Table 4.

Lead results in tomato and lettuce from 16 of the principal markets in Quito, Ecuador.

Market	Zone	TOMATO (Solanum lycopersicum)				LETTUCE (Lactuca sativa)
		Lead content in samples [mg/kg] (dry weight)	Lead content in samples [mg/kg] (fresh weight)	RSD [%]	Relative recovery [%]	Lead content in samples [mg/kg] (dry weight)	Lead content in samples [mg/kg] (fresh weight)	RSD [%]	Relative recovery [%]
1	South	<0.250	<LOQ	--	93.9 %	0.499	0.024	2.3%	87.7 %
2	South	2.327	0.209	0.5%	115.6 %	0.787	0.036	1.3%	105.2 %
3	South	0.544	0.052	1.0%	103.9 %	0.808	0.032	1.7%	116.1 %
4	South	0.810	0.079	0.3%	88.0 %	1.005	0.038	1.5%	118.6 %
5	Central	1.637	0.162	0.2%	116.1 %	1.182	0.060	0.2%	82.3 %
6	Central	0.994	0.091	1.6%	90.6 %	0.996	0.039	1.5%	102.8 %
7	Central	0.472	0.045	2.9 %	95.5 %	0.636	0.024	0.5%	94.3 %
8	Central	<0.250	<LOQ	--	86.1 %	0.254	0.010	2.5%	93.2 %
9	North	ND	ND	--	103.6 %	ND	ND	--	112.6 %
10	North	<0.250	<LOQ	--	87.1 %	<0.250	<LOQ	--	103.8 %
11	North	<0.250	<LOQ	--	102.2 %	<0.250	<LOQ	--	115.5 %
12	North	0.437	0.041	2.7%	103.3 %	<0.250	<LOQ	--	108.4 %
13	Bioferia	1.018	0.110	1.3%	118.0 %	1.077	0.066	1.1%	99.2 %
14	Bioferia	0.938	0.099	0.7%	93.0 %	<0.250	<LOQ	--	118.1 %
15	Bioferia	0.526	0.053	1.3%	94.8 %	0.557	0.029	1.6%	81.3 %
16	Bioferia	ND	ND	--	116.8 %	<0.250	<LOQ	--	113.9 %
Threshold valuesa			0.100				0.300
Acceptance limitsb				16.0 %	75.0–120.0 %			16.0 %	75.0–120.0 %

RSD: Relative standard deviation; <LOQ: lower than the limit of quantification; ND: Not detectable.

^aFAO/WHO. General Standard for Contaminants and Toxins in Food and Feed CXS 193–1995 (Revision 2019).

^bAOAC. Guidelines for Single Laboratory Validation of Chemical Methods for Dietary Supplements and Botanicals.