APPENDIX
D
Special Application Notes
SPECIAL LOW VOLUME PROCEDURE:
Preparing Paper Discs
1
Use a (Mieth or equivalent) 1/8 inch diameter punch to create a
supply of paper discs. Punch only one thickness of paper stock
at a time, to prevent paper discs from sticking together. That,
along with static electricity will make it difficult to pick up a sin-
gle disc with the tweezers.
2
After punching, remove paper discs from the retainer of the
punch. Store discs in a clean, static-free container.
As stated before, very low volume tests require careful and consis-
tent technique to achieve reliable results. The following are impor-
tant for you to consider when running samples with very low vol-
umes:
•
Use only single sample discs. Because of their small size, you
must be careful not to load more than one.
•
Discs must be punched cleanly–no ragged edges.
•
The sample holder must be kept very clean.
•
Do not exceed 4 µL of sample in the special sample holder.
Using too much sample fluid can severely contaminate the
thermocouple.
•
The paper disc must be completely saturated by sample fluid. If
not fully saturated the disc may appear patchy. In this condition,
data will be inconsistent and repeatability will be poor.
NOTE:
Very small samples of less than 2 microliters can be successfully mea-
sured using lighter paper for the discs. You should experiment with various
papers. Be cautious that some papers contain electrolytes that make them
unsuitable. Successful results have been achieved using standard labora-
tory lint-free tissue.
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