Swellable microneedles for nitrate detection in food

Abstract

Nitrate is used as a food additive to preserve meat and extend shelf-life. Nitrate inhibits microorganisms that cause spoilage. Epidemiological research has been reported that high nitrate dietary intakes are associated with gastric cancer, bladder cancer, and pancreatic cancer. This study aims to detect nitrate in food using swellable microneedles. The swellable microneedles were developed based on poly(methyl vinyl ether-alt-maleic acid) (PMVE/MA) and poly(ethylene glycol) (PEG) and incorporated with colorimetric paper for nitrate detection. Our data demonstrated the microneedles could absorb liquid containing sodium nitrate and reacted with the reagents in the test strip on the microneedles. The detection limit of this microneedle-based technique is 500 ppm which is the cutoff level of nitrate permitted to be used in food by the Ministry of Public Health of Thailand. This developed technique requires only one step of sample preparation.