, and untargeted detection of doping agents (UDDA) is the holy grail for anti-doping strategies. The present study examined major factors impacting UDDA with metabolomic data processing, including the use of blank samples, signal-to-noise ratio thresholds, and the minimum chromatographic peak intensity. Contrary to data processing in metabolomics studies, both blank sample use (either blank solvent or plasma) and marking of background compounds were found to be unnecessary for UDDA in biological samples, the first such report to the authors' knowledge. The minimum peak intensity required to detect chromatographic peaks affected the limit of detection (LOD) and data processing time for untargeted detection of 57 drugs spiked into equine plasma. The ratio of the mean (ROM) of the extracted ion chromatographic peak area of a compound in the sample group (SG) to that in the control group (CG) impacted its LOD, and a small ROM value such as 2 is recommended for UDDA. Mathematical modeling of the required signal-to-noise ratio (S/N) for UDDA provided insights into the effect of the number of samples in the SG, the number of positive samples, and the ROM on the required S/N, highlighting the power of mathematics in addressing issues in analytical chemistry. The UDDA method was validated by its successful identification of untargeted doping agents in real-world post-competition equine plasma samples. This advancement in UDDA methodology will be a useful addition to the arsenal of approaches used to combat doping in sports.

Assessing the quality consistency of red yeast medicinal material by five-wavelength fusion fingerprint and ultraviolet quantum fingerprint corresponding with antioxidant activity analysis

In this study, a five-wavelength fusion fingerprint (FWFFT) combined with all-ultraviolet(UV) and antioxidant methods was used to explore the quality consistency of red yeast (RYT) samples. 1,1-Diphenyl-2-picrylhydrazyl Free Radical (DPPH) was used for antioxidant experiments, combined with high performance liquid chromatography (HPLC), and grey correlation analysis (GCA) was performed with chromatographic peak area. The results showed that multi-wavelength fusion technology compensates for the shortcomings of single-wavelength technology, and the combination with UV avoids of the one-sidedness of single technology. Simultaneously, the fingerprint peak of the sample and the antioxidant activity had a high correlation, and the antioxidant activity had a corresponding relationship with the content of the two controls. This study provides a comprehensive and reliable method for the quality consistency evaluation of traditional Chinese medicines (TCM).

Influence of ethanol content on the detection of volatile components in Huangjiu

Huangjiu (Chinese rice wine) is a traditional Chinese fermented wine with a unique flavor. The components of this wine are complex, and the ethanol content of different Huangjiu preparations varies greatly. In this study, changes in the chromatographic peak areas of the volatile components of Huangjiu samples with different ethanol contents were measured using headspace-gas chromatography (HS-GC). The influence of ethanol on the quantitative detection of different volatile components of Huangjiu at gas-liquid equilibrium was also analyzed. When the ethanol content of Huangjiu was in the range of 10%-19% vol, the peak areas of 16 volatile components (i. e., sec-butanol, n-propanol, isobutanol, n-butanol, isoamyl alcohol, β-phenyl-ethanol, acetaldehyde, isovaleraldehyde, benzaldehyde, ethyl formate, ethyl acetate, isobutyl acetate, isoamyl acetate, ethyl hexanoate, ethyl lactate, and diethyl succinate) were negatively correlated with the ethanol content. Increases in the ethanol content of the liquor changed the gas-liquid equilibrium of most other trace volatile components. In addition, only the peak area of acetal was positively correlated with ethanol content. The content of acetal in Huangjiu was affected by the alcohol content, and its decomposition reaction occurred along with the dilution process. The influence coefficient of ethanol content on the peak area of the above compounds ranged from -12.4% to 4.9%. The vapor pressure of most volatile components decreased with increasing ethanol content, and different components were affected in different ways. Compared with those of other components, the peak areas of methanol, furfural, and acetic acid were less affected by the ethanol content. These components were also affected by other factors, such as ionization and chemical reactions occurring during the dilution process. When different wine samples were adjusted to the same ethanol content, the concentration of volatile components in these samples became proportional to the total chromatographic peak area and the influence of the matrix effect of ethanol on the quantitative analysis was effectively eliminated. Thus, when researchers use pretreatment methods based on the principle of gas-liquid balance to carry out the quantitative detection of flavor components, they should adjust different rice wine samples to the same alcohol content to effectively control the matrix effect caused by differences in ethanol content and achieve accurate quantitative analysis.

