A sensitive method based on the fluorescence quenching eect of the Tb3+
-Tiron complex is proposed for the determination of
alkali-labile phosphoprotein phosphorus (ALP) released from fish plasma. The detection limit was 5.4 ng/ml (S/N=2), and the relative
standard deviation of the quenching eect (6 replicates) was 4.6%. The results obtained by the proposed method were in good agreement
with those obtained by the colorimetric assay. The advantages of the present method are its relatively simple detection procedure, the
lack of toxic organic solvents, and high sensitivity