eXtreme|FV® vs SPE for the Analysis of Pesticides in Orange Juice by GC/MS

Uday Sathe1, Karine Aylozyan1, Lisa Wanders2, Joe Machamer2, & Sam Ellis2
1Micro Quality Labs
2Thomson Instrument Company

Abstract

Pesticides act as toxins when found in sufficient quantities as residues in food. This is of particular importance for orange juice because it is consumed in high quantities by children. Sensitive, rapid, and cost effective analytical methods are required in order to reduce the risk to consumers.

Solid Phase Extraction (SPE) is a common sample preparation technique used prior to GC or LC analysis of pesticides in food. Typically, SPE is used to concentrate analytes, reduce interference from co-eluting molecules or to clean up/”filter” sample particulates. Drawbacks to the use of SPE include cost, sample preparation time, large sample volumes, use and disposal of organic solvents, and potentially poor recoveries. The continuing development of higher sensitivity instrumentation and improved filtration devices has led many labs to investigate whether methods can be adapted to eliminate the SPE step.

Thomson eXtreme® Filter Vials offer multi-layer filtration for viscous samples and samples containing up to 30% solid particulates. Filtration time from unfiltered sample transfer to filtered sample in an autosampler ready vial is only 15 seconds. The filter vial consists of two parts: a filter vial shell and a plunger which includes the multi-layer filter on one end and a vial cap on the other end. Samples are filtered by pipetting the sample into the filter vial shell, inserting the plunger into the shell, and then pushing the plunger into the shell.

Prior to the introduction of the eXtreme|FV®s, many samples containing high levels of particulates were only “filtered” by using an SPE step in the method. These methods are readily amendable to the replacement of the SPE step with a much faster and lower cost eXtreme|FV® step.

Experiment

Samples were prepared and analyzed at Micro Quality Labs, Burbank, CA.

Sample Preparation

  1. Spike 10mL of commercially available High Pulp Orange Juice with 1mL of 1 ppm pesticide standard mix in a 40mL vial.
  2. Add one pack (approximately 6g) of Restek Extraction Salts (Restek catalog #26236) to the spiked orange juice.
  3. Extract the spiked orange juice with 4 x 25mL portions of methylene chloride.
  4. Concentrate to dryness using a Turbovap II concentrator.
  5. Dissolve the residue in approximately 10mL of acetonitrile.
  6. Vortex and sonicate the re-suspended residue with frequent swirling.
  7. Split the re-suspended residue into two 5mL portions.
  8. Dilute each 5mL portion with acetonitrile to 10mL using a volumetric flask.
  9. Label one flask “for SPE” and the other “for Thomson eXtreme|FV®”.

SPE Cleanup Prior to Analysis - Restek 6mL Combo SPE Cartridge

  1. Wash one Restek 6mL Combo SPE Cartridge (packed with 200mg CarboPrep 200 and 400mg PSA Restek catalog #26127) with acetonitrile.
  2. Add the 10mL portion of the re-suspended residue from the flask labeled “for SPE” to the SPE cartridge.
  3. Elute the sample from the cartridge with 50mL of acetonitrile.
  4. Concentrate the eluted sample to 10mL using a Turbovap II concentrator.

eXtreme|FV® Cleanup Prior to Analysis

  1. Add 400µL of the re-suspended residue from the flask labeled “for Thomson eXtreme|FV®” to the shell of one Thomson eXtreme|FV® 0.45µm, PTFE (Thomson Part Number 85540-500).
  2. Insert plunger completely.

Analysis

Samples were analyzed utilizing an Agilent Technologies® GC/MS, 7000 Triple Quad system equipped with a 7890A GC system and 7693 auto sampler.

