Dynamic capillary diffusion system for monoterpene and sesquiterpene calibration: quantitative measurement and determination of physical properties

This article describes a method for preparation of low concentration gas standard mixtures of biogenic volatile organic compounds (BVOCs) emitted primarily by plants. A set of 10 plant volatiles including α-pinene, β-pinene, 3-carene, linalool, methyl salicylate, α-cedrene, β-caryophyllene, β-farnesene, aromadendrene and α-humulene was used in the study. Gas standard mixture of these compounds was generated using a capillary diffusion system (CDS). Diffusion coefficient (D) and saturation vapour pressure (p _s) data of these compounds were calculated from experimentally determined gas chromatographic retention indices (RI) and empirical relationships between D and p _s versus RI. A comparison of the calculated and measured concentrations of investigated compounds has proved that designed CDS can be successfully used for the proper quantification of BVOCs.     

Free amino acids,biogenic amines,and ammonium profiling in tobacco from different geographical origins using microwave‐assisted extraction followed by ultra high performance liquid chromatography

This work describes a rapid, stable, and accurate method for determining the free amino acids, biogenic amines, and ammonium in tobacco. The target analytes were extracted with microwave‐assisted extraction and then derivatized with diethyl ethoxymethylenemalonate, followed by ultra high performance liquid chromatography analysis. The experimental design used to optimize the microwave‐assisted extraction conditions showed that the optimal extraction time was 10 min with a temperature of 60°C. The stability of aminoenone derivatives was improved by keeping the pH near 9.0, and there was no obvious degradation during the 80°C heating and room temperature storage. Under optimal conditions, this method showed good linearity (R ² > 0.999) and sensitivity (limits of detection 0.010–0.081 μg/mL). The extraction recoveries were between 88.4 and 106.5%, while the repeatability and reproducibility ranged from 0.48 to 5.12% and from 1.56 to 6.52%, respectively. The newly developed method was employed to analyze the tobacco from different geographical origins. Principal component analysis showed that four geographical origins of tobacco could be clearly distinguished and that each had their characteristic components. The proposed method also showed great potential for further investigations on nitrogen metabolism in plants.     

Amperometric Biosensors for Tyramine Determination Based on Graphene Oxide and Polyvinylferrocene Modified Screen‐printed Electrodes

A comparison of the analytical characteristics of two tyramine biosensors, based on graphene oxide (GRO) and polyvinylferrocene (PVF) modified screen‐printed carbon electrodes (SPCE), is reported. Diamine oxidase (DAOx) or monoamine oxidase (MAOx) was immobilized onto the PVF/GRO modified SPCE to fabricate the biosensors. Surface characteristics and electrochemical behaviour of the modified SPCEs were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX) and cyclic voltammetry (CV). Electrode surface composition and experimental variables such as pH and working potential were optimized in order to ensure a high performance. Under optimum experimental conditions, both DAOx/PVF/GRO/SPCE and MAOx/PVF/GRO/SPCE biosensors exhibited wide linear dynamic ranges for tyramine from 9.9×10^?7 to 1.2×10^?4 M and from 9.9×10^?7 to 1.1×10^?4 M, respectively. MAOx/PVF/GRO/SPCE biosensor showed higher sensitivity (11.98 μA mM^?1) for tyramine determination than the DAOx/PVF/GRO/SPCE biosensor (7.99 μA mM^?1). The substrate specifity of the biosensors to other biogenic amines namely histamine, putrescine, spermine, spermidine, tryptamine, β‐phenylethylamine and cadaverine was also investigated. The developed biosensors were successfully used for tyramine determination in cheese sample.     

离子色谱法同时测定水源水中的5种生物胺

建立了离子色谱(IC)同时测定水源水中5种生物胺(BA)(腐胺、尸胺、组胺、亚精胺和精胺)的方法。样品经0.45 μm水膜过滤后,用TSK-GEL SuperIC阳离子交换柱(150 mm×4.6 mm)分离,以甲磺酸水溶液为流动相梯度淋洗,流速为1.0 mL/min,非抑制电导检测,进样量为100 μL。实验结果表明,5种生物胺可以实现基线分离;在1.0～30.0 mg/L范围内,其峰面积与质量浓度之间的线性关系良好;保留时间的相对标准偏差(RSD)均不高于0.02%,峰面积的RSD小于2.08%;加标回收率为96.0%～107.0%。该法简便、快捷、准确,可以用于水源水中腐胺、尸胺、组胺、亚精胺和精胺5种生物胺的同时测定。     

Evaluation of the Relationship among Biogenic Amines,Nitrite and Microbial Diversity in Fermented Mustard

