GB/T 4 2513.2-2023 specifies the molybdenum blue Spectrophotometric method, spec-trophotometry for the determination of phosphorus content in nickel alloys. This standard applies to a variety of nickel alloys, clearly states the principle of the method, lists the required equipment and reagents in detail, strictly regulates the steps of preparation, dissolve and color reaction of the sample, and clarifies the calculation and representation of the results. Following this standard, the phosphorus content in nickel alloys can be accurately determined, providing key data support for mass control and performance evaluation of nickel alloy production, helping related industries to ensure that products meet mass requirements, and promoting the stable application of nickel alloys in various fields.