TABLE OF CONTENTS Ultraviolet spectroscopy is applicable to the determination of phenolic antioxidants in aqueous and alcoholic simulant liquids and also to one of the fatty simulants, liquid paraffin, recommended by the British Plastics Federation (BPF). Full details of the procedure, which is capable of determining down to l-2 ppm of Santonox R in the simulent liquids, is given next. With the exception of the 5% citric acid simulent, errors are generally of the order of less than 10% of the determined concentration. Typical recoveries of Santonox R in the 5% citric acid extractant were between 15% of the expected result.
Reagents:
Citric acid AR
Ethanol AR
Sodium carbonate AR
Liquid paraffin BP (OD in 1 cm cell at 280 nm < 0.2 versus water)
Cyclohexane - for spectroscopy
5% w/v citric acid - prepared from citric acid AR and deionised water
50% w/v ethanol solution - prepared from ethanol and deionised water
Quartz cells of 1 cm path length are used for all spectroscopic measurements.
Using Deionised Water as Extractant
Shake the vessel containing the test extractant vigorously to obtain a uniform haze of Santonox in suspension in deionised water and immediately dispense 44.1 ml of the test extractant into a standard flask and dilute to 100 ml with ethanol. Wait half an hour before proceeding.
Obtain the spectrum of this solution and of the blank (50% w/v
