Application of Derivative Variable-angle Synchronous Scanning Phosphorimetry in a Microemulsion Medium for the Simultaneous Determination of 2-Naphthoxyacetic Acid and 1-Naphthalenacetamide

The applicability of derivative variable-angle synchronous scanning (DVASS) microemulsion phosphorimetry at room temperature (ME-RTP) was demonstrated for the simultaneous determination of the plant growth regulators 2-naphthoxyacetic acid and 1-naphthalenacetamide in soil samples. This technique permits linear or non-linear paths to be scanned at preselected angles through the excitation–emission phosphorescence matrix in order to obtain the highest signal values and interference-free bands. The phosphorescence emission of the two compounds was obtained using sodium sulfite as an O2 scavenger and thallium nitrate as an external heavy atom salt perturbed in sodium docecyl sulfate microemulsion aqueous solutions. A statistical model of the central composite design type to obtain the optimum phosphorescence responses was applied. The increased selectivity afforded by the DVASS technique permitted the demonstration of its applicability to the simultaneous determination of phosphorescent signals of these two compounds obtained in a microemulsion medium which show closely overlapped profiles giving mean recoveries of 89.0% (n = 5) for 1-naphthalenacetamide and 103.5% (n = 5) for 2-naphthoxyacetic acid, with an RSD of 7.35 and 5.90%, respectively, in real samples.