Hemoglobin measurement at 540nm or 430nm?

[Greg Smith]

In article <32F2151B.63E1 at biol.rug.nl>, Leendert Hamoen
<l.w.hamoen at biol.rug.nl> wrote:

> According to some literature the release of hemoglobin from erythrocytes 
> after the addition of surfactants is measured at 540 nm. We measure a 
> much higher absorption at 430 nm compared to 540 which is consistent 
> with the fact that hemoglobin is red. Does anybody know why I should 
> measure hemoglobin release at 540 nm in stead of 430 nm?
> 
> Thanks in advance, Leendert Hamoen

In my experience, 430 nm is often TOO sensitive.  Typical samples would
have to be diluted to get a reading that falls in the linear range.  540
nm is thus more convenient.  I'd use 430 nm if I had very dilute samples,
but first I'd check that I was reading in the linear portion of the
absorbance vs concentration curve.  

M. Gedde