Monitoring of pesticide residues on cucumber, tomatoes and strawberries in Gaza Governorates, Palestine

Three techniques of gas chromatography (GC) either with flame photometric-detector (FPD), electron capture detector (ECD), or with mass-spectrometry (MS) were applied for identification and quantification of pesticide residues on 45 samples of cucumber, tomatoes, and strawberries in fifteen locations in Gaza Governorates. GC-FPD analysis showed the presence of four different organo-phosphorus (OP) pesticides, their levels were very low and below maximum residue limits (MRL's). GC-ECD detected ten different pesticides at levels below the MRL's. Using the GC-MS technique, alpha and beta-endosulfan, chlorpyrifos, carbofuran, chlorfluazuron, triadimenol I and II, penconazole, coptafolmetabolite, pyrimethanil and iprodione were detected and confirmed on some samples of cucumber, tomatoes and strawberries. All GC-MS pesticide residues detected on tomato were below the MRL's except chlorfluazuron while on strawberry were below the MRL's except penconazole, chlorfluazuron and pyrimethanil, but on cucumber were slightly higher than the MRL's except alpha and beta-endosulfan. Also, statistical analysis of pesticide residues in all samples showed that most of the detected residues mean were significantly lower than the MRL's (p < 0.05). Generally, tomatoes showed the least number and level of pesticide residues by all the GC-techniques. On the other hand, strawberries showed greater number and levels of pesticide residues, particularly by the GC-MS technique. These results indicate that the protective period to elapse before harvesting should be increased especially on strawberry. The results also can help in risk assessment of consumers exposure to the expected pesticide residues.