Determination of nitrate and nitrite in agricultural crops distributed in northeast of Iran

Background and objective: Intake of nitrate and nitrite through food products may lead to toxicity and carcinogenicity in human. Agricultural crops which have a great share in daily basket of people are prone to nitrate accumulation. Therefore, we aimed to determine the concentration of nitrate and nitrite in some agricultural crops distributed in Mashhad city (northeast of Iran).Materials and methods: Green vegetables, lettuce, tomato, potato, onion, carrot, watermelon, melon, rice, and wheat were analyzed in our study. Green vegetables were included to parsley, leek, and basil. The samples were collected from April ۲۰۱۷ to March ۲۰۲۰ from local market of Mashhad. Molecular absorption spectrophotometric method was used for determination of nitrite and nitrate concentration in the samples.Results and conclusion: Due to the low concentration of nitrite in the products, total nitrite (sum of nitrite and nitrate concentration) is reported in the results. The highest concentration of total nitrite was detected in lettuce (۱۰۷۸ ±۳۶۰.۹۷ mg/kg) and green vegetables (۸۶۰.۵۳ ±۳۲۳.۴۳ mg/kg), respectively. Carrot (۱۷۱.۶۰ ±۹۸.۴۴ mg/kg) and potato (۱۶۰.۶۶ ±۷۳.۷۴ mg/kg) were moderately contaminated by the pollutants. The lowest contamination was observed in melon (۷۲.۴۰ ±۵۶.۴۱ mg/kg), wheat (۲۴.۶۵ ±۲۸.۳۹ mg/kg), watermelon (۲۲.۲۲ ±۲۵.۶۰ mg/kg), rice (۲۰.۸۱ ±۱۹.۹۸ mg/kg), tomato (۱۱.۷۵ ±۱۰.۷۹ mg/kg), and onion (۹.۲۹ ±۱۱.۹۰ mg/kg), respectively. Compared to the maximum permitted level of total nitrite determined by the Iranian regulation, approximately ۳۴% of green vegetables and ۸% of lettuce were rejected. In addition, ۴۸% of potato samples were out of range of total nitrite. As a conclusion, strict control and monitoring of the agricultural crops is required to ensure safety of the products delivered to the consumers.

کلیدواژه ها:

Agricultural crops ، maximum permitted limit ، Nitrate ، nitrite ، Spectrophotometric method