Separation and Determination of Salicylic Acid and Its Hydroxylating Products by Capillary Electrophoresis with Non-contact Conductivity Detection

Salicylic acid (SA),a common siezing agent for hydroxyl free radical (·OH),and its hydroxylating products with the ·OH free radical,i.e.,2,3-dihydroxybenzoic acid (2,3-DHBA) and 2,5-dihydroxybenzoic acid (2,5-DHBA),were separated and determined by capillary electrophoresis with non-contact conductivity detection. Under optimum conditions,the above mentioned compounds were separated and detected within 10 min. Linear relationship between response signal and concentration of either of the 3 compounds was kept in the range of 0.03-15.0 mg·L-1,with detection limits of 0.01 mg·L-1. Test for precision was made at the concentration level of 0.7 mg·L-1 of each of the 3 compounds with 8 determinations,value of RSD′s for measurements of peak area were found to be 2.9% (for SA),3.2% (for 2,3-DHBA) and 3.6% (for 2,5-DHBA).