Supercritical Fluid Extraction of Residual Pesticides in Spinach

By Kenichi Akao

Introduction

Supercritical Fluid Extraction of Residual Pesticides

The extraction of residual pesticides in foods has been typically been performed by solvent extraction . This method, however, takes approx. 4 – 5 hours per extraction, and requires large quantities of organic solvent. In recent years, supercritical fluid extraction (SFE) using supercritical carbon dioxide has attracted much attention as an alternative method to the solvent extraction method.

JASCO has developed a fully automated residual pesticide extraction system, and applied this system to the analysis of a spinach sample. Extracted components were analyzed by GC-MS/MS.

Experimental

The fully automated residual pesticide extraction system was used for this application. A schematic of the system is shown in Figure 1.

Figure 1. Schematic of a fully automated system for supercritical fluid extraction of residual pesticides
System configuration: 1 = carbon dioxide cylinder, 2 = liquefied carbon dioxide delivery pump, 3 = modifier, 4 = modifier delivery pump, 5 = preheating coil, 6 = solvent for trap elution, 7 = rinse solution for trap column, 8 = solvent delivery pump, 9 = switching valve for flow line, 10 = oven, 11 = extraction vessels, 12 = 6-vessel changer, 13 = release valve, 14 = automatic back pressure regulator, 15 = trap column, 16 = 3-way valve, 17 = 6-way flow line switching valve, 18 = collection tubes, 19 = system controller. Supercritical CO2 delivered by pump 2 passes through one of vessels 11 in which the sample is loaded and then pesticides are extracted. The extracted pesticides are concentrated by a trap column, is eluted by acetonitrile (2 mL) delivered by pump 8, and is collected in one of collection tubes 18. This system is automatically controlled by 19, system controller.

Supercritical fluid extraction conditions:

extraction tube : 10 mL (10 mm x 127 mm), supercritical fluid : CO2, back pressure = 15 MPa, extraction time : 30 min, flow rate : 2mL/min, trap column : ODS (4.6 mm x 50 mm, 30 µm), solvent for trap elution : acetonitrile 2 mL (flow rate : 2mL/min).

As an analytical sample, spinach was selected. Sixty-eight kinds of pesticides were added to the spinach to be a concentration of 0.1 ppm for each pesticide except captan, 1 ppm and acetamiprid, 0.5 ppm. Two grams of the spinach and 2 g of Hydromatrix (a dehydrating agent) were loaded in each extraction vessel; SFE was applied at an extraction pressure of 15 MPa, at an extraction temperature of 40°C, for an extraction time of 30 min; the extracted components were adsorbed on a trap column; the trapped components were eluted with acetonitrile; the acetonitrile solution was evaporated to dryness with nitrogen gas; and the residue was dissolved in 3 mL of acetone containing 0.05% of PEG200 and PEG400. A portion of this solution was injected onto the GC.

Keywords

residual pesticides, , SFE, supercritical fluid extractions

Results

Chromatograms of the standard mixture (upper), the sample added with the standard (middle), and the blank (lower) are shown in Figure 2.

Figure 2. GC chromatograms of wheat flour sample
Upper : standard mixture (68 components)
Middle : sample added with standard mixture
Lower : blank Measurement conditions

