Quantification of synthetic phenolic antioxidants in dry foods by reversed-phase HPLC with photodiode array detection

Propyl gallate (PG), octyl gallate (OG), 2-and 3-tert-butyl-4-hydroxyanisole (BHA), 3,5-di-tert-butyl-4-hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ) are permitted in a limited number of food products according to local legislations, with individual maximum limits in each case. This study describes an in-house validated reversed-phase HPLC method for the quantitative determination of PG and BHA in gravies and dehydrated soups, BHA in bouillons, dehydrated meat and dry pet food, and OG in dehydrated meat. Two extraction methods were developed to optimise the recovery of the phenolic antioxidants. Methanol was more suitable for the extraction of BHA and OG from dehydrated meat, PG from gravies and BHA from hard and soft bouillons while hexane/2-propanol was more suitable for the extraction of BHA from gravies and dehydrated soups, and PG in dehydrated soups. On the other hand, PG could not be quantified accurately in soft bouillons using either of these extraction methods, due to a lack of selectivity. The relative standard deviation of repeatability was between 0.9 and 5.5% and recoveries from spiked samples in the ranges 85–106% for PG, 95–104% for BHA and 83–85% for OG. The procedure allows also the detection of 2 mg/kg of TBHQ and BHT, which are not permitted in the EU for use in dehydrated soups, bouillons, gravies and dehydrated meat.