Rapid Forecast Method for Nickel Release in Simulated Jewelry Based on Accelerated Extraction

In response to the issue of long testing cycles for nickel release in jewelry of the standard method, key migration conditions such as migration temperature, migration time, simulated sweat acidity, and migration solution volume in standard method together with nickel release rules under different migration temperatures and time were studied, and a fast forecast method based on accelerated extraction was proposed for determining nickel release in simulated jewelry with different substrates. The simulated jewelry sample with area of 2.7 cm² was intercepted, and suspended in a testing container. Then 2.7 mL approximately 1∶1 of the ratio of sample area (cm²) to volume (mL) of simulated sweat of simulated sweat was added, completely immersing the sample. After sealing, the testing system was settled at 50 ℃ for 31 h. 1 mL of 5% (volume fraction) nitric acid solution was added, and the mixed solution was diluted to 5 mL by simulated sweat. The resulting solution was determined by inductively coupled plasma atomic emission spectrometry. It was shown that the migration temperature had a greater impact on the nickel release compared to other migration conditions. At 30, 40, 50 ℃, the nickel release and relative nickel release rate (the ratio of nickel release between this method and standard EN 1811: 2015) were larger at 50 ℃ for 24, 48, 72, 168, 240 h of migration. The regression model between relative nickel release rate and migration time at 50 ℃ was a power function, and the migration time at 100% relative nickel release rate was 31 h, which was much lower than the 168 h used in standard EN1811: 2015. The proposed method was used for the analysis of copper alloy, nickel alloy, stainless steel, and copper zinc alloy samples (simulated jewelry), and the results obtained were consistent with those given by EN 1811: 2015, with RSDs (n=5) of the determined values less than 6.0%.