Abstract
A new approach based on the use of polydimethylsiloxane (PDMS) membranes doped with Griess reagents for in situ determination of and - in real samples is proposed. The influence of some doping compounds, on the properties of the PDMS membranes, such as tetraethyl orthosilicate (TEOS), or/and ionic liquids (OMIM PF6) has been studied. Membrane characterization was performed. To apply the procedure to determination, dispersed Zn nanoparticles (ZnNPs) were employed. The analytical responses were the absorbance or the RGB components from digital images. Good precision (RSD < 8%) and detection limit of 0.01 and 0.5 mgL−1 for and , respectively, were achieved. The approach was satisfactory when applied to the determination of and in drinking waters, irrigation and river waters, and waters from canned and fresh vegetables. The results obtained were statistically comparable with those by using nitrate ISE or UV measurement. This approach was transferred satisfactory to 96 wells for multianalysis. This study enables the improvement in the on-site determination of and in several matrices. It is a sustainable alternative over the reagent derivatizations in solution and presents several advantages such as being versatile, simplicity, low analysis time, cost, and energy efficiency. The response can be detected visually or by portable instruments such as smartphone.
Highlights
Nitrite and nitrate are widely present in environmental samples like water, soil, food and agricultural products
Doped polymeric reactions can be used for catalytic reactions, this is the case of polysulfone membranes doped with ionic liquid [21], or polybenzimidazole-based nanofiltration membrane doped with azido derivatized cinchona-squaramide bifunctional catalyst [22]
Taking into account the ratio and the number of reagents used in solution, these reagents were entrapped in a PDMS membrane
Summary
Nitrite and nitrate are widely present in environmental samples like water, soil, food and agricultural products. Often the protocols described for this determination indicate that the procedure should be carried out in the laboratory either in batch or continuous mode (flow injection analysis) These methodologies are far from the actual needs of analytical methods that combine high sensitivity, accuracy and rapid analysis with simplicity, portability, low cost and access for non-qualified citizen groups. One option to stabilize reagents is to embed them in solid supports; materials such as polymers can be used as an inert matrix support [13,14] This approach is being used for the development of optical sensors and microfluidic devices [15,16,17,18]. Doped polymeric reactions can be used for catalytic reactions, this is the case of polysulfone membranes doped with ionic liquid [21], or polybenzimidazole-based nanofiltration membrane doped with azido derivatized cinchona-squaramide bifunctional catalyst [22]
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