The Thermo Scientific Trace GC Ultra fitted with DBWAXTER produced good quality peaks of VFA (in water ) initially after installation. But when I tried analysis after 2 months, ended up in getting no peaks or irregular peaks. The Thermo Scientific agent found no issues with the instrument. I tried almost all possible hit and trials. What could be the possible issue?
Temperature programme : Oven 110oC 2min, ramping 10oC/min to 200oC at 2min, Flow rate 2ml/min, inlet and detector at 220 and 250oC.
Often, in the column package, are contained vials to be used to check column performances. If not, purchase the recommended ones and try a run in the indicated conditions. If you obtain positive results, then the problem is in your sample preparation, otherwise it could depends on the coumn
1) inject the VFA calibration standards for linearity graph and sample blank.if you get R2 >0.99,then your instrument is ok. 2) inject sample blank for identifying interference at the RT of VFA. if you get the interference more than your LOD limit you need to change your extraction process to minimize the interference.3 ) prepare a spiked sample and calculate the % recovery to optimize your method performance.
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