Residual analysis of nitric oxide fumigation on fresh fruit and vegetables

•Nitric oxide is a newly discovered fumigant and is safe to fresh products.•Nitric oxide fumigation leaves no residue in forms of NO3− and NO2− ions on fresh products when it is terminated properly with N2 flush.•Nitric oxide has advantages as a safe and effective alternative fumigant to methyl bromide.

Nitric oxide (NO) is a newly discovered fumigant which is effective against a wide range of postharvest pests. To register NO with US EPA for commercial use as a pesticide and to ensure its safety to consumers, it is necessary to analyze residues of NO fumigated products. In this study, we analyzed nitrate (NO3−) and nitrite (NO2−) ion concentrations in liquid extracts as residues on 20 fresh products at 24 h after 16 h fumigation treatments and compared them from untreated controls to determine effects of nitric oxide fumigation. Each product was subjected to two identical NO fumigation treatments except one treatment was terminated by flushing with N2 and the other terminated by flushing with air. For most products, there were no significant differences in NO3− or NO2− level between the treatment that was terminated with nitrogen flush and the control. Only when NO fumigation treatment was terminated by flushing with normal air, there were significantly higher NO3− and NO2− concentrations in all fumigated products than both control and N2 flushed fumigated products. NO2− concentration was generally not detectable in both fumigated and control products. Therefore, our results indicated that there were no significant levels of residues from NO fumigated fresh products at 24 h after fumigation when fumigation was terminated properly with nitrogen flushing.