Hi, recently i did an analysis on 2 hair samples to try and detect alcohol (or ethylglucuronide). This is the protocol i followed. I used HPLC and did not get any results. The machine was capable to detect another persons alcohol in hair analysis but not mine. This person used another protocol to extract the ethylglucuronide so I think I went wrong with the method but I don't know where the error lies.
What is the detection method? MS I suppose. You must see at least the internal standard you added.
You may check this recent review "Ethyl glucuronide hair testing: A review"
in Forensic Science International 300 (2019) 106–119.
Hi Ella Peeters,
for the problem can be caused by several things.
First the detector: Which detector is used?
If you are using a UV detector, neither your analyte nor your standard will be displayed, because there are no UV-active molecule components in your molecules. If you are using a MS, it is helpful to optimize the system for the standard first. I suspect that standard and analyte are better detected in negative mode than in positive mode. Ion passage should also be optimized to produce maximum signal.
Sample preparation: Make sure that the SPE cartridges, probably C18, are well conditioned before sample introduction. In particular, pretreatment with 2-3 cartridge fills of methanol is mandatory to 1. activate the phase and 2. wash out production impurities. The latter applies to all SPE cartridges regardless of the phase. The flow rate should not exceed 0.5 ml/min during conditioning and sample loading. Too high a flow rate will cause breakthroughs or even complete loss.
I hope I can help you a little with these tips.
Best regards
Joachim Horst
Without providing more details (SPE sobent type, detection) this protocol make little sense to me.
Glucuronides in general, are polar, water soluble compounds.
So, first you extract EtG with water, this is OK.
Then you condition your SPE cartridge with water and methanol, this would be also OK providing the sorbent is of hydrophilic nature (for C18 types of sorbents the order of solvents is methanol then water).
Next you are trying to elute EtG with methanol. This is really strange. Why not with water? And even stranger for me is the final step i.e. reconstituting the extract with almost pure ACN.
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