Triple Quadrupole LC/MS Analysis of Aflatoxins in Various Food Samples

INTRODUCTION

Triple quadrupole LC/MS analysis of aflatoxins in food samples eliminates the need for expensive immuno-affinity cleanup columns and reduces the probability of false positives to almost zero.

Aflatoxins are highly carcinogenic secondary metabolites of the molds aspergillus flavus and aspergillus parasiticus and are found in grains, corn, peanuts, and other foodstuffs. The action level for these toxic naturally occurring compounds is typically 20 ppb around the world for food and animal feed. Japan has a more aggressive limit of 10 ppb for Aflatoxin B1 and is now changing that to 10 ppb total aflatoxin. This method uses the highly selective and sensitive triple quadrupole LC/MS/MS in Multiple Reaction Monitoring (MRM) mode and can achieve sensitivities in food matrices that are well below these action levels. In addition, the expensive immuno-affinity solid phase extraction (SPE) is compared, in this limited study, to the very inexpensive dispersive solid phase extraction (DSPE) and found to be equivalent.

Figure 1. LC/MS/MS chromatogram of aflatoxin B1, B2, G1, and G2 standards at 1 ppb

The method was developed with the Agilent 6460 Triple Quadrupole LC/MS with focusing Agilent Jet Stream Technology and the Agilent 1200 Series LC including the Agilent 1260 Infinity Binary Pump and the 1200 Series High Performance Well Plate Sampler SL Plus. This high-performance method achieves near baseline separation of each of the four compounds in less than 5 minutes. In addition, the method uses three transition ions: one for quantitation and two for qualifiers providing sensitive and accurate quantitation and confirmation by comparing ion ratios and retention times to standards. This eliminates false positives and the need for further analysis to obtain confirmation. The use of stable isotope internal standards added to the samples prior to extraction provides correction for any matrix affects in both extraction and analysis, and assures near zero probability of false negatives.

Figure 2. LOD results observed for Aflatoxins B1, B2, G1, and G2 with dispersive SPE sample preparation

The Agilent LC/MS/MS provides the necessary limits of reporting for aflatoxins and reduces false positives and negatives to the lowest levels of probability. This provides the assurance needed for a safe food supply. With DSPE for sample preparation, the day-to-day method is cost-effective and efficient.

KEY BENEFITS

• Agilent 6460 Triple Quadrupole LC/MS provides high sensitivity for carcinogenic aflatoxins with limits of detection (LODs) well below action levels in food and feed.

• The highly selective LC/MS/MS requires less expensive sample preparation.

• Quantitation and confirmation are performed in one analysis.

• More samples can be analyzed and reported faster.

• Agilent provides everything needed from dispersive SPE material to columns and supplies.

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