A spectrophotometric procedure, using carboxypeptidase A, for the quantitative measurement of ochratoxin A.

In the method described, ochratoxin A is eleaved into ochratoxin alpha (free isocoumarin chromophore) and phenylaline, using carboxypeptidase. Detection is based on the difference in fluorescence excitation spectra of ochratoxin A (380 NM, maximum) and ochratoxin alpha (340 nm, maximum). The quantitation of ochratoxin A is based on the loss of fluorescence intensity at 380 nm. The method has been used for the quantitative determination of as little as 4 mug ochratoxin A/kg barley and barley meal but it could be extended to other products.