Dear all, I bought a new Zic-Philic column Febuarary 2017 and used the conditons of (NH4)2CO3 with ACN, pH=9. The column is the new one and metal coat. When I connected to Mass spec, the background is really high, m/z =212.0948 , peak height = 5.3E7. If disconnect from HPLC, the background is fine without 212.0948. The batch is 641794, sorbent: FC098478, dimension: 150X2.1, 5uM. Does anybody here has used the similar column and find the issue? Please help me !! Thanks.