Smartphone-Assisted Fluorescence Determination of Inorganic Phosphorus Using a Samarium Metal–Organic Framework
Xin Zhou, Bing Liu, Zhiyong Chen, Ling Xu
Abstract
Inorganic phosphori are widely used in food, whose quantitative detection method is of significance. This work presents a Sm-DDB (H 4 DDB = 1,3-di(3′,5′-dicarboxylphenyl)benzene), which acts as a ratiometric fluorescence sensor to monitor PO 4 3–, H 2 PO 4 –, and (PO 3 ) 6 6– with high sensitivity. The determination factors of pH, MOF dosage, and fluorescence response time are optimized as 7.35, 1 mg, and 2 min, respectively. The sensitivity tests show the linear fitting equations of I 465 / I 598 = 0.00363· C P + 1.49183 ( I 465 and I 598: the emission intensities at 465 and 598 nm; C p = inorganic phosphorus concentration) for PO 4 3–, I 465 / I 598 = 0.00272· C P + 1.55944 for H 2 PO 4 –, and I 465 / I 598 = 0.00957· C P + 1.55122 for (PO 3 ) 6 6– with LODs being 1.00 μM for PO 4 3–, 1.33 μM for H 2 PO 4 –, and 0.38 μM for (PO 3 ) 6 6– . The detection method was applied in frozen shrimp, marine fish, and bacon, whose fluorescence recoveries of around 100% demonstrate its reliability. The analytical results are close to those determined by the phosphomolybdenum blue method. The Sm-DDB test paper shows an obvious emission color change, whose blue/red (B/R) values can be recognized by a smartphone APP. This work provides a smartphone-assisted visualization detection method for PO 4 3–, H 2 PO 4 –, and (PO 3 ) 6 6– .