Thanks for your responses.
Actually, most of the time we don't know what the substance we are testing
for is, especially when dealing with fish kills. We have been approached by
suppliers to use Vibrio fischeri but the test kit is very expensive (both
the machine and the recurrent costs) and it doesn't make sense to purchase
one especially when we only get less than 10 incidents a year. These kits
require multiple dilutions and then calculations for an EC50.
Others are much simpler with a single test and % inhibition calculation.
I think they are all trying to confuse me!
Chris Whitworth <chris at chris-whitworth.demon.co.uk> wrote in message
news:hsnxgAAs0a28EwfF at chris-whitworth.demon.co.uk...
> This is a really complicated subject. I do it for a living sometimes!
> There are many tests, they all measure something different and are not
> comparable. Many of the suppliers claims need careful consideration
> (I'm being tactful). For example one well promoted test a few years ago
> sensitivity to measured toxins was totally obscured by natural
> substances such as manganese.
>> Be very careful. Email me via my website if you want more detail.
>>> Chris Whitworth
> Please put the world back how you found it before leaving. Others may
> use it later.
>>> Website: WWW.SPAMTRAPREMOVEEnvironmental-monitoring.co.uk