5.1.1 AquaLab Models CX-2 and Series 3 are available from Decagon Devices Inc., P.O.Box 835, 950 NE Nelson Court, Pullman, Washington USA 99163. The Canadian distributor is Meyer Service and Supply Ltd., 119 Warner Drive RR1 Long Sault, Ont. K0C 1P0.

5.2.1 Reference salts: ACS reagent grade, fine crystal, available from scientific supply houses. See Table 1 for a list of the reference salts which may be used.

5.2.2 Reference humidity standards, available from Decagon distributors.

5.2.3 Disposable sample cups from Decagon or equivalent.

5.2.4 Test containers - 120 mL or 240mL Mason-type glass jar with screw-caps and gaskets or equilavent

5.2.5 AquaLab cleaning kit (optional)

6.1.1 In the laboratory prior to analysis, except for shelf-stable foods, keep sample units refrigerated or frozen, depending on the nature of the product. Thaw frozen samples in a refrigerator, or under time and temperature conditions which prevent microbial growth or death. Maintain package integrity until the point of measurement to prevent water loss, which may alter the water activity.

6.1.2 Analyze sample units as soon as possible after their receipt in the laboratory.

6.2.1 Certified humidity standards are preferred and may be purchased.

6.2.2 To prepare in-house reference humidity standards, place selected reference salt in a labeled test container to a depth of about 4 cm. Add distilled water in gradual increments with constant stirring until no more water is absorbed and there is some free liquid on top of the slush. At this point they are ready to use and will keep indefinitely, if contained in manner to prevent substantial evaporation losses.

6.2.3 To use the in-house reference humidity standard for the AquaLab, use the liquid portion of the mixture only.

6.2.4 Replace either of the purchased or in-house humidity standards if they become contaminated or expired.