Improvement of analytical determination of cyproconazole and propiconazole in fruit crops

Goal. Development and unification of the method of simultaneous determination of cyproconazole and propiconazole in fruits (apples, peaches, grapes) by gas-liquid chromatography (GC).
 Methods. The active substances were determined by gas-liquid chromatography (GC) using a gas chromatograph «Perkin Elmer 8410» with an NPD detector. Propiconazole and cyproconazole were identified by the retention time of the compounds, quantification by the calibration dependence of the chromatographic peak area of the analyte on its concentration in the calibration solution by correlation and regression analyzes.
 Results. The choice of the method of determination is limited by the physicochemical properties of the active substance and the characteristics of the object under study (matrix). The optimal conditions for determination were selected using a chemical-analytical monitoring algorithm and a system for multiquantitative determination of pesticides in matrices. According to them, the matrices are analyzed in stages: extraction, purification, qualitative and quantitative determination. Cyproconazole and propiconazole are low-polar compounds (µ of their cis- and trans-isomers are 4.43; 4.71 and 3.80; 4.20 D, respectively), so extraction was performed with chloroform (ε 5.1). Purification of extracts from coextractive substances of matrices was performed by TLC. Compounds were identified by retention time, and quantification (C, µg/ml) was performed on the areas of chromatographic peaks (S, mm2) in the range of linear detection (2—10 ng) according to the linear regression equations: Sc = 11.991 C — 6.096 (R2 = 0.998); Sp = 13.721 C – 4.221 (R2 = 0,994). The average value of measurement is 81.0—87.8%; standard deviation 2.21—5.38%; confidence interval (P 0.95; n = 15) 1.94—4.72%.
 Conclusions. Optimal selective conditions for the analysis of triazole derivatives by chromatographic methods provide simultaneous determination of test compounds and quality control of fruit crops on the content of residual amounts of cyproconazole and propiconazole at the level of hygienic standards (MAL 0.05—0.10 mg/kg).

Control of contamination of raw milk by antibiotics

Foreign biologically active substances that can be contained in milk of cows, which having a negative impact on the health and quality of life of people are antibiotics. Intensive use of antibiotics in veterinary practice contributes to the globalization of micro doses in the environment, accelerates the evolution and spread of resistant forms of microorganisms. The principle of prioritizing the safety of dairy products, based on the mandatory control of raw milk for the content of residual amounts of antibiotics, is implemented in accordance with the requirements of regulatory and technical documents. There is a need to use high-tech laboratory methods of detection of antimicrobial drugs in raw materials and livestock products. The purpose of the research was to control the contamination of raw milk by antibiotics. Raw milk of morning milking from cows of Black-and-White breed was used for the research. Milk was obtained at the zoo station of the Federal State Budgetary Educational Institution of Higher Education “Russian State Agrarian University – Moscow Timiryazev Agricultural Academy”. In the samples residual amounts of antibiotics of diff erent pharmacological groups, most widely used in productive animal husbandry were determined. Sampling of raw milk and their preparation for research was carried out in accordance with State Standard T 26809.1-2014. The determination of residual amounts of antibiotics was carried out by the method of an internal standard for the areas of chromatographic peaks of identifi ed compounds using a calibration characteristic obtained by analyzing calibration solutions of known compounds under similar conditions. It was established that monitoring the health of lactating cows, strict compliance with the rules for the use of veterinary medicines, the exclusion of errors in the technology of production of feed and feed additives, contribute to minimizing contamination of raw milk by antibiotics.

