Decagon Devices AquaLab 4TE Operator's Manual page 123

other terms have any temperature dependence.
A further advantage of unsaturated salts is that there is no solid phase
present to aff ect the water activity of the solution. Salt in saturated
solutions can exist in diff erent states and result in uncertainty in the
water activity values.
Instructions for Using Decagon's Verifi cation Standards
Simply empty one vial of standard solution into a sample dish and
place the dish immediately into the AquaLab for measurement. Each
vial will fi ll a sample dish to just less than half full. Th e following
table shows the expected values.
Verifi cation Standard
Distilled H2O
0.5m KCl
8.5M LiCl
13.4M LiCl
NOTE: If you need to obtain a Material Safety Data Sheet (MSDS) for
any of these standards, a printable version is available on our website at
www.decagon.com/msds.
Verify the AquaLab is functioning properly with any two of these
solutions. We recommended that you choose a standard from the
range in which you are measuring and distilled water (or another
solution from the table).
1. Place the verifi cation standard (do not start with water) in AquaL-
ab for measuring. When a fi nal reading is reached, check it against
the value listed above. If it within ±0.003, place your second solu-
6M NaCl
Water Activity
1.000 ±0.003
0.984 ±0.003
0.760 ±0.003
0.500 ±0.003
0.250 ±0.003
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AquaLab
Appendix C