称取约0.2 g水产饲料样品，加入250 g·L^-1氢氧化钾-甲醇溶液10 mL，于60℃加热6 h，每隔2 h涡旋振荡一次，然后以3 000 r·min^-1转速离心15 min，取0.10 mL上清液加入提前加入34~38 mL水的40 mL棕色进样瓶内，用盐酸（1+9）溶液调节pH至6~8后，再加入2 mol·L^-1乙酸钠缓冲溶液0.3 mL和乙基化试剂0.05 mL，进行衍生化反应后，加水定容至40.0 mL，混匀后用吹扫捕集-气相色谱-原子荧光光谱仪进行测定。结果表明：甲基汞的质量在500 pg内与荧光强度呈线性关系，方法的检出限（3s/k）为2 μg·kg^-1，测定下限（10s/k）为5 μg·kg^-1。加标回收率在94.7%~98.8%之间，测定值的相对标准偏差（n=6）为4.9%。

The aquatic feed sample (about 0.2 g) was added into 10 mL of 250 g·L^-1 potassium hydroxide-methanol solution. The mixture was heated at 60 ℃ for 6 h, vortex oscillated every 2 h, then centrifuged at 3 000 r·min^-1 for 15 min. 0.10 mL of the supernatant was added into a 40 mL brown sample bottle with 34-38 mL of water added in advance, and the pH of the solution was adjusted to 6-8 with HCl (1+9) solution. 0.3 mL of 2 mol·L^-1 sodium acetate buffer solution and 0.05 mL of ethylation reagent were added to carry out derivatization. Then the solution was made up to 40.0 mL with water. After mixing well, purge and trap-gas chromatography-atomic fluorescence spectrometer was used for determination. The results showed that the fluorescence intensity was kept linear with the mass of methylmercury within 500 pg. The detection limit (3s/k) of the method was 2 μg·kg^-1, and the lower limit of determination (10s/k) was 5 μg·kg^-1. Values of recovery obtained by standard addition method were between 94.7% and 98.8%, and the relative standard deviation (n=6) of determined values was 4.9%.