Determination of complexation ability of rhubarb with copper ions by ultra-high performance liquid chromatography

Gandou decoction (GDD) is a traditional Chinese medicine prescription that has been widely used to treat copper metabolism disorders in China with remarkable clinical effect and lower toxicity. However, evaluation of the complexation ability of copper ions is challenging, which hinders screening and discovery of coordinate active ingredients in GDD. An analytical method is needed to determinate the complexation ability of chemical constituents with copper ions. In this study, a rapid and accurate method based on ultra-high performance liquid chromatography (UHPLC) was developed to determine the complexing ability of rhubarb with copper ions. First, the optimal coordination reaction conditions between active ingredients of rhubarb and copper ions were determined. The samples were separated using an Agilent Eclipse Plus C18 column (50 mm×2.1 mm, 1.8 μm) with 5 μL injection volumes. The mobile phase was gradient eluted with methanol and water containing 0.1% (v/v) phosphoric acid at a flow rate of 0.3 mL/min. The detection wavelength was 254 nm and the column temperature was 30 ℃. Under the optimized chromatographic conditions, the rhubarb constituents were effectively separated. Next, peak areas of rhubarb were calculated before and after the coordination reaction between copper ions. The complexing ability of active ingredients in rhubarb with copper ions was evaluated by calculating the rate of changes of their chromatographic peak areas. Finally, ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was used to identify the coordination active ingredients in rhubarb extract. Focusing on the coordination reaction conditions between active ingredients of rhubarb and copper ions revealed that the active ingredients of rhubarb and copper ions reached equilibrium by coordination reaction at pH 9 for 12 h. Methodological evaluation revealed the good stability and repeatability of the method. Under these conditions, 20 major components of rhubarb were identified by UPLC-Q-TOF-MS. According to the coordination rate of each component and copper ions, eight components with strong coordination were screened out (gallic acid 3-O-β-D-(6'-O-galloyl)-glucopyranoside, aloe emodin-8-O-β-D-glucoside, sennoside B, l-O-galloyl-2-O-cinnamoyl-glucoside, chysophanol-8-O-β-D-(6″-O-acetyl)-glucoside, aloe-emodin, rhein and emodin). The respective complexation rates of the components were 62.50%, 29.94%, 70.58%, 32.77%, 34.61%, 26.07%, 28.73% and 31.78%. Compared with other reported methods, the presently developed method can be used to screen the active ingredients of traditional Chinese medicines that have complexing ability with copper ions, especially in complex mixture systems. This study describes an effective detection technology for evaluating and screening the complexing ability of other traditional Chinese medicines with metal ions.

Identification and synthesis of metabolites of the new antiglaucoma drug

Introduction: The determination of biotransformation products is an essential part of the preclinical trial of original medicines. These studies have not been conducted before for the new drug 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide. Identification and synthesis of metabolite substances are necessary for subsequent tests of bioavailability, linearity of pharmacokinetics, accumulation, distribution and excretion. Materials and methods: The study was carried out on Wistar rats and rabbits of the Soviet Chinchilla breed. The substance of the drug was administered to animals intraperitoneally. The collection of animal blood samples was performed before administration and 1 h, 2 h, 4 h, 24 h after administration into K3EDTA-tubes. A part of each sample was centrifuged to separate the plasma. Rat urine samples were taken before administration and at intervals of 0-2 h, 2-4 h, 4-6 h, 6-24 h after administration of the drug. The HPLC-MS/MS method was used to identify metabolites in biological fluids. The assumed biotransformation products were synthesized after preliminary analysis. The structure of the obtained substances was confirmed by NMR spectroscopy and high-resolution mass spectrometry. Then, a comparison was carried out with the compounds identified in biological fluids by retention time, ratios of chromatographic peak areas at the main MRM-transitions using HPLC-MS/MS. Results and discussion: A metabolite formed by addition an oxygen atom to a drug molecule, as well as an acylated metabolite were detected during the analysis of plasma and blood samples. A compound with an increased molecular weight of 1 dalton compared to the drug substance was also present in a rat urine. N-hydroxy-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide, 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonic acid, which could potentially be obtained during biotransformation, as well as N-acetyl-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide were synthesized. Repeated HPLC-MS/MS tests confirmed the correctness of the initial hypothesis. It was found that a sulfonic acid derivative is formed in urine as a result of decomposition of N-hydroxymetabolite during sample collection. Conclusion: The studied drug is metabolized by formation of two metabolites: N-hydroxy-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide and N-acetyl-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide. N-hydroxymetabolite is able to decompose in biological fluids samples with formation of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonic acid.

