Dear all,
I am doing biodegradation experiment to remove low level of crude oil in seawater. To measure the biodegradation of oil, I use a GC-FID and extract the sample with hexane and clean on florisil column.
Without presence of bacteria, the GC-FID give a reliable signal for the hydrocarbon between C7 to C40. However, presence of bacteria induce a high signal between C16 to C33, masking the signal of crude oil.
Could I just filter the bacteria with a membrane filter 0.22 µm? Does the filter keep the bacterial lipid without retaining the oil? Or other method exist to remove the bacteria and the bacterial product?
Thanks in advance for your answer.
I wonder if gcfid- solid phase microextraction (spme) will do. It works really well to trap volatile compound of hydrocarbons including diesel. But you need to heat up the sample first in order to trigger the volatility. It may not work if you want to keep your bacteria alive after the detection.
My 2 cents
Dear Farrah
Thanks for the answer. I have already heard about but before switching to a new technique I wanted to know if it was an easy way to be rid of the bacteria signal.
Best regards
You could perform a silica alumina chromatography for your sample. I often use 1% deactivated alumina and 5% deactivated silica gel eluded with 100ml of DCM for all biota samples; fish fry, oyster and mussels. My target compound is also aliphatic and aromatic petroleum hydrocarbons from oil. So yes I do get an excellent removal of lipid or non-target compounds. When I run for both gc-fid and gc-ms the peaks are well separated without other disturbance. Also if you still find lipid or large noise or high disturbance in your peak you could load your sample for a gel permable column hplc. This allows you to only obtain your target compound range.
My lab, we have also performed the analysis for bacterial biodegradation of crude oil too. We also performed extraction of the samples. We could remove all bacteria and bacterial products through the silica alumina chromatography proceed with gel permeable column hplc. Since compacting of silica and alumina acts to trap non-target compounds, it also acts as a filter for larger residues or molecules such as bacteria and their products.
Dear Andrew Loh thank for your answer and you proposition will be considered.
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