Ionic-liquid doped polymeric composite as passive colorimetric sensor for meat freshness as a use case

• Published in: Talanta (Oxford) 2021-02, Vol.223 (Pt 2), p.121778-121778, Article 121778
• Main Authors: Ballester-Caudet, A., Hakobyan, L., Moliner-Martinez, Y., Molins-Legua, C., Campíns-Falcó, P.
• Format: Article
• Language: English
• Subjects: Ammonia atmospheres; Colorimetric sensor; Colorimetry; Flexible calibration; In situ analysis; Ionic liquid; Ionic Liquids; Meat - analysis; Meat freshness; Passive dispositive; Polymeric composite; Polymers; Silicon Dioxide
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2020.121778

A composite membrane containing 1,2-naphthoquinone-4-sulfonic acid sodium salt (NQS) embedded in an ionic liquid (IL)- polydimethylsiloxane (PDMS)- tetraethyl orthosilicate (TEOS)- SiO2 nanoparticles (NPs) polymeric matrix is proposed. The selected IL was 1-methyl-3-octylimidazolium hexafluorophosphate (OMIM PF6). It is demonstrated that ILs chemical additives of PDMS influenced the sol-gel porosity. The sensor analytical performance for ammonia atmospheres has been tested as a function of sampling time (between 0.5 and 312 h), temperature (25 °C and 4 °C) and sampling volume (between 2L and 22 mL) by means of diffuse reflectance measurements and sensor photos, which can be registered and saved as images by a smartphone, which permit RGB measurements too. Flexible calibration was possible, adapting it to the sampling time, temperature and sampling volume needed for its application. Calibration linear slopes (mA vs ppmv) between 1.7 and 467 ppmv−1 were obtained for ammonia in function of the several studied conditions. Those slopes were between 48 and 91% higher than those achieved with sensors without ILs. The practical application of this sensing device was demonstrated for the analysis of meat packaging environments, being a potential cost-effective candidate for in situ meat freshness analysis. NQS provided selectivity in reference to other family compounds emitted from meat products, such as sulphides. After 10 days at 4 °C ammonia liberated by the assayed meat was 20 ± 4 μg/kg and 18 ± 3 μg/kg, quantified by using diffuse reflectance and %R measurements, respectively. Homogeneity of the ammonia atmosphere was tested by using two sensors placed in two different positions inside the packages. [Display omitted] •A new synthetic strategy for preparing polymeric composites with ionic liquids is proposed.•The mass nature of the solid colorimetric sensor is demonstrated and kinetic parameters stablished.•Flexible calibration is possible in function of the sampling time, temperature and sampling volume.•The study of meat freshness as a use case was also proposed.•The sensor could be a new green and cost-effective alternative to control of meat freshness.