Internal standard optimization advances sensitivity and robustness of ratiometric detection method

We design a p-aminothiophenol (pATP) modified Au/ITO chip to determine nitrite ions in lake water by a ratiometric surface-enhanced Raman scattering (SERS) method based on nitrite ions triggering the transformation of pATP to p,p '-dimercaptoazobenzene (DMAB). Intriguingly, by using the SERS peak (at 1008 cm-1) from benzoic ring deforming as an internal standard instead of the traditional peak at 1080 cm-1, the detection sensitivity of the method was improved 10 times. We detect nitrite with pATP/Au/ITO chip via ratiometric SERS method. With the 1008 cm-1 SERS peak from ring deformation as the internal standard (replacing the traditional 1080 cm-1 C-S stretching peak), the detection sensitivity is 10-fold increase.