After the samples were extracted by ethyl acetate

the supernatant were cleansed by acidic alumina and extracted by potassium carbonate. The extracts were then reacted with acetic anhydride. The products were detected by gas chromatography with ECD detector via an external standard method following being extracted by n-hexane. The linearity of three compounds were held in 5~100 μg/L

with correlation coefficient R

2



>

0.999. The detection limits for the GC method (S/N=3) of the nitrophenolate were 5 μg/kg. The tests for recovery were carried by addition of standard at concentration of 10~100 μg/kg. The result indicated that the residue content of p-nitrophenol sodium

o-nitrophenol sodium and 2-methoxy-5-nitropenolate sodium were 86.4%~ 89.6%

82.8%~ 84.3% and 89.9%~ 92.2%，respectively

while the relative standard deviations were less than 15%. This method can be used to determine the residue content of nitrophenolate in edible portion of fish and shrimp.