STUDY OF THE CHEMICAL COMPOSITION OF STACHYS PALUSTRIS L. ESSENTIAL OIL PRODUCING IN THE ASTRAKHAN REGION

Samples of essential oil from the ground part of Stachys palustris L., which grows wild in the Astrakhan region, were obtained by hydrodistillation, and the dependence of its yield on the growing season of the plant was studied. The duration of the hydrodistillation process was set experimentally to study the dynamics of changes in the results of essential oil over time. The yield of essential oil is observed in % when converted to the weight of absolutely dry raw materials. The highest yield of essential oil was obtained from plants in the flowering phase (0.19–0.20%). Quantitative analysis of the main components of Stachys palustris L. essential oil was carried out by GC-MS method. The quantitative content of essential oil components was calculated from the areas of gas chromatographic peaks without using correction factors. It was found that the composition of the essential oil of Stachys palustris L. was very specific. 47 compounds belonging to various classes have been identified. It has been established that the composition of the essential oil of the Stachys palustris L. is very specific. 47 compounds corresponding to the class were identified. Compound classes include fatty acids and acid esters (36.23%), carbonyl compounds (14.25%) and oxygenated basic sesquiterpenes (12.90%), phenols (5.85%). Among the sesquiterpenoids, the predominant component of the essential oil is hexahydrofarnesylacetone (7.5%). The oil also contains (Z)-phytol (6.78%), thymol (4.2%), β-ionone (3.36%) and β-caryophyllene (2.87%). Nonspecific components of the essential oil of the taxon Stachys palustris growing in the Astrakhan region are coumarin (10.27%) and coumaran (0.36%).

DETERMINATION OF METHYL PARATHION IN VEGETABLES BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

Organophosphorus pesticides are one of the most widely used insecticides, which are mainly used in grain, vegetables and fruits. Methyl parathion is a kind of organophosphorus pesticide, which belongs to nerve agent. It can cause different degrees of poisoning to human and livestock and cause serious environmental pollution. Therefore, it is of great significance to establish an effective method for detecting methyl parathion residues in agricultural products. The determination of methyl parathion is often carried out by gas chromatography, but because of the strong polarity and thermal instability of methyl parathion, gas chromatography brings certain difficulty. The High Performance Liquid Chromatography (HPLC) method was researched for the testing of Methyl Parathion residues in vegetables, and the chromatographic conditions for sample extraction, purification and detection were screened and optimized. In vegetables, the matrix is complex, the pesticide residue is low, and there are many interference factors. The main residual components are not easy to separate, enrich and purify, so the detection of related pesticides is not accurate. After lots of experimental exploration, the chromatographic conditions by acetonitrile extraction agent, methanol:water (73:27) as mobile phase and UV detection wavelength choosing 270 nm was selected finally. What’s more, QuEChERS (Quickly, Easy, Cheap, Effective, Rugged, Safe) method, a new pretreatment technology for pesticide residue detection in agricultural products developed in the world recent years, was used for pretreatment of three kinds of vegetables, and PSA and GCB were selected as purifying agents for sample pretreatment ultimately. The experimental results displayed that the chromatographic peak area of Methyl Parathion exhibiting a good linear relationship with its concentration in the 0.05 μM~20 μM range, and the standard curve equation is Y=4833.5x-32.64, the correlation coefficient is 99.96%. The average recoveries of Methyl Parathion in three kinds of vegetables (Lettuce, Cucumber and tomato) were between 87.38% and 114.12% at the three spiked levels of 0.5, 2 and 8μM, and the relative standard deviation (RSD) was between 1.72% and 6.2%. This method has the good points of simple operation, accurate and reliable, and is suitable for the detection of MP pesticide residues in various vegetables.

Some Lessons Learned on the Impact of the Storage Conditions, Syringe Wash Solvent, and the Way of GC-MS Injection on the Reproducibility of Metabolomic Studies.

