I was offered a job about 1 year ago, used a detox drink and popped for diluted. Had to retest and failed at 27 ng, guess then ran a GC/MS since my first test was diluted.
Drug tests are not conducted in that manner. The urine sample has to be positive for a particular drug(s) on the initial screen for them to run the confirmation GC/MS. The sample doesnt get GC'd on the sole basis of being diluted.

If your sample GC'd at 27 ng, then the sample had failed the initial screen as well.