Dioxin/Furan Mixtures for Food/Feed and GC-MS/MS Analysis

Dioxins and furans have been considered one of the most toxic environmental pollutant classes for many decades. As has been evidenced from numerous accidental contamination events, they have also been one of the costliest environmental pollutants as well. Monitoring for these dangerous chemicals has been mandated for decades and traditionally done by use of high-resolution gas chromatography with mass spectrometry (HRGC-MS). But in recent years the use of GC-MS/MS has developed as a viable option for testing, especially in food and feed methods where it is now approved for confirmatory testing in the EU food/feed directives. But are you using the proper standards to do this type of analysis?

It is well known that the major route of human exposure to dioxins and furans is through food consumption, and it is here that a major focus has occurred to actively reduce and potentially eliminate these chemicals from our food sources. In 2002 the European Union took legislative action and introduced strict guidance for maximum allowable limits for dioxins and furans in food and animal feed. While HRGC-MS was the basis for all testing at that time, in 2014 it was determined that methods using newer GC-MS/MS-based systems could be used to confirm dioxin and furan testing results. This acceptance has opened a much broader approach to analytical testing in food and feed. 

There are two points of interest regarding analytical standards used in dioxin and furan testing for food and feed: 

1. Most laboratories are still using US EPA methods developed in the 1990s 
The older EPA methods were developed when isotopically labeled standards were still quite rare, and not all 17 analytes have ¹³C- surrogate standards. Over the years CIL has developed many new “non-2,3,7,8 containing” dioxin and furan standards which can be used as injection/recovery standards, allowing the use of all 17 ¹³C-labeled “2,3,7,8-containing” congeners as surrogate/extraction standards. 

2. Use of triple-quadrupole GC/MS-MS systems require some low-level calibrant to set minimum detection levels (MDL) 
Due to the lack of signal:noise calculations in GC-MS/MS systems, an accurate and very low-level calibration level must be used to establish MDLs. 

CIL developed the Food/Feed/QQQ Calibration Series and labeled and unlabeled spiking mixtures specifically to resolve these issues. We believe these are the most appropriate standards for analysis of dioxins and furans in food and feed, and utilizing GC-MS/MS because:

• All 17 “2,3,7,8-containing” isotopically labeled (¹³C) extraction standards are included
• “Non 2,3,7,8-containing” isotopically labeled (¹³C) injection standards are included
• Ten (10) calibration series levels with native concentration ranges from 10 fg/µL to 200 pg/µL TCDD equivalence are useful for low-level analysis for food/feed and other matrices (blood, etc.), and higher levels for contaminated products or other higher level environmental samples
• Extra-low-level calibration levels (10, 20 fg/µL) may be used with GC-MS/MS triple-quadrupole instruments to establish minimum detection levels
• Calibration series includes relative native concentrations 1:2:5 for tetra/penta:hexa/hepta:octa homolog levels
• Spiking solutions at standard concentration and 10× concentration to meet the needs of labs with smaller or larger demands
• Use of ¹³C₆-1,2,3,4-tetrachlorodibenzo-p-dioxin cleanup standard rather than ³⁷Cl₄-TCDD for extracts requiring extra processing.