Min Zhang, Tao Zhang, Ying Liang
Dec 1, 2018
Citations
0
Influential Citations
17
Citations
Journal
Sensors and Actuators B: Chemical
Abstract
Abstract A new fluorescent reagent, 4,5-dimethoxyphthalaldehyde (M2OPA) is synthesized for the determination of ammonium in environmental waters. M2OPA has a similar molecular structure as o-phthalaldehyde (OPA), a commonly used fluorescent probe for ammonium, but M2OPA has two methoxy groups joining the benzene ring of OPA. Ammonium is reacted with M2OPA and sulfite to form a fluorescent derivative, which has a maximum of excitation (λex) and emission (λem) located at 380 and 485 nm, while the λex and λem of OPA reaction are 360 and 430 nm. The M2OPA assay has a rapid reaction and enhanced fluorescent intensity, compared with the OPA-based assay. To realize the ammonium detection in field, a hand-held portable laser diode (LD) fluorometer is developed as the detector for the M2OPA assay. Two LDs of 405 nm in parallel are used as the light source, allowing the detector to operate in single- and dual-laser beam modes. This allows for different linear ranges (0–5 and 0–2 μM, respectively). A photomultiplier tube is used for emission light detection. Limits of detection of 6.5 and 3.5 nM are obtained by using single- and dual-laser beam modes, respectively.