Metabolomics based on two-dimensional gas chromatography coupled with mass spectrometry is making high demands on accuracy at all stages of sample preparation, up to the storage and injection into the analytical system. In high sample flow conditions, good repeatability in peak areas and a list of detectable metabolites is sometimes challenging to obtain. In this research, we successfully obtained good repeatability for the peak areas of MSFTA-derivatives of 29 core blood plasma metabolites. Six different strategies of storage and injection were investigated and evaluated for the reproducibility of the obtained data. As the essential factors, we considered popular GC-MS syringe washing solvents (methanol and pyridine); storage conditions (freshly prepared samples and stored for 24 h in ambient temperature or in the refrigerator); scheme of injection (one injection per intact vial or three sequential injections per vial). Our GC×GC-MS results demonstrated that the usage of pyridine as a syringe wash solvent and triple injecting the sample from the same vial was the most appropriate for minimizing the coefficient of variation (CV) of the results obtained (in general, <10%). The prolonged storage of samples does not have a noticeable effect on the change in the areas of chromatographic peaks of metabolites, although it reduces CV in some cases. These storage and injection recommendations can be used in future study protocols for the GC×GC-MS analysis of blood plasma.

A protocol for setting-up robust hydrophobic interaction chromatography targeting the analysis of intact proteins and monoclonal antibodies.

Hydrophobic interaction chromatography (HIC) is a chromatographic technique that mainly targets the separation of biomolecules (intact proteins, monoclonal antibodies, etc.) based on the difference in surface hydrophobicity while applying non-denaturing conditions. This protocol paper provides guidelines for setting-up robust HIC analysis and considers the instrument configuration, mobile-phase and sample preparation, as well as chromatographic conditions and settings. The separation of a mixture of intact proteins and monoclonal antibodies is demonstrated by applying conventional HIC conditions, that is, using a mildly hydrophobic (C4) stationary phase in combination with an inverse ammonium sulphate gradient dissolved in aqueous phosphate buffer. The effect of sample-preparation conditions on sample breakthroughs is presented. Finally, good run-to-run repeatability (relative standard deviation<2%) is demonstrated for five different columns obtained from three different column lots, considering chromatographic retention, peak width, peak area and column pressure.

Untargeted GC-MS metabolomics to identify and classify bioactive compounds in Combretum platypetalum subsp. oatesii (Rolfe) Exell (Combretaceae).

Combretum platypetalum is used in traditional African healing practices against different infections. Unfortunately, no scientific knowledge of its phytochemical composition exists, except for the isolation of two compounds from the leaves. Scientific study has been limited to the leaves only, despite the applications of stems and roots in traditional medicine practice and natural product drug discovery programs. Omics was applied to identify and classify different volatile and semivolatile bioactive compounds in the leaf, stem, and root parts of C. platypetalum. The thermal stability of the plant constituents at 60-65°C extraction temperature by Soxhlet and maceration at room temperature on the type, class, and concentration of compounds in the leaf was further investigated. A GC-MS untargeted metabolomics approach, automated deconvolution by the Automated Mass Spectral Deconvolution and Identification System (AMDIS) for GC-MS data, preprocessing by Metab R, and multivariate statistical data analysis were employed in this study. A total of 97 phytoconstituents, including 17 bioactive compounds belonging to the terpenoids, flavonoids, long-chain fatty acids, and other unclassified structural arrangements distributed across C. platypetalum, were identified for the first time. A correlation (r = 0.782; P = 0.000) between Soxhlet and maceration extraction methods relative to resolved chromatographic peak areas of metabolites was established. Findings corroborate the reported bio-investigation of its leaf extracts, its traditional uses, and previous findings from the Combretum genus. The results substantiate the possible applications of C. platypetalum in natural product drug discovery and provide a guide for future investigations.