Biogenic amines (BAs) and nitrites are both considered harmful compounds for customer health, and are closely correlated with the microorganisms in fermented mustard (FM). In this study, BAs and nitrite contents in fifteen FM samples from different brands were analyzed. The concentrations of cadaverine in one sample and of histamine in one sample were above the toxic level. Moreover, five FM samples contained a high level of nitrite, exceeding the maximum residue limit (20 mg/kg) suggested by the National Food Safety Standard. Then, this study investigated bacterial and fungal communities by high-throughput sequencing analysis. Firmicutes and Basidiomycota were identified as the major bacteria and fungi phylum, respectively. The correlations among microorganisms, BAs and nitrite were analyzed. Typtamine showed a positive correlation with Lactobacillus and Pseudomonas. Cadaverine and nitrite is positively correlated with Leuconostoc. Furthermore, thirteen strains were selected from the samples to evaluate the accumulation and degradation properties of their BAs and nitrite. The results indicated that the Lactobacillus isolates, including L. plantarum GZ-2 and L. brevis SC-2, can significantly reduce BAs and nitrite in FM model experiments. This study not only assessed the contents of BAs and nitrite in FM samples, but also provided potential starter cultures for BAs and nitrite control in the FM products industry.     

Analysis of Biogenic Amines Using Immunoassays,HPLC, and a Newly Developed IC-MS/MS Technique in Fish Products—A Comparative Study

In this study, comparative analyses were carried out with ion chromatography mass-spectrometry (IC-MS/MS) which has no derivatization step, high-performance liquid chromatography (HPLC) technique, as well as two quantitative and two semi-quantitative immunoassays. The results demonstrated that HPLC and quantitative immunoassay methods were well-correlated with IC-MS/MS in determining histamine in various types of fish products. The best correlation was observed with the HistaSure ELISA Fast Track kit (R² = 0.9903). More than half of the values (68%) obtained by two methods were also statistically similar. The results of semi-quantitative test kits also supported histamine values estimated by quantitative methods, with some exceptions. The best results were found for HistaSure Lateral Flow in supporting the quantitative techniques. Therefore, these methods are found suitable for monitoring histamine in fish products in terms of food safety. Good correlations were also observed HPLC and IC-MS/MS in determining cadaverine, putrescine, and tyramine with the highest value observed for tyramine as R² = 0.9785. However, no correlation was observed for other biogenic amines, and the majority of the results were significantly different from each other for these amines (p < 0.05). The differences may be caused by the drawbacks reported previously for HPLC. However, further studies are required to confirm the possible effects. This study provides a comparative evaluation of several methods in terms of their suitability in determining biogenic amines in fish products for both monitoring and regulatory purposes.     

Fluorometric assay of amino acids and amines by use of 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole(NBD-F) in high-performance liquid chromatography

Summary The reaction of a newly developed fluoregenic reagent, 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole(NBD-F), with amino acids and biogenic amines was investigated. NBD-F was reactive to both primary and secondary amines including amino acids and biogenic amines such as catecholamines. The amino acids were reacted with the reagent, separated by high-performance liquid chromatography on -Bondapak C₁₈ and detected at 10 to 100 fmol level. A few g of protein hydrolysates, rabbit pyruvate kinase M₁, rabbit aldolase A and papain, were adequate for the amino acids quantitation. An automatic amino acid analyzer with fluorometric detection by the post-column derivatization with NBD-F enabled the amino acid profile analysis in blood samples present in a paper disc of 3 mm diameter.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Synthesis of New Benzoimidazole Derivatives

The reactions of cryptotanshinone and tanshinone llA with cadaverine and putrescine were investigated. Six new compounds, four with imidazole functional groups and two with oxazole groups, were obtained. The possible reaction mechanism was proposed.     

Quantification of acetone emission from pine plants

Acetone emission from pine plants (pinus sylvestris) is measured by continuously stirred tank reactor. Under a constant light intensity, acetone emission rates increase exponentially with leaf temperature. When leaf temperature is kept constant, acetone emission increases with light intensity. And acetone emission in darkness is also detected. Acetone emitted from pine is quickly labeled by 13C when the plants are exposed to air with 630 mg/m313CO2. However, no more than 20% of acetone is 13C labeled. Acetone emission from pine may be due to both leaf temperature-controlled process and light intensity-controlled process. Based on these understandings, an algorithm is used to describe the short term acetone emission rates from pine.     

Interference of the Simultaneous Presence of Different Biogenic Amines on the Response of an Amine Oxidase–Based Biosensor

Abstract

The application of an amine oxidase–based biosensor, which was selective for several biogenic amines, was examined for the simultaneous detection of cadaverine, putrescine, and histamine. The biosensor response parameters in mixtures containing cadaverine or putrescine were 1.14 times less than the sum of corresponding parameters in single-substrate solutions. Histamine did not cause any change of the biosensor response in the presence of cadaverine and/or putrescine. This “screening” of biosensor signal parameters by putrescine and cadaverine should be considered during calibration of amine oxidase–based biosensors used for the detection of biogenic amines.