Development of soybean certified reference material for pesticide residue analysis

• Published in: Talanta (Oxford) 2014-02, Vol.119, p.255-261
• Main Authors: Yarita, Takashi, Otake, Takamitsu, Aoyagi, Yoshie, Kuroda, Youko, Numata, Masahiko, Iwata, Hitoshi, Watai, Masatoshi, Mitsuda, Hitoshi, Fujikawa, Takashi, Ota, Hidekazu
• Format: Article
• Language: English
• Subjects: Certification; Certified reference material (CRM); Glycine max - chemistry; Homogeneity assessment; Isotope-dilution mass spectrometry; Mass Spectrometry - methods; Organophosphorus pesticide; Pesticide Residues - analysis; Pyrethroid pesticide; Reference Standards; Stability assessment; Uncertainty; Uncertainty estimation
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2013.11.011

A soybean certified reference material for pesticide residue analysis was developed by the National Metrology Institute of Japan. Three organophosphorus (diazinon, fenitrothion, chlorphyrifos) and one pyrethroid (permethrin) pesticides were sprayed on soybeans three times before harvest. These soybeans were freeze pulverized, homogenized, bottled, and sterilized by γ-irradiation to prepare the candidate material. Three isotope-dilution mass spectrometric methods that varied in terms of the solvents used for extraction of the target pesticides, the clean-up procedure, and the injection techniques and columns used for quantification via gas chromatography/mass spectrometry were applied to the characterization. Each target pesticide was quantified by two of these analytical methods, and the results were in good agreement. Homogeneity and stability assessment of the material demonstrated that the relative standard uncertainties due to the inhomogeneity and the instability for an expiry date of 55 months were 1.89–4.00% and 6.65–11.5%, respectively. The certified pesticide concentrations with expanded uncertainties (coverage factor k=2, approximate 95% confidence interval) calculated using the results of the characterization and the homogeneity and stability assessment were 21.7±3.2μg/kg for diazinon, 88±21μg/kg for fenitrothion, 11.1±3.2μg/kg for chlorpyrifos, and 20.1±4.3μg/kg for permethrin (as the sum of the constituent isomers). [Display omitted] •A first bean CRM for pesticide residue analysis, NMIJ CRM 7509-a: pesticides in soybean powder, has been developed.•The raw soybean was cultivated so that the target pesticides (diazinon, fenitrothion, chlorphyrifos, and permethrin) were remained in it.•The concentration of each target pesticide was characterized by two isotope-dilution mass spectrometric methods.•Homogeneity and stability assessment of the material were also carried out according to the ISO Guide 35.•Certified concentrations and their uncertainties were provided: the concentrations were in 3.7–44% (relative) to the corresponding Japanese MRLs.