Solution indicatrix pH Taylor (for the 2000 series), phenol red, 0.75 oz, dropper bottle

SHELF LIFE OF REAGENTS All reagents have a shelf life, whether they are liquids, powders, crystals, tablets, or test strips. If kept dry, powders and crystals are very stable; acids also have a long shelf life. The date of manufacture is not the determining factor in shelf life — storage conditions are more important. Like all perishable products, reagents are sensitive to environmental influences and will keep longer under controlled conditions.

To this end, we recommend:

Keeping reagents at a constant temperature between 36 °F and 85 °F (2 °C and 29 °C); extreme temperature fluctuations, for example moving them from a refrigerator to the trunk of an overheated car, cause reagent deterioration.
Keeping them out of direct and prolonged exposure to sunlight. (Note: their brown plastic bottles help protect reagents that are very sensitive to light.)
Separating reagents from treatment chemical containers.
Replacing caps immediately and tightening them carefully to limit exposure to air and moisture.
Avoiding swapping bottle caps, placing caps on dirty surfaces, pouring reagents into contaminated containers, or touching the pads on test strips.
Taylor formulates its reagents so that they retain their effectiveness for at least one year, with a few rare exceptions (the liquid molybdenum indicator is one; after four months, it must be tested periodically against a standard). As a general precaution, replace all reagents that are more than one year old, or at the start of a new testing season.