Determination of the antioxidants and UV stabilizers Irganox 3114, Irganox 1330, Irganox 1076 and Irgaphos 168 in a polyolefin granulate by the standard addition method, on an ARION® Plus C18, 5 µm column (250 mm × 4.6 mm, ARI-5720-LM46). Isocratic elution with 92–98.5 % MeOH / ethyl acetate at 2 ml/min and 25 °C, UV detection at 276 nm. All four additives elute within 11 minutes; the note compares the untreated sample with the same sample after standard addition.