HPLC (High-Performance Liquid Chromatography) grade water is ultra-pure water with very low levels of impurities that could interfere with chromatographic analysis. Key specifications include low UV absorbance, high resistivity (typically 16-18 megaohms), and freedom from particulate matter and dissolved gases. It is often filtered through a 0.22-micron filter and sealed in solvent-rinsed containers to maintain purity. UV Absorbance:HPLC grade water should have low absorbance in the ultraviolet (UV) range, typically measured at wavelengths like 200 nm, 210 nm, and 254 nm. Absorbance values should be below 0.01 AU at these wavelengths. This low absorbance is crucial because high UV absorbance can interfere with the detection of analytes during HPLC analysis.