Bi solution (Bismuth standard solution, 10,000 µg/mL in 2.0 mol/L HNO3) is a specialty chemical reagent primarily used in analytical chemistry for instrument calibration and trace metal analysis. It serves as a reference standard for techniques such as Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), enabling precise quantification of bismuth in complex samples.

Applications include environmental monitoring (e.g., detecting bismuth in water and soil), quality control in pharmaceuticals (where bismuth compounds are used in medications), metallurgical analysis of alloys and solders, and food safety testing. As a niche additive in analytical workflows, it supports research in materials science and toxicology, but is not intended for direct use in formulations or industrial processes due to its acidic matrix.