Highly Sensitive Determination of Antibiotic Residues in Aquatic Products by High-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Antibiotic drug residues are crucial to ensure food safety and minimize risk to human health. Herein, a sensitive high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) method was developed and validated for the determination of antibiotic residues (mainly amphenicols) consisting of chloramphenicol (CAP), thiamphenicol (TAP), florfenicol (FF), and florfenicol amine (FFA) in aquatic products. Amphenicols were well separated on a Kinetex F5 (100 mm × 3.0 mm, 2.6 µm) chromatographic column with the mobile phases of 1 mM ammonium acetate aqueous solution and methanol solution and measured after positive and negative electrospray ionizations using four internal standards. To our knowledge, it was the first time to report the good performance of F5 column and four internal standards for the determination of amphenicols. The established method featured a good linear relationship between chromatographic peak area ratios and the concentrations of amphenicols (R2 > 0.992), a wide and low detection matrix-based range of 0.01–5 μg/L, a low detection limit of 0.01 μg/kg, etc. The spiked assays evidenced the accuracy and reliability of the developed method with the recoveries between 84.0 and 105%, the intraday relative standard deviations (RSDs) over the range of 0.769–13.7%, and the interday RSDs over the range of 0.582–13.3%. Finally, the proposed method was applied to investigate amphenicol residues in various aquatic products, including fish, shrimp, crab, shellfish, and other aquatic species.

Determination of the species origin and thrombin-like enzyme content of Bothrops atrox venom by ultra-high performance liquid chromatography-tandem mass spectrometry based on marker peptide

蛇毒血凝酶类药物是以蝮蛇蛇毒为原料制备的止血药,主要活性成分为蛇毒类凝血酶(svTLEs)。不同蛇种来源的svTLEs结构不同,止血机制不同,药理作用也存在差异,因此准确鉴别蛇毒种属来源和svTLEs含量对于保障该类产品的质量至关重要。研究基于蛋白质组学技术,筛选出了具有种属特异性的矛头蝮蛇svTLE特征肽,并建立了基于特征肽的超高效液相色谱-串联质谱(UHPLC-MS/MS)检测矛头蝮蛇蛇毒种属来源及类凝血酶含量的方法。采用胰蛋白酶对纯化的矛头蝮蛇svTLE进行酶解,利用纳升液相色谱-四极杆/静电场轨道阱高分辨质谱(Nano LC-Q-Exactive-MS)和Proteome Discoverer 2.2软件分别进行多肽的检测和鉴定,通过BLAST搜索与Uniprot数据库对比分析,筛选出具有种属特异性的矛头蝮蛇svTLEs特征肽“EAYNGLPAK”。针对该特征肽对酶解温度、酶解时间和酶用量等样品前处理方法进行了优化,利用超高效液相色谱-串联质谱,以m/z 481.9>315.2和481.9>485.2作为检测离子对,采用ESI+模式进行了多反应监测(MRM)定性定量分析。结果显示,特征肽在2.5~30 ng/mL范围内线性关系良好,相关系数(r)大于0.9996,多水平加标回收率范围为95.5%~101.9%,各水平平行测定结果的相对标准偏差(RSD)为1.1%~3.2%,完全能够满足实际样品检测需求。方法简便快捷,灵敏度高,专属性强,可用于矛头蝮蛇蛇毒种属鉴别及svTLE含量测定,从源头保证血凝酶类产品的质量,并可为其他蛇毒类产品的质量控制提供参考。

Quality Evaluation of Market Acacia catechu by Fingerprint-Chemical Pattern Recognition

