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Method Abstract
for Post-column Liquid Chromatography 112
Expanded HPLC Method for
N-Methyl Carbamates
Post-column Analysis of Pesticides
in Food and Potable Water Samples
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Carbamate pesticides are
widely used around the world to protect crops. In
addition, they are used as biocides for industrial
or other applications and in household products.
Though carbamates are biodegradable compounds and
bioaccumulation usually happens only to a low
extend it is important to monitor produce to make
sure enough time has elapsed between harvest and
applying pesticides. Also, because of their high
solubility, carbamates can leach into ground
waters in porous soils and consequently find their
way into drinking water supplies.
As part of FDA’s pesticide
monitoring program individual lots of domestic and
imported foods and feeds are sampled and tested
for pesticide residues to enforce the tolerances
set by EPA. There are 11 compounds mandated by
USEPA Method 531.2 for drinking water but they
represent only a fraction of the carbamates that
require monitoring in domestic and imported
products. Methyl carbamates are separated using a
reversedphase column and then readily react with
o-phthalaldehyde and a mercaptan after hydrolysis
to form highly fluorescence compounds. This
post-column reaction is the basis for official EPA
Method 531.2 and AOAC Method 985.23.
This new expanded method is
suitable for detecting a wide range of carbamates;
post-column derivatization with fluorescence
detection is a sensitive and selective method for
residue analysis in water, food and feed samples.
This method employs the same HPLC and post-column
equipment and chemicals as USEPA Method 531.2 and
will allow laboratories to increase the range of
tested compounds.
ACKNOWLEDGEMENTS:
Pickering Laboratories would like to thank John
Casanova and Frank Schenck (FDA) for their help
with this project.
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COLUMN: |
Expanded resolution
C8 analytical column 4x250 mm,
P/N 0840250 Guard column P/N 18ECG001 |
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FLOW RATE: |
0.8 mL/min |
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COLUMN TEMPERATURE: |
45° C |
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MOBILE PHASE: |
Water/Methanol |
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POST-COLUMN SYSTEM: |
Pinnacle PCX or
Vector PCX |
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REACTOR VOLUME: |
0.5 mL |
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REACTOR TEMPERATURE: |
100° C |
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REAGENT 1: |
CB130 |
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REAGENT 2: |
100 mg of OPA and 2 g
of Thiofluor in 950 mL of CB910 Diluent |
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REAGENTS FLOW RATE: |
0.3 mL/min |
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DETECTION: |
Fluorescence detector
λEX = 330
nm
λEM = 465 nm |
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HPLC GRADIENT:
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0
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85
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15
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2
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85
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15
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42
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30
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70
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46
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30
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70
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46.1
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0
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100
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50
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0
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100
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EQUILIBRATION: |
10 min |
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Separation of the carbamates standard mixtures
provided by FDA.
| 1 |
Aldicarb
sulfoxide (Standak) |
13 |
3-Hydroxycarbofuran |
25 |
Banol |
| 2 |
Butoxycarboxim |
14 |
Butocarboxim |
26 |
Isoprocarb (MIPC) |
| 3 |
Aldicarb
sulfone |
15 |
Aldicarb |
27 |
2,3,5-Trimethacarb |
| 4 |
Oxamyl) |
16 |
Metolcarb |
28 |
3,4,5-Trimethacarb |
| 5 |
Methomyl |
17 |
Cloethacarb |
29 |
Fenobucarb (BPMC) |
| 6 |
Ethiofencarb sulfone |
18 |
Bendiocarb |
30 |
Methiocarb |
| 7 |
Ethidimuron |
19 |
Carbetamide |
31 |
BDMC |
| 8 |
Thiofanox sulfoxide |
12 |
Propoxur |
32 |
Bufencarb |
| 9 |
Thiofanox sulfone |
21 |
Carbofuran |
33 |
Promecarb |
| 10 |
Formetanate HCl |
22 |
Carbaryl |
34 |
Zectran |
| 11 |
Ethiofencarb sulfoxide |
23 |
Ethiofencarb |
35 |
Aminocarb |
| 12 |
Dioxacarb |
24 |
Thiofanox |
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