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Method Abstract
for Post-column Liquid Chromatography 108
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There are a number of
carbamate pesticide compounds employed worldwide
which are not included in the 10 compounds
mandated by USEPA Method 531.1 and AOAC Protocol
29.A05. This Application Note describes methods
for separating as many as 23 compounds, using a
Pickering C8, 5µm silica, column with either
Water/Acetonitrile or Water/Methanol gradients.
Instruments, post-column derivatization and
detection protocols, and reagents remain
unchanged, as described Pickering’s brochure,
Post-Column LC Systems for Environmental Pesticide
Analysis (B-CA5) and User’s Manual 0101-0002.
Although there are only two co-elutions in each of
the solvent gradient protocols, the compounds were
assigned to two separate test mixtures, A and B,
in order to demonstrate the full range of
separation. The differences in selectivity between
the Acetonitrile and Methanol protocols enable the
user to employ both solvent systems as a means of
confirming peak identification. The following
comparison of Acetonitrile to Methanol might be
helpful in choosing which solvent system will be
for used routinely, and which will be for
confirmation:
• Acetonitrile generally exhibits higher
sensitivity and baseline noise.
• It also costs more and its disposal is more
restricted.
Eleven of the most widely
occurring carbamate compounds and BDMC (internal
standard) are supplied by Pickering Laboratories
in its qualitative test mixtures, Cat. No.
1700-0063. These are designated by * in the test
mixture tables below. Other compounds may be
purchased from suppliers of environmental
standards. A few may vary considerably in
homogeneity and availability.
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| 1 |
Aldicarb
sulfoxide (Standak) |
9 |
Carbaryl
(Sevin) |
17 |
Ethiofencarb |
| 2 |
Aldicarb
sulfone |
10 |
Methiocarb (Mesurol) |
18 |
Thiofanox Sulfoxide |
| 3 |
Oxamyl (Vydate) |
11 |
BDMC
internal standard |
19 |
Thiofanox Sulfone |
| 4 |
Methomyl
(Lannate) |
12 |
Butocarboxim sulfoxide |
20 |
Methiocarb sulfoxide |
| 5 |
3-Hydroxy carbofuran |
13 |
Butocarboxim sulfone |
21 |
Methiocarb sulfone |
| 6 |
Aldicarb
(Temik) |
14 |
Ethiofencarb sulfoxide |
22 |
3-Ketocarbofuran |
| 7 |
Propoxur
(Baygon) |
15 |
Ethiofencarb sulfone |
23 |
Thiofanox |
| 8 |
Carbofuran (Furadan) |
16 |
Butocarboxim |
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COLUMN: |
4.0 x 250 mm,
Pickering Cat. No.
0840250 |
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SAMPLE INJECTION: |
10 µl in MeOH (for
all chromatograms shown) |
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MOBILE PHASE: |
Solvent A: HPLC-grade Water
Solvent B: HPLC-grade Acetonitrile (MeCN) |
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PROGRAM: |
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0
|
90
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10
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|
|
2
|
90
|
10
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isocratic
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|
46
|
49
|
51
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linear
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46.1
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30
|
70
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step
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|
49
|
30
|
70
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isocratic
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EQUILIBRATION TIME: |
13 minutes |
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ELUANT FLOW RATE: |
0.80 mL/minute |
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COLUMN TEMPERATURE: |
37 °C |
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REAGENT 1: |
0.3 mL/minute, CB130
Hydrolysis Reagent |
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REAGENT 2: |
0.3 mL/minute, OPA
reagent1 for derivatization |
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REACTORS: |
Hydrolysis: 100 °C,
500 µL
Derivatization: Ambient, 100 µL |
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FLOURESCENCE
DETECTION:: |
Excitation: 330 nm
Emission: 465 nm |
|
|
|
|
| 1 |
Aldicarb
sulfoxide (Standak) |
9 |
Carbaryl
(Sevin) |
17 |
Ethiofencarb |
| 2 |
Aldicarb
sulfone |
10 |
Methiocarb (Mesurol) |
18 |
Thiofanox Sulfoxide |
| 3 |
Oxamyl (Vydate) |
11 |
BDMC
internal standard |
19 |
Thiofanox Sulfone |
| 4 |
Methomyl
(Lannate) |
12 |
Butocarboxim sulfoxide |
20 |
Methiocarb sulfoxide |
| 5 |
3-Hydroxy carbofuran |
13 |
Butocarboxim sulfone |
21 |
Methiocarb sulfone |
| 6 |
Aldicarb
(Temik) |
14 |
Ethiofencarb sulfoxide |
22 |
3-Ketocarbofuran |
| 7 |
Propoxur
(Baygon) |
15 |
Ethiofencarb sulfone |
23 |
Thiofanox |
| 8 |
Carbofuran (Furadan) |
16 |
Butocarboxim |
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MOBILE PHASE: |
Solvent A: HPLC-grade Water
Solvent B: HPLC-grade Acetonitrile (MeOH) |
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PROGRAM: |
|
0
|
88
|
12
|
|
|
2
|
88
|
12
|
isocratic
|
|
42
|
34
|
66
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linear
|
|
46
|
34
|
66
|
isocratic |
|
46.1
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0
|
100
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step
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|
49
|
0
|
100
|
isocratic
|
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___________________
1 o-Phthalaldehyde (O120) and
Thioflour™ (3700-2000), Pickering’s brand of
Dimethylaminoethanethiol•HCI, in OPA Diluent
(CB910)
REFERENCE:
R.T. Krause, J. Chromatography, 185,
615-624 (1979)
R.T.
J. Chromatographic Science, 16, 281-288
(1978)
H.A.
Moye, S.J. Scherer and P.A. St. John, Anal.
Letters, 10, 1049-1073 (1977)
A. de
Kok and M. Hiemstra, J. AOAC int’l, 75,
1063-1072 (1992)
Official Methods of Analysis, 15th Ed., AOAC
Int’l, Arlington, VA, (291-293)
Method 531.1, U.S. Environmental Protection Agency
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