Chromatography Forum

Hello,

Recently I performed an infusion with high amount of analyte ~10,000ng/mL at higher flow rate 30uL/min.
In my MRM method I have noticed that the background signal of mobile phase for my analyte, the one that was infused, is high ~1500-2000counts, whereby the I.S. which was not infused gives normal counts ~20-30. I have waited about 1 hour and have noticed counts dropped a bit for the analyte to 300-500, but is still much higher than normal (38) counts Any ideas, or advice as to and how to flush/purge the MS system? I think it is just a waiting game to let the N2 gas clear the ion transfer capillary and quadruples. I have also come to realize next time I will infuse only ~2,000ng/mL at a lower flow rate of 10uL/min.

Thanks.

Hello,

Recently I performed an infusion with high amount of analyte ~10,000ng/mL at higher flow rate 30uL/min.
In my MRM method I have noticed that the background signal of mobile phase for my analyte, the one that was infused, is high ~1500-2000counts, whereby the I.S. which was not infused gives normal counts ~20-30. I have waited about 1 hour and have noticed counts dropped a bit for the analyte to 300-500, but is still much higher than normal (38) counts Any ideas, or advice as to and how to flush/purge the MS system? I think it is just a waiting game to let the N2 gas clear the ion transfer capillary and quadruples. I have also come to realize next time I will infuse only ~2,000ng/mL at a lower flow rate of 10uL/min.

Thanks.

Carryover can happen in a lot of places. Try replacing any tubing or fittings that you used for the infusion with new ones. You could also try flushing the system with LC grade isopropanol.