kerozene contamination analysis by gaz chromatography 1

[rafikk]

Huy guy

In order to determine the contamination of the kerosene’s (JET A1 ) sample with an diesel fuel, I used the gas chromatography, in order to analyze kerosene fuel JET A1, I had injected the non contaminated kerosene in less than 1 microliter of liquid sample into a 50 meter GC capillary column with a flame ionization detector then I injected the contaminated kerosene, I remarked that the contaminated kerosene had an additional pic associated to heavy compound, my chromatography apparatus haven’t an incorporated retention’s time library
Need , diesel , gasoline and kerosene retention’s time library in order to identify the contamination pic.
I will be very grateful for you help
Thanks

 

[efp]

Here are the steps I used for fuel characterization when I was a lowly chemist:

1) Obtain standard reference materials of diesel, kerosene and gasoline. If you are performing qualitative (i.e. is it or isn't it) analyses as opposed to regulatory or QC work then you can get these at the local station. If you are at a facility that uses this stuff frequently, you might want to start collecting small quantities of each delivery.

2) Create working standards from these SRM's. For the conditions that I used most often, 10-50 uL fuel per mL MeCl2 seemed to work well. I then made 1-2 uL injections into the GC. Save these chromatograms - these are the reference chromatograms that you asked about. These standards will give you volume/volume concentrations. Use difference weighing to get w/v concentrations if you need them. Rinse syringes until you are sure they are clean and then a couple more times.

3) Analyze reagent blanks frequently; particularly between standard runs and your unknown sample.

4) Make up samples in the same solvent as your standards and analyze them under the same conditions.

5) Compare the chromatograms with the standards.


Now the bad news:
Almost every gasoline/kerosene sample I ever ran had traces of diesel and vice versa. I never investigated it much but I attributed it to using the same pipelines and transport trucks for all fuel types. I guess a gallon or 2 crossover in a 1000 or 10000 gallon batch didn't matter much. NO, I didn't contaminate them with my lab equipment!
If you allow a low boiling fuel to evaporate, it will begin to resemble higher boiling fuels. That is, the chromatogram will appear to "shift" to the right. This is particularly troublesome when looking for accelerants in arson cases.
Just be very careful before making an assessment. If you have a 50/50 mix, you should be able to discern it with ease. I would be very cautious in claiming that I had found 100 ppm diesel in kerosene without some additional data.

 

[rafikk]

Thank's

It’s seem a good method to determine the percentage of the contamination by using standard.
I will collect sample from each delivery and i'll make my own standard chromatogram library .

It’s right that most often the kerosene is contaminated by diesel, in our cases we use a same pipelines for both diesel and kerozene.So we need to know the percentage of the kerosene’s contamination in order to correct the freezing point of the kerosene, according the contamination’s value we ad the weak contaminated kerosene to the strong contaminated one, in order to decrease it's freezing point.
I’ll inform you for the cromatography's results that I’ll have!