Three Different Spectrophotometric Methods for Simultaneous Determination of Pyriproxyfen and Chlorothalonil Residues in Cucumber and Cabbage Samples

Table 2

The accuracy of the proposed methods for simultaneous determination of pyriproxyfen and chlorothalonil in a binary mixture.

Compound	Methods of analysis	Concentration (μg·mL^−1)	Recovery (%)	RSD (%)
Pyriproxyfen	Zero-crossing technique at ^1D281.80 nm	1.0	95.69	4.18
		20.0	102.97	1.38
		30.0	99.28	1.26
	Peak-to-baseline technique at ^2D281.40 nm	1.0	97.95	4.86
		20.0	101.12	1.91
		30.0	100.86	1.40
	Zero-crossing technique at ^2D285.60 nm	1.0	95.34	4.45
		20.0	102.09	1.68
		30.0	101.76	0.83
	Ratio spectra derivative ^1DD272 nm	1.0	95.10	4.05
		20.0	101.99	2.32
		30.0	101.05	0.63
	Ratio spectra derivative ^1DD286 nm	1.0	95.26	3.92
		20.0	101.60	1.07
		30.0	99.60	0.77
	Mean centering of ratio spectra at 278 nm	1.0	95.24	4.51
		20.0	102.39	2.08
		30.0	100.41	1.48
Chlorothalonil	Peak-to-baseline technique at ^1D329.20 nm	0.5	104.30	3.33
		4.0	101.01	1.33
		7.0	100.96	1.10
	Zero-crossing technique at ^2D262.60 nm	0.5	104.08	3.99
		4.0	102.18	2.37
		7.0	102.13	1.89
	Zero-crossing technique at ^2D266 nm	0.5	104.60	4.54
		4.0	102.42	2.32
		7.0	101.82	1.32
	Ratio spectra derivative ^1DD228 nm	0.5	101.23	4.56
		4.0	100.92	2.36
		7.0	99.65	1.32
	Ratio spectra derivative ^1DD262 nm	0.5	103.12	3.75
		4.0	100.65	1.93
		7.0	98.58	1.4
	Mean centering of ratio spectra at 254 nm	0.5	104.58	4.22
		4.0	100.77	1.44
		7.0	100.64	1.22