AOAC Guidance on FA Immunoassay Validation (August 2023)

Table 1: Principal measurands, analytes and measurement systems for allergens 215 Measurand Analyte Matrix

Measurement procedure /system

Mass fraction (e.g., mg/kg) of total protein in a foodstuff Mass fraction (e.g., mg/kg) of total protein from the allergenic source (e.g., total milk protein) in matrix (e.g., cookies) Mass fraction (e.g., mg/kg) of total protein from the allergenic source (e.g., total milk protein) in matrix (e.g., cookies)

nitrogen (*)

Foodstuff

Kjeldahl or Dumas

Peptides (*)

LC-MS or LC-MS/MS

Foodstuff, but usually needs to be more specific as to the matrix

Protein (*)

Immunoassay (Relevant epitopes)

(*) A conversion between the analyte and the measurand is required and also between the allergenic food source 216 and its protein content. There remains work to be done to harmonize such conversion factors. There is a need to 217 specify the food commodity and its characteristics in sufficient detail to be of value to the customer and/or a risk 218 assessor. For example, if the quantity value obtained (measurand) depends on the nature of the calibrator, details 219 of the calibrator should be given. 220 4.2. Reporting Units 221 4.2.1. At a minimum for food, beverage, and non-surface environmental samples, method developers 222 must provide concentrations in units of: Mass of total protein from allergenic food per mass of 223 food or environmental sample (e.g., mg total peanut protein per kg food, mg total milk protein per 224 kg food, mg total peanut protein per kg rinse water, mg total peanut protein per L rinse water) 225 4.2.2. Method developers may provide additional concentration units if desired, e.g., mass of allergenic 226 food per mass of food (e.g., mg peanut per kg food) or mass of protein fraction per mass of food 227 (e.g., mg casein per kg food), but definitions must be provided for other units. 228 4.2.3. For environmental surface samples, method developers must provide amounts in units of mass of 229 total protein from allergenic food per defined swabbing area in accordance with a prescribed 230 swabbing protocol (e.g., µg total peanut protein per 100 cm 2 ) 231 4.3. Calibrant 232 Method developers must provide the following information on calibrants: 233 4.3.1. What is the calibrant for the method? 234 4.3.2. How was the concentration value of the calibrant assigned? 235 4.3.3. Is the calibrant made from raw or processed material? 236 4.3.4. Was the calibrant extracted or purified? If so, how? 237 4.3.5. How is the concentration of the calibrant expressed? 238 4.3.6. Is the calibrant commercially available? 239 4.4. Test material preparation 240