Tuesday, March 25, 2008

Let's talk about TLCs Part 3 - Phosphomolybdic Acid (PMA) Stain

PMA Stain is a highly versatile general stain for developing TLC plates. The stain is easily prepared by dissolving 10 wt. % phosphomolybdic acid in ethanol. More PMA can be used however as stains go PMA is relatively expensive.
TLCs developed with PMA stain upon heating give green/dark green/dark blue spots on a yellow/green background (see picture).
Phosphomolydic acid (PMA) Stain Recipe
100 ml container
100 ml Ethanol
10 g Phosphomolybdic acid, H3[P(Mo3O10)4] · xH2O
Alternatively, you can go for the more expensive solution and buy ready made PMA stain from Aldrich (see picture). Where I've worked in the past we simply poured some of the ready made stuff into a jar and use it for our TLC plates. At the end of the day we poured it back into the Aldrich flask and rinsed with some ethanol. Using this method the stain lasts for a very long time. I never had any problems storing the stain at room temperature despite Aldrich's recommendation to refrigerate.
See under Vanilin Stain for general staining guidelines. D!

Thursday, March 20, 2008

100% Edible

Finally, I'm returning to normal. I'm back at the University working at full force and I've got the energy to do a bit of blogging again. Let's start with a nice and easy post. One of the new people at the University turned up with the following Fluka product the other day. Pretty sweet and good quality chocolates too. Apparently, Fluka is a Swiss based company and once a year (around Christmas I believe) they give their customers a truck load of these containers.One of the guys in the lab immediately grabbed the phone and gave Fluka Australia a call to hear if they stocked this item too. Unfortunately, this appears to be a Switzerland only bonus. The product also isn't listed in their catalogues.
Also my "great" idea of introducing Google adds on Curly Arrow was short lived. A lot of the adds where completely irrelevant to this blog so it's all been deleted again. D!