Carbon paste electrodes modified with palmitic acid and stearic acid for the determination of folic acid (vitamin B9) in both aqueous and biological media

Abstract

Carbon paste electrodes chemically modified with either palmitic acid or stearic acid have been employed for selective and sensitive determination of folic acid in aqueous and biological media. The use of the medium-exchange technique for increasing the selectivity of the process for analyzing the vitamin in biological media is recommended. Calibration plots have been drawn, and detection limits of 5 × 10−9 M, 1 × 10−8 M and 5 × 10−7 M were achieved in aqueous, urine and serum samples respectively after accumulating for 60 s. The effect of possible interfering materials such as copper(II) and calcium(II), representing metal ions, and ascorbic acid and uric acid, representing organic compounds, has also been taken into consideration. A comparison of the adsorptive accumulation at the carbon paste electrode with that at the modified electrodes has also been made.