Determination of nitrate and nitrite in human saliva with a specially designed microfluidic paper-based analytical device (μPAD)

For many years, the concentration of nitrite and nitrate anions in human saliva was believed to be correlated with disfunctions and infections in the mouth. However, recent studies have reported some benefits to the presence of these ions in the oral cavity. In any case, there is a connection between the NOX salivary concentration and the human health and therefore it has become more and more relevant to understand this connection. Nowadays, there are several methods that allow this determination for a number of concentration ranges and types of samples, but these methods have limitations like requiring high volume of reagents and sample, the time of analysis, the use of complex lab equipment, the need of constant power, specialized technicians, the production of toxic waste, among others.