5.5 Minute LC-MS/MS Analysis of Mycotoxins in Peanut Powder

• Fast analysis for higher sample throughput.
• Excellent separation improves accuracy for 12 regulated mycotoxins.
• Quick and easy sample preparation (dilute-filter-shoot).

Certain fungi that can grow on agricultural products produce toxic metabolites known as mycotoxins. Modern food processing procedures cannot completely remove these compounds if they are present, so strict monitoring protocols have been established. Although a universal method for the analysis of mycotoxins would allow highly efficient screening, it is very challenging to develop such a method due to differences in physiochemical properties of mycotoxins, extraction efficiencies, and matrix effects. Zhang et al. published a multi-lab study [1] aimed at providing labs with an analytical procedure that could be broadly applied to the analysis of a variety of mycotoxins in many different matrices. Using that work as inspiration, we developed the following LC-MS/MS method that resolves 12 FDA regulated mycotoxins within the pressure limits of traditional HPLC instruments.

In this example, mycotoxins were analyzed in a peanut powder matrix. The use of a relatively short column format, the selectivity of the Biphenyl stationary phase, and the efficiency of 2.7 µm Raptor superficially porous particles provided excellent separations in a fast 5.5 minute analysis (total cycle time of 7 minutes). A coeluting matrix compound that shared the most abundant MRM transition for mycotoxin HT-2 (447.3-285.3) was observed, so a less abundant transition (447.3-345.3) was selected for quantitation. To increase sensitivity, an ammonium buffer was used to promote better ionization of mycotoxins. The Raptor Biphenyl column worked very well for the 12 mycotoxins studied in the cited work, but for longer compound lists containing isobaric mycotoxins with similar structures, the Raptor FluoroPhenyl phase may be necessary to provide adequate chromatographic resolution. The selectivity of the Raptor Fluorophenyl column is demonstrated in this analysis of 20 mycotoxins.

This method showed excellent precision and accuracy for the 12 FDA regulated mycotoxins that were evaluated during a validation study that covered a variety of matrices (including multiple sources of cornmeal and brown rice flour, in addition to the peanut powder example shown here). Restek would like to thank Dr. Zhang for his technical support during this project.

	Peaks	tR (min)	Conc. (ng/g)	Precursor Ion	Product Ion 1	Product Ion 2
1.	Deoxynivalenol	0.62	50	297.3	249.3	231.2
2.	Fumonisin B1	2.45	50	722.5	352.4	334.5
3.	HT-2	2.60	50	447.3	345.3	285.3
4.	Fumonisin B3	2.85	50	706.5	336.4	318.4
5.	Fumonisin B2	3.23	50	706.5	336.3	141.2
6.	T2	3.31	50	489.3	245.2	387.4

	Peaks	tR (min)	Conc. (ng/g)	Precursor Ion	Product Ion 1	Product Ion 2
7.	Aflatoxin G2	3.74	5	331.2	313.3	189.3
8.	Zearalenone	3.96	50	319.3	283.3	187.2
9.	Aflatoxin G1	4.22	5	329.2	243.2	200.2
10.	Aflatoxin B2	4.43	5	315.3	287.3	259.2
11.	Aflatoxin B1	4.99	5	313.3	285.2	241.2
12.	Ochratoxin A	5.19	5	404.2	239.3	358.3

Matrix interference was observed for HT-2 transition 447.3-285.3 in peanut powder. Therefore, 447.3-345.3 was chose for quantification.

Column	Raptor Biphenyl (cat.# 9309A52)
Dimensions:	50 mm x 2.1 mm ID
Particle Size:	2.7 µm
Pore Size:	90 Å
Guard Column:	Raptor Biphenyl EXP guard column cartridge 5 mm, 2.1 mm ID, 2.7 µm (cat.# 9309A0252)
Temp.:	40 °C
Standard/Sample
Inj. Vol.:	5 µL
Mobile Phase
A:	Water, 2 mM ammonium formate, 0.1% formic acid
B:	Methanol, 2 mM ammonium formate, 0.1% formic acid
	Time (min) Flow (mL/min) %A %B %C 0.00 0.5 70 30 0.6 0.5 70 30 0.7 0.5 50 50 3.0 0.5 25 70 4.5 0.5 25 75 5.0 0.5 10 90 5.2 0.5 10 90 5.21 0.5 25 75 6.00 0.5 25 75 6.01 0.5 70 30 7.00 0.5 70 30

Detector	MS/MS
Ion Mode:	ESI+
Mode:	MRM
Instrument	UHPLC
Sample Preparation	Weighed 1.00 gram of peanut powder in a 50 mL centrifuge tube and added 2.00 mL of water. Vortexed at 3000 rpm for 5 min followed by the addition of 4.0 mL of extraction solvent (50:50 water:acetonitrile, v/v). The tube was then vortexed at 3000 rpm for 5 min followed by centrifugation for 15 min at 4200 rpm. 475 μL of the supernatant was filtered through a Thomson SINGLE StEP Nano filter vial (0.2 μm, cat.# 25882). The sample was then fortified with 25 μL of a standard solution prepared in water at 1000 ng/mL (100 ng/mL for aflatoxins and ochratoxin A) as part of the matrix-matched calibration curve. Vortexed at 3000 rpm for 1 min prior to analysis.
Notes	Want even better performance when analyzing metal-sensitive compounds? Check out Inert LC columns at www.restek.com/inert.

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Want even better performance when analyzing mycotoxins and other metal-sensitive compounds? Learn more at www.restek.com/inert

References

1. K. Zhang, M.R. Schaab, G. Southwood, E.R. Tor, L.S. Aston, W. Song, B. Eitzer, S. Majumdar, T. Lapainis, H. Mai, K. Tran, A. El-Demerdash, V. Vega, Y. Cai, J.W. Wong, A.J. Krynitsky, T.H. Begley, A collaborative study: determination of mycotoxins in corn, peanut butter, and wheat flour using stable isotope dilution assay (SIDA) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), Journal of Agricultural and Food Chemistry, 65 (33) (2017) 7138-7152. https://www.ncbi.nlm.nih.gov/pubmed/27983809.