1996 FDA Science Forum

Abstract # A-18

Collaborative Study of Molar Absorptivities of Aflatoxins B₁, B₂, G₁, and G₂ in Acetonitrile, Methanol and Toluene-Acetonitrile (9 + 1). S. Nesheim and M.W. Trucksess, CFSAN, FDA, Washington, DC

Four laboratories participated in a study to determine the molar absorptivities of the aflatoxins in three replacement solvents for benzene for use in the calibration of standard aflatoxin solutions. Three test sample vials containing approximately 25 µg of each individual aflatoxin were prepared and sent to each collaborator. Each collaborator dissolved the aflatoxin in each vial in 2 mL solvent, measured the UV spectrum, and reported the absorptivity maxima near 350 nm. The concentrations of the aflatoxins in the test samples were determined by dissolving an identical test sample in benzene-acetonitrile (98+2) and following the procedure in 971.22. These concentrations were in turn used to determine the absorptivities in the other 3 solvents. The absorptivity results are shown in the table below:

Solvent Absorptivity for Aflatoxin

B₁ B₂ G₁ G₂

CH₃CN 20,700 22,500 17,600 18,900

MeOH 21,500 21,400 17,700 19,200

Toluene/CH₃CN 21,500 19,300 16,400 18,300

Solvent	Absorptivity for Aflatoxin
	B₁	B₂	G₁	G₂
CH₃CN	20,700	22,500	17,600	18,900
MeOH	21,500	21,400	17,700	19,200
Toluene/CH₃CN	21,500	19,300	16,400	18,300

Abstract # A-18

Solvent Absorptivity for Aflatoxin B1B2G1G2 CH3CN 20,70022,500 17,600 18,900 MeOH 21,50021,400 17,700 19,200 Toluene/CH3CN 21,50019,30016,400 18,300

Solvent Absorptivity for Aflatoxin

B₁ B₂ G₁ G₂

CH₃CN 20,700 22,500 17,600 18,900

MeOH 21,500 21,400 17,700 19,200

Toluene/CH₃CN 21,500 19,300 16,400 18,300