Autosampler loop volume is 50 microliter. When I mix my sample with the buffer by autosampler ( using insert or not), fifty fifty, the peak areas are never reaching the expected value. When I mix them by hand and inject 50 microliters with autosampler the areas are 10 times higher than the autosampler mixing operation.
Sample is extracted in %100 acetone and the buffer is ammonium acetate solution (1 M). I have tried to control between the steps of the autosampler pretreatment. I saw bubbles and realize that the needle can not aspirate and dispense 50 microliter effectively.
How can I solve this problem?
why dont you try a lower injection volume , we usually inject 1 to 5 µL in our nexera , and its precision is great .
As Kong rightly said, while working with this type of high volatile solvents, better to reduce the volatility by adding aq.buffers. This improves the aspiration precision of your autosampler and avoids the non-reproducebility.
Yeghig Armoudjian
I am trying to determine the marine phytoplankton pigments and lower injection volumes means lower detection limits and in the nature some of them are really rare. I can not reduce the injection volume. Do you think is it the main problem?
Rajareddy Kallem and Rajareddy Kallem,
As written for all this type of methods +4 centigrade for autosampler is enough to prevent acetone evaporation for a while. But I will try. Thanks a lot!
According to my experience, total volume of some solvent mixtures,such as methanol and water, is lower than sum of the added volumes. If your solvent obeys from this, you should calculate the concentration according to the final (real) volume.
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