Chromatography Forum

This particular GCMS method calls for our GC oven to start at 90 Celsius, followed by 5 degree/minute ramp up to 130 celsius, then 40 degree/minute up to 240 and hold for 5 minutes.

Our one and only molecule of interest comes off the column at about 104 celsius.

Are there any downsides to doing a faster ramp up to 240 for a 5 minute hold?

e.g. am I going to drastically shorten the life of the GC oven by ramping at 60 or 70 degrees/minute?

am I going to harm the column by increasing the temp too quickly?

Thanks for any advice.

This particular GCMS method calls for our GC oven to start at 90 Celsius, followed by 5 degree/minute ramp up to 130 celsius, then 40 degree/minute up to 240 and hold for 5 minutes.

Our one and only molecule of interest comes off the column at about 104 celsius.

Are there any downsides to doing a faster ramp up to 240 for a 5 minute hold?

e.g. am I going to drastically shorten the life of the GC oven by ramping at 60 or 70 degrees/minute?

am I going to harm the column by increasing the temp too quickly?

Thanks for any advice.

It shouldn't harm the column ramping faster, you just have to make sure the instrument can heat the oven that fast. In the past such fast oven heating was done with small separate ovens that were less space to heat so they could be heated more quickly. I can't remember what the max rate is on the 7890s.

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Our one and only molecule of interest comes off the column at about 104 celsius.
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Then consider whether you really need to go so high up to 240 degC !

According to the Agilent specs if you're on 120V 40°C/min would be the max you could get, a higher voltage (230V) 75°C/min is achievable.

This particular GCMS method calls for our GC oven to start at 90 Celsius, followed by 5 degree/minute ramp up to 130 celsius, then 40 degree/minute up to 240 and hold for 5 minutes.

Our one and only molecule of interest comes off the column at about 104 celsius.

Your analyte elutes at a relatively low temperature. The fast ramp is just to clean other crap off the column for the next injection.

So a fast ramp might be borderline reproducible if at the maximum, but what do you care, you've already measured your analyte. We typically would use the fastest ramp we could get to clean out such stuff to make the overall run times shorter, more throughput.

Does anything elute after your peak of interest ?

Come to think of it, does anything elute before your peak of interest ?

What are you trying to separate from what, in what ?. There might be easier, quicker ways.

Peter