I've tried priming the syringe wash line with 1:1 IPA water and and priming the syringe was line with 100% IPA for 15 mins. I've tried running hundreds of water blanks hoping the syringe wash would flush out the contamination. We've tried running water samples with 1:1 IPA water as the mobile phase. Someone said to prime the syringe wash line with 0.1 M NaOH. I'm not sure what kind of contamination it was, looked like a small red pellet. Any thoughts? Its been 2 weeks.