The Usual Suspects, you know them. It’s “those guys.” They have a reputation. They create chaos, mayhem, disorder. Generally not someone you want to be around or interact with. This is a good way to describe the unsavory characters that make up the list of contaminants in the U.S. EPA 8270 method -- the figurative Keyser Sozes of environmental chemistry. I’m sure many environmental analysts out there feel the same.
The U.S. EPA 8270 method is a regulatory method that emanates from the U.S. EPA office of resource conservation and recovery. It is used to analyze solid and semisolid environmental hazardous waste samples for SVOC (semi-volatile organic compound) contamination. The 8270 method creates challenges for environmental analysts due to the need for simultaneous identification and quantitation for a mix of acid, base and neutral compounds in a broad concentration range. Not to mention that these compounds are all extremely hazardous environmental pollutants. I cringe every time I crack a standard vial open.
Why is the method such a pain?
The unique mix of contaminants, their multiple chemical characteristics and properties, as well as the nature of hazardous waste sample types all contribute to the difficulty of the method. Within the compound list itself are potentially active, reactive, absorptive and thermally labile compounds. Below is a list of specific problems identified in the method itself:
Adsorption to walls of glassware during extraction and storage
Hydrolysis during extraction accelerated by acidic or basic conditions and storage
Low extraction efficiencies
Oxidation during extraction accelerated by basic conditions and storage
Low chromatographic response
Many of these problems can lead to even bigger problems in our data. Because of this many of these compounds require "special treatment” or consideration when preparing and analyzing samples for these contaminants.
What influence does my GC-MS system have?
Our GC-MS system parameters must be optimized to address the issues that these compounds create. The delicate balance of instrument settings and condition as well as extraction conditions optimize the results generated from our analysis. Some of the considerations for optimizing 8270 analysis are listed here:
Ultimately we want to protect the quality of our data so that there is confidence in our measured result. After all, the data we generate is being used to ensure environmental and public health.
Optimizing GC Parameters for Environmental Sample Analysis
Thankfully, many analysts and instrument manufacturers have worked on solutions for this method and provided guidance on this puzzling task. For me, the best guidance that I can offer is to review a talk given at our annual POPS symposium in 2015 by The Great Jack Cochran. In his lecture, Jack drops some supreme knowledge for keeping GC-MS systems optimized when analyzing environmental samples. For all of our environmental organic analysts out there it is definitely worth the time to sit and listen. Thank me later!
To help our current and future users with the many challenges that this method brings we have created the U.S. EPA 8270 analyzer kit. The 8270 kit was designed to remove the guesswork and manage all the considerations from the bulleted list above. The kit provides an optimized plug-and-play methodology complete with validated instrument method settings, injection sequence templates and method reports specific for EPA reporting criteria. With our efforts we hoped to help remove many of the optimization steps new users would have to endure when setting up the 8270 method.