Some users of LaMotte test kits are unaware of how to determine the reagent shelf-life, or that length of time when a reagent can, given proper care, produce accurate and reliable results. The incorrect basic guideline used by most seems to be one year from the date of opening. This can lead to both a waste of useful reagents and precious budgeted money. It can also lead to the use of reagents long past their shelf-life because they have only recently been opened.

On the lower, left corner of the label of each LaMotte reagent is a six or seven digit number. This is not a code number, but the lot number of that reagent. A lot number records the date of manufacture and identifies the reagent as part of a specific batch of reagent produced on that date. The first two digits of the lot number identify the week, and the third digit identifies the year of manufacture.

For example using the label above: A reagent with a lot number of 257717 was manufactured the 25th week of the year 2007.

Using the Reagent Shelf-Life Chart (below) and using the information provided within the lot number found on the reagent bottle, the expiration date of the reagent can easily be determined. This date of expiration can then be marked on the label or on a data sheet. This will ensure proper planning for ordering refills.

To determine a reagent's expiration date,

Reagents should be stored at 25°C (room temperature) and away from heat, humidity, moisture, direct sunlight and cold conditions. The storage temperature should be kept as constant as possible, without large fluctuations in temperature. Reagents should not be kept refrigerated, unless specified otherwise in the kit instructions or packing literature for the reagents (for example, Coliscan Easygel®). Reagents should not be stored in work vehicles, utility rooms, pool and pump houses or other environments where conditions may be harsh. Exposure to such conditions will compromise the quality and stability of reagents and shorten reagent shelf lives.