Merck
  • Home
  • Search Results
  • Development of a new cucumber reference material for pesticide residue analysis: feasibility study for material processing, homogeneity and stability assessment.

Development of a new cucumber reference material for pesticide residue analysis: feasibility study for material processing, homogeneity and stability assessment.

Analytical and bioanalytical chemistry (2015-01-30)
Susana Grimalt, Stefan Harbeck, Penka Shegunova, John Seghers, Berit Sejerøe-Olsen, Håkan Emteborg, Marta Dabrio
ABSTRACT

The feasibility of the production of a reference material for pesticide residue analysis in a cucumber matrix was investigated. Cucumber was spiked at 0.075 mg/kg with each of the 15 selected pesticides (acetamiprid, azoxystrobin, carbendazim, chlorpyrifos, cypermethrin, diazinon, (α + β)-endosulfan, fenitrothion, imazalil, imidacloprid, iprodione, malathion, methomyl, tebuconazole and thiabendazole) respectively. Three different strategies were considered for processing the material, based on the physicochemical properties of the vegetable and the target pesticides. As a result, a frozen spiked slurry of fresh cucumber, a spiked freeze-dried cucumber powder and a freeze-dried cucumber powder spiked by spraying the powder were studied. The effects of processing and aspects related to the reconstitution of the material were evaluated by monitoring the pesticide levels in the three materials. Two separate analytical methods based on LC-MS/MS and GC-MS/MS were developed and validated in-house. The spiked freeze-dried cucumber powder was selected as the most feasible material and more exhaustive studies on homogeneity and stability of the pesticide residues in the matrix were carried out. The results suggested that the between-unit homogeneity was satisfactory with a sample intake of dried material as low as 0.1 g. A 9-week isochronous stability study was undertaken at -20 °C, 4 °C and 18 °C, with -70 °C designated as the reference temperature. The pesticides tested exhibited adequate stability at -20 °C during the 9-week period as well as at -70 °C for a period of 18 months. These results constitute a good basis for the development of a new candidate reference material for selected pesticides in a cucumber matrix.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Ethyl acetate, ReagentPlus®, ≥99.8%
Sigma-Aldrich
Toluene, anhydrous, 99.8%
Sigma-Aldrich
Ethyl acetate, anhydrous, 99.8%
Supelco
Cypermethrin, PESTANAL®, analytical standard
Supelco
Ethyl acetate, analytical standard
Supelco
Diazinon, PESTANAL®, analytical standard
Supelco
Imidacloprid, PESTANAL®, analytical standard
Supelco
Toluene, analytical standard
Supelco
Acetonitrile, analytical standard
Supelco
Methomyl, PESTANAL®, analytical standard
Sigma-Aldrich
Acetonitrile, anhydrous, 99.8%
Sigma-Aldrich
Acetonitrile, electronic grade, 99.999% trace metals basis
Supelco
Tebuconazole, PESTANAL®, analytical standard
Sigma-Aldrich
Acetonitrile, for DNA synthesis
Supelco
Endosulfan, PESTANAL®, analytical standard
Sigma-Aldrich
Ultrapure Acetonitrile, for DNA synthesis
Sigma-Aldrich
Acetonitrile, for DNA synthesis
Supelco
Cypermethrin, certified reference material, TraceCERT®
Sigma-Aldrich
Ethyl acetate, ≥99%, FCC, FG
Supelco
Azoxystrobin, PESTANAL®, analytical standard
Sigma-Aldrich
Methanol-12C, 99.95 atom % 12C
Sigma-Aldrich
Ethyl acetate, natural, ≥99%, FCC, FG
Supelco
N-(6-Chloro-3-pyridylmethyl)-N-cyano-N-methylacetamidine, PESTANAL®, analytical standard
Sigma-Aldrich
[3-(3,5-Dichlorophenyl)-2,4-dioxoimidazolidinyl]-N-(methylethyl)carboxamide, 97%
Supelco
Toluene, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Acetonitrile, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Methanol solution, NMR reference standard, 4% in methanol-d4 (99.8 atom % D), NMR tube size 5 mm × 8 in.
Sigma-Aldrich
Methanol solution, NMR reference standard, 4% in methanol-d4 (99.8 atom % D), NMR tube size 3 mm × 8 in.
Tiabendazole, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
Acetonitrile, for preparative HPLC, ≥99.8% (GC)