Preparation of matrix-matched calibration standards for accurate determination of elemental concentrations in uric acid stones by LA-ICP-MS

Accurate determination of elemental concentrations in uric acid (UA) stones is crucial for understanding their formation process. However, the lack of matrix-matched calibration standards has limited the application of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in this field. This study addresses this limitation by preparing a synthetic UA precipitate (UA-1) doped with 17 elements using a recrystallization method. Reference concentrations of these elements were measured using pneumatic nebulization-ICP-MS (PN-ICP-MS) for calibration purposes. The synthetic standard was characterized through 30 random spot analyses, demonstrating a homogeneity of approximately 5%. Using this synthetic standard, a reliable analytical method was developed, achieving limits of detection (LODs) ranging from 0 to 0.42 μg g^-1. The method's accuracy, with relative deviations between -8.33% and 0 and correlation coefficients (<i>R</i>²) greater than 0.99, confirms its reliability. Additionally, elemental distribution differences observed across various zones in a real UA stone suggest that this method offers a promising approach for the precise analysis of elemental concentrations in UA stones.