Simultaneous detection of melamine and cyanuric acid using powder X-ray diffraction

Abstract

A novel, non-destructive, powder X-ray diffraction (P-XRD) approach was developed and validated for the simultaneous detection of melamine (ME) and cyanuric acid (CA). Sample holders, and a range of P-XRD X-ray tube parameters (voltage: 25–45 kV; current: 25–45 mA), and scanning conditions (scan step size: 0.006–0.10°; step time: 50–150 s) were experimented at 2θ conditions. Based on the obtained diffraction patterns, the following conditions were optimized: sample holder: reflection-transmission spinner, tube voltage: 45 kV, tube current: 45 mA, scan step size: 0.006°, and scan step time: 150 s. The crystalline properties were assessed and phase quantification of both ME and CA was performed using Rietveld refinement, aligning to the International Center for Diffraction Data (ICDD) PDF4+ 2023 library. The approach was validated considering repeatability, precision, and linearity, and recovery and stability studies also support the findings. The limit of detection (LOD) was found to be 0.2 to 1 wt. % per phase of powder sample. Then, spiked and real food powder samples were screened for ME and CA. To date, there is no nondestructive technique available to simultaneously detect ME and CA in a single run. The developed P-XRD approach can find vast applications in quality testing facilities.