Happy Tuesday! The final question for 2018 focuses on the EPA 500 Series methods that have been developed to quantify organic contaminants in drinking water. For those unfamiliar, EPA Method 525.2 outlines the extraction and quantification of organic compounds in drinking water. The EPA eventually revised the method and released Method 525.3. The updated revision incorporates a number of changes to improve the extraction and quantification of drinking water contaminants.
Which of the following is not one of the changes that were incorporated into Method 525.3?
(a) The extraction media was changed from C18 to divinylbenzene (DVB) to improve recoveries over a wider pH range
(b) The internal standard is now added to the final extract, instead of being added to the solution prior to the extraction
(c) A Laboratory Reagent Blank (LRB) is not required to be measured as long as a series of Laboratory Fortified Blanks (LFB) are measured
(d) Perylene-d12 is no longer used as a surrogate
(e) The use of Selected Ion Monitoring (SIM) mode is an option to increase the sensitivity for measuring those compounds that are near the instrument’s detection limits
Submit your guess in the comments below and stay tuned for the answer next Tuesday!