Compound/Sample NameAvg. PPM SPE+ Routine Syringe FilterAvg. PPM eXtreme|FV® PTFE (W/O SPE)
Alachlor0.0430.053
Aldrin0.0250.032
Azinphos-ethyl0.0180.095
Azinphos-methyl0.0230.115
BHC-alpha (benzene hexachloride)0.0260.033
BHC-beta0.0540.073
BHC-delta0.0620.081
BHC-gamma (Lindane, gamma HCH)0.0320.043
Bromophos-ethyl0.0250.057
Bromopropylate0.0630.076
Carbophenothion0.0510.071
Chlordane-cis (alpha)0.040.052
Chlordane-oxy0.0340.042
Chlordane-trans (gamma)0.0390.049
Chlorfenvinphos0.0610.071
Chlorpyrifos0.0350.047
Chlorpyrifos-methyl0.0350.046
Cyfluthrin I0.0820.113
Cyhalothrin (lambda)0.0760.091
Cypermethrin I (Zeta)0.0820.117
Cypermethrin II (CAS # 52315-07-8)0.080.113
Cypermethrin III (Beta)0.0580.104
Cypermethrin IV (CAS # 52315-07-8)0.070.097
DCPA (Dacthal, Chlorthal-dimethyl)0.040.048
DDD-o,p’0.0520.06
DDD-p,p’0.0560.066
DDE-o,p’0.0430.039
DDE-p,p’0.0450.057
DDT-o,p’0.0350.065
DDT-p,p’0.0320.078
Deltamethrin0.0530.102
Diazinon0.0280.035
Dicofol0.0330.028
Dieldrin0.0410.052
Dimethoate0.0610.077
Endosulfan I (alpha isomer)0.0410.076
Endosulfan II (beta isomer)0.0530.065
Endosulfan sulfate0.0610.074
Endrin0.0450.058
Ethion0.0570.069
Etrimfos0.030.038
Fenchlorphos oxon0.0470.061
Fenitrothion0.0410.053
Fenpropathrin0.0680.078
Fensulfothion0.10.117
Fenthion0.0410.05
Fenthion sulfone0.0810.107
Fenthion sulfoxide0.1060.134
Fenvalerate I0.0760.106
Fenvalerate II (CAS # 51630-58-1)0.0550.073
Fluvalinate-tau I0.0780.082
Fluvalinate-tau II (CAS # 102851-06-9)0.0580.084
Fonofos0.0230.028
Heptachlor0.0220.029
Heptachlor endo-epoxide (isomer A)0.0390.048
Heptachlor exo-epoxide (isomer B)0.0370.045
Hexachlorobenzene00.019
Malaoxon (metabolite of Malathion)0.070.086
Malathion0.0440.055
Mecarbam0.0520.062
Methidathion0.0630.08
Methylpentachlorophenyl sulfide0.0010.036
Mirex0.0420.056
Octachlorodipropyl ether (S421)0.0210.047
Omethoate0.0520.061
Paraoxon0.0710.08
Parathion0.0390.049
Parathion-methyl0.0350.045
Pendimethalin0.0380.048
Pentachloroaniline0.0020.049
Pentachloroanisole0.0170.021
Permethrin I0.0680.097
Permethrin II (trans)0.0710.115
Phosalone0.0050.089
Phosmet0.0310.104
Piperonyl butoxide0.1170.105
Pirimiphos-ethyl0.0440.053
Pirimiphos-methyl0.040.05
Procymidone0.0640.082
Profenofos0.0580.071
Prothiofos0.0330.06
Quinalphos0.0420.061
Quintozene0.020.028
Ronnel (Fenchlorphos)0.0310.04
Tecnazene (TCNB)0.0110.014
Tetradifon0.0620.077
Vinclozolin0.0430.052

SPE -vs- eXtreme|FV®
Comparison of spiked pesticide recoveries

OJ pesticides

Conclusions

The Thomson eXtreme 0.45µm, PTFE Filter Vials patented (Part#: 85540-500) yielded 26% higher recoveries on average when tested with 87 common pesticides. In the cases highlighted in the results table, greater than 428% recovery increases were seen. In the case of Hexachlorobenzene, no pesticide was detected in the sample prepared by SPE and 0.019 ppm was detected in the sample prepared with the eXtreme|FV®. The use of Thomson eXtreme 0.45µm, PTFE Filter Vials as a substitute for SPE conforms to USP Method 561.

The results show Thomson eXtreme|FV®s offer a viable alternative with higher recovery and less preparation time compared to SPE for the preparation of juices prior to pesticide analysis.

Time = Money

Table.1*Significant time & money savings because lengthy wash steps are eliminated!
To process 6 samplesTraditional SPE or GPCQuEChERS with SPE clean-upQuECHERS with Thomson Filter Vial clean-up*Thomson Filter Vial Benefits
Estimated (min.)12020101
Solvent used (mL)9010-1550.5
Chlorinated waste (mL)30nonenonenone
Specialized equipmentSeparatory funnels, water bath, evaporator, etc.Vacuum pump, vacuum manifoldnonenone

Thomson Instrument Company is not affiliated with Micro Quality Labs Inc. Micro Quality Labs Inc. is not affiliated with Thomson Instrument Company or endorse Thomson’s products. Restek or its products are not affiliated with Thomson Instrument Company.

Title

eXtreme|FV® vs SPE for the Analysis of Pesticides in Orange Juice by GC/MS

Description

Pesticides act as toxins when found in sufficient quantities as residues in food. Solid Phase Extraction (SPE) is a common sample preparation technique used prior to GC or LC analysis of pesticides in food. eXtreme|FV® offer multi-layer filtration for viscous samples and samples containing up to 30% solid particulates.

PDF Application

Product Used in Application

eXtreme|FV® - PTFE 0.45µm

Pre-Split Septum, Blue Cap

pn#85540-200

Related Products

© 2021 Thomson |
Solutions At Work™

LinkedIn