Advisory Committee on Health Effects of Endocrine Disruptors
The Supplement II to the Intermediary Report
1.2.3.2

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[Notes]

1. The column switching-LC/MS permits direct injection of the sample, thus avoiding contamination in pretreatment. It also facilitates quantitation because the NP isomers give a single peak on the chromatogram.
2. The nonyl group in NP isomers is straight or branched. Commercially available standard NP products accordingly consist of either the straight form only or a mixture of various branched forms. The mixed type is preferable for the present purpose, since environmental and biological samples usually give peak patterns corresponding to them. It should be noted, however, the peak patterns of the commercial products may vary among manufacturers, or even among lots from a single manufacturer.
3. Commonly used substances for correction in the mass spectrometry of NP are straight-chain 4-n-NP (with deuterium and 13C) and 4-(1-methyl)octylphenol-d5. Since differences in physical and chemical properties of the straight- and branched-chain molecules may present problems in correction, the two substances were compared and the latter was chosen here. Since the retention time for 4-(1-methyl)octylphenol-d5 is different from that for NP, the correction is still less than perfect. Future development of mixed standards with deuterium and 13C is desired.
4. E.g. Tosoh TSK-Precolumn BSA/ODS-S (4.6 x 10 mm, 5 μm). Other products with equivalent recovery ratio and purification performance may be used.
5. The β-glucuronidase concentration is not restricted to this value. However, the deconjugation condition should always be checked beforehand.
6. Direct injection with column switching is the preferred method for small numbers of samples. Since the recovery ratio and purification performance of the extraction column are effective for about 20 samples only, Procedure B is preferable for analysis of a large number of samples.
7. E.g. Geiman Japan's P/N Ekicrodisc 13 CR 0.45 μm PTFE.
8. E.g. Kanto Chemical's Mightysil RP 18 GP.
9. The concentration of ammonium acetate is so chosen that the maximum response is obtained in a range of 0 to 2 mM. The solutions were prepared here so that both water and acetonitrile contain 0.02% ammonium acetate.
10. Up to 10% methanol may be contained for column cleaning. The extraction ratio should then be checked.
11. The definitions of the detection and determination limits follow those given in the Manual for Water Quality Survey Related to Dioxins, Environment Agency, July 1998.

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