I am using choline chloride: ethylene glycol (molar ratio 1:2) as extractor to desulfurize dibenzothiophene (DBT) in n-dodecane. The initial concentration of DBT is 100 ppm. Condition of experiment are,
Temperature (degree Celsius): Room temperature, 40, 60, 80
Duration: 6 hours (for each consequent hour, the oil is collected for GC-SCD analysis)
Stirring: 300 rpm
Theoretically, the sulfur content must decrease after analyzed by GC-SCD, but the result shows an increase beyond 100 ppm.
Is there any explanation whether the ionic liquid is not suitable at high temperature, or the GC-SCD is broken? I do not have any idea where is the sulfur came from.
Thank you.
Dear Grzegorz Boczkaj,
More than 150%.
For example, at 40 degree celsius, after 6 hour stirring, the sulfur content analyzed by GC-SCD is 138 ppm.
What is the reproducibility of your method - ie. RSD for 3 repetitions. What is your quantification method?
Dear Grzegorz Boczkaj,
Only one repetition.
For quantification method, did you mean the statistical method?
Prior to these srudiea you should perform a calibration and validation of your method.
Prepare a model/calibration solutions of your sulfur compounds in known concentration at few concenctration levels like 1,10,100,500 ppm in hydrocarbon matrix like mixture of n-C7 and toluene; perform extration by DES; perform an analysis of each sample 3 times, check if you obtain linsarity peak area vs concentration; check the RSD of peak area of each calibr. point.
Regards
G
What are you analysing exactly with the GC-SCD? Is it the DBT/dodecane mixture or the extract?
Dear Valerie Steele,
I am analyzing the S content in the model oil (n-dodecane), since DBT has 1 sulfur atom in the structure.
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