Nitrites are well known additives used in food industry aspreservatives.
Their ability to increase the shelf life and quality of foodmakes it an important ingredient in storage process 1. Nitrites are anti-oxidants which helps in inhibiting thegrowth of Clostridium Botulinumspores in frozen meat and its products 2,3. Major concern on nitrites lies inthe formation of N-nitrosamines, which are potential carcinogens and causes detrimentaleffects . Nitrites can exert acute toxiceffects in humans mainly in infants causing methemoglobinemia 4-7. Nitritesare vasodilators causing decrease of blood pressure and also the ingestednitrite causes gastrointestinal illness. Hence, these nitrites exert toxicity andthere is a requisite to keep a check on the presence of nitrites in food andother edible products 8,9.Several techniques like chromatography, spectrophotometry, spectrofluorimetryand chemiluminescence have been reported in the quantification of nitrite at tracelevel concentration 10,11.
Though these methods are widely used in nitritequantification, they require prolonged sampling procedures, use of carcinogenicor toxic dyes/reagents and require skilled personnel to operate some of theseinstruments. In recent years, electrochemical techniques have been widelyexplored by the chemists to find suitable sensing platforms in overcoming the limitationsof the above-mentioned techniques. The electrochemical sensing strategies canbe designed selectively to suit the nature of analyte as well as itscomplexicity.
These electrochemical sensors are easy to fabricate which providevery good sensitivity and selectivity to the target analyte. They are lessexpensive and can be used in the wide potential window 12.In recent years, chemically modified electrodes (CMEs) havebeen extensively used in the quantitative analysis and sensor technology.
The useof these electrodes in electroanalysis has gained a significant focus veryrecently in the form of use and throw type disposable sensors. These CMEs are target specific, simple andsensitive and can be used in various forms like carbon paste electrodes, modifiedglassy carbon electrode with carbon nanotubes or a wide variety of nanocompositematerials. Several such modifications have been recently reported in the developmentof nitrite sensors 13-15. These conventional solid electrodes are expensive andrequire frequent time-consuming electrode pretreatment procedures and theanalytical responses obtained are less reproducible.
The use of screen-printedelectrodes (SPEs) in electroanalysis is pronounced recently and gained asignificant attention by the electrochemists due to their target analytespecificity, configuration and easy adaptation. SPEs are mass produced solidmicroelectrode strips which are inexpensive, easy to carry and hand heldsensors. These eco-friendly small electrode miniatures include advantages likeon-site determination of target species, low cost, portability, high reproducibilityand low sample volume in the quantification of target analyte. Moreover, theworking electrode surface of the SPEs can be modified using wide range ofmodifier molecules 16-19. Chitosan(CS) is ? -1,4 glucosamine and a conductingbiodegradable polymer. It is known to show a good electrochemical activity for thedetection of nitrite ions 20-21. In order to enhance the sensitivity withreduced ohmic drop, several metal nanoparticles and have been incorporated intothe CS matrix and used as a composite material in nitrite measurement 22-23.
These modifications enhance the conductivity ofmatrix and increase the electrontransfer activity on the electrode surface. Metal nanoparticles such as Au, Fe,Cu, Co, Zn have been used as an electrocatalysts in the electrode fabricationtechnology in the measurement of nitrite due to their redox activity and highelectrocatalytic nature 24-28. Ag metal nanoparticles (AgNPs) have beenexplored as a potent material for nitrite ion sensing due to their high electrocatalyticactivity and non-toxicity 29-31.There are no reports available on the use of silver metal nanoparticlesincorporated chitosan matrix in the quantification of nitrite till now. This isthe first report which describes about the use of silver metalnanoparticles-chitosan(AgNP/CS) composite in the measurement of nitrite attrace level.
This composite has been embedded on the surface of graphitescreen-printed electrodes and used as a disposable sensor strips in the nitritequantification at trace level concentration.