In order to investigate if there was matrix effect, the slopes and
intercepts of the linear equations for the calibration curves in solvent
and in the matrix were compared by the t-test. Significant difference
(p < 0.05) was observed between intercepts of the curves
for putrescine, histamine, tyramine and phenylethylamine and also
between the inclinations of the curves for cadaverine (Table 2).
These results confirmed the matrix effect and, therefore, calibration
curves in a soy sauce matrix were used.