Keys to a successful, accurate water activity reading
Machine Prep:
• Warm the machine up for at least 15 minutes.
• Check a verification salt closest to the value of your sample (see flow chart below).
• If the salt reads correctly, then check distilled H2O.
• If the salt reads incorrectly, you need to clean the meter and maybe adjust the linear offset. (Refer to your manual for instructions.)
Sample Prep:
• Sample must be homogeneous, representative of the product being tested.
• Temperature of sample must be within 4°C of the meter. The closer the temp.,the quicker your readings will be.
• Keep sample covered when storing, heating, or cooling.
• Don't overfill sample dishes. Half full is sufficient.
• Make sure all users know and folow a standard sample preparation technique. (Contact Decagon for SOP template document.)
Remember these few steps and you can be sure your readings are as accurate as possible!
Calibration diagram.
Clean cups and pure standards keep your AquaLab running strong.
USING CLEAN cups and checking your AquaLab with verification standards will ensure that your readings are as accurate as possible. Here's why:
Cups
Contaminated cups reduce accuracy. Even after cleaning out a cup, residue can be left in the cup, causing contamination. We strongly recommend that cups be used only once. Single use of cups will ensure that your samples have a fresh chamber to be stored in and that your sample will not be contaminated.
Verification Standards
AquaLab's performance should be verified daily. Verification salts are an essential tool in testing your meter's cleanliness and accuracy. By checking a salt, you have a quick indicator to let you know if you need to clean and possibly adjust your meter. Decagon makes this procedure hassle free by offering independently verified, prepackaged salts, in 4 different aw ranges, 0.250, 0.500, 0.760, and 0.984.
Disposable sample dishes and verification salts can be purchased directly from Decagon by calling 800-755-2751.