NITRATE AND NITRITE IN FRESH VEGETABLES FROM QUEENSLAND

Vegetables were collected near peak harvest from the main production regions in Queensland and were analysed for residues of nitrate and nitrite. A small sample of hydroponic produce was also included in the survey. Nitrite-N from 1 to 4 mg kg(-1) was found only in dwarf beans and in lettuces. Levels of nitrate in potatoes, cabbages and beets were higher than those reported in other surveys and exceeded threshold limits set in one other country. The median nitrate-N concentration measured in hydroponic lettuce (465 mg kg(-1) nitrate-N) was more than twice the median concentration for field-grown lettuce. Poor correlation between total N and nitrate in vegetables raises doubts about the use of total N alone as an indicator of N status.