Carbon deposits on a quartz cell

Question

What is the reason for the appearance of black carbon deposits on a quartz cell in an air-acetylene flame? The ratio of air/acetylene gas mixture is 13.5 / 2 and flow rate 10 dm3/min. Agilent 240fs with VGA 77.

evanclay · Answer

Hi Paul, 
 Thanks for attaching the photos. This does confirm there is excessive acetylene flow - so there is a fault with the gasbox in your instrument. I would recommend you request a service call to get this checked. 
 In the interim, you should be able to complete your analysis by with the acetylene flow set to the minimum flow of 1.5 L/min. While there is still some carbon build-up on the cell, this is on the outside of the cell and should not impact on the light throughput through the centre of the cell. 
 Hope this helps you, 
 Cheers Eric

Carbon deposits on a quartz cell

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