Optimization of a microchip electrophoresis method with electrochemical detection for the determination of nitrite in macrophage cells as an indicator of nitric oxide production

A ME-EC method that uses transient isotachophoresis and a Pt black-modifed working electrode to enhance the signal and detect nitrite as well as other electrochemically active species was reported. First, a stacking method to enhance the signal of nitrite through the addition of NaCl to the run buffer was developed that provided a 5.2-fold decrease in the LOD for nitrite. Then, a procedure to modify a Pt working electrode with Pt black for the detection of nitrite was optimized. This electrode modification was then coupled with a ME-EC method, and a signal enhancement for nitrite, hydrogen peroxide, and ascorbic acid was obtained. The use of a Pt black-modified working electrode resulted in an increased sensitivity for nitrite. This method was then used to detect nitrite as an indicator of NO production in a bulk cell lysate sample. The incorporation of the tITP system and Pt black-modified working electrode improved the method previously reported by our group by increasing the sensitivity and decreasing the LOD.