摘要
甲、乙、丙、丁酸在土壤圈广泛存在,通常含量较低,测定时易受基质中杂质干扰,难以准确定性定量。采用偶联酰胺化法将具有紫外高灵敏响应的吲哚基团引入其结构中,生成酰胺类衍生物,即可在液相色谱-二极管阵列/紫外检测器(HPLC-DAD/UV)下间接高灵敏度检测,达到准确测定的目的。衍生化操作步骤如下:先将适量样品和2-(N-吗啉代)乙磺酸(MES)水溶液加入反应小瓶中,使反应体系pH保持约5.5,再加入适量的1-乙基-(3-二甲基氨基丙基)碳二亚胺(EDC)水溶液,交联反应20 min后再加入适量的N-羟基丁二酰亚胺(NHS)水溶液,之后经偶联反应适当时间后再加入色胺的乙腈水溶液,酰胺化反应过夜,第二天用超纯水定容终止反应,待测。实验表明:在衍生化过程中,当保持MES︰EDC︰NHS︰色胺︰羧基≈10︰7︰3︰7︰1(摩尔比)的比例,加入NHS后偶联反应45min时效果较佳。该方法中四种有机酸的检测限范围为0.008~0.046mg·L^(–1),标准工作曲线的线性决定系数R^(2)为0.991~0.998,平均回收率为85.9%~123%,方法精密度为1.69%~8.41%,可以满足有机分析要求。与液相色谱法直接测定小分子单羧酸相比,发现直接法测试结果与衍生-液相色谱法测试结果基本一致,但衍生法可以修正直接法中杂质干扰带来的阳性误差,同时提升低浓度单羧酸样品中有机酸的检出率,定性与定量结果更可靠。
【Objective】Formic, acetic, propionic and butyric acid exist widely in the natural ecological environment, but their contents are usually low. Thus, their accurate qualitative and quantitative determination is often hindered by impurities in the sample matrix. 【Method】Using the coupling amidation method, low molecular monocarboxylic acids(LMMAs) can form new derivatives with high sensitivity to ultraviolet(UV) light. This was achieved by incorporating the indole group into LMMAs’ structure, which made it possible for the low-level LMMAs to be detected by high-performance liquid chromatography with diode array detector(HPLC-DAD) under a specific wavelength UV light with high response. As a result, we observed the accurate determination of LMMAs. Through experimentations, we propose the following steps: first, a suitable amount of sample and MES(2-Morpholinoethanesulfonic Acid) aqueous solution were added into a small bottle with the reaction system adjusted to about pH≈5.5. This was followed by the addition of EDC(1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride) aqueous solution. After 20 minutes of cross-linking reaction, a suitable amount of NHS(N-Hydroxy succinimide) aqueous solution was added to promote coupling reactions. After an appropriate period, a tryptamine aqueous solution(containing acetonitrile) was added into the reaction system for amidation overnight. This was followed by the addition of ultrapure water to a certain volume and prepared for determination. 【Result】The experimental results showed that for an optimized observation, the mole ratio of MES: EDC: NHS: tryptamine: carboxylic acid should be maintained at about 10 : 7 : 3 : 7 : 1 around and after 45 minutes of coupled reaction and the addition of tryptamine aqueous solution for amidation. The detection limit for the four organic acids in this method was from 0.008 to 0.046 mg·L^(–1), and the linear determinate coefficient R^(2) of the standard working curve was around 0.991–0.998. The average recovery rate ran
作者
陈虹
唐昊冶
钟明
刘晓东
王如海
俞元春
CHEN Hong;TANG Haoye;ZHONG Ming;LIU Xiaodong;WANG Ruhai;YU Yuanchun(Soil and Environment Analysis Center,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China;Co-Innovation Center for the Sustainable Forestry in Southern China,College of Biology and the Environment,Nanjing Forestry University,Nanjing 210037,China)
出处
《土壤学报》
CAS
CSCD
北大核心
2022年第6期1594-1605,共12页
Acta Pedologica Sinica
基金
中国科学院南京土壤研究所“135”创新基金(20752010028)资助。
关键词
小分子单羧酸
偶联
酰胺化
液相色谱检测
Low molecular monocarboxylic acids
Coupled
Amidation
Liquid Chromatography
