Agilent Technologies Inc. announced a highly sensitive method for analyzing polybrominated diphenyl ethers (PBDEs), a class of toxic chemicals found in thousands of consumer products. This gas chromatography/mass spectrometry (GC/MS) method can detect PBDEs at the lowest levels available in sediment and sewage sludge, as low as 1 part per billion (ppb).
PBDEs are flame retardants added to plastic widely used in household products and electronics devices, including computers, televisions, clothing, carpets and furniture. These chemicals can enter the environment through the dust and residue from such products or through landfill seepage. PBDEs do not degrade easily and can accumulate in the environment and in the bodies of animals and humans.
Research suggests that human exposure to these chemicals is increasing exponentially. A Swedish study found PBDE levels in the breast milk of Swedish women had doubled about every five years in the last three decades (1). A U.S. study showed PBDE levels in the milk of North American women were 10 to 100 times higher than European women's, with an average level of 73.9 ppb (2).
The chemical structure of PBDEs is very similar to polychlorinated biphenyls (PCBs), a group of flame retardants banned in the 1970s because of their toxicity. Although their effects on human health are still under investigation, PBDEs have been found to cause hormonal and neurological problems in laboratory animals. Due to health concerns, the European Union and the state of California have enacted legislation restricting the use of PBDEs.
Gas chromatography is a fast and sensitive method for detecting PBDEs, but the high boiling points and low thermal stability of the three most widely used commercial PBDEs (pentaBDE, octaBDE and decaBDE) can complicate this type of analysis. In GC, a sample must be vaporized before it can be analyzed. Because of their high boiling points these PBDEs require high heat to vaporize, but they are heat-sensitive compounds and will decompose when exposed to high temperatures.
This method reduces degradation by using short GC columns with thin-film internal coatings. Short columns and thin films reduce the time that PBDEs are on the column, thereby minimizing their exposure to high temperatures.
Agilent scientists used this method to analyze sewage sludge from municipal waste-treatment plants. Using an Agilent DB-1 column with an Agilent 6890/5973 inert GC/MS system, the researchers easily achieved the minimum detection limits set by the French Normalization Association (AFNOR). These limits are 1 ppb in sediments and 10 ppb in sewage sludge for pentaBDE, and 50 ppb in sediments and 500 ppb in sewage sludge for both octaBDE and decaBDE.