The Validation of the Wheat Gluten ELISA Kit.

Background: It is important to analyze the presence of wheat/gluten in food to avoid wheat allergy or celiac disease. Objective: The Wheat/Gluten ELISA kit was developed to measure total wheat protein or gluten content in wheat, barley, and rye cereals as raw materials, and processed foods. Validation as to whether this kit is suitable for quantifying total wheat protein/gluten was carried out. Methods: The Wheat/Gluten ELISA kit was designed as a sandwich ELISA based on antigliadin polyclonal antibody. Selectivity, interference study, matrix study including incurred food, robustness, stability, and lot-to-lot consistency studies were conducted for the Wheat/Gluten ELISA kit. Incurred matrix studies were also conducted in an independent laboratory. Results: The analysis of 38 different substances revealed no cross-reactivity above the LOQ except for oats. Recoveries of the spiked samples were mostly in the range of 75-140%, including an independent laboratory result. The LOD of the ELISA was found to be 0.02-0.16 mg/kg. Robustness testing proved that extraction time and incubation time of first reaction and enzyme reaction had no significant influence on quantified value. The stability at 2-8°C was found to exceed 12 months. Good lot-to-lot consistency was observed. Conclusions: The Wheat/Gluten ELISA kit showed good analytical performance in the quantitative analysis of total wheat protein/gluten in the identified food products using the AOAC Performance Tested Method(s)SM program. Highlights: The Wheat/Gluten ELISA kit was validated and showed good analytical performance in the quantitative analysis of total wheat protein/gluten in food.

Validation of the RIDASCREEN(®)FAST Milk Kit.

The RIDASCREEN(®)FAST Milk test is a sandwich ELISA for the rapid quantification of milk proteins in various foods. The specific antibodies target casein and ß-lactoglobulin. Samples are extracted and can then be analyzed in less than 40 min. The calibration curve covers a range from 2.5 to 67.5 mg/kg milk protein. The assay was validated with cookies, infant formula, chocolate dessert, ice cream, and sausages. All negative samples were found well below the LOQ of 2.5 mg/kg. Recoveries of the spiked samples were mostly in the range of 80-120%. The LOD of the ELISA was found below 1 mg/kg. The analysis of 39 different substances of interest revealed that no cross-reactivity above the LOQ occurred. Ruggedness testing proved that variations in incubation temperature, reagent volume, incubation time, extraction temperature, and extraction time had no significant influence. The stability at 4-8°C of three independent lots was investigated and found to exceed 18 months. Very good lot-to-lot consistency and no significant loss of the analytical capacity over the shelf life were observed. Incurred cookies and chocolate dessert samples were prepared and analyzed by an independent laboratory; mean recoveries of 94.4 and 102.2% and mean SDs of 10.9 and 6.3%, respectively, were found. For the 0 mg/kg level for both materials, all samples tested returned values of <2.5 mg/kg. Therefore, the analytical performance claims of the manufacturer were confirmed.