environmental
Applications
note
RestekCorporation • (800)356-1688 •
#59142
environmental
CarboPrep™ SPE Cleanup of Method 8141A Organophosphorous
Pesticides and Herbicides
Organophosphorus pesticides (OPP) are widely applied in
agriculture and home use. With the decline of organochlo-
rine pesticides, OPPs have become the most widely used
class of insecticides in the US.
1
Analysis of OPPs requires
protection of prepared samples from thermal- and photo-
degradation and special detectors. In addition, the US EPA
does not recommend GPC or Florisil
®
cleanup techniques for
solvent-extracted samples. This makes gas chromatography
(GC) analysis of low-level, complex matrices even more
difficult. This Applications Note shows how CarboPrep
™
90
solid phase extraction (SPE) cartridges may be useful as an
alternative in the cleanup of sample extracts containing OPP.
Using Rtx
®
-CLPesticides columns also will help to improve
GC analysis of these insecticides.
CarboPrep
™
SPE cartridges contain a nonporous, chromato-
graphic grade- graphitized carbon that is optimized for
cleanup of environmental sample extracts. Graphitized
carbon packings also have been effective in the concentra-
tion and extraction of a variety of pesticides in drinking
water samples.
2
The high flow rates that can be used with this
material allow rapid extraction of 1 to 4 liters of aqueous
samples. The cartridges have a low background level,
especially suitable for pesticides. The carbon surface
provides maximum capacity with a minimum bed weight,
reducing the volume of solvent used during extraction.
Studies using spiked solvent samples show that CarboPrep
™
90 SPE cartridges may be useful as an alternative in the
cleanup of OPP insecticides before nitrogen phosphorus
detection (NPD) or flame photometric detection (FPD)
analysis. Previous studies at Restek have shown excellent
performance in the recovery of organochlorine pesticides in
sample extracts.
3
The same SPE cartridge and preparation
method were used to extract the OPPs as in the previous
studies (see procedure outlined in Figure 1).
Repetitive extracts show that 80% of the compounds tested
exhibited greater than 80% recovery (Table 1). The average
recovery range (n=5) was 42% for monocrotophos to 109%
for merphos. CarboPrep
™
90 SPE cartridges also were shown
to remove sample matrix interferences such as hydrocarbons
and humic substances that cause chromatographic interfer-
ence peaks and leave nonvolatile organic residue in the
injection port. For fast, quantitative recovery of OPP
compounds, CarboPrep
™
90 SPE cartridges offer a better
alternative than GPC or Florisil
®
SPE.
References:
1. “Recognition and Management of Pesticides Poisonings”.
/
oppfead1/safety/healthcare/handbook/handbook.htm, p.34
2. “Development of aMultiresidueMethod forAnalyzing PesticideTraces inWater,”
C.Crescenzi,A.DiCorcia ,E.Guerriero,R.Samperi,ES&T, 1997,31479-488.
3. “CarboPrep
™
SPECleanup ofMethod 8081AChlorinated Pesticides” Restek
Application Note #59110.
Table I
Recovery of OPP from Solvent Extracts Using
CarboPrep
™
90 SPE Cartridges
Analyte
% recovery
avg. n=5
RSD
dichlorvos
91.6
5.8
mevinphos
90.7
8.9
ethoprop
103.1
8.7
phorate
101.7
10.2
naled
103.1
9.0
tributylphosphate (surrogate)
106.8
8.9
demeton-o
101.3
9.9
diazinon, demeton-s (coelution)
104.2
9.8
disulfoton
105.5
10.9
ronnel
101.9
10.1
merphos
109.3
8.9
chlorpyrifos
96.1
0.7
fenthion
103.6
9.8
parathion-methyl
103.1
10.1
trichloronate
101.6
14.7
tokuthion
98.8
11.1
stirofos
101.2
9.3
bolstar
98.1
7.9
fensulfothion
78.9
11.2
triphenylphosphate (surrogate)
92.9
9.1
azinphos-methyl
86.6
7.4
coumaphos
83.1
10.2
trichlorfon
55.0
12.9
thionazin
90.0
8.4
fonophos
94.6
8.1
dicrotophos
76.0
10.7
dichlorofenthion
95.3
9.1
chlorpyrifos methyl
101.8
9.9
aspon
91.9
7.9
fenitrothion
81.5
22.6
crotoxyphos
92.8
7.9
avg. n=4
RSD
TEPP, sulfotepp (coelution)
84.7
0.4
dimethoate
82.3
17.4
monocrotophos
42.4
21.7
malathion
81.8
14.7
parathion-ethyl
80.3
13.9
EPN
64.4
14.7
terbufos
93.8
9.6
dioxathion
59.3
8.4
phosphamidon
68.7
10.0
chlorfenvinphos
80.4
10.5
carbophenothion
78.8
8.2
ethion
80.5
10.5
leptophos
91.3
1.7
famphur
78.5
7.1
phosmet
83.0
6.7
azinphos-ethyl
83.0
9.3
