Analysis of vitamin C, nitrates and nitrites in tomato juice with highly efficient liquid chromatography

Abstract

The results of analysis of vitamin C, nitrates and nitrites in tomato organically and conventionally grown as well as one commercial tomato juice are reported. Conventionally grown tomato was provided from four markets in Belgrade and one of the largest hypermarkets. Organically grown tomato originated from Vršac region. Analysis was performed by high performance liquid chromatography with UV detection and determination of analytes content was done by external calibration. Limit of detection and limit of quantification limits were determined for vitamin C (0, 03 μg/mL and 0,05 μg/mL), nitrates and nitrites (0,05 μg/mL and 0,10 μg/mL). Good linearity for all analytes was confirmed in the range 1,0 - 20,0 μg/mL. According to the results, content of vitamin C in analyzed samples varied from 0,26 mg/100g to 20,46 mg/100 g. Concentration of nitrates in 6 different samples of tomato juice was in the range between 4,788 and 16,632 mg/100 g. Concentration of nitrites were below limit of quantification of applied method (1 mg/kg).

U radu su prikazani rezultati analize vitamina C, nitrata i nitrita u plodovima paradajza organski i konvencionalno gajenog, kao i jednog industrijskog soka od paradajza. Konvencionalno gajen paradajz je nabavljen na četiri beogradske pijace i u jednom od najvećih beogradskih supermarketa, a organski je uzgajan u regionu Vršca. U analizi je primenjena reverzno-fazna visokoefikasna tečna hromatografija sa UV detekcijom, a određivanje sadržaja je izvedeno primenom eksterne kalibracije. Određeni su limiti detekcije i kvantifikacije, koji iznose 0,03 μg/mL odnosno 0,05 μg/mL za vitamin C, a 0,05 μg/mL odnosno 0,10 μg/mL za nitrite i nitrate. Dobra linearnost za određivanja vitamina C, nitrita i nitrata potvrđena je u opsegu koncentracija od 1,0 μg/mL do 20,0 μg/mL. Ispitivanjem sadržaja vitamina C u različitim uzorcima soka od paradajza, pokazano je da sadržaj istog varira u opsegu 0,26 - 20,46 mg/100 g. Analizom sadržaja nitrata i nitrita u 6 različitih uzoraka soka od paradajza utvrđeno je da sadržaj nitrata varira u rasponu 4,788 - 16,632 mg/100 g. Sadržaj nitrita u svim analiziranim uzorcima je ispod granice kvantifikacije primenjene metode (1 mg/kg).