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Application Note # CA 284781

Screening for Pyrethroid Insecticides in Sediment Samplesby GC/MS/MS

Abstract

A simple screening method for Pyrethroid insecticides in

sediment samples is described. Electron impact ionization

(EI) with tandem MS/MS in combination with programmed

temperature vaporization injection (PTV) were used in order

to obtain excellent specificity and low limits of detection.

IntroductionPyrethroids are synthetic chemical insecticides whose

chemical structures were adapted from the chemical struc-

tures of the pyrethrins. Pyrethroids have been modified to

increase their stability in sunlight. They are toxic to aquatic

organisms at extremely low concentrations, especially to

invertebrates that are at the bottom of the food chain (1).Many of the compounds end up in wastewater outfalls due

to ineffective water treatment. As a result, state and federal

agencies have initiated monitoring programs to characterize

the extent of contamination in water supplies and their

potential impact on aquatic life. In general, there are no set

requirements for minimum detection or reporting levels.

However, the lowest reporting level that can be achieved by

a given technique is desired.

The Scion TQ triple quadrupole mass spectrometer in EI

mode with PTV injection is ideal for screening sediment

extracts at low to sub-part-per-billion concentrations.

Experimental

451-GC Gas Chromatographic Conditions

Column: BR-5ms, 30 m x 0.25 mm x 0.25 um

Carrier: He 1.0 mL/min

Injector:PTV with 3.4 mm ID Siltek FrittedLiner, 8 uL injection

Injector Conditions:60 C hold 0.4 min to 310 C at200 C/min, hold 30 min

Column TemperatureProgram:

55 C, hold 3 min, ramp to 200 at40 C/min, hold 1 min; ramp to

310 C at 5 C/min, hold 1 min.

Scion TQ MS Conditions

Ion SourceTemperature: 250 C

TransferlineTemperature: 280 C

Filament Delay time: 12 min

Filament EmissionCurrent: 80 uA

Dwell Time: 100 ms each transition


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Calibration standards in hexane were prepared at 0.1, 1, 5, 10, 25, 50, 100, and 200 ppb. In addition, a

blank sediment matrix was spiked at concentrations of 0.5, 5, 10, 25, 50, 100, and 200 ppb.

Compound Name RT (min) RT Window Precursor Product Collision Energy

Lambda Cyhalothrin_Ep1+2 19.150 1.000 208 181 -10

19.150 1.000 181 152 -20

Fenvalerate+Esfenvalerate 24.230 1.000 167 125 -15

24.230 1.000 225 91 -25

24.230 1.000 225 119 -10

Bifenthrin 17.560 0.500 181 165 -18

17.560 0.500 181 166 -10

17.560 0.500 181 115 -40

trans+cis-Permethrin 20.880 1.000 183 168 -18

20.880 1.000 183 128 -20

20.880 1.000 183 152 -20

Cypermethrin-Isomers 22.580 1.200 181 152 -20

22.580 1.200 181 127 -30

Cyfluthrin-Isomers 21.980 1.200 226 206 -1521.980 1.200 206 151 -15

Resmethrin_1+2 16.690 1.000 171 128 -12

16.690 1.000 171 143 -12

Fenpropathrin 17.860 0.500 265 181 -20

17.860 0.500 265 210 -10

Deltamethrin-1+2 25.200 1.000 253 174 -10

25.200 1.000 253 172 -10

Table 1: MS/MS Parameters for Pyretroids Insecticides

Figure 1: Optimized scan

information for each compound

is downloaded directly from the

factory installed library.

Bifenthrin MRM transitions

are shown here.


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Sample preparation: 5 g copper powder/magnesium sulfate

was added to 20 g wet sediment. The mixture was

extracted with 2 x 75ml 50:50 acetone:hexane using a

shaker at 185 rpm (2 x15 minutes). The extracts were

concentrated to a final volume of 2 mL and cleaned up on

Florisil Sep Pak.

ResultsThe Scion TQ has a unique software feature known as

Compound Based Scanning (CBS) that was used to easily

set up the MRMs required for the analysis. The pyrethroids

were found in the Factory Library within the CBS software,

and were directly downloaded into the scan acquisition

method. (Figure 1). In addition, the data handling table is

automatically created and linked to the scan acquisition

method. This saves time because the operator does not

have to create additional tables and manage changes to the

analytical method.

The use of MS/MS provided excellent sensitivity and

specificity for the analysis. Compounds detected in the

sediment sample spiked at 0.5 ppb are shown in Figure 2.

Calibration curves prepared in pure solvent (hexane) and

in blank sediment extracts were linear indicating no matrix

interference from the sediment extract. An example

calibration curve is shown in Figure 3.

Conclusion

PTV injection combined with the sensitivity and specificity

of MS/MS result in excellent low-level screening of

pyrethroids in river and lake sediments.

The Scion TQ with Compound Based Scanning allows

easy set-up and management of the pyrethroid MRM

parameters. Compound MRM information is loaded directly

into the method by choosing them from a factory or user

created library. It links the mass spectrometer acquisition

table directly with data handling parameters, streamlining

the data process.

Figure 2: MS/MS for Bifenthrin (top), two epimers

of lamda-cyhalothrin (mid), and cyfluthrin isomers

(bottom) in the sediment matrix

Bifenthrin

Cyfluthrin isomers

Lambda-cyhalothrin Epimres 1 and 2


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BrukerDaltonicsiscontinuallyimprovingitsproductsandreservestheright

tochangespe

cificationswithoutnotice.

BrukerDaltonics02-2012

,##284781

Bruker Daltonik GmbH

Bremen Germany

Phone +49 (0)421-2205-0

Fax +49 (0)421-2205-103

[email protected]

Bruker Daltonics Inc.

Billerica, MA USA Fremont, CA USA

Phone +1 (978) 663-3660 Phone +1 (510) 683-4300

Fax +1 (978) 667-5993 Fax +1 (510) 490-6586

[email protected] [email protected]

www.bruker.com/ms

For research use only. Not for use in diagnostic procedures.

AcknowledgementsCalifornia Department of Food and Agriculture

References1 http://www.beyondpesticides.org/pesticides/factsheets/Synthetic%20Pyrethroids.pdf

Author:Ed George

Keywords

Scion TQ

GC/MS/MS

Sediment SamplesEnvironmental Testing

Instrumentation & Software

Scion TQ

451-GC

436-GC8400 A/S

Figure 3: Calibration curves for Bifenthrin prepared in hexane from

0.1 to 200 ppb (plot at left) and those prepared in a spiked sediment

extract (plot at right) calibrated from 0.5 ppb to 200 ppb.

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