Carry over in my blanks after maintenance

This is a TQ system running MRM or MS1/MS2 Scan mode?  Would you please share a spectrum of the peaks?  Are they your normal sample peaks?

When you cleaned the inlet, did you also replace the split vent trap?  Did you check that the side arm of the SS inlet is clean?  You may need to have the copper split vent line replaced that goes between the inlet body and the split vent trap. It captures a lot of stuff before the split vent trap and it needs to be either rinsed out or replaced every...well, it's sample matrix and number of sample dependent.

One other easy thing to try.  Set up your GC for 1.5psi inlet, 500ml/min split and slowly hand inject 80 or so uL of your normal sample solvent – without acquiring the data. Then reload your normal run method and turn the oven up to the normal run final oven temperature and let it sit there for some minutes to make sure that any residue is out of there.  This sort of rinses out the inlet using a very high split ratio and very low column flow.

Quad clean? It's never recommended for an operator to clean the quad as the chances of disaster are high.  Quad cleaning is only about ion peak shapes, like in tune, and ion throughput and not chromatographic peaks.

This is a TQ system running MRM or MS1/MS2 Scan mode?  Would you please share a spectrum of the peaks?  Are they your normal sample peaks?

When you cleaned the inlet, did you also replace the split vent trap?  Did you check that the side arm of the SS inlet is clean?  You may need to have the copper split vent line replaced that goes between the inlet body and the split vent trap. It captures a lot of stuff before the split vent trap and it needs to be either rinsed out or replaced every...well, it's sample matrix and number of sample dependent.

One other easy thing to try.  Set up your GC for 1.5psi inlet, 500ml/min split and slowly hand inject 80 or so uL of your normal sample solvent – without acquiring the data. Then reload your normal run method and turn the oven up to the normal run final oven temperature and let it sit there for some minutes to make sure that any residue is out of there.  This sort of rinses out the inlet using a very high split ratio and very low column flow.

Quad clean? It's never recommended for an operator to clean the quad as the chances of disaster are high.  Quad cleaning is only about ion peak shapes, like in tune, and ion throughput and not chromatographic peaks.