Standard mixture solution contains 68 components as below:
1: Acephate, 2: Acetamiprid, 3: Bendiocarb, 4: Bitertanol, 5: Butylate, 6: Captan, 7: Carbaryl 8: Chinomethionat, 9: Chlorfenvinphos, 10: Chlorpyriphos, 11: Cyfluthrin, 12: Cypermethrin, 13: Deltamethrin, 14: Diazinon, 15: Dichlofluanid, 16: Dichlorvos, 17: Diethofencarb, 18: Dimethylvinphos, 19: EPN, 20: Esprocarb, 21: Ethiofencarb, 22: Ethoprophos, 23: Fenarimol, 24: Fenitrothin, 25: Fenobucarb, 26: Fensulfothion, 27: Fenvalerate, 28: Flucythrinate, 29: Flusilazole, 30: Flutolanil, 31: Fluvalinate, 32: Imibenconazole, 33: Iprodione, 34: Isofenphos , 35: Isofenphos P=O, 36: Isoprocarb, 37: Lenacil, 38: Malathion, 39: Mefenacet, 40: Mepronil, 41: Methamidophos, 42: Metolaclior, 43: p,p’-DDE, 44: Paclobutrazol, 45: Pencycuron, 46: Pendimethalin, 47: Permethalin, 48: Phenthoate, 49: Phosalone, 50: Pirimifos-methyl, 51: p,p’-DDD, 52: Pretilachlor, 53: Propiconazole, 54: Pyraclofos, 55: Pyridaben, 56: Pyridaphenthion, 57: Pyrimidifen, 58: Quinalphos, 59: Tefluthrin, 60: Terbucarb, 61: Terbufos, 62: Thenylchlor, 63: Tolclofos-methyl, 64: Triadimenol, 65: a-BHC, 66: ß-BHC, 67: ?-BHC, 68: d-BHC.

As shown in Table 1, among the 68 pesticides, 47 exhibited more than 70% recovery, and 61 more than 50% recovery. The recovery of acetamiprid and butylate was 20% and 45%, respectively. Acephate, captan, dichlofluanid, and methamidophos exhibited less than 10% recovery; their high hydrophilicity and adsorption on the dehydrating agent seemed to be responsible for a poor recovery in SFE.

No.	Pesticide	Recovery (%)	No.	Pesticide	Recovery (%)
1	Acephate	9.2	35	Isofenphos P=O	98.0
2	Acetamiprid	19.8	36	Isoprocarb	89.1
3	Bendiocarb	113.0	37	Lenacil	79.9
4	Bitertanol	64.0	38	Malathion	91.8
5	Butylate	45.1	39	Mefenacet	87.4
6	Captan	3.8	40	Mepronil	75.7
7	Carbaryl	130.5	41	Methamidophos	4.7
8	Chinomethionat	97.0	42	Metolachlor	97.7
9	Chlorfenvinphos	76.1	43	p,p'-DDE	71.7
10	Chlorpyriphos	84.0	44	Paclobutrazol	111.6
11	Cyfluthrin	59.1	45	Pencycuron	59.9
12	Cypermethrin	86.7	46	Pendimethalin	95.6
13	Deltamethrin	57.8	47	Permethalin	57.3
14	Diazinon	78.6	48	Phenthoate	77.0
15	Dichlofluanid	2.9	49	Phosalone	73.5
16	Dichlorvos	60.1	50	Pirimifos-methyl	90.2
17	Diethofencarb	101.5	51	p,p'-DDD	81.8
18	Dimethylvinphos	90.9	52	Pretilachlor	88.9
19	EPN	75.0	53	Propiconazole	76.1
20	Esprocarb	79.1	54	Pyraclofos	76.6
21	Ethiofencarb	44.1	55	Pyridaben	68.6
22	Ethoprophos	95.2	56	Pyridaphenthion	92.4
23	Fenarimol	73.0	57	Pyrimidifen	77.0
24	Fenitrothion	107.8	58	Quinalphos	82.9
25	Fenobucarb	89.0	59	Tefluthrin	64.5
26	Fensulfothion	101.6	60	Terbucarb	89.3
27	Fenvalerate	64.5	61	Terbufos	52.2
28	Flucythrinate	56.9	62	Thenylchlor	96.4
29	Flusilazole	86.5	62	Tolclofos-methyl	83.5
30	Flutolanil	92.1	64	Triadimenol	93.4
31	Fluvalinate	50.7	65	a-BHC	92.0
32	Imibenconazole	63.2	66	ß-BHC	92.7
33	Iprodione	105.4	67	Y-BHC	88.1
34	Isofenphos	57.1	68	d-BHC	106.4

This document has been prepared based on information available at the time of publication and is subject to revision without notice. Although the contents are checked with the utmost care, we do not guarantee their accuracy or completeness. JASCO Corporation assumes no responsibility or liability for any loss or damage incurred as a result of the use of any information contained in this document. Copyright and other intellectual property rights in this document remain the property of JASCO Corporation. Please do not attempt to copy, modify, redistribute, or sell etc. in whole or in part without prior written permission.

