Reagent Shelf Lives

How to Determine Reagent Manufacture and Expiration Dates. Most users of water quality 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 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 (sometimes 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 (1990’s) of manufacture. For example, a reagent with a lot number of 257717 was manufactured the 25th week of the year 1997. A reagent with the lot number of 0872321 was manufactured the 8th week of the year 1997. With the knowledge of a reagent’s shelf-life (see chart) 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.

Presented in the table is the shelf-life of monitoring reagents commonly used for water quality analysis. Using this table and the lot number found on each reagent bottle will assist the user in determining the reagents expiration date, planning refill orders, saving money, as well as ensure reliable and accurate.

Avoid Waste, Save Money, and Ensure Accurate Test Results

You have just purchased a water quality test kit which includes several different reagents OR you have just inherited one from a previous monitor/educator and several questions come to mind:

1. If I do not use all these reagents during my testing, and given proper care, how long will they stay reliable?

2. How do I determine whether a reagent is still good?

3. Do I consider when they were purchased or when they were opened to determine their length of usefulness?

Global Learning and Observations to Benefit the Environment (GLOBE) is a worldwide network of students, teachers, and scientists working together to study and understand the global environment. By participating in GLOBE, teachers guide their students through daily, weekly, and seasonal environmental observations such as air temperature, precipitation, and water quality. Using the Internet, students send their data to the GLOBE Student Data Archive. Each day, images created from the GLOBE student datasets are posted on the World Wide Web, so students and visitors to the GLOBE web site can visualize the students' environmental observations. Scientists and other students use this data for their research and provide feedback to the students to enrich their science education.

Reagent Shelf Life for the GLOBE Program

Kit Modules

Reagent Name

Order Code

Shelf Life

Dissolved Oxygen
Code # 5860
Code # 7414

Manganous Sulfate Solution

4167

3 Years

Alkaline Potassium Iodide Azide

3 Years

Sulfuric Acid, 1:1

3 Years

Sodium Thiosulfate

1 Years

Starch Indicator

Sulfamic Acid Powder

2 Years

Bromcresol Green-Methyl Red

Alkalinity Titration Reagent B

2 Years

Salinity Kit
Code # 7459

Salinity Indicator Rgt A

3 Years

Salinity Titration Rgt B

2 Years

Soil NPK Kit
Code # 5880

Nitrate Tabs

2 Years

Phosphorous Tabs

3 Years

Potassium Tabs

3 Years

Floc Ex. Tabs

3 Years

pH Buffer

Buffer 4

Bufffer 7

Buffer 10

Conductivity
Standard

STD (718 m mhos/cm)

Nitrate Code
#3615

Mixed Acid Reagent

3 Years

Nitrate Reducing Reagent

1 Years