Sedex 75 elsd - stretching limits

[vestelshirley]

Am desparate to use elsd for sugar analysis but have sulfuric aid acid in the sample solution - not mobile phase. Could get acid concentration to about .05M. Would 10 uL injection of such degrade optics or could it be cleaned? I have a Sedex 75.

[Gilson_PLC2020]

Sedex 55 & 75 are quite simple and accessible internally if you are up to getting your tools out and taking things apart. The biggest pain is all the many allen head screws that you need to remove to get the case off. Once inside IIRC the black tubes (one houses the lamp and the other the optical sensor) just pull off the main flow tube (also black) - they seal with o-rings and there might be a grub screw to loosen. TBH it's a long time since I've had one apart.

[vestelshirley]

It looked as if it could be cleaned afterwards. Was concerned about sensors being exposed. Cleaning is not a big problem. We do a good bit of this to hold costs down and get things going again asap. Doesn't always work but we always try. So, probably use an internal standard and a good clean afterwards.
Thanks.

[unmgvar]

I wonder,
would using a lyophiliser in your case and freeze dry the sugars, could it help to remove some of the sulfuric acid?
not all of it but maybe most of it, like TFA?
never tried it but maybe it s an interesting experiment?

[HW Mueller]

H2SO4 is not volatile.
I am not familiar with ELSD, but wonder what such a small bolus of H2SO4, which will most likely come out at a different rt than the sugars, could do.

[vestelshirley]

My main concern was whether or not I could get ok data without screwing up the elsd. A previous comment suggested that if I wanted to do a very tedious opening and closing, the sample pathlength could be cleaned, so no permanent damage would be done with the injection of a few nanoliters of sulfuric acid. So, if I am in a pinch, I probably can get by with an internal standard (just in case of optics getting cloudy over a lengthy run) and a tedious cleanup of the elsd.
In a pinch. If all someone needs is total sugars (reducing and nonreducing), I will probably stick with the phenol-sulfuric acid colorimetric assay.
Thanks to all.