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The Effects of Aluminum Silicate Adsorbents on the Extraction Efficiency of Mycotoxins in Animal Feeds

Ryan J. Malone, Julie L. Brunkhorst, Craig W. Humphrey, Sara L. Herron, Amy N. Pope, Ben M. Lohmeyer, Kelley M. Renkemeyer, and Bruce R. Malone

Trilogy Analytical Laboratory , Washington, MO 63090

 

Abstract

Aluminum silicates are commonly used as additives in animal feeds to minimize the adsorption of mycotoxins by the animal. An evaluation was conducted to determine if the presence of commercially available aluminum silicates in animal feeds affects the analytical extraction efficiency of mycotoxins. Naturally contaminated aflatoxin, zearalenone, fumonisin, and ochratoxin swine feeds with and without added adsorbents were analyzed by HPLC using acetonitrile/water (84/16 or 50/50) and methanol/water (70/30) exraction solvents. The results of this evaluation demonstrate that the presence of an aluminum silicate adsorbent does not affect the extraction efficiency of ochratoxin, fumonisins, or zearalenone from swine feed when using either methanol/water (70/30) or acetonitrile/water (84/16 or 50/50) as extraction solvents. There was a 58.8% decrease in the aflatoxin extraction efficiency from swine feed using a methanol/water (70/30) extraction solvent when an aluminum silicate was added at the supplier's recommended dosage (2.5 kg/ton). An increasing dose of aluminum silicate added to the swine feed correlated to the decrease in aflatoxin concentration. There was no loss of aflatoxin extraction efficiency in swine feed containing aluminum silicates when acetonitrile/water (84/16) was used.

 
Procedure

A. The adsorption of aflatoxin B1 using aluminum silicate A (2.5 kg/ton inclusion rate) for zearalenone, fumonisin B1, and ochratoxin A using aluminum silicate B (1.0 kg/ton inclusion rate) were evaluated in a pH 5.0 aqueous buffer solution at a toxin concentration of 3 ug/ml.

- All solutions were prepared in triplicate and mixed by rotation at 37°C for 3 hours.

 

Procedure continued

- The free and bound toxins were separated by centrifuging for 10 minutes
- The solutions were analyzed separately by HPLC to calculate the % adsorption.

B. Mycotoxins adsorbents were added to separate swine feeds, naturally contaminated with aflatoxins, zearalenone, fumonisins, and ochratoxin A at the manufacturer suggested inclusion rate. Each feed was extracted with acetonitrile/water (84/16 or 50/50) and methanol/water (70/30) and analyzed by HPLC with 10 replicates each.

Aflatoxin
- Aluminum silicate A with inclusion rate of 2.5 kg/ton
- HPLC analysis - AOAC Method #994.08

Zearalenone
- Aluminum silicate B with inclusion rate of 1.0 kg/ton
- HPLC analysis - MacDonald, S. Et Al, Journal of AOAC International, Vol. 88, No. 6, 2005

Fumonisins
- Aluminum silicate B with inclusion rate of 1.0 kg/ton
- HPLC analysis - AOAC Method #2001.04

Ochratoxin A
- Aluminum silicate B with inclusion rate of 1.0 kg/ton
- HPLC analysis - AOAC Method #2000.03

C. Both mycotoxin adsorbents were added to separate swine feeds, naturally contaminated with aflatoxins, zearalenone, fumonisins, and ochratoxin A at 7 different inclusion rates. Each feed was extracted with acetonitrile/water (84/16 or 50/50) and methanol/water (70/30) and analyzed by HPLC with triplicate analyses.

- The appropriate mycotoxins adsorbents were added at 0, 0.25, 0.50, 1.0, 2.5, 5.0, 10.0, and 25.0 kg/ton.
- The adsorbents, naturally contaminated swine feeds, and HPLC methods were the same as procedure B.

 
Conclusions

All mycotoxins were bound >94% in aqueous buffer solution when using the commercially available aluminum silicates at the suggested inclusion rates.

Fumonisins, Ochratoxin A, and Zearalenone in Swine Feed:

- No effects on the extraction efficiency were observed when using either methanol/water (70/30) or acetonitrile/water (84/16 or 50/50) at the recommended adsorbent B inclusion rate (1.0 kg/ton) or larger doses up to 25 kg/ton.

Aflatoxins in Swine Feed:

- No effects on the extraction efficiency were observed with acetonitrile/water (84/16) at the recommended adsorbent A inclusion rate (2.5 kg/ton) or larger doses up to 25 kg/ton
- 58.8% decrease in the extraction efficiency was observed using methanol/water (70/30) at the recommended adsorbent A inclusion rate (2.5 kg/ton)
- The amount of aflatoxin adsorption by the aluminum silicate was directly proportional to the amount added to the swine feed when using the methanol/water (70/30) as the extraction solvent.
- The use of methanol/water (70/30) as an extraction solvent for the analysis of animal feeds containing aluminum silicates, will result in a significant underestimation of aflatoxin regardless of methodology.

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