Study of low-molecular weight organic acids in maize roots under the stress of cadmium using capillary zone electrophoresis.

An indirect CE method was developed for the study of low-molecular weight organic acids (LMWOAs) in maize under the stress of cadmium. The influences of indirect reagents (phthalate, salicylic acid, and benzoic acid), coion concentration, and pH were studied. A buffer composed of 15 mmol/L benzoate and 0.2 mmol/L CTAB (pH 5.7) was used in the organic acid determination. The detection limit ranged between 0.5 and 6 micromol/L. The RSD (n = 14) of the method was found to be in the range of 0.11-0.49% for migration time and 1.25-4.72% for peak area. In the maize roots, obvious increases of LMWOAs were observed when the plants were under the stress of cadmium and/or organic acids. The recovery of standard organic acids added in real samples ranged from 85 to 116%.