Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7644018 | Microchemical Journal | 2013 | 5 Pages |
Abstract
This work describes the construction and evaluation of a microflow-analyzer with an in-chip cadmium column used to determine total nitrate and nitrite ion concentrations in freshwater. Deep UV photolithography in urethane-acrylate photoresist was used to create channels (390 μm deep and 410 μm wide) and a chamber (1.00 mm Ã 0.65 mm Ã 20 mm) where cadmium granules were manually packed before the device was sealed. No clogging or leaks were observed for flow rates greater than 2.0 mL minâ 1. The efficiency of converting NO3â to NO2â was estimated at 97.5% by propelling 2.7 μL of nitrate and nitrite working solutions through the column at 40 μL minâ 1. Based on the peak heights, a linear response (R = 0.994) was found for the concentration range studied (0.23 to 2.26 mg N Lâ 1 as NO3â), providing a limit of detection of 0.15 mg N Lâ 1. Considering the determination of total NO2â and NO3â in six freshwater samples, no significant differences (95% confidence level) were obtained by comparing the results for the proposed device with the reference spectrophotometric method. In addition, a 24-fold reduction in the residue generation was estimated for the procedures using the micro-analyzer when compared to a classical flow injection analysis (FIA) system. This performance meets Brazilian regulations for quantifying NO3â in freshwater and follows the principles of green chemistry.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Lorrana N.N. Nóbrega, Laiz de O. Magalhães, Alexandre Fonseca,