Unstable ISTD only in no-gas Mode

The ISTD of my 7700 is fluctuating immense but only in no-gas mode, in He-mode is everything fine with the stability-graph. I have a recovery from about 20 to 180% with all 3 ISTD’s (Sc,In,Lu), they have the same deviation in the same way. It happens spontaneously with every kind of sample, even with a blank.  I’d be happy if someone has any suggestions to solve this problem.

Parents
  • The sample uptake is 30 at a speed of 0.3 and the stabilization time is 30. I have tried a uptake time by 45 and stabilization by 25, because  my second 7700 has this settings and works fine but there was no improvement. The Problem with the instability exists around 2 years so the tubing, nebulizer and cones were changed multiple times, while the batch was'nt changed for the last years.
    Is it normal that i have a He-flow of 0.07ml/min during the No-Gas mode?
    Also strange is that sometimes the recovery of He and no-gas mode are going in the opposite direction.

Reply
  • The sample uptake is 30 at a speed of 0.3 and the stabilization time is 30. I have tried a uptake time by 45 and stabilization by 25, because  my second 7700 has this settings and works fine but there was no improvement. The Problem with the instability exists around 2 years so the tubing, nebulizer and cones were changed multiple times, while the batch was'nt changed for the last years.
    Is it normal that i have a He-flow of 0.07ml/min during the No-Gas mode?
    Also strange is that sometimes the recovery of He and no-gas mode are going in the opposite direction.

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