Effect of organic additives on silver release from nanosilver-polyethylene composite films to acidic food simulant.

The effects of organic additives (Irgafos 168, Irganox 1076, Tinuvin 622, Chimassorb 944, UV-P, and UV-531) on silver release from nanosilver-polyethylene composite films into an acidic food simulant (3% acetic acid) were investigated using inductively coupled plasma mass spectrometry. The limits of detection and quantification, coefficient of determination, and recoveries of the method used were 3.7ngL-1, 12.4ngL-1, 0.999, and 89-113%, respectively. The results indicated that additives can affect silver release via two simultaneous processes: (i) reactions between organic additives and silver that promote silver release from the composite film to the acidic food simulant; and (ii) the promotion or inhibition of silver release by affecting silver oxidation. High temperature and humidity treatment of the composite films was found to significantly increase silver release by promoting silver oxidation.

Effect of antioxidants and light stabilisers on silver migration from nanosilver-polyethylene composite packaging films into food simulants.

The effect of exposure time, temperature and food simulants, especially additives, on the release of silver from nanosilver-polyethylene composite films to food simulants was studied. Two different type of nanosilver-polyethylene composite films (with or without additives) were chosen to conduct the experiment with the aim of exploring the behaviour of silver migration. It was shown that the migration of silver into 50% ethanol at 40 and 70°C was much less than that into 3% acetic acid. With the increase of exposure time and temperature, the release of silver increased. The migration even continued after a long exposure time (14 days at 20°C, 10 days at 40°C, and 6 days at 70°C respectively). Only about 0.15‰ of silver migrated from composite films with the additives into 3% acetic acid after 6 days of exposure at 70°C, while about 1.3% of silver migrated from composite films that did not contain additives under the same conditions. This could be because the addition of the antioxidants and light stabilisers prevents silver from being oxidised, which is an important way for the release of silver.

[Determination of p-tert-butylcatechol in styrene monomer by gas chromatography/mass spectrometry].

An efficient method for the determination of p-tert-butylcatechol (TBC) in styrene monomer by gas chromatography/mass spectrometry (GC/MS) has been established. The sample was injected directly, and separated by gas chromatography with capillary column (HP-1, 30 m x 0.32 mm i.d. x 0.25 micron), then determined by a mass-spectrometer with electron impact (EI) at selected ion monitoring (SIM) mode. There was a good linear relationship within the range of 5 mg/kg-50 mg/kg (r2 = 0.9987). Compared with the colorimetric determination by a spectrophotometer (ASTM D4590), the method was proved to be fast and accurate.