Chromatography Forum

Hello fellow analysts

Anyone out there with expirience using SPE for honey sample prep.

Trying to clean up honey to analyse Beerepellents with GC-MS.
(Benzaldehyde, Phenol, p-Dichlorobenzene, Phenylacetaldehyde, Nitrobenzene, Naphthalene, Thymol)

at the moment Testing Strata-x 33u Polymeric Reverse Phase (30mg/3mL)

conditioning:
3 mL MeOH
3 mL H2O
load:
10 mL Sample (5g honey in 6.4 mL --> ~ 10 mL)
wash:
3 mL 10% MeOH
elution
2x 0,5 mL 100%MeOH

works perfect for Benzaldehyde, Phenol, Phenylacetaldehyde, Nitrobenzene, Thymol using standard mix
bad recovery for p-Dichlorobenzene, Naphthalene when using standard mix (could life with that if the rest works)

Using fortified honey is a different story.
looks only good for nitrobenzene
recovery
Benzaldehyde (33%), Phenol (198%), Phenylacetaldehyde (70%), Nitrobenzene (103%), Thymol (160%)

I greatly apriciate any advice or help you can give me.

Hello fellow analysts

Anyone out there with expirience using SPE for honey sample prep.

Trying to clean up honey to analyse Beerepellents with GC-MS.
(Benzaldehyde, Phenol, p-Dichlorobenzene, Phenylacetaldehyde, Nitrobenzene, Naphthalene, Thymol)

at the moment Testing Strata-x 33u Polymeric Reverse Phase (30mg/3mL)

conditioning:
3 mL MeOH
3 mL H2O
load:
10 mL Sample (5g honey in 6.4 mL --> ~ 10 mL)
wash:
3 mL 10% MeOH
elution
2x 0,5 mL 100%MeOH

works perfect for Benzaldehyde, Phenol, Phenylacetaldehyde, Nitrobenzene, Thymol using standard mix
bad recovery for p-Dichlorobenzene, Naphthalene when using standard mix (could life with that if the rest works)

Using fortified honey is a different story.
looks only good for nitrobenzene
recovery
Benzaldehyde (33%), Phenol (198%), Phenylacetaldehyde (70%), Nitrobenzene (103%), Thymol (160%)

I greatly apriciate any advice or help you can give me.

I have a feeling that the compounds for which you got low recoveries using the standard mix were too hydrophobic for a methanol elution. They are probably still retained by the sorbent. p-Dichlorobenzene and naphthalene both have logPs above 3, while the other compounds (with the exception of Thymol) are in the 1-2 range. You will probably have to increase the strength of your elution to a solvent like acetonitrile. Maybe this will help with the fortified honey too (although I can't be sure). Hope this helps!

I would probably bag the traditional approach and go with unbuffered QuEChERS. Dilute 1:1 with deionized water first. Make sure that all plastic is free of PAHs. Clean up by passing acetonitrile extract through a dual phase endcapped C10/PSA cartridge. 20 minute procedure.

I have a feeling that the compounds for which you got low recoveries using the standard mix were too hydrophobic for a methanol elution. They are probably still retained by the sorbent. p-Dichlorobenzene and naphthalene both have logPs above 3, while the other compounds (with the exception of Thymol) are in the 1-2 range. You will probably have to increase the strength of your elution to a solvent like acetonitrile. Maybe this will help with the fortified honey too (although I can't be sure). Hope this helps!

thanks for your response
you are right for the p-DCB and Naphthalene
I eluted first with aliqouts of MeOH and then with ACN
evaporated ACN at 60°C with N2 stream and reconstituted with MeOH found some amount (probably evaporated parts of the Compounds as well)
used in a second experiment n-Hexane and found the missing p-DCB and Naphthalene
however i can not use n-hexane for elution (tryed it with honey sample) as I elute a lot of other stuff form the cartridge which is meesing up my liner pretty quickly

Do you think the low recovery of the orthers with real sample could also be due to bad elution?
As with standards the elution works perfect for Benzaldehyde, Phenol, Phenylacetaldehyde, Nitrobenzene, Thymol.

Could it also be that the capacity of the 30mg/3mL cartridge is to low. As there is also a lot of stuff from honey that is bound to the cartridge.
I am thinking of going for a 60mg/3mL cartridge to increase the capacity.

I would probably bag the traditional approach and go with unbuffered QuEChERS. Dilute 1:1 with deionized water first. Make sure that all plastic is free of PAHs. Clean up by passing acetonitrile extract through a dual phase endcapped C10/PSA cartridge. 20 minute procedure.

Thanks for your respons

I have some QuEChERS test samples including the dispersive SPE Clean-Up stuff (MgSO4/PSA, or MgSO4/PSA/C18)
unvortunately they are all buffered

I talked to our supplier but they do not have dual phase endcapped C10/PSA cartridge

However i have some C8 cartridges (500mg/3mL) lieing around.

As it seems there is some problem with evaporation of the compounds during evaporation of the organic solvent
any suggestions about how to get rid of the ACN and not loos the compounds of interest?

I don't whant to injection ACN to my GC-MS system.