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.