Separation of phenolic acids in soil and plant tissue extracts by co-electroosmotic capillary electrophoresis with direct UV detection

A capillary zone electrophoretic method for the analysis of phenolic acids in soil and plant extracts was developed with direct UV detection using a p hosphate electrolyte solution. The electrophoretic separation required the phenolic acids to be charged ai a pH above their pKa in order to achieve th eir migration towards the anode. Electroosmotic flow (EOF) was reversed in direction by adding tetradecyltrimethylammonium bromide (TTAB). Factors aff ecting the separation selectivity, including the buffer pH and EOF modifier s, were investigated systematically. Eight phenolic acids were separated an d detected in 10 min using an electrolyte containing 25 mM phosphate, 0.5 m M TTAB and 15% acetonitrile (v/v) at pH of 7.20. linear plots for the test phenolic acids were obtained in a concentration range of 0.01 - 1 mM with d etection limits in the range of 1.0 - 7.0 muM. The recoveries ranged from 9 2.8 io 102.3% in soil and plant tissues samples spiked ai 100 muM and the r elative standard deviation based on he peak area were ranged 2.0 to 4.5%. T he proposed method was used for the determination of phenolic acids in plan t tissue and soil extracts with direct injection.