The AI for N-nitroso-esmolol is 1500 μg/d, the MMD is 30.2g/d, and the acceptable limit is 49.67ppb. According to FDA requirements, loq should be less than or equal to 10%, which is 4.9 ppb. Currently, due to the low detection limit, there is a significant difference in test results between different devices (≥50%). Can this test data be used? As an emergency medication, can esmolol do not use MDD and instead use other limits? The current AMES results are also not ideal.