Effect of bentonites on fluorometric selenium determination

Area of Science:

• Analytical Chemistry
• Animal Nutrition
• Trace Element Analysis

Background:

• Accurate quantification of selenium (Se) is crucial for animal feed analysis.
• The AOAC fluorometric method (3.097-3.101) is a standard technique for Se determination.
• Bentonites, commonly used as feed additives, have been observed to interfere with this analysis.

Purpose of the Study:

• To identify the cause of interference by bentonites in the AOAC fluorometric method for Se analysis.
• To develop a modified procedure to overcome this interference and ensure accurate Se measurements.

Main Methods:

• Investigated the interaction between bentonite's insoluble residue and the piazselenol intermediate.
• Implemented a modified analytical procedure involving dilution, reduction with HCl, and centrifugation.
• Analyzed the clear supernatant liquid for accurate Se quantification.

Main Results:

• Bentonite's insoluble residue binds the piazselenol, leading to underestimation of Se.
• The modified method, utilizing dilution and centrifugation, effectively removes the interfering residue.
• Accurate Se analysis is achievable even in the presence of bentonite using the proposed technique.

Conclusions:

• Bentonite-induced errors in Se analysis can be reliably avoided by employing a simple dilution and centrifugation step.
• This modification ensures the integrity of the AOAC fluorometric method for Se determination in feeds containing bentonites.
• The findings provide a practical solution for accurate selenium monitoring in animal nutrition.