In this paper, we developed a non-equilibrium rapid replacement aptamer (NERRA) assay that performed ultra-fast (in 30 s) quantitative detection of phthalic acid esters (PAEs) without waiting for the reaction to reach equilibrium. NERRA assay employed fluorescence PoPo3 dye intercalated in an ssDNA aptamer to selectively detect and quantify the PAEs in water. As the intercalated dye was replaced by the PAEs and quenched in the water, the rate of fluorescence change became proportional to PAEs concentration. The sensitivity of NERRA assay was first evaluated with a commercial spectrofluorometer. The selectivity for PAE mixture, individual PAEs, and non-phthalate compounds were also investigated. NERRA assay was also able to quantitatively detect the PAEs in a common plastic product (picnic mat), and the results were compared with those of gas chromatography mass spectrometry. Finally, a custom analyzer (8.5 cm × 8.5 cm × 16.5 cm) was built to demonstrate the portability of the NERRA assay. Using a commercial spectrofluorometer, NERRA assay was able to quantitatively detect a PAE mixture in 30 min with an LOQ of 0.1 μg/L. Using the portable custom analyzer, the detection time was shortened to 30 s with a tradeoff in the LOQ (1 μg/L). In both cases, the LOQs remain within the environmentally relevant PAE concentrations of 0.1–1472 μg/L.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea ( NRF-2019R1A2C2 084233 , NRF-2019R1F1A1 058562 ). The authors appreciate the experimental assistance from Seo Won Cho, Ki Ae Kim, and Minkyung Kang. The authors also acknowledge Prof. Ji Yi Lee for her support for the GC/MS analysis.
© 2020 Elsevier B.V.
- Endocrine disrupting chemicals
- Phthalic acid esters (PAEs)
- Portable device
- Ultra-fast detection