Determination of pyrethroid pesticides in cinnamomi cortex

In Japan, maximum residue levels (MRL) have been set for eight pesticides (alpha-BHC, beta-BHC, gamma-BHC, delta-BHC (BHCs), p,p'-DDE, o,p'-DDT, p,p'-DDD, p,p'-DDT (DDTs)) in 14 crude drugs (below 0.2 ppm as total of BHCs, below 0.2 ppm as total of DDTs). There are fears that pesticides present in crude drugs for which MRL are set will be changed from BHCs and DDTs to other pesticides with MRL setting as the turning point. There are few surveys of pyrethroid pesticide in crude drugs distributed in Japan. The actual situation of pyrethroid pesticides in crude drugs distributed in Japan after setting MRL is not unclear and should be clarified. Although a method to analyze permethrin, cypermethrin and fenvalerate in 11 crude drugs was reported, it is not adequate because the recovery rates of permethrin, cypermethrin and fenvalerate from Cinnamomi cortex were very low and the method, including liquid-liquid partition is difficult. In this study, we developed a method using solid-phase extraction to analyze permethrin, cypermethrin and fenvalerate in Cinnamomi cortex with acceptable recovery rates. The sample solution was determined by gas chromatography/mass spectrometry with negative chemical ionization. The recovery rates of permethrin, cypermethrin and fenvalerate from Cinnamomi cortex were between 87.9 and 90.7%. Five samples of Cinnamomi cortex were analyzed according to the proposed method. No samples contained permethrin, cypermethrin and fenvalerate over detection limits. The proposed method could analyze permethrin, cypermethrin and fenvalerate in all crude drugs for which MRL are set.