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Development of melamine certified reference material in milk using two different isotope dilution mass spectrometry techniques.
J Chromatogr A. 2011 Sep 28; 1218(39):6907-13.JC

Abstract

A new certified reference material (CRM) of melamine in milk GLHK-11-02 was developed aiming to address the great demand from the testing community after the melamine crises. The material was prepared by adding an appropriate quantity of melamine into the skimmed milk samples and the final product was in the form of fine lyophilized powder. Characterization of the material relied on two newly developed gravimetric isotope dilution mass spectrometry (IDMS) methods, one using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and another gas chromatography-mass spectrometry (GC-MS). Experimental parameters with crucial effects on the performance of the two IDMS methods were thoroughly investigated. These included purity of standard used, equilibration time of isotopes, efficiency of extraction methods as well as possible interferences from the matrix and melamine analogues. Precision was found to be excellent with a coefficient of variation of 2.5% for the LC-IDMS/MS (n=46) and 1.9% for the GC-IDMS (n=30) respectively. Using one-tail Student's t-test at 95% confidence interval, analytical data sets generated from the two methods were found to exhibit no significant difference. Measurement accuracy of the methods was further verified through an Asia Pacific Metrology Program (APMP) pilot study. Analytical results of the present LC-IDMS/MS for the two milk test samples at the concentration level of about 0.45 and 3.5 mg kg(-1) were proven to be very good. There were excellent overlaps between our results and the assigned reference values, and the absolute deviation was less than 3.2%. Both the LC-IDMS/MS and GC-IDMS methods were shown to be sufficiently reliable and accurate for certification of the melamine CRM. Certified value of melamine in dry mass fraction in GLHK-11-02 was 1.14 mg kg(-1). Expanded uncertainty due to sample inhomogeneity, long term and short term stability and variability in the characterization procedure was at 7.1% or 0.08 mg kg(-1). The CRM is primarily used to provide a complete method validation for and to improve the technical competence of melamine analysis to food and chemical testing laboratories.

Authors+Show Affiliations

Analytical and Advisory Services Division, Government Laboratory, 88 Chung Hau Street, Homantin Government Offices, Hong Kong.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

21872867

Citation

Hon, Phoebe Y T., et al. "Development of Melamine Certified Reference Material in Milk Using Two Different Isotope Dilution Mass Spectrometry Techniques." Journal of Chromatography. A, vol. 1218, no. 39, 2011, pp. 6907-13.
Hon PY, Chu PW, Cheng CH, et al. Development of melamine certified reference material in milk using two different isotope dilution mass spectrometry techniques. J Chromatogr A. 2011;1218(39):6907-13.
Hon, P. Y., Chu, P. W., Cheng, C. H., Lee, T. C., Chan, P. K., Cheung, S. T., & Wong, Y. C. (2011). Development of melamine certified reference material in milk using two different isotope dilution mass spectrometry techniques. Journal of Chromatography. A, 1218(39), 6907-13. https://doi.org/10.1016/j.chroma.2011.08.021
Hon PY, et al. Development of Melamine Certified Reference Material in Milk Using Two Different Isotope Dilution Mass Spectrometry Techniques. J Chromatogr A. 2011 Sep 28;1218(39):6907-13. PubMed PMID: 21872867.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Development of melamine certified reference material in milk using two different isotope dilution mass spectrometry techniques. AU - Hon,Phoebe Y T, AU - Chu,Patricia W S, AU - Cheng,Chi-ho, AU - Lee,Terry C L, AU - Chan,Pui-kwan, AU - Cheung,Samuel T C, AU - Wong,Yiu-chung, Y1 - 2011/08/16/ PY - 2011/03/18/received PY - 2011/07/13/revised PY - 2011/08/07/accepted PY - 2011/8/30/entrez PY - 2011/8/30/pubmed PY - 2011/12/13/medline SP - 6907 EP - 13 JF - Journal of chromatography. A JO - J Chromatogr A VL - 1218 IS - 39 N2 - A new certified reference material (CRM) of melamine in milk GLHK-11-02 was developed aiming to address the great demand from the testing community after the melamine crises. The material was prepared by adding an appropriate quantity of melamine into the skimmed milk samples and the final product was in the form of fine lyophilized powder. Characterization of the material relied on two newly developed gravimetric isotope dilution mass spectrometry (IDMS) methods, one using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and another gas chromatography-mass spectrometry (GC-MS). Experimental parameters with crucial effects on the performance of the two IDMS methods were thoroughly investigated. These included purity of standard used, equilibration time of isotopes, efficiency of extraction methods as well as possible interferences from the matrix and melamine analogues. Precision was found to be excellent with a coefficient of variation of 2.5% for the LC-IDMS/MS (n=46) and 1.9% for the GC-IDMS (n=30) respectively. Using one-tail Student's t-test at 95% confidence interval, analytical data sets generated from the two methods were found to exhibit no significant difference. Measurement accuracy of the methods was further verified through an Asia Pacific Metrology Program (APMP) pilot study. Analytical results of the present LC-IDMS/MS for the two milk test samples at the concentration level of about 0.45 and 3.5 mg kg(-1) were proven to be very good. There were excellent overlaps between our results and the assigned reference values, and the absolute deviation was less than 3.2%. Both the LC-IDMS/MS and GC-IDMS methods were shown to be sufficiently reliable and accurate for certification of the melamine CRM. Certified value of melamine in dry mass fraction in GLHK-11-02 was 1.14 mg kg(-1). Expanded uncertainty due to sample inhomogeneity, long term and short term stability and variability in the characterization procedure was at 7.1% or 0.08 mg kg(-1). The CRM is primarily used to provide a complete method validation for and to improve the technical competence of melamine analysis to food and chemical testing laboratories. SN - 1873-3778 UR - https://www.unboundmedicine.com/medline/citation/21872867/Development_of_melamine_certified_reference_material_in_milk_using_two_different_isotope_dilution_mass_spectrometry_techniques_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0021-9673(11)01186-1 DB - PRIME DP - Unbound Medicine ER -