Determination of Sulfonamide Residues in Food by Micellar Liquid Chromatography

Figures & data

FIGURE 1 The basic molecular structure of a surfactant molecule.

FIGURE 2 The normal micelle.

FIGURE 3 Solubilization.

Table 1 Structures of the sulfonamides studied

R		R
	Sulfadiazine		Sulfamerazine
	Sulfaguanidine		Sulfathiazole
	Sulfadimethoxine		Sulfamethazine
	Sulfacetamide

Table 2 Statistical analysis of sulfonamide determination in honey (n = 5)

Sulfonamide	Added	Found	Recovery	R.S.D.	Accuracy
	(μg/g)	(μg/g) (± SD)	(%)	(%)	(%)
DSI
Sulfamerazine	1.25	1.26 ± 0.02	100.8	4.20	0.8
Sulfathiazole	1.25	1.26 ± 0,04	100.8	6.99	0.8
Sulfaguanidine	1.25	1.25 ± 0,08	100.0	3.82	0.0
SPE
Sulfadiazine	0.50	0.50 ± 0,01	100.0	2.83	0.0
Sulfamerazine	0.50	0.50 ± 0,01	100.6	1.90	0.0
Sulfathiazole	0.50	0.51 ± 0,01	102.0	4.23	2.0
Sulfaguanidine	0.50	0.49 ± 0,09	97.0	3.57	2.0
LLE
Sulfamerazine	0.05	0.051 ± 0.002	102.0	2.8	2.0
Sulfathiazole	0.05	0.051 ± 0.006	102.0	3.9	2.0

FIGURE 4 Chromatogram MLC of 14 sulfonamides. The mobile phase: SDS = 0.04 M; pH = 4.6; 2-Pr-OH = 2%; [PO₄] = 0.01 M; T = 40°C; flow rate, 1 mL/min. Peaks: 1. sulfathiocarbamide, 2. sulfaproxyline, 3. sulfachloropyridazine, 4. sulfafurazole, 5. sulfacetamide, 6. sulfadimethoxine, 7. sulfadiazine, 8. sulfisomidine, 9. sulfamerazine, 10. sulfathiazole, 11. sulfamethazine, 12. sulfanilamide, 13. sulfaguanidine, 14. sulfaquinoxaline.

FIGURE 5 MLC (DSI) chromatograms of (a) sample of honey, (b) sample of honey with additionally introduced sulfonamides in the amount 0.25 μg/g; mobile phase: SDS = 0.04 M; pH = 3.5; 2-PrOH = 2%; [PO₄] = 0.01 M; T = 40°C. Peaks: 1. sulfadiazine, 2. sulfamerazine, 3. sulfathiazole, 4. sulfaguanidine.

FIGURE 6 MLC chromatograms of (a) extract of meat without sulfonamides, (b) extract of meat with sulfonamides added in the amount of 0.25 μg/g; mobile phase: SDS = 0.04 M; pH = 2.8; 2-PrOH = 2%; [PO₄] = 0.01 M; T = 40°C. Peaks: 1. sulfadiazine, 2. sulfamethazine, 3. sulfadimethoxine.

Table 3 Statistical analysis of determination of sulfonamides in poultry meat and bovine blood serum (n = 5)

	Added	Found	Recovery	Accuracy	R.S.D.
Meat	(μg/g)	(μg/g) (± SD)	(%)	(%)	(%)
Sulfadiazine	0.500	0.497 ± 0.011	99.4	0.6	4.26
	0.250	0.234 ± 0.004	93.6	6.4	3.67
Sulfamethazine	0.500	0.515 ± 0.014	103.0	−3.0	5.25
	0.250	0.241 ± 0.007	96.4	3.6	6.00
Sulfadimethoxine	0.500	0.487 ± 0.013	97.4	2.6	5.35
	0.250	0.218 ± 0.006	87.2	12.8	5.91
Blood serum	(μg/mL)	(μg/mL) (± SD)	(%)	(%)	(%)
Sulfadiazine	0.500	0.488 ± 0.021	97.7	2.4	6.60
	0.200	0.189 ± 0.003	94.5	5.5	3.74
Sulfamethazine	0.500	0.498 ± 0.021	99.6	0.4	6.28
	0.200	0.186 ± 0.003	93.0	7.0	4.04
Sulfadimethoxine	0.500	0.485 ± 0.089	97.0	3.0	4.12
	0.200	0.184 ± 0.004	92.0	8.7	4.86

Table 4 Statistical analysis of sulfonamide determination in milk (n = 5)

	Added	Found	Recovery	Accuracy	R.S.D.
DSI	(μg/mL)	(μg/mL)	(%)	(%)	(%)
Sulfacetamide	0.10	0.105	105	5	7.1
	0.50	0.51	102	2	6.2
Sulfamethazine	0.10	0.103	103	3	5.5
	0.50	0.51	102	2	4.9
Sulfathiazole	0.10	0.104	104	4	5.3
	0.50	0.51	102	2	4.8
Sulfadimethoxine	0.10	0.105	105	5	4.8
	0.50	0.52	102	4	3.8
SPE	(μg/mL)	(μg/mL)	(%)	(%)	(%)
Sulfacetamide	0.05	0.051	102	2	5.0
	1.00	1.01	104	1	4.3
Sulfamethazine	0.05	0.052	104	4	4.2
	1.00	1.01	101	1	3.9
Sulfathiazole	0.05	0.051	102	2	5.3
	1.00	1.03	103	3	5.5
Sulfadimethoxine	0.05	0.052	104	4	8.0
	1.00	1.03	103	3	6.7
LLE	μg/mL	μg/mL	(%)	(%)	(%)
Sulfacetamide	0.05	0.051	102	2	4.2
	0.50	0.51	102	2	4.0
Sulfamethazine	0.05	0.049	98	−2	3.9
	0.50	0.49	98	−2	4.1
Sulfathiazole	0.05	0.051	102	2	4.8
	0.50	0.50	100	0	4.0
Sulfadimethoxine	0.05	0.052	104	4	3.5
	0.50	0.49	98	−2	2.0

Table 5 Statistical analysis of determination of sulfonamides in eggs (n = 5)

	SPE			LLE
Sulfonamide	1	2	3	4	1	2	3	4
Added	0.05	0.05	0.05	0.05	0.05	0.05	0.05	0.05
(μg/mL)	0.40	0.40	0.40	0.40	1.00	1.00	1.00	1.00
Found	0.049	0.051	0.049	0.048	0.049	0.049	0.051	0.048
(μg/mL)	0.40	0.40	0.40	0.40	1.01	1.01	1.00	1.03
Recovery	98	102	98	96	98	98	102	96
(%)	100	100	100	100	101	101	100	103
R.S.D.	4.2	5.3	5.1	3.4	8.0	5.7	6.6	3.5
(%)	2.9	4.3	3.5	3.1	7.7	4.3	6.5	3.2
Accuracy	−2	2	−2	−4	−2	−2	2	−4
(%)	0	0	0	0	1	1	0	3

FIGURE 7 MLC (DSI) chromatograms of (a) milk without sulfonamides, (b) milk with sulfonamides introduced in the amount of 0.25 μg/g; mobile phase: SDS = 0.04 M; pH = 3.5; 2-PrOH = 2%; [PO₄] = 0.01 M; T = 40°C. Peaks: 1. sulfacetamide, 2. sulfamethazine, 3. sulfathiazole, 4. sulfadimethoxine.

Table 6 Limits of detection (μg/kg)

	Honey	Meat	Serum	Milk	Eggs
DSI	250	—	—	100	—
SPE	250	—	—	50	25
LLE	20	25	25	25	25