A QUICK TEST BASED ON CATALDO'S METHOD TO DETERMINE NITRATE IN FRESH TISSUE EXTRACTS

摘要

Leafy vegetables could accumulate nitrate (NO3-) above limits safe for humans, hence it would be advisable to customarily determine their NO3- concentration. We wanted to develop a quick test to determine NO3- concentration in fresh tissue extracts and estimate the error of using this test to identify samples with NO3- concentrations above the World Health Organization (WHO) threshold. There was a positive linear relationship (P 0.001) between NO3- concentrations determined by the quick test and by potentiometry in dry tissue extracts. Samples were classified as "acceptable" or "excessive" according to their potentiometric NO3- concentration, using a critical level of 75% (p) of the observed NO3- distribution. According to the Cate-Nelson model, the quick test identified as "acceptable" from 5.6% to 15.4% of samples that were in the "excessive" category. In spite of this error rate, the quick test use would improve consumers' protection, because no controls on vegetables NO3- concentration are available in Uruguay.