“For it’s one, two, three strikes you’re out…” Many of you probably know the song “Take Me Out to The Ballgame” from baseball. You might be wondering: what does baseball have to do with mycotoxin analysis? Think of it this way: the umpires in baseball are required to make important decisions in every game with 99% accuracy. When it comes to laboratory results, this type of accuracy is critical.
There are many ways to express laboratory findings. For instance, mycotoxins are routinely reported as “parts per billion” (ppb) or “parts per million” (ppm); bacterial and fungal tests are reported as the number of colony-forming units; and proximates such as protein, fat, and fiber are reported as percentages. These are just a few examples, and there are many other types of analyses that have their own specific reporting units. No matter the unit of expression, the critical determination of the result is how it was achieved and that the results obtained have a specific degree of confidence.
Laboratory methods are researched and validated with detailed criteria to ensure quality and reproducible results. Most of the methods we use at Trilogy are AOAC® Official Methods of Analysis. These methods are validated with several organizations worldwide to determine specificity, accuracy, precision, linearity, etc. Along with other approaches used, these methods are validated in-house at Trilogy using similar method criteria on various sample matrices.
From the method validation, the limits of detection and quantification are determined. “Limit of detection” (LOD) is the lowest concentration level that can be determined from a blank having a signal to noise ratio greater than or equal to 3. “Limit of quantification” (LOQ) is typically defined as 10 times the LOD. Blanks of chemical reagents and sample matrices are both used during method development. These blanks are used to check for interferences at or near the retention time of the analyte and assist in the calculation of the signal to noise ratio. Signal to noise is a measure of how strong the analyte peak is compared to the background noise. This is determined by taking the average area of the analyte peak divided by an average area of background noise that is close to the limit of detection. While there are many ways to express laboratory reporting limits, LOD and LOQ are the most common. Some laboratories also use a “reporting limit” (RL), which is a value that is determined by the laboratory. This value may or may not be statistically determined; it is based on the experience and confidence level of the laboratory.
As you can see, there can be many variations when it comes to reporting laboratory results. It is important to have an understanding of the different ways laboratory findings can be expressed in order to be able to interpret your results. Whether your results are reported as LOD, LOQ, RL, or some other reporting limit, it’s essential not to “strike out.” Make sure your laboratory hits a “home run” by using validated methods.