UPLC法同时快速测定湿地土壤中的五种低分子量有机酸

A Fast and Simultaneous Determination of Five Organic Acids in Wetland Soils by Ultra-performance Liquid Chromatography

研究了超高效液相色谱(UPLC)法同时测定湿地土壤中柠檬酸、草酸、苹果酸、酒石酸和丁二酸等5种有机酸的方法,并测定了武昌湖、巢湖和鄱阳湖湿地土壤样品中的有机酸组成含量,为揭示有机酸在土壤-植物-根际环境中的转运、分配和分泌提供理论依据.结果表明:利用UPLC法可以快速地分离5种有机酸,比HPLC分离时间缩短1倍左右;各有机酸的加标回收率为99.17%~103.55%,相对标准偏差为0.48%~1.92%,检测限为0.05~0.18 mg/kg,该方法线性关系优良(R^2>0.997);除了鄱阳湖湿地土壤样品的酒石酸未能检测出,其他湿地土壤样品中的5种有机酸都能检测出;不同湿地土壤样品的优势有机酸种类不同,武昌湖湿地土壤中的柠檬酸和苹果酸对有机酸总量贡献较大,巢湖湿地土壤中的柠檬酸对有机酸总量的贡献最大,鄱阳湖湿地土壤中丁二酸占有机酸总量的比例小于10%;湿地土壤有机酸含量多集中在土壤深度为30~50 cm处,这与该区域植物根系分布及微生物活性较高有关.

A method of fast and simultaneous measuring concentrations of citric acid,oxalic acid,malic acid,tartaric acid and succinic acid in wetland soils using the ultra-performance liquid chromatography was established,and characteristics of organic acids in wetland soils of Wuchanghu lake,Chaohu lake and Poyanghu lake were determined to better reveal transfer,allocation and exudate of organic acids in the soil-plant-rhizosphere.The results showed that the five organic acids can be separated successfully by UPLC and the separation time was about a half of that of HPLC.The recovery rate,relative standard deviation and detection limit for target organic acids were 99.17%-103.55%,0.48%-1.92%and 0.05-0.18 mg/kg,respectively,and the linear fitting coefficients(R^2)were greater than 0.997.All of the five organic acids were determined in wetland soils,except tartaric acid,which wasn't detected in soils from the Poyanghu lake.The contents of organic acids in different wetland soils varied,citric and malic acids were the dominant acids in soils of the Wuchanghu lake,the content of citric acid was maximum in soils of the Chaohu lake,the percentage of succinic acid to the total amount of organic acids was lower than 10%for soils from the Poyanghu lake.The highest contents of organic acids were found in soils obtained from the depth of 30-50 cm along soil profiles,which may relate to dense distribution of root and high activity of microbial activity at this depth.