Evaluation of the Accuracy and Precision of Quick Tests and Labs Currently Testing Deoxynivalenol

This proficiency test was completed to evaluate the accuracy and precision of seven labs and five quick tests currently testing deoxynivalenol (DON) levels in animal feed ingredients. The following labs were analyzed in this proficiency test: Midwest Labs, NDSU, SGS, Trilogy Labs, MVTL, Romer Labs, and Neogen. Quick tests analyzed were: Charm ROSA® DONQ2, Envirologix QuickScan DON FLEX, Neogen Reveal® Q+, Romer AgraStrip® DON WATEX, and Vicam DON-V®. Two subsamples were pulled from eight corn and eight corn distiller's dried grains with solubles (DDGS) samples to be analyzed in duplicate by each lab for a total of four observations per initial sample. The same subsampling procedure was used for quick test analysis with eight corn samples and seven corn DDGS samples, again tested in duplicate for a total of four observations per initial sample. All quick tests were completed following test protocol by the same technician trained in each test. Samples were also analyzed in quadruplicate by the Schmale Lab at Virginia Tech which was used as a control. All deoxynivalenol levels were reported in parts per million (ppm). Accuracy was measured calculating z-scores using the Virginia Tech sample mean and standard error as the population mean and standard error. Variability within lab and quick test was measured by calculating coefficient of variation (CV) among the four readings per sample. For the seven labs analyzed, average CV ranged from 16-60% in corn and 2-10% in corn DDGS. Lab z-scores ranged from 5.04-9.16 in corn and 1.11-16.39 in corn DDGS. It was common for the same corn sample to yield DON results varying 2 ppm and the same corn DDGS to yield DON results varying up to 6 ppm among the different labs. For the five quick tests analyzed, average CV ranged from 7-22% in corn samples, and 3-20% in corn DDGS; only two quick tests had CV below 10% for both commodities. Average z-scores in corn ranged from 6.97-42.80, with only two quick tests below 10. Average z-scores for corn DDGS ranged from 6.67-11.51, with three quick tests below 10. It was common for the same corn and corn DDGS to yield DON results ranging 3 ppm among the different quick tests. This proficiency test identified two labs and two quick tests that perform far superior to their competition and demonstrated that the reliability of mycotoxin testing data is largely impacted by the labs or quick tests used.