Organochlorine Pesticides in Ginseng Root
Authors: Wong W F , Lam W H , Fung W H , Muendo B M , Karau G M , Hanen K , Silva A , Zhang Q , Sudsiri N , Styarini D 
Published: September 2019

Ginseng is one of the most important traditional herbal medicines for health care and treatment of diseases. Trading of ginseng and related products is a multi-million dollar business. Four major countries including South Korea, China, Canada and the United States are the biggest producers and account for more than 99% of the total ginseng production around the world (i.e. about 80,000 tons). The Commission Regulation of European Union sets up that the maximum residue level (MRL) for hexachlorocyclohexane (sum of alpha, beta and delta isomers, except lindane) is 0.02 mg/kg and that for lindane is 1 mg/kg in ginseng. The use of reliable methods for measurement of these organochlorine pesticides is important in safeguarding the quality of ginseng and related products and public health.

The Government Laboratory, Hong Kong (GLHK) previously coordinated and completed CCQM-K95 "Mid-polarity Analytes in Food Matrix: Mid-polarity Pesticides in Tea". Two organochlorine pesticide residues,beta-endosulfan and endosulfan sulfate, were selected for analysis. It is noteworthy that participating institutes in CCQM-K95 found that wetting of test samples prior to extraction was crucial for complete extraction of the incurred analytes in the test material of dried tea. It is apparent that sample extraction is a real technical challenge in the analysis of dried plant material.

Ginseng root is collected after years of cultivation. It represents a higher level of analytical challenge for the participating national metrology institutes (NMIs) and designated institutes (DIs) in measuring the incurred organochlorine pesticides in dried ginseng/ginseng root, where the pesticides have been gradually accumulated in the plant material for several years. In this regard, GLHK proposed a new APMP supplementary comparison on determination of organochlorine pesticides in ginseng root at the APMP TCQM meeting in November 2015. The supplementary comparison was further discussed at the CCQM OAWG meeting in April 2016. The Chair of APMP TCQM approved the proposed supplementary comparison for 2016/17 with a study number of APMP.QM-S11 in May 2016. To allow wider participation, a pilot study APMP.QM-P32, was run in parallel with this supplementary comparison.

Evidence of successful participation in formal, relevant international comparisons is needed to document calibration and measurement capability claims (CMCs) made by national metrology institutes (NMIs) and designated institutes (DIs).

Seven NMIs/DIs participated in this Supplementary Comparison APMP.QM-S11 Organochlorine pesticides in ginseng root. Participants were requested to evaluate the mass fractions, expressed in μg/kg, of alpha-hexachlorocyclohexane (α-BHC, CAS No. 319-84-6) and gamma-hexachlorocyclohexane (Lindane, CAS No. 58-89-9) in a relatively complex food/plant material, termed ginseng root. The purpose of the comparison is to enable participating laboratories to demonstrate their capability in the determination of organochlorine pesticides in a relatively complex food/plant material. All participating laboratories performed wetting before extraction. Different extraction methods such as soxhlet extraction, accelerated solvent extraction, ultrasonic extraction, QuEChERS technique, shaking and vortex were used among the participants. For the instrumental analysis, all laboratories employed GC techniques for chromatographic separation and most laboratories used MS related techniques for detection and quantification. For α-BHC, the consensus mean was 413 μg/kg with standard deviation of 35.3 μg/kg from 4 participating institutes' results. For lindane, the consensus mean was 104 μg/kg with standard deviation of 10.9 μg/kg from 5 participating institutes' results.

Successful participation in APMP.QM-S11 demonstrates the following measurement capabilities in determining mass fraction of organic compounds, with molecular mass of 100 g/mol to 500 g/mol, having low polarity pKow < -2, in mass fraction range from 10 μg/kg to 1000 μg/kg in food/plant matrices.

KEY WORDS FOR SEARCH

Ginseng, Organochlorine Pesticide, alpha-hexachlorocyclohexane, gamma-hexachlorocyclohexane, Lindane, α-BHC

Main text

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The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).