Salting-Out Assisted Liquid-Liquid Extraction for Quantification of Ammonia Compounds in Food Samples

Extraction of ammonia compounds from food samples is a challenging topic due to the hydrophilic property of ammonia. A simple and rapid extraction method was developed for the determination of ammonia in a type of local bread (Ahari bread) and milk samples using a salting-out assisted liquid-liquid extraction and spectrophotometry. Acetonitrile was used to clean up, and potassium chloride salt solution was added to separate the acetonitrile and aqueous phase by creating two phases. The ammonia concentration in the aqueous phase was determined based on a colorimetric method. Various parameters affecting absorption intensity were optimized using the response surface methodology. Then, the optimized parameters were applied to establish a valid analytical method. The developed method was used to quantify ammonia compounds in food samples, i.e. Ahari bread and milk, by the standard addition method. The linearity of the method was from 2.5 to 40 μg/mL with a coefficient of determination (R2) of 0.994, and numerical values of a limit of detection (LOD), and limit of quantification (LOQ) was found to be 0.038 and 1.29 μg/mL, respectively. The accuracy (%error) and precision (%relative standard deviation) were in the acceptable range. The established extraction technique and standard addition method could detect ammonia in real food samples. These data showed that the established analysis approach is a simple and sensitive technique for extraction and determination of ammonia concentration in foodstuff.