The Adsorption and Desorption Capabilities of an Aluminum Silicate Analysis for Endotoxins

Julie L Brunkhorst, Amy Pope, Heather Henderson, Ronald Niemeijer

Trilogy Analytical Laboratory, Washington, MO 63090




Aluminum silicates are commonly used as additives in animal feeds to minimize the adsorption of mycotoxins and other toxic compounds by the animal. An evaluation was conducted to determine if Endotoxins could be analyzed for adsorption and desorption capabilities in an aluminum silicate. An Endotoxin solution was prepared in a buffered solution and then added to a recommended dosage of an aluminum silicate. The buffered solutions were then analyzed for adsorption and desorption using pH 5 for adsorption and pH 6.5 for desorption. Results proved that the analysis of Endotoxins could be performed with an aluminum silicate yielding 98.8% efficiency.



1 kg/ton
Endotoxin Binder Table 1.png


0.5 kg/tonEndotoxin Binder Table 2.png



All solutions used in this analysis were made from LAL water and all glassware and test tubes were Endotoxin free.

Solutions made were:

1N Hydrochloric Acid
1N Sodium Hydroxide
pH 5 Buffer
pH 6.5 Buffer
Endotoxin Standard 40 EU/ml in pH 5 Buffer

All solutions were then tested for Endotoxins to determine background or concentration.

An aluminum silicate was weighed to represent 0.5 kg/ton and also 1kg/ton.

The 40 EU/ml Endotoxin in pH 5 buffer standard was added to the weighed aluminum silicates.

The samples were then incubated at 37°C for 3 hours while rotating.

Samples were then centrifuged and decanted into clean test tubes (any unbound Endotoxin will be in solution).

For desorption, pH 6.5 Buffer was added to the test tubes containing the bound Endotoxin.

The samples were then incubated at 37°C for an additional 3 hours while rotating.

Samples were then centrifuged and once again decanted into clean test tubes.

Adsorption and Desorption blanks, samples and standards were tested by a quantitative LAL FDA licensed cartridge system.

  • Endotoxin binding capabilities were obtainable for this study
  • The Aluminum Silicate used for this analysis gave sufficient binding efficiency
  • Percent binding was similar between 0.5 kg/ton and 1 kg/ton

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