Analysis of deoxynivalenol, masked deoxynivalenol, and Fusarium graminearum pigment in wheat samples, using liquid chromatography-UV-mass spectrometry

Tolerable limits set for deoxynivalenol (DON) do not consider DON conjugates such as DON-3-glucoside. Conjugates may be metabolized in vivo to DON. Such masked mycotoxins and the potentially toxic Fusarium pigment are not routinely analyzed in cereals. We quantified DON, DON-3-glucoside, and a red Fusarium pigment in hard red spring wheat, using a new liquid chromatography-mass spectrometry method. Extraction protocols using centrifugation and shaking, and methanol-methylene chloride (50:50 [vol/vol]) or acetonitrile-water (84:16 [vol/vol]) were assessed. Purposively and randomly selected hard spring wheat samples were extracted with solvent filtered through a C18 column and analyzed using liquid chromatography-UV-mass spectrometry. Isocratic mobile phase (70% methanol) was used. Recoveries were 96.4% (DON) and 70.0% (DON-3-glucoside), while limits of detection were 1 microg/kg (MS) and 10 microg/kg (UV), and limits of quantification were 1 microg/kg (UV) and 0.5 microg/kg (MS), respectively. The pigment limits of quantification and limits of detection on the MS were 4.3 and 0.0005 microg/kg, respectively. The purposively selected samples had DON, DON-3-glucoside, and pigment averages of 3.4 +/- 4.0 microg/g, 3.8 +/- 8.3 microg/g, and 0.31 +/- 3.71 g/kg, respectively. The randomly selected spring wheat had lower mean levels of DON (1.4 +/- 2.3 microg/g), DON-3-glucoside (0.2 +/- 1.0 microg/g), and pigment (147.93 +/- 247.84 microg/g). Analytical tools such as this new liquid chromatography-UV-mass spectrometry method can be used to quantify masked and parent mycotoxins, plus a potentially toxic pigment for risk assessment.