Production of the class-specific antibody and development of direct competitive ELISA for multi-residue detection of organophosphorus pesticides

Figures & data

Figure 1.  Synthetic route of haptens (PB and PC).

Figure 2.  The chemical structure of the generic haptens reported by Piao et al. (2009).

Table 1. Titres of antisera with different combination of immunogen and coating antigen.

	Titration of antibody induced by PB-KLH		Titration of antibody induced by PC-KLH
Coating antigen	Ab-1	Ab-2	Ab-3	Ab-4
PB-OVA	1,300,000	1,100,000	190,000	210,000
PC-OVA	200,000	180,000	1,200,000	1,800,000

Figure 3.  Standard inhibition curves of methyl parathion (PM) by direct competitive ELISA using Ab-1 (diamonds) and Ab-4 (squares).

Table 2. Cross-reactivity (CR) with organophosphate pesticides.

Table 3. Variability of intra- and inter-assay of the ELISA curve for methyl parathion (PM).

	Intra-assay^a		Inter-assay^b
Concentration of PM (mg L^−1)	Mean inhibition (%)±SD	CV (%)	Mean inhibition (%)±SD	CV (%)
20	92.77±0.02	0.02	100.01±12.23	0.34
4	82.18±0.13	0.04	87.77±10.06	4.71
0.8	66.53±0.01	0.07	70.59±8.15	11.5
0.16	32.43±0.04	0.12	41.31±4.04	12.2
0.032	10.14±0.07	0.71	14.83±3.08	24.4
Mean	56.81±0.05	0.20	62.90±7.51	10.63
^aResults were the means at 22 times on the same day.
^bResults were the means at three times on seven different days.

Figure 4.  Standard inhibition curves of methyl parathion (PM) in 0.01 mol L⁻¹ PBS (diamonds) and different matrices by direct competitive ELISA (n=3). Pure water (squares), drinking water (circles) and river water (triangles) were diluted with PBS by 2, 5 and 10 folds with 0.01 mol L⁻¹ PBS, respectively.

Table 4. Recovery studies of methyl parathion (PM) from spiked water samples.

Sample	Spiked level (mg L^−1)	Measured level^a (mg L^−1)	Recovery^a (%)	CV (%)
Drinking water	0.15	0.07±0.00	74.67±4.51	6.03
	0.3	0.25±0.09	83.00±3.28	3.95
	0.45	0.48±0.93	105.93±5.60	5.28
Pure water	0.15	0.10±0.01	95.67±12.50	13.06
	0.3	0.31±0.02	104.67±8.03	7.67
	0.45	0.40±0.01	89.83±1.21	1.35
River water	0.15	25.35±0.81	130.67±3.53	2.69
	0.3	0.21±0.00	70.30±1.39	1.98
	0.45	0.48±0.04	106.77±9.09	8.51
^aResults were the means by three times.