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‘Positive List’ Chemicals by GC-MS on the SLB-5ms

By: Katherine K. Stenerson, Takeyoshi Ide, Michael D. Buchanan, Reporter US Volume 27.5

Katherine K. Stenerson, Takeyoshi Ide1, and Michael D. Buchanan

mike.buchanan@sial.com

1. Sigma-Aldrich, Tokyo, Japan

Introduction

In May of 2006, the Japan Ministry of Health, Labour and Welfare (MHLW) introduced regulations for the levels of agricultural chemical residues allowed in plant-based and animal-based foods. This list of chemicals includes pesticides, feed additives, and veterinary drugs. The goal of this regulation is to prevent the distribution of foodstuffs containing these residues at levels above specific limits. Products that exceed these limits cannot be sold in Japan. The analysis of these chemicals involves either liquid chromatography-mass spectrometry (LC-MS) or gas chromatography-mass spectrometry (GC-MS). In this article, the applicability of the SLB™-5ms capillary GC column was determined for the analysis of the chemicals listed in the GC-MS sections of the regulations.

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Experimental

A set of six standards covering the range of GC-amenable MHLW-regulated chemicals was located and obtained from a commercial source in Japan. Each mixture contained analytes at 20 μg/mL in acetone. An SLB-5ms column was selected because of several features, namely its low bleed characteristics and high inertness.

GC-MS run conditions were optimized to yield good chromatography for all analytes. These conditions are summarized in Table 1, and were used for the analysis of each of the six standards. Note that these conditions differ slightly from those stated in the MHLW methodology. Specifically, a higher initial oven temperature and a slower ramp rate were used to obtain better peak shape and spacing. Additionally, a smaller injection volume was used to ensure that the inlet liner contained the resulting expansion volume of the acetone solvent, and to minimize band broadening. Table 1 lists the MHLW methodology condition if different from that used for this work.

Table 1 GC-MS Conditions for Figures 1-6 (28471-U)

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Results and Discussion

The resulting chromatography is shown in Figure 1 through Figure 6. Because each chromatogram was generated using identical GC-MS conditions, a composite list of analyte retention times in minutes could be assembled. This convenient list is shown in Table 2, and also includes the Chemical Abstracts Service Registry Number (CASRN) for each analyte. The corresponding Figure and Peak ID is integrated so users can easily locate individual analytes on one of the six chromatograms.

Figure 1 ‘Positive List’ Mix 1 on the SLB-5ms

Figure 2 ‘Positive List’ Mix 2 on the SLB-5ms

Figure 3 ‘Positive List’ Mix 3 on the SLB-5ms

Figure 4 ‘Positive List’ Mix 4 on the SLB-5ms

Figure 5 ‘Positive List’ Mix 5 on the SLB-5ms

Figure 6 ‘Positive List’ Mix 6 on the SLB-5ms

Table 2 Retention Times of ‘Positive List’ Chemicals on the SLB-5ms

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Conclusion

The wide variety of functionality exhibited by this large list of analytes requires a column with both low bleed characteristics and high inertness. The SLB-5ms column was shown to be applicable for the MHLW ‘positive list’ methodology, able to produce good peak shape and resolution for most analytes. This work also led to the generation of a table of analyte retention times that should prove useful to food analysts who need a reference to help determine the elution order of their specific compound list on the SLB-5ms.

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Materials

     

References

  1. www.mhlw.go.jp/english, Japan Ministry of Health, Labour and Welfare web site.
  2. Analytical Methods for Residual Compositional Substances of Agricultural Chemicals, Feed Additives, and Veterinary Drugs in Food, Department of Food Safety, Japan Ministry of Health, Labour and Welfare.

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