Properties of neutral phosphate buffer extractable organic matter in soils revealed using size exclusion chromatography and fractionation with polyvinylpyrrolidone

Abstract

A neutral phosphate buffer (NPB) extraction method has been used to estimate the amount of available N in soil. However, the properties of soil NPB-extractable organic N have not been fully elucidated. The purpose of the present study was to characterize the properties of organic matter in the NPB extracts of soils. The NPB extracts were obtained from three soil samples, and the organic matter in the extracts was separated into three fractions according to its solubility in acid and adsorption onto polyvinylpyrrolidone (PVP). High-performance size exclusion chromatography (HPSEC) with ultraviolet (UV) and fluorescence detections was applied to the NPB extracts and their fractions. The HPSEC analysis of the NPB extract revealed the presence of a single broad peak, irrespective of the detection methods. The broad peak was identified as humic substances using the on-flow measurements of UV absorption spectra and fluorescence emission spectra. Among the fractions, the PVP-non-adsorbed fulvic acid (FA) fraction accounted for the largest proportion of organic C or N in the NPB extract, followed by the PVP-adsorbed FA and humic acid (HA) fractions. The peak of humic substances was observed for all fractions using HPSEC with the on-flow measurement of UV absorption and fluorescence emission spectra. The molecular weight of the humic substances varied with each fraction. When the Coomassie Blue-reactive substances (CBRS) were quantified using a Bradford protein assay, they were detected in the NPB extract and almost half were distributed in the PVP-non-adsorbed FA fraction. However, humic substances were considered to be the main constituents of CBRS in the soil NPB extract because of their reactivity with Coomassie Blue and the absence of proteinaceous materials. Furthermore, an incubation experiment revealed that the organic matter available to microorganisms was included in the HA and PVP-non-adsorbed FA fractions. Based on the HPSEC analysis of the NPB extracts and their fractions, it was observed that the humic substances in the NPB extract, particularly in the HA and PVP-non-adsorbed FA fractions, were available to microorganisms.     

高效液相色谱法测定无核白葡萄赤霉素残留

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水发海参中甲醛的气相色谱法测定

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松树皮原花青素的超声提取、超滤膜分离中试研究

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HLB固相萃取-高效液相色谱法测定婴幼儿奶粉中、对羟基苯甲酸酯类的研究

建立了固相萃取（SPE）-高效液相色谱同时测定婴幼儿奶粉中对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯、对羟基苯甲酸丁酯含量的方法。在选定的条件下各组分的相关系数均大于0．9991,线性范围0．5～50mg／L,回收率为95．2％～104．3％,相对标准偏差为2．1％～4．4％。     

茶叶中茶多酚检测方法研究进展

对茶叶主要活性成分茶多酚的检测方法进行了综述,介绍了茶多酚总量测定方法分光光度法、近红外光谱法、电化学分析方法,以及茶多酚组分测定方法色谱法、毛细管电泳法,重点介绍了应用最广的儿茶素检测方法高效液相色谱法,对其样品前处理及色谱条件进行了详细分析,以期为茶多酚检测方法学进一步发展提供理论依据。     

鸡血浆中黄芩苷及绿原酸的HPLC法建立

建立了测定鸡血浆中复方慢呼抗口服液主要成分黄芩苷和绿原酸的高效液相色谱法.流动相为乙腈、1％冰醋酸,梯度洗脱30 min,黄芩苷和绿原酸的波长分别为280、327 nm,流速1 mL/min.分别采用高氯酸法、甲醇乙腈法、正丁醇法处理血浆,选取最优方法进行考察.甲醇乙腈法处理血浆,方法专属性好,回收率较高,线性关系良好,精密度及准确度较高,可用于药代动力学研究.     

液质联用法测定饲料中14种抗菌药物的研究

建立了液相色谱-串联质谱(LC-MS/MS)联用技术同时测定饲料中硝基咪唑类、硝基呋喃类、喹噁啉类14种抗菌药物的分析方法.样品通过乙腈-水(60:40,V/V)溶液提取,HLB固相萃取柱净化后上机测定.在正离子模式下通过两对离子对进行定性定量分析.结果表明,14种药物在2～100 ng/mL范围内线性关系良好,相关系数均大于0.99,空白饲料在三个添加浓度下的回收率为46.5％～114.4％,批内、批间相对标准偏差均＜20％,检测限为20 μg/kg.该方法适用于饲料中14种抗菌药物的同时测定.     

高效液相色谱-紫外检测法测定饲料中醋酸氯地孕酮

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代谢组学及其相关技术与应用研究

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