EPA rule for Specific UV Absorbance (SUVA) for Total Organic Carbon (TOC) Analysis
Specific UV Absorbance (SUVA) is an analysis of drinking water that uses UV absorbance at 254nm to identify dissolved organic carbon (DOC) levels. UV absorbance is easily determined using a spectrophotometer
Previous studies established a relationship between SUVA and the levels of humic substances that are removed during enhanced coagulation and/or enhanced softening. Utilizing this relationship allows for a cheap and easy method to determine whether enhanced coagulation or softening is required based off of the exemption allowed in Stage 1 D/DBPR and Stage 2 D/DBPR. Removing the extra disinfection from the process can save a water district money when it comes to TOC removal.
Under Stage 1 D/DBPR, Standards Method 5910B was the only EPA approved method for SUVA determination. Stage 2 D/DBPR approved EPA Method 415.3 (Revision 1.1, 2005) for TOC, DOC and SUVA determination. This one method not only combines all three tests, but also provides increased quality control procedures to ensure testing accuracy, including calibration verification procedures for all instruments utilized in the method.
According to the EPA method, the verification of the spectrophotometer can be done with a commercially prepared check standard. This method specifically mentions the In-Spec® photometric standards, manufactured by GFS Chemicals, Inc, which were utilized by the EPA to validate their spectrophotometer when developing 415.3. The In-Spec® photometric standards are NIST traceable, non-toxic, have a one-year shelf life and require no preparation to use.
Data provided at 254nm for In-Spec UV Standards 1 through 30.