Acacia catechu (L.f.) Willd, a leguminous plant, is included in the 2020 edition of the Chinese Pharmacopoeia and is mainly used to treat eczema, mouth ulcers, diarrhea, bruising, and traumatic hemorrhage. However, there are imported and domestic Acacia catechu samples available in China, and their quality and price are very different, which seriously affects the safety and stability of their clinical application. Importantly, there is no simple and effective method for identifying or classifying grades of Acacia catechu. In this study, 47 batches of commercial Acacia catechu were used for identifying or classifying grades of Acacia catechu using high performance liquid chromatography (HPLC) combined with chemometric analysis. Firstly, gradient elution was adopted with 0.05% phosphoric acid water (A)-methanol (B) as the mobile phase to establish chromatographic conditions. The HPLC chromatograms of 47 batches of Acacia catechu samples were analyzed by the “Similarity Evaluation System for Chromatographic Fingerprint of TCM” software (version 2012A). The common peaks of Acacia catechu were identified to evaluate the similarity. Based on the determination results of fingerprint chromatographic peak area, the quality of the collected Acacia catechu was evaluated by chemometric methods such as CA, PCA, and OPLS-DA. The results showed that the collected Acacia catechu samples were significantly divided into three categories. The first-class samples were all imported Acacia catechu except S9 sample, which was domestic Acacia catechu; the second-class samples were partly domestic Acacia catechu and partly imported Acacia catechu; and the third-class samples were all domestic Acacia catechu. Moreover, OPLS-DA of 47 batches of samples showed that the contents of catechin and the total contents of catechin and epicatechin could be used as key indicators for assessing the quality of Acacia catechu. The developed HPLC fingerprint and quantitative analysis method of multi-indicator components can be used for classification and quality evaluation of market Acacia catechu, which has a significant reference value for developing Acacia catechu grade quality standards.

Qualitative Differences and Emission Persistence of Volatile Organic Compounds from Bio-Based Particleboards.

An attempt to reduce, replace, or even eliminate the synthetic resins from wood-based panels alongside broadening the array of raw lignocellulosics is still essential and attractive. Many pretreatments of lignocellulosics have been studied, among which steam explosion (SE) resulted in superior physical-mechanical properties of the obtained binder-less boards. However, the SE pretreatment leads to a relatively strong odor, which is even emitted from the obtained binder-less boards independent of the raw lignocellulosic, raising concern about the use of the boards. Emissions of volatile organic compounds (VOCs) were investigated in the framework of the study from binder-less boards obtained from different SE raw lignocellulosics and SE-untreated suberinic acids-bonded particleboard. VOCs were collected by headspace solid-phase microextraction (HS-SPME) and analyzed by gas chromatography–mass spectrometry (GC–MS) for 28 days with an interval of 2 weeks. The results showed that the number of detected VOCs and their chromatographic peak area varied significantly depending on the raw lignocellulosic, board density, and post-treatment (overlayering), decreasing over time. The lowest area of detected VOCs was demonstrated by the suberinic acids-bonded particleboard, while the highest area was detected from the high-density binder-less board obtained from SE hemp shives with the main compound of furfural (up to 70%) in all board types.

Rapid screening and confirmation of 86 illegally added chemicals in fishery drugs by ultra performance liquid chromatography-quadrupole-time-of-flight mass spectrometry

建立了超高效液相色谱-四极杆-飞行时间质谱法快速筛查与确证渔药中86种非法添加禁限用药物的方法。渔药以80%(v/v)乙腈水溶液进行提取,通过稀释降低基质效应,采用ACQUITY PREMIER HSS T3色谱柱进行分离,以甲醇和0.1%甲酸水溶液作为流动相进行梯度洗脱,采用电喷雾双喷离子源(Dual AJS ESI)正离子模式分析检测。建立了86种药物的一级精确质量数据库和二级碎片质谱库。在全扫描采集模式下,以化合物的色谱保留时间、精确质量数、同位素分布和同位素丰度比定性;在Target MS/MS采集模式下,通过二级碎片离子的匹配进一步确证化合物,以准分子离子峰的峰面积定量,实现渔药样品中多目标药物的快速定性定量分析。86种药物在各自的线性范围内均呈现良好的线性关系,相关系数均大于0.99,中草药制剂和抗生素粉剂的定量限(LOQ)范围分别为1~15 mg/kg和5~75 mg/kg,添加回收率范围为76.8%~112.1%,相对标准偏差(RSD, n=3)小于11.7%。该方法快速、简便、准确、灵敏,适用于不同种类渔药中禁限用非法添加药物的高通量筛查。将该方法应用于浙江省渔用投入品质量安全监督抽检项目中,共筛查60个样品,其中8种中草药制剂筛查出说明书中未明确标明的药物成分,1种抗生素粉剂未检出有效成分。该研究为渔药的质量安全监控提供了有效的技术手段。

