Griess-doped polyvinyl alcohol thin film for on-site simultaneous sample preparation and nitrite determination of processed meat products

To facilitate on-site nitrite determination for processed meat products, Griess-doped polyvinyl alcohol film was synthesized in the bottom of a plastic tube for in-tube determination. The tube's aperture was used to control the sample dimensions. Each sample, cut into eight sectors, was subjected to nitrite extraction by water. Use of tap water or commercial drinking water vs. ultrapure water was associated with < 2% differences in nitrite levels. The use of film and digital image colorimetry showed a low limit of detection (12.6 ± 0.5 µg L^-1), good precision (1.0%RSD, n = 5 days), and good accuracy (93.2 ± 3.5 to 108.5 ± 1.8%recovery). Using these methods, sodium nitrite concentrations in 700 processed meat products for sale in Phuket, Thailand, were found to range from 6.8 ± 0.2 to 113.6 ± 1.3 mg kg^-1. These results showed no significant differences with the HPLC standard method (p > 0.05, n = 45).