Carry over test failure.
<p><span>Hi, </span></p><p></p><p><span>After the PE, one of our UPLC sytems failed the carry over test. We've been cleaning the system for a week, and it stilled failed. The preblank was clean, but the postblank have about 0.02% carry over. We used the same column, MP and sample on the other systems, and those system passed with just one trial. Did anyone ever has the similar issue? Any suggestion?</span></p><p></p><p><span>Thanks,</span></p><p><span>Julia</span></p>