About the Author

Mr. Akao, is the Applications Group Manager at JASCO Corporation, with many years at the company working on applications in electronic and vibrational spectroscopy, and is an expert in IR and Raman spectroscopy.

Introduction

Supercritical Fluid Extraction of Residual Pesticides

JASCO has developed a fully automated residual pesticide extraction system, and applied this system to the analysis of a spinach sample. Extracted components were analyzed by GC-MS/MS.

Experimental

The fully automated residual pesticide extraction system was used for this application. A schematic of the system is shown in Figure 1.

Supercritical fluid extraction conditions:

Keywords

residual pesticides, , SFE, supercritical fluid extractions

Results

Chromatograms of the standard mixture (upper), the sample added with the standard (middle), and the blank (lower) are shown in Figure 2.

No.	Pesticide	Recovery (%)	No.	Pesticide	Recovery (%)
1	Acephate	9.2	35	Isofenphos P=O	98.0
2	Acetamiprid	19.8	36	Isoprocarb	89.1
3	Bendiocarb	113.0	37	Lenacil	79.9
4	Bitertanol	64.0	38	Malathion	91.8
5	Butylate	45.1	39	Mefenacet	87.4
6	Captan	3.8	40	Mepronil	75.7
7	Carbaryl	130.5	41	Methamidophos	4.7
8	Chinomethionat	97.0	42	Metolachlor	97.7
9	Chlorfenvinphos	76.1	43	p,p'-DDE	71.7
10	Chlorpyriphos	84.0	44	Paclobutrazol	111.6
11	Cyfluthrin	59.1	45	Pencycuron	59.9
12	Cypermethrin	86.7	46	Pendimethalin	95.6
13	Deltamethrin	57.8	47	Permethalin	57.3
14	Diazinon	78.6	48	Phenthoate	77.0
15	Dichlofluanid	2.9	49	Phosalone	73.5
16	Dichlorvos	60.1	50	Pirimifos-methyl	90.2
17	Diethofencarb	101.5	51	p,p'-DDD	81.8
18	Dimethylvinphos	90.9	52	Pretilachlor	88.9
19	EPN	75.0	53	Propiconazole	76.1
20	Esprocarb	79.1	54	Pyraclofos	76.6
21	Ethiofencarb	44.1	55	Pyridaben	68.6
22	Ethoprophos	95.2	56	Pyridaphenthion	92.4
23	Fenarimol	73.0	57	Pyrimidifen	77.0
24	Fenitrothion	107.8	58	Quinalphos	82.9
25	Fenobucarb	89.0	59	Tefluthrin	64.5
26	Fensulfothion	101.6	60	Terbucarb	89.3
27	Fenvalerate	64.5	61	Terbufos	52.2
28	Flucythrinate	56.9	62	Thenylchlor	96.4
29	Flusilazole	86.5	62	Tolclofos-methyl	83.5
30	Flutolanil	92.1	64	Triadimenol	93.4
31	Fluvalinate	50.7	65	a-BHC	92.0
32	Imibenconazole	63.2	66	ß-BHC	92.7
33	Iprodione	105.4	67	Y-BHC	88.1
34	Isofenphos	57.1	68	d-BHC	106.4

JASCO

Industry

Technique

Supercritical Fluid Extraction of Residual Pesticides in Spinach

Introduction

Supercritical Fluid Extraction of Residual Pesticides

Experimental

Supercritical fluid extraction conditions:

Keywords

Results

About the Author

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Industry

Technique

Introduction

Supercritical Fluid Extraction of Residual Pesticides

Experimental

Supercritical fluid extraction conditions:

Keywords

Results

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About the Author

Supercritical Fluid Extraction of Residual Pesticides in Spinach

Introduction

Supercritical Fluid Extraction of Residual Pesticides

Experimental

Supercritical fluid extraction conditions:

Keywords

Results