EPH and VPH now used in Massachusetts, Connecticut and Maine

AAI passed the complete full initial quality assurance trial of the original EPH/VPH methodology established and provided by the Massachusetts DEP.  Since that time EPH and VPH has undergone changes and Massachusetts has allowed labs to modify the procedures to a more performance based methodology. Most recently AAI has modified the method to use Gas Chromatography and Mass Spectrometry to more accurately and specifically identify and quantitate the target analytes for both methods.

The EPH method is based on a solvent extraction, silica gel  solid phase extraction - fractionation process and combined gas Chromatography/Mass Spectrometry (GC/MS) analysis.  Unlike other GC/FID procedures, the GC/MS method is not subject to 'false positive' bias in reporting the target analytes in the PAH fraction.  In this fraction, without the advantage of Mass Spectrometry regular hydrocarbons may give false positives in this portion of the test.  This is a significant factor since the target analytes are the most hazardous part of the contamination that is being evaluated.

VPH analysis is based on a purge-and-trap gas chromatography (GC) procedure using Photo Ionization and Flame Ionization detectors (PID/FID).  The VPH method is designed to measure the collective concentrations of aliphatic and aromatic petroleum hydrocarbons.  As in the case with EPH, by producing discrete data, the VPH method also provides for the measurement of individual VPH target analytes, Benzene, Toluene, Ethyl benzene, Xylenes (BTEX) ,  as well as Methyl-tert-butyl ether and Naphthalene. GC/MS for this part of the analyses gives AAI the ability to identify Benzene, MTBE, Naphthalene etc. with the highest level of certainty, so that you can advise your client or the regulators about the significance of the results that AAI produce.  If you have no choice except to use PID and FID, please let AAI know in advance since we need to schedule the PID/FID instrument.                                  

EDB  Analysis GC/MS         

Historically, ethylene dibromide (EDB) has been used as a lead scavenger in gasoline and aviation fuel. Characterized as a probable human carcinogen, US EPA has set a Maximum Containment (MCL) level of 0.05 parts per billion (ppb) in drinking water.  To provide our clients with reporting limits below the EPA's  enforced MCL of 0.05 ppb AAI analyzes samples for the presence of EDB by a modified US EPA Method 8260B in SIM mode.  This allows for the detection limit of EDB with increased sensitivity, because in SIM mode the MS gathers data for only the masses of interest rather than looking for all masses over a wide range. With this method AAI can achieve a quantitation level as low 4.0 parts per trillion(ppt)  This is more than ten times lower than the MCL and allows for samples to be diluted while still maintaining reporting limit integrity.

10/20/2009 12:19