Reduction of methomyl and acetamiprid residues from tomatoes after various household washing solutions

Figures & data

Table 1. Washing solutions in study groups.

Group	Washing solutions	Groups	Washing solutions
1	Distilled water (25°C)	10	Acetic acid (5%) + Sodium chloride (5%)
2	Distilled water (40°C)	11	Sodium chloride (5%) + Sodium bicarbonate (5%)
3	Acetic acid (C2H4O2) (5%)	12	Lemon juice (5%) + Sodium chloride (5%)
4	Sodium chloride (NaCl) (5%)	13	Acetic acid (5%) + Sodium chloride (5%) + Sodium bicarbonate (5%)
5	Ethanol (C2H6O) (5%)	14	Lemon juice (5%)
6	Sodium bicarbonate (NaHCO3) (5%)	15	Mineral water
7	Hydrogen peroxide (H2O2) (3%)	16	Zam-zam water
8	Sodium hypochlorite (NaClO) (5%)	17	Whey
9	Liquid soap (1%)	18	Milk

Table 2. LC-MS/MS analysis condition.

LC-MS/MS	LCMS-8030 Triple Quadrupole Series
Column	Inertsil ODS-4 2.1 mm x 50mm, 3µm
Ionization techniques	ESI
Column oven temperature	limit 40 °C, max 85 °C
Polarity	+
Injection volume	10 µL
Injection rate	0.5 mL/min
Starting Mobile Phase B	5.0%
Nebulizing Gas Flow	2 L/min (Nitrogen)
Drying gas	12 L/min (Nitrogen)
Desolvation Line Temperature	250°C
Ion source voltage	4500 V
Injection block temperature	250ºC
Heat block temperature	400ºC
Pressure limit (pump A, pump B)	Max 3000 Bar, Min 0 Bar
Pump mode	Binary gradient
LC Stop time	8 min

Table 3. Gradient Conditions.

Time	Concentration
0 min	Pump B: 5.0%
3 min	Pump B: 95.0%
5 min	Pump B: 95.0%
5.1 min	Pump B: 5.0%
8 min	Control post

Table 4. Pesticide residues in tomato samples in each group.

Groups	Washing solutions	Methomyl (mg/kg)	Acetamiprid (mg/kg)
Control	(No washing)	4.776 ± 0.805	0.503 ± 0.137
1	dH2O (25°C)	3.389 ± 0.568 ^a	0.304 ± 0.019 ^a
2	dH2O (40°C)	3.160 ± 0.438 ^a	0.294 ± 0.009 ^a
3	C2H4O2 (5%)	2.000 ± 0.131^b,d,f	0.143 ± 0.035 ^b,d
4	NaCl (5%)	2.428 ± 0.280 ^b	0.265 ± 0.050 ^b
5	C2H6O (5%)	1.944 ± 0.798^b,d	0.184 ± 0.085 ^b
6	NaHCO3 (5%)	2.184 ± 0.585^b,c	0.158 ±0.043^b,c
7	H2O2 (3%)	2.421 ± 0.827 ^b	0.192 ± 0.086 ^b
8	NaClO (5%)	1.547 ± 0.447^b,e,g	0.096 ± 0.033^b,e,g,i
9	Liquid soap (1%)	2.184 ± 0.302^b,c	0.177 ± 0.057 ^b
10	C2H4O2+ NaCl (5%)	1.634 ± 0.159^b,e,g	0.029 ± 0.009 ^b,e,h,j,k,l,m
11	NaCl + NaHCO3 (5%)	2.316 ± 0.272 ^b	0.058 ± 0.021^b,e,g,i
12	Lemon juice + NaCl (5%)	2.651 ± 0.184^b,u	0.089 ± 0.018 ^b,e,g,i
13	C2H4O2+ NaCl + NaHCO3 (5%)	1.616 ± 0.269^b,e,g	0.068 ± 0.012^b,e,g,i
14	Lemon juice (5%)	2.041 ± 0.195^b,d	0.166 ± 0.043 ^b,c
15	Mineral water	2.653 ± 0.341^b,u	0.159 ± 0.041^b,c
16	Zam-zam water	1.755 ± 0.139^b,d,g	0.232 ± 0.072^b,n,o,p,r
17	Whey	1.333 ± 0.289^b,e,h.	0.093 ±0.021 ^b,e,g,i,s
18	Milk	1.767 ± 0.524^b,d,g	0.065 ± 0.046 ^b,e,g,i,t

^a: p<0.01 with respect to control; ^b: p<0.001 with respect to control; ^c: p<0.05 with respect to group 1; ^d: p<0.01 with respect to group 1; ^e: p<0.001 with respect to group 1; ^f: p<0.05 with respect to group 2; ^g: p<0.01 with respect to group 2; ^h: p<0.001 with respect to group 2; ⁱ: p<0.01 with respect to group 4; ^j: p<0.001 with respect to group 4; ^k: p<0.05 with respect to group 5; ^l: p<0.01 with respect to group 7; ^m: p<0.05 with respect to group 9; ⁿ: p<0.001 with respect to group 10; °: p<0.01 with respect to group 11; ^p: p<0.05 with respect to group 12; ^r: p<0.01 with respect to group 13; ^s: p<0.05 with respect to group 16; ^t: p<0.01 with respect to group 16; ^u: p<0.05 with respect to group 17.

Figure 1. Total ion chromatogram of pesticide standards for methomyl (a) and acetamiprid (b).

Figure 2. Percentage of detected average methomyl residues after 18 different washing processes in tomato samples.

Figure 3. Percentage of detected average acetamiprid residues after 18 different washing processes in tomato samples.