Fate of cymoxanil, difenconazole and acetamiprid residues on grape varieties during modified atmospheric storage

Grapes are sprayed with an array of agro-chemicals to eliminate the danger of damaging pests that demands a strategic post-harvest storage. Modified atmospheric storage (MAS) using treatments T0 at 10 °C and `T0 at 20 °C, both with 0 % carbon dioxide while T1 at 10 °C and T2 at 20 °C, both with 10% carbon dioxide, were applied for 3 doses (recommended dose, double than recommended and triple dose) of pesticides on two varieties of grapes under field conditions. Samples were taken at 0th day, 3rd day, 7th day, 15th day, 20th day, 25thday, 30th day and 33rd day intervals from MAS and were extracted using acetonitrile (ACN) and cleaned up by florisil adsorbent column. High performance liquid chromatography (HPLC), equipped with diode array detector, ODS-Hypersil C-18 column was used to separate and quantify the pesticides by employing ACN-MeOH mobile phase with a flow rate of 1 mL min−1 in gradient mode. Mathematical model (Yt = Y0e−kt) was applied on average of all doses, which fitted best to the first order kinetics. Half-lives (HLs-50% of residues decayed) and DT90 (90% of residues decayed) values were also calculated. Regarding HLs of acetamiprid, best treatments were T1 and T2 where T1 (7.51) and T2 (4.02) presented good decay at low temperature when CO2 was used in combination and also reported good shelf stability of grapes. Likewise, the trend was witnessed from cymoxanil and difenconazole pesticides and grape varieties. Moreover, black grape variety indicated more degradation of residues as compared to perlette, which could be attributed to its acidity, composition and anatomical structure. Hence, MAS is a practicable approach not only to enhance the shelf life of produce but also for dissipation of field applied agro-chemicals.