I am considering analyzing headspace volatiles from bacterial cultures by SPME-GC-MS. I need to estimate the number of fibers I need.
I used SPME to determine volatile flavor in the cigarette and never change the fiber until I finished method validation about 100 injections., Check my publication in my profile.
I determined volatiles from dried plants. I run 200 injection and I never changed fiber. Everyday, before and after samples inject I cleaned the fiber.
Yes, SPME fibers are reusable. I use headspace-solid phase microextraction for several samples and the fiber is quite resistant over successive thermal desorptions. Take care of yours and you will never have to change that often. I would say 100-200.
Absolutely, they are reusable. How many times will depend on the temperature of your injector, the nature of your analytes, etc. With the appropriate QA/QC protocol you will find out when the retention capability of your fiber starts to decline.
Yes SPME fibre are reusable but their capacity to sorb the analytes declined with time and number of injections. In order to test this change we make a test along time with a model mixture of known volatile compounds in a non-volatil solvent.
Indeed, they are reusable. In our experience can be reused more than 100 times without problems. It is a robust and simple technique for what you want to measure. Check my publication in my profile.
With no handlig mistakes, for headspace analysis, using a PDMS fiber at least 100 extractions. I got once a PDMS working almost a year, almost all days. Other fibers are not so robust. The DVB/car/PDMS will be the best choive for bacterial volatiles however it wont last as much as a PDMS fiber.
The way we check the decline of the fiber with a model mixture is very usefull in order to decide when a fiber is too old and needs to be discarded. We have an automatic sampler (Gerstel coupled with GC-MS) and usually with DVB/CARB/PDMS or CARB/PDMS we used 50-60 times for Headspace-SPME determinations of VOC in polymer.
SPME fibers can be used according to the manufacturer for 100 injections, but their use depends as mentioned before, the analytical matrix , temperature, and extraction mode , if headspace can reach up to 200 shots, but if Immersive much less .
Iwould use PA ones. I used for more than 200 injection without loose of activity. Another important thing is if you use acids to lower the pH. It strongly affects the fiber lasting.
With manual use, number of samples per fiber largely depends on analyst care and fatigue. With automated SPME we have experienced up to 1000 samples even with the more sensitive dvb/car/pdms fiber.
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