Switched from ZA standard add back to SO2 standard add

Reconnected SO2 cal cylinder to 1/8" SO2 standard addition line at 09:50AM
After 2 days of "ZA Cals", the SO2 peak has disappeared.
Still not sure if we need to correct for SO2 "memory" from the telfon valve.
But after a couple of days of ZA flush, the telfon valve has cleaned up.
Need to take a closer look at this.