In addition to removing the epoxy coating, it has been reported that the NaOH leaches some Cu, making the determination of the Cu content of the NaOH solution important. However, results from other studies indicate that the Cu leached by NaOH is usually negligible . For example, Jadav and Hocheng reported that (0.43 ± 0.001) μg/g Cu was leached . Therefore, in this work, the determination of the Cu content of the spent NaOH solution was not undertaken.