Tool of the Month: Chloride Test Strips for feed uniformity test

Name: Chloride Quantab Test Strips 

Cost: $103 

Available at: Manufacturer’s website

Intended use

Chloride Quantab Test Strips have various industrial uses to measure chloride concentration in an aqueous sample. This article introduces the application of the strips in the feed mixture uniformity test. Multiple methods are employed in the feed industry to assess the consistency of mixtures. Among these, the prevalent ones involve chemical tests for minerals, amino acids, and chloride ion content. To accurately evaluate the uniformity of the mixture, it is important that the marker used originates from a single source, is approved for use in feed, and has a precise analysis method. Additionally, the marker should have an adequate number of particles per gram to ensure its detectability when obtaining a sample from the mixer. One of the common markers used in feed mills to assess feed uniformity is salt, which is used in diets from 0.2 to 0.5%. The salt’s particle size should be smaller than 400 microns when using a Chloride Quantab Test Strip to test the feed mixture uniformity.

Using the Chloride Quantab Test Strip to test feed uniformity

Take at least ten 100-g feed mixture samples from the different locations of a mixer, considering the sampling protocol explained in the previous article. Then follow the instructions below for each sample separately to measure chloride concentration:

  1. Using a 0.1-g readability scale, weigh a 10-g feed mixture sample into a cup and add 90 grams of hot distilled water to make an aqueous solution. 
  2. Stir the mixture for 30 seconds, let it sit for 60 seconds, and then stir it again for another 30 seconds.
  3. Filter the solution using a funnel and filter paper to eliminate suspended particles and transfer the solution into a test tube/cup.
  4. Insert a Chloride Quantab Test Strip into the liquid (Figure 1). Notice that the same lot of Chloride Quantab Test Strip should be used for all ten samples to obtain reliable, accurate results.
Figure 1. A Chloride Quantab Test Strip in a test solution at the beginning of the test. 
All Photos in this article are credited to the Government of Canada, Canadian Conservation Institute

5. After the column of the strip becomes fully saturated, an indicating band located horizontally at the top, which is sensitive to moisture, changes its color from yellow to black. This color transformation serves as a signal indicating the completion of the test (Figure 2).

Figure 2. Color change in the top horizontal completion band of the strip from yellow (left picture before exposure to a test solution) to black (right picture after completion of a test for chloride ions)

6. At the completion of the test, read the number at the top of the white peak (Figure 3)

Figure 3. Read the number at the top of the white peak. This picture shows a reading of 2.6 (consider that each gridline between 2 and 3 represents 0.2 increments)

7. Use the conversion charts on the back of the Chloride Quantab Test Strip bottle to convert strip reading to chloride ion percentage. The scales are unique for each batch of strips (Figure 4).

Figure 4. Conversion charts on the back of the Chloride Quantab Test Strip bottle to convert strip reading to chloride ion percentage.

8. Calculating the Coefficient of Variation (CV) from the results of 10 samples within a batch to determine mixing uniformity.

Example: Chloride ion concentration in 10 feed samples as follows: 0.31, 0.30, 0.35, 0.27, 0.31, 0.35, 0.25, 0.22, 0.35, 0.34. To find the tracer’s CV follow the following steps:

9. The interpretation of CV results was explained in our previous article. Briefly, a CV of less than 10% was considered as excellent uniformity, 10 to 15% as good uniformity, 15 to 20% as fair uniformity, and greater than 20% as poor uniformity by Herrman and Behnke (1994). However, the Guide to Feed Mixing protocol from the University of California, Davis suggests a 5% CV as the industry standard for most ingredients.

How does it work?

A Chloride Quantab Test Strip consists of a thin plastic strip with a capillary column impregnated with brown silver dichromate. After dipping the strip in the solution sample, the liquid enters through a small hole at the bottom of the column and then wicks up the column by capillary action. Chloride ions in the solution react with the silver dichromate, producing a white region of silver chloride on the column. The length of the white region can be converted to a chloride ion concentration using the calibration information supplied with the test strips. The test strips are available in two concentration ranges: 30 to 600 mg/L (30 to 600 parts per million [ppm]) and 300 to 6,000 mg/L (300 to 6,000 ppm).


Fahrenholz, A. 2019. Best practices: Mixing and sampling. Animal Feed Science and Technology. (Link)

Government of Canada. Test for Chloride Ions in Iron Treatment Solutions Using Quantab Test Strips – Canadian Conservation Institute (CCI) Notes 4/4. (Link)

Herrman, T. and K. Behnke. 1994. Testing mixer performance. MF1172. Kansas State University Agricultural Experiment Station and Cooperative Extension Service Bulletin, Manhattan, KS: Kansas State University (Link)

Stark, Ch., and Saensukjaroenphon M. 2017. Testing Mixer Performance. Kansas State University. (Link)

Zinn, R. A. 2020. A Guide to Feed Mixing. University of California, Davis. (Link)

About the author(s)

Research Associate at Poultry Innovation Partnership | + posts