高效液相色谱法测定铬超富集植物李氏禾根系分泌物中的有机酸

建立了高效液相色谱（HPLC）测定Cr超富集植物李氏禾根系分泌物中低相对分子质量有机酸的分析方法。采用XSelect HSS T3色谱柱（250 mm×4.6 mm，5 μm，Waters），以40 mmol/L磷酸二氢钾-磷酸缓冲溶液（pH=2.40）作流动相，流速1.0 mL/min，柱温25℃，在波长205 nm处检测。该方法在13 min内简便快速地分离出8种有机酸（草酸、酒石酸、苹果酸、乳酸、甲酸、乙酸、马来酸和柠檬酸），且峰形良好。有机酸的检出限（LOD）为0.12~12.32 mg/L；草酸的加标回收率为73.15%，其他有机酸的加标回收率为94.54%~109.98%。李氏禾的根系分泌物中各有机酸含量分别为酒石酸（130.90±1.44）μg/g（根干重）、苹果酸（1031.34±4.38）μg/g（根干重）、乳酸（65.54±1.01）μg/g（根干重）、马来酸（0.96000±0.00367）μg/g（根干重）和柠檬酸（201.50±1.13）μg/g（根干重）。该方法简便快速，灵敏可靠，适用于植物根系分泌物样品中有机酸的测定。

Determination of organic acids in the root exudates of Cr-hyperaccumulator Leersia hexandra Swartz using high performance liquid chromatography

High performance liquid chromatography (HPLC) was used for the separation and quantification of the low molecular-mass organic acids in the root exudates of Cr-hyperaccumulator Leersia hexandra Swartz. Eight organic acids, oxalic, tartaric, formic, malic, lactic, acetic, maleic and citric acids, were separated on an XSelect HSS T3 column (250 mm×4.6 mm, 5 μm) within 13 min with the mobile phase of 40 mmol/L potassium dihydrogen phosphate-phosphorous acid at pH 2.40, a flow-rate of 1.0 mL/min, a detection wavelength of 205 nm and a column temperature of 25℃. This is a simple and highly sensitive method for the separation of the eight organic acids with well-shaped peaks. The limits of detection (LODs) for the eight acids ranged from 0.12 mg/L to 12.32 mg/L. Under the optimized conditions, tartaric, malic, lactic, maleic and citric acids in the root exudates were detected with high linearities, acceptable recoveries and excellent precisions. The contents of these acids calculated in the root exudates were (130.90±1.44) μg/g (root dry weight (DW)) for tartaric acid, (1031.34±4.38) μg/g (root DW) for malic acid, (65.54±1.01) μg/g (root DW) for lactic acid, (0.96000±0.00367) μg/g (root DW) for maleic acid and (201.50±1.13) μg/g (root DW) for citric acid. The proposed HPLC method is quite suitable for the simultaneous determination of organic acids in the root exudates of Leersia hexandra Swartz, and can be used in other plant root exudates as well.