A cost-effective microfluidic device for determination of biodiesel content in diesel blends

• Published in: Sensors and actuators. B, Chemical Chemical, 2023-09, Vol.390, p.134033, Article 134033
• Main Authors: Soares, Samara, Ramos-Lorente, Celia E., Ruiz-García, Isidoro, Rocha, Fábio R.P., Erenas, Miguel M., Orbe-Payá, Ignacio de, López-Ruiz, Nuria, Capitán-Vallvey, Luis F.
• Format: Article
• Language: English
• Subjects: Alkyl esters content; Diesel blends; Digital image colorimetry; Microfluidics; Quality control; Renewable fuel
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2023.134033

The increasing production and extensive use of biodiesel in the latest years call for the development of fast and cost-effective procedures for point-of-care analysis. One of the main quality parameters is the biodiesel content in diesel blends, which needs to conform to regional legislations. In this work, a microfluidic device exploiting chemical derivatization of alkyl esters and detection by smartphone-based digital-image colorimetry was developed. It was designed to ensure proper experimental conditions for chemical derivatization, including reagent release, and photometric measurements. Analytes reacted with alkaline hydroxylamine yielding the corresponding alkyl hydroxamates, measured as colored Fe(III) complexes. Analytical response was based on the measurement of the G (green) channel from RGB color system. By taking methyl linoleate as a model compound, a linear response was obtained from 0.1% to 0.6%(v/v) (Analytical signal = 69.6 +2.1 C, r = 0.999), coefficient of variation (n = 10) of 4.0% and limit of detection (99.7% confidence) of 0.04%(v/v). Procedure consumes 1.2 µL of sample, 230 µg of hydroxylamine, 480 µg of NaOH, 14 µg of Fe(III) and equivalent to 1.2 µL of 69%(v/v) HNO3. Accurate results were achieved in relation to the MIR reference method, with agreement at the 95% confidence level. •Microfluidic device with smartphone-based digital image for point-of-care analysis.•Practical and environmental friendly determination of biodiesel in diesel blends.•Cost-effective and easily constructed microfluidic device.•Exploitation of pNIPAN polymer as a reagent compartment.•Application to biodiesel produced from different raw materials.