What is a standard solution?

A standard solution is a solution that contains a specified concentration of a parameter, such as chlorine or iron. When a standard solution is used in place of a sample and tested, the result should match the concentration of the standard. A matching result will give confidence that the test is working correctly. Any significant discrepancies (greater than 10%) indicate a problem that must be investigated. Hach carries many Standard Solutions at concentrations that fall within most test ranges.Some standard solutions are so unstable that they are difficult to make and use and are therefore not available. Such standards include hydrogen sulfide, chlorine dioxide, dissolved oxygen, and ozone. Chlorine standards are available only at high concentrations, and must be diluted with high-quality dilution water using glassware that has no chlorine-demand.Standard solutions can also be used to calibrate instruments such as colorimeters and spectrophotometers, as well as electrochemical meters such as pH and pH/ISE meters. Varying concentrations of a standard solution can be used to make a calibration curve that in turn can be used to find the concentration of samples.