unwashed biodiesel in column?

[ece]

I have a question on biodiesel analysis. Is it considered non-kosher to put an unwashed sample of biodiesel (that still has some soap, methanol, residual catalyst) potentially into the column? If I let it settle for a long time, there are fewer soaps, but what are the consequences?

We are using an anhydrous catalyst, so it doesn't create water. But I worry about unwashed biodiesel and it's effects on our column and stationary phase.

Not having to wash it though would save me days of time and resources to prep the biodiesel before silyating.

Any thoughts?

[AZBiodiesel]

i have to do biodiesel analysis as well and have only done a few runs with washed biodiesel. But I am tempted to do the same thing to see what the chromatogram looks like. From my extremely limited knowledge i would think that any excess catalyst and sodium or potassium ions in the form of soaps would be a bad thing for the column.

If you are worried about the time it takes to wash the biodiesel (Im assuming you are doing water washes?) then maybe you could try using magnasol d60 (magnesium silicate) to remove any excess glycerin, soaps and to some extend monos, di's and tri's) in your sample prep. Its pretty quick just pour it into your bio, mix for a half hour and filter it out. But make sure you filter it below 1 micron. But I don't think it takes out methanol very well. So you could also try ionic resin beads (purolite/amberlite) which will scrub out the soap, glycerin and methanol immediately.
Probably shouldn't do this though if you are doing astm 6584, but if you are just checking for FAME's then it could save you time?

[ece]

AZ

Yeah, we have some magnesol, we just need a vacuum and a filter to extract it. What I've been doing is rough washing where I just add a little bit of water to the sample, roughly wash it, drain it, repeat for about 2-3 times let settle in a heated water bath, then have drawn off of that.

I'm not too concerned about glycerol, more about generating kinetic data from glycerides.


I noticed you had some questions about calibration. Did that work out for you? How are your biodiesel samples looking?

[AZBiodiesel]

the samples look good. I am using a 5m guard column and 15m db-5ht column from agilent. I have a couple chromatograms i can put up here, im not too familiar with how to do that though.

With the calibration Im getting closer to what I want out of chemstation but it still seems like i have to do all the real calculations in excel which is fine but i was hoping to everything in chemstation.

I would say the resin beads sound like your best bet, get purolite to send you some samples. You can run the bio right thru a little column of them or stir them around in a reactor for a little while, then you can use a relatively large filter to get them out. And the bio is ready to go after that. They are expensive to buy, but you can recharge them 4 or 5 times with a methanol wash, and it would take a while to exhaust them if you are only using them to clean up samples for assay. I don't know how well they interact with triglycerides though, but it sounds like you want those left in your sample anyway.

[ece]

Yeah we're getting some purolite, we're tired of spending days and days washing and settling, not to mention tons of soapy waste water generated in the process. Now that it is economical, and that it can be recharged with methanol rinses, we're looking forward to seeing what kind of results we can get from it. Bubble washing does work, but it's labor intensive.

Have you been happy overall with purolite? I'd like to know from an actual user.

Does purolite sell small samples of these? That would make my bench work miles easier right now. I'm so bottlenecked with samples I made earlier in the week that are still washing. But the rep hasn't told us he can give us small samples sizes that I can use in the lab.

Good to see your samples are looking ok, but you do need the calibration curves generated so you know exactly what your glyceride numbers are (cause you have to put those in to calc the amounts), as well as to have the assurance that your column is responding repeatably and for the appropriate concentrations, even if you can still get a good feel for it by looking at the peaks themselves. Having used 3 columns already, the calibration slopes and y-intercepts for me have not changed that much for every time I've installed a new one, but I always calibrate it anyway to make sure it is performing up to standard.

[AZBiodiesel]

i haven't done any quantitative analysis with purolite yet, im planning on it soon. but just visually you can see it cleans up the bio really well, it gets nice and clear. We don't actually use the stuff in production yet, we currently use magnasol, but are planning on maybe switching to the beads in the future. Just tell the sales rep that you are a lab working for a biodiesel company and you need to do some tests with the beads before you buy it, they should send you some samples. I don't think they sell it in small volumes. we bought a 50 gallon drum of the stuff for about a thousand dollars.