SIMPLE AND SENSITIVE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY FLUORESCENCE METHOD FOR THE DETERMINATION OF CITRININ - APPLICATION TO THE ANALYSIS OF FUNGAL CULTURES AND CHEESE EXTRACTS

A new and highly sensitive method for the detection of the important m ycotoxin, citrinin, has been developed. Spectroscopic studies demonstr ate that the fluorescence of this metabolite is influenced by the pH o f the environment. This fact was exploited in the chromatographic dete rmination of citrinin with fluorescence detection. The proposed method , based on the addition of 1 M hydrochloric acid as an acidic post-col umn reagent, has a limit of detection of 0.9 . 10(-7) M. Analytical va lidation shows that linearity can be assumed from 2 . 10(-7) to 10(-4) M citrinin. The repeatability and reproducibility are satisfactory, w ith R.S.D.=5.1% (n=9, c=10(-5) M) and R.S.D.=7.2% (n=9, c=10(-5) M). T he method was also applied to the determination of this mycotoxin prod uced by mould cultures isolated from soft cheese and also from soft ch eese and also from cheese extracts spiked with citrinin. The specifici ty of the method is demonstrated and the necessity for post-column aci dification is illustrated on real samples.