PharmPK Discussion - Use of sodium vapor lamps to avoid sample degradation

PharmPK Discussion List Archive Index page

On 24 Apr 2002 at 11:31:04, "Prashant V Bodhe" (prashnvb.-a-.rediffmail.com) sent the message


Dear All

It is very common to use sodium vapour lamp in BA/ PK study to
avoid photodegradation. Is there any technical rationale/
information available for this (preferably published original
article).

I have recently come across one laboratory which used array of
zero voltage light bulb, which I felt is an irrational thing to
do, by common sense. Anyone knows about frequency of the light
emitted by these bulbs.

Thanks

Dr. Prashant

Back to the Top

On 25 Apr 2002 at 10:44:25, helmut.schuetz.at.chello.at sent the message


Dear Dr Prashant,

in my opinion, there is simply no rationale (or at least just a 'rumour').
I guess, there was a 'knowledge' transfer from (instable) stock
solutions to plasma
samples, which does not hold any verification.

The best way to avoid sodium vapor lamps, is to validate the
degradation: to get
preliminary information analyse a set of spiked plasma samples
exposed for e.g. one
hour (or whatever your sample preparation time is) to differing
conditions: Na-lamp,
fluorescent lights, halogen bulbs, direct sunlight, daylight through
a window... I
expect in many cases you will end up with no differences (besides analytical
variability) at all.
If you find some degradation, validate the method for conditions with the least
annoyances (e.g. 'without exposure to direct sunlight').
If you have a method already validated with a Na-lamp, cross-validate
it for more
human conditions: run a set of 'illuminated' QC samples (LLOQ, low,
intermediate,
high) in triplicates for three days with the 'dark' method for a
formal proof of
'no-degradation'.

In my expirience 'dark room conditions' are just bad for analytical
precision: it is
very difficult to handle (mostly yellow) plasma samples in
monchromatic yellow light.

Regards

Helmut Schuetz

Biokinet GmbH
Nattergasse 4
A-1170 Vienna/Austria
helmut.schuetz.at.chello.at

Back to the Top

Want to post a follow-up message on this topic? If this link does not work with your browser send a follow-up message to PharmPK@boomer.org with "Use of sodium vapor lamps to avoid sample degradation" as the subject

PharmPK Discussion List Archive Index page