At the present time the R5 ELISA (R7001 Ridascreen Gliadin) is widely regarded as the best available formally validated ELISA for assessing final food product for gluten. The R5 ELISA is one of only two commercially available ELISAs validated at the levels used for regulatory purposes and official governmental methods (the other is the Morinaga Wheat Protein ELISA). The R5 ELISA is included in the FDA’s Question and Answer page on the gluten-free labeling rule as one of the methods the agency will use for rule enforcement if testing a product becomes necessary.

Testing each sample in duplicate does two things: it helps guard against laboratory error and it helps ensure that the sample tested is homogenized. This means that any "contaminant" (in this case gluten) is well distributed within the sample. If the results of the two extractions are fairly similar a reasonable amount of confidence can be placed in the results. Some products may be more difficult to homogenize than others. 

Gluten Free Watchdog, LLC conducts follow-up testing of labeled gluten-free products that test greater than or equal to 20 parts per million of gluten within one year of the original test date. Manufacturers can request that retesting occur sooner than one year (please see the manufacturer page). 
Foods NOT labeled gluten-free are not retested as the manufacturer is making no warranties regarding the gluten-free status of their product.

Products labeled gluten-free and products appearing to be free of gluten-containing ingredients (but not labeled gluten-free) may be selected for testing. Consumers and health care providers may request product testing via our contact form. A request for testing does not automatically mean that a product will be tested. Almost all products currently tested by Gluten Free Watchdog are consumer/dietitian requests.

 

Products tested are purchased by Gluten Free Watchdog, LLC at retail outlets. Exceptions are made when a product is very difficult to find or must be ordered in bulk.