Novel Microfluidic Advances Enabling Autonomous, Long-Duration, Analysis of Nitrite/Nitrate

LMT proposes to develop two novel microfluidic innovations: (1) a novel long-path (250-mm), folded, on-chip absorption cell utilizing lock-in amplified detection to enable high colorimetric sensitivity; (2) a novel on-board system for mixing reagents and standards from dry chemical constituents to enable their in-situ preparation thereby enabling long-duration deployments where pre-mixed consumables would have otherwise degraded. These two innovations will enable the construction of the In-situ Nitrate/Nitrite Analyzer (INNA), a deployable microfluidic system for the continuous, autonomous, long-duration analysis of nitrate and nitrite in natural waters that will feature unprecedented sensitivity and autonomous deployment durations for this class of robust microfluidic system. INNA will be able to detect nitrate and nitrite down to single-digit nano-molar levels, making the instrument suitable for monitoring nutrients even in the oligotrophic open ocean where levels of these compounds can be below 10 nM. The system will rely upon the well-understood and widely-used colorimetric Griess assay for nitrite.