Univariate data analysis versus multivariate approach in liquid chromatography. An application for melamine migration from food contact materials

The aim of this work is focused on the melamine migration from food contact materials (FCMs), considering data obtained from univariate analysis versus that obtained from multivariate approach in liquid chromatography coupled to diode array detector.Plastic food contact materials are made from monomers and additives. Moreover, non-intentionally added substances (NIAS) can be part of the composition of the FCM: raw material impurities or process by-products, inks or adhesives.Any compound present within a FCM can migrate to foodstuff. Specific migration of some substances from plastic FCMs to food/simulant is limited by European legislation in force (Commission Regulation No 10/2011).Quantification of analytes in migration samples through a univariate analysis could lead to erroneous results. As an example, in liquid chromatography NIAS can interfere when coeluting with analytes or when they have close retention time. In that case, an overestimation would happen and the verification of the compliance of the specific migration limit (SML) of a substance would be incorrect.A solution to the problem can be found in the application of a chemometric tool with the second-order advantage, which allows the unequivocal identification of analytes. Specifically, for this work, PARAFAC/PARAFAC2 decomposition technique along with tensors arranged from HPLC-DAD data of migration (test and kinetics) samples were used for the identification and quantification of melamine.Results of melamine quantity found in migration samples from five types of melaware by means of a multivariate approach were compared to results obtained with a univariate data analysis carried out with values of chromatographic peak area as response. The comparison reveals that in test samples, univariate analysis supposes an overestimation in the quantity of melamine of 30 % on average, with respect of the concentration obtained from the multivariate approach. Besides, in kinetics samples it is remarkable that for one migration cycle the melamine found was 10 times above the one that obtained with PARAFAC decomposition.Summing up, multivariate data analysis of migration samples supposes a great advantage in order to comply with the established regulation about migrants and to decrease the false non-compliant results.

Co-pyrolysis of biomass and plastic: Synergistic effects and estimation of elemental composition of pyrolysis oil by analytical pyrolysis–gas chromatography/mass spectrometry

This paper presents a study on the pyrolytic behavior of mixtures of lignocellulosic biomass with hydrocarbon plastics using analytical pyrolysis-GC/MS. Semi-quantitative analysis using chromatographic peak areas was used to investigate the composition of the pyrolysis oils and to highlight the occurrence of synergistic effects. A new method is also proposed to estimate the elemental composition of the pyrolysis oil based on the peak areas and brute formulas of the pyrolysis products. The results indicate that synergistic effects during co-pyrolysis favor secondary pyrolysis of holocellulose and polystyrene oligomers, and hinder radical chain-scission of polyethylene chains. H/C and O/C values of the pyrolysis oils were improved by the addition of plastic, indicating a decrease in the content of oxygenated pyrolysis products. The best performances were observed for the mixture containing 70% fir wood and 30% polyethylene, in which synergistic effects led to both an increase of H/C and a decrease of O/C.

Determination of Benzo(α)pyrene in Infant Formula Using High Performance Liquid Chromatography and Dispersive Liquid–Liquid Microextraction

Background: Benzo(α)pyrene (BaP) is one of the most familiar polycyclic aromatic hydrocarbons (PAHs) to evaluate food safety and quality and can be present in infant formulas An analytical method for the extraction and quantification of BaP in infant formula milk has been established by dispersive liquid–liquid microextraction (DLLME) followed by high-performance liquid chromatography with fluorescence detector. Methods: BaP was first extracted from matrices of infant formula milk via acetonitrile and then DLLME was used for further purification and preconcentration of target analyte. Results: Under the optimum extraction conditions, 150 µL of dichloromethane as extraction solvent, 3 mL acetonitrile as disperser and cleaner solvent and 1 mL volume sample, the accuracy of the method was between 89-97%. The limits of detection and quantification were 0.12 and 0.35 ng/ml, respectively. There was a linear relation (R2=0.998) between chromatographic peak area and concentrations in the range of 0.5 to 15 ng/mL. Conclusion: The proposed method is applicable to the quantification of BaP in infant formula milk with acceptable accuracy and precision.