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Just discovered today that I was using the pipettor in the Hanna Ca test incorrectly. There are two stops as the plunger is pushed down, the first one to measure, the second one to eject the liquid. Here is the data.
When I push the plunger to the first stop and draw up a sample of RODI and then eject it, I measure 0.100 g or 100 microliters. When I push the plunger to the second stop and draw up a sample of RODI and then eject it, I measure 0.123 g or 123 microliters.
When I run the rest using one or the other pipette stop, I obtain 284 ppm Ca when I use the first stop to withdraw a tank water sample and 346 ppm when I use the second stop. The ratio of 346/284 is 1.22, essentially identical to the ratio of the above volumes 0.123/0.100.
I did not bother to look through the forum to see if this topic was discussed a million times already. Sorry if this is tiresome old news.
When I push the plunger to the first stop and draw up a sample of RODI and then eject it, I measure 0.100 g or 100 microliters. When I push the plunger to the second stop and draw up a sample of RODI and then eject it, I measure 0.123 g or 123 microliters.
When I run the rest using one or the other pipette stop, I obtain 284 ppm Ca when I use the first stop to withdraw a tank water sample and 346 ppm when I use the second stop. The ratio of 346/284 is 1.22, essentially identical to the ratio of the above volumes 0.123/0.100.
I did not bother to look through the forum to see if this topic was discussed a million times already. Sorry if this is tiresome old news.
