Qualitative Determination of Pesticides in a Roma Tomato,

Iceberg Lettuce, and a Macintosh Apple

Karen SandersChemistry 481

12/4/08

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Varian Saturn 3800-2200 GC/MS

• Similar to the Varian Saturn 3800-2000 GC/MS used in this experiment.

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Restek Pesticide Standard

Manufactured by Restek Company

Labeled, “Organochlorine Pesticide Mix AB#2”

Held in a solvent mixture of 50:50

Hexane/Toluene.

Varian Saturn 3800-2000 GC-MS Parameters for Restek Standard and Roma Tomato

Separation

Carrier Gas: Helium

Volume Injected: 1 mL

Flow Rate: 1.8 ml/min

Stationary Phase:

5% Phenyl-95% polydimethylsiloxane

Column Temp: 80 °C for 1 minute, increasing to 240 °C at 10 °C/min,

increasing to 265 °C at 10 °C/min, and holding for 10 min.

Oven Temp: 275°C

Injector Port Temp:

270 °C

Solvent Delay: 5 minutes

Column Size: 30 m x 0.25 mm ID, 0.25 um

Mode: Split-less

Restek Standard of Organochlorine

Pesticide Mix AB#2: Chromatogram

18/20 Pesticides Found

Roma Tomato

Kroger Brand

Originated from California, U.S.A.

Unwashed prior to analysis

Reagents

Florisil, also known as activated magnesium silicate had a 30-60

particle mesh size and was manufactured by Fluka Analytical.

CH2Cl2 was of the Aldrich Brand and Reagent Grade.

Na2SO4 and alumina were manufactured by Fisher Scientific and were both reagent grade.

Pesticide Extraction Procedure for the Roma Tomato

“Development of Matrix Solid Phase Dispersion (MSPD) Method for the Determination of Pesticide Residues in Tomatoes by GC/MS”. Published in the Journal of the Brazilian Chemical Society. (2006)

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2.0 g of Roma tomato were ground with 0.5 g of alumina with a mortar and pestle.

The mixture was separated by column chromatography. Mobile phase: 20 mL of CH2Cl2

Stationary phase: 0.5 g Florisil and 3.0 g of Na2SO4.

Pentadecanoic acid, 13-methyl ester

Dibutyl Pthalate

Tomato Extract: Total Ion Current Chromatogram

Ion Search of Mass Spectrum

Pentadecanoic acid, 13-methyl ester from the carbon components of the plant

Dibutyl Pthalate a plasticizer

No pesticides; known for low pesticide content.

Solvent seems to be interfering with peaks therefore, solvent delay time was increased.

Iceberg Lettuce

Ocean Mist Brand

Originated from the Ocean Mist Farms in California, U.S.A

Unwashed prior to analysis

Pesticide Extraction Procedure for the Iceberg Lettuce

5.9 g of iceberg lettuce was ground in a mortar and pestle with 2 mL of CH2Cl2.

The mixture was gravity filtered and the solvent was then subjected to the same column chromatography procedure as was utilized for the tomato.

Carrier Gas: Helium

Flow Rate: 1.8 ml/min

Injection Volume 2 mL

Column Temp: 80 °C for 1 minute, increasing to 240 °C at 10 °C/min,

increasing to 265 °C at 10 °C/min, and holding for 10 min.

Oven Temp: 275°C

Injector Port Temp:

270 °C

Solvent Delay: 10 minutes

Total Time of Run 50 minutes

Mode: Split

Varian Saturn 2000 GC-MS Parameters for Iceberg Lettuce Separation

Iceberg Lettuce Extract: Total Ion Current Chromatogram

Ion Search of Mass Spectrum

Pentadecanoic Acid Linoleic Acid Ether Ester Pthalate Long Chain Alchols

No Pesticides

Macintosh Apple

Apple Ridge Brand Macintosh Apple

Originated from Jack Brown Produce in Sparta, MI U.S.A.

Unwashed before analysis

Pesticide Extraction Procedure for the Macintosh Apple

One apple was ground in a blender.

4 g was mixed with CH2Cl2.

CH2Cl2 was decanted and concentrated down to 1 mL.

Subjected to the same column chromatography parameters as before; except doubling of the reagents.

Varian Saturn 2000 GC-MS Parameters for Macintosh Apple Separation

Carrier Gas: Helium

Flow Rate: 1.8 ml/min

Injected Volume: 3 mL

Column Temp: 80 °C for 1 minute, increasing to 240 °C at 10 °C/min,

increasing to 265 °C at 10 °C/min, and holding for 10 min.

Oven Temp: 275°C

Injector Port Temp:

270 °C

Solvent Delay: 10 minutes

Total Time of Run 30 minutes

Mode: Split

Macintosh Apple Extract: Total Ion Current Chromatogram

Ion Search of Mass Spectrum

Endosulfin Endosulfin II Endrin Ketone Linoleic Acid Ethyl Ester (essential fatty

acid) 1-Hexacosene (hydrocarbon)

Pesticides!

Sources of Error

Used Florisil which had a particle mesh size of 30-60.

However, several sources state that a 60-100 particle mesh size is suitable for pesticide residue analysis (SIGMA)4

References

1. National Pesticide Information Center. npic.orst.edu (12/01/08)

2. University of Central Missouri. www.ucmo.edu (12/01/08)

3. Filho, M. Adalberto; Navickiene, Sandro; Dorea, S. Haroldo. “Development of the MSPD Method for the Determination of Pesticide Residues in Tomatoes by GC-MS”. J. Braz. Chem. Soc. 2006, 17, 1-8.

4. Sigma-Aldrich. www.sigmaaldrich.com. (12/01/08)