Yo siempre he usado la ultracentrifugacio en gradiente de densidad con KBr para separar las lipoproteínas. con 3,6gr de Kbr por cada 10 ml de suero, se otienen perfectamente las bandas de las lipoproteinas. Le aconsejo lea mis artículos Salvador et al. JAFC 2007 y 2009 y el de Higuero et al. Anal. Biochem. 2011. Espero le sean de ayuda. Un saludo.

I used to do a lot of lipoprotein separation by density gradiënt and found the best method of removing even the closest layers was to take a box of glass pipettes and gently heat each one so that you can then pull the narrow end into an even narrower tip about a cm long or more. With a little bit of practise you can learn what is the right temperature to soften the glass sufficiently to draw out the tip so that you get a microtip of about 1 mm diameter at the most. You can then cut this cleanly with a small glass cutter (looks like a blunt razor blade). Put a small rubber bulb over the large end and insert the microtip into the meniscus of each layer and then very gently aspirate. With practise (and I did this for my PhD and subsequent research) you can accurately remove exactly each layer you want and anything above or in between you can aspirate and discard if you wish. Use a fresh pipette for each aspiration to prevent contamination. This was the methodtaught to me by Dr. Frank Lindgren the father of density gradiënt lipoprotein separation.

Harry Magnani

I have used the method of microtip aspiration as out lined by Harry Magnani above,when the bands are not thick and sticky. For bands too sticky,  you will have to use a ultracentrifuge thin tub slicer (Beckman) for full recovery. You can also recentrifuge your collected band  in a "shallower" gradient for purer separation as suggested by Sven Schenk.  David K. Y. Lei

Hi everyone!!! Can somebody tell me the formula to calculate how many grams of KBr I need to add to my buffer to make a determine density?

Thanks!!!