Table 2.

The mean amounts of pesticide residues and coefficients of variation (CV%) of wastewater samples collected from the three sites at El-Khairy drainage (A: start, B: middle, and C: end) and recovery (%) percentages ± RSD of pesticides from spiked blank water samples using GC–MS

Site	Rt (min)	Pesticide	Amount (µg/L)	CV%		Recovery (%) ± SEM
				Intra-assay	Inter-assay	0.5 (µg/L)	5 (µg/L)
A	6.565	Lenacil	0.7214	4.56	7.28	89.42 ± 4.18	91.73 ± 5.72
	13.558	Chlorpyrifos	28.162	3.47	6.51	93.57 ± 3.67	93.78 ± 4.87
	15.869	Cypermethrin	4.1404	4.67	8.57	87.65 ± 6.14	94.06 ± 5.71
	16.243	Bifenthrin	0.0517	4.18	9.14	93.26 ± 5.21	95.37 ± 5.08
	17.274	Carbofuran	7.8813	5.16	8.03	91.64 ± 3.67	93.45 ± 4.19
	20.197	Permethrin	0.2081	3.81	6.72	93.46 ± 4.12	95.08 ± 4.61
B	13.588	Chlorpyrifos	16.049	3.47	6.51	93.57 ± 3.67	93.78 ± 4.87
	15.472	Cypermethrin	3.2407	4.67	8.57	87.65 ± 6.14	94.06 ± 5.71
	16.228	Bifenthrin	0.0912	4.18	9.14	93.26 ± 5.21	95.37 ± 5.08
	18.509	Tolfenpyrad	1.0241	5.76	8.05	91.06 ± 6.08	93.28 ± 5.28
	20.149	Permethrin	0.0927	3.81	6.72	93.46 ± 4.12	95.08 ± 4.61
C	5.866	Oxamyl	5.0731	7.81	10.11	92.59 ± 3.64	95.03 ± 3.12
	9.317	Dicloran	0.0817	5.04	9.54	89.71 ± 4.05	91.24 ± 3.56
	9.857	Simetryn	2.3045	4.91	8.63	92.61 ± 3.84	93.26 ± 3.81
	10.529	Sulfotep	1.0251	5.06	7.55	88.64 ± 4.05	89.17 ± 4.23
	13.308	Chlorpyrifos	23.087	3.47	6.51	93.57 ± 3.67	93.78 ± 4.87
	15.648	Cypermethrin	2.3408	4.67	8.57	87.65 ± 6.14	94.06 ± 5.71
	20.465	Ethofumesate	0.0981	6.18	9.07	88.43 ± 5.09	90.13 ± 4.64

^*Inter-assay and intra-assay precision results were calculated from the analyzed concentrations of each standard pesticide in fortified laboratory blank water samples