Titanium dioxide has been used as a marker for determining diet digestibility indirectly, but some authors have expressed difficulty in measuring TiO2 concentrations in fecal material. We developed an accurate and precise method to determine TiO2 concentrations in equine feces. The method includes dry-ashing samples, digestion with (NH4)2SO4 in concentrated sulfuric acid, followed by the addition of H2O2 to produce a yellow to orange color that can be read spectrophotometrically. Accuracy was tested by spike recovery, and precision was tested by examining the coefficient of variation (CV) between duplicates of 449 individual samples. The method described here was compared with a previously published method by examining CV between duplicates of samples analyzed using both methods and comparing them using a paired t-test. Titanium dioxide spike recovery averaged 106%, and the CV between duplicates averaged 4.0%, with 79% of sample pairs having a CV of <5%. When compared with a previously published method, the method described here had a lower CV between duplicates (P < 0.0001). The method described here provides an accurate and precise quantitative analytical procedure for TiO2 in equine fecal samples.
Keywords: digestibility; feces; marker; method; titanium dioxide.
Titanium dioxide is a marker fed to animals to help determine diet digestibility indirectly by measuring the concentration of TiO2 in fecal samples. This paper describes an accurate and precise method to analyze TiO2 in equine feces. The precision of this method is demonstrated by the low variation between sample duplicates. This method requires fewer sample replicates for analysis, leading to less labor, expense, and waste in the laboratory.
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