Hybrid Fluorometric Flow Analyzer for Ammonia

Abstract

We describe a robust, highly sensitive instrument for the determination of ambient ammonia. The instrument uses two syringe pumps to handle three liquids. The flow configuration is a hybrid between traditional flow injection (FI) and sequential injection (SI) schemes. This hybrid flow analyzer spends approximately 87% of its time in the continuous flow FI mode, providing the traditional FI advantages of high baseline stability and sensitivity. The SI fluid handling operation in the remaining time makes for flexibility and robustness. Atmospheric ammonia is collected in deionized water by a porous membrane diffusion scrubber at 0.2 L/min with quantitative collection efficiency, derivatized on-line to 1-sulfonatoisoindole, and measured by fluorometry. In the typical range for ambient ammonia (0-20 ppbv), response is linear (r2 = 0.9990) with a S/N = 3 limit of detection of 135 pptv (15 nM for 500 microL of injected NH4+(aq)) with an inexpensive light emitting diode photodiode-based detector. Automated operation in continuously repeated, 8-min cycles over 9 days shows excellent overall precision (n = 1544 p(NH)3 = 5 ppbv, RSD = 3%). Precision for liquid-phase injections is even better (n = 1520, [NH4+(aq)] = 2.5 microM, RSD = 2%). The response decreases by 3.6% from 20 to 80% relative humidity.

Sampling free and particle‐bound chemicals using solid‐phase microextraction and needle trap device simultaneously

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Fluorescent Chemosensor for Quantitation of Multiple Atmospheric Gases

“…A chemical sensor essentially consists of transducer for converting the chemical information into diverse electronic or optical signals like frequency current, voltage, color, fluorescence and surface plasmon resonance [1][2][3][4]. Gas sensors are of paramount importance, as they allow much convenient and routine detections of several gases/vapors which can be hazardous to human health [5][6][7].…”

A Multiple Processing Hybrid Flow System for Analysis of Formaldehyde Contamination in Food

“…17 This flow system for the analysis of HCHO in air is based on the concept of a hybrid flow analyzer. 22 The system is more robust than the conventional FI system due to using syringe pumps.…”

“…In this work, a flow system based on hybrid flow 22 was developed for the analysis of HCHO in food. The procedure is different from one presented earlier by Eom et al for monitoring HCHO in air.…”