Lowry protein determination (follow up)

James Wee jywee at charter.net
Fri Jul 4 03:15:32 EST 2003

Thanks. I prepared my blank by adding NaOH first, adjust it to 1mL using
distilled water. Secondly, I added CuSO4+NaKTartrate+ 2%Na2CO3, and Folin
reagent the last. Before I took the reading of the samples, I blanked the
Beckman spectrophotometer using the blank solution have I prepared. Thus,
all the sample readings are adjusted. Could this be a problem?


"EK" <nobody at elnino.com> wrote in message
news:3r2Na.52$Y4.12560 at news.uchicago.edu...
> "James Wee" <jywee at charter.net> wrote in message
> news:vg7bqu5sp0r973 at corp.supernews.com...
> > Thanks for your comment. I checked through all my reagents and found
> > there is something wrong with IN NaOH that I used. After using the new
> NaOH,
> > the readings are low now. It intercepts with y-axis at  0.04. I wonder
> > the NaOH solution (which contains more NaOH) makes the color darker.
> >
> > James
> >
> >
> >
> Make your NaOH at least once every couple of weeks and keep it in tightly
> closed bottle, or use a stopper with CaOH trap. NaOH will absorb CO2 from
> air to form insoluble Na2CO3. Also, some microorganisms can live in
> solutions of such a strength(plus the strenth will be reduced in time as a
> result of growth). Your high values are most probably due to the presence
> growth of contaminating species that as you can guess are made of
> too. By the way, I still don't understand how your blank would not be at
> zero. Do you compare your values for blank with numbers someone gave you
> a guideline?
> -Emir

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