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Singapore, Singapore

Teo T.L.,Chemical Metrology Laboratory | Quan C.,China Institute of Metrology | Cheow P.S.,Chemical Metrology Laboratory | Huang T.,China Institute of Metrology | And 3 more authors.
Accreditation and Quality Assurance | Year: 2012

A bilateral comparative study between two metrology institutes was conducted for the determination of ethanol in bioethanol fuel by isotope dilution mass spectrometry. Measurement procedures were independently developed by the Health Sciences Authority (Singapore) and the National Institute of Metrology (People's Republic of China). The methods used included headspace gas chromatography-high-resolution mass spectrometry, headspace gas chromatography-mass spectrometry (GC-MS) and direct injection to GC-MS. An investigation of all potential sources of uncertainty, including a component of uncertainty due to the effect of using different instruments such as gas chromatography-flame ionization detector method, commonly adopted for the analysis of organic volatiles, was carried out. The results of the analyses are consistent within the associated measurement uncertainty of each laboratory, reported at approximately 95% confidence level. © 2011 Springer-Verlag.


Koh G.,Chemical Metrology Laboratory | Gui E.-M.,Chemical Metrology Laboratory | Teo T.-L.,Chemical Metrology Laboratory | Lee T.-K.,Chemical Metrology Laboratory
Journal of Separation Science | Year: 2013

A high-accuracy double isotope dilution mass spectrometric method using an exact matching approach with GC coupled to a mass spectrometer for the analysis of cyanuric acid in fortified milk powder was developed. Various parameters for sample clean-up such as the type of SPE cartridge, GC column and type of derivatizing agent used were investigated. The method was found to be linear in the concentration range of 0.03 to 2 mg/kg of cyanuric acid in milk powder. LOD and LOQ were found to be 0.9 and 3 μg/kg, respectively. Recoveries in the range of 95.7 to 102.2% were obtained for the in-house fortified milk powder samples, with RSD of measurements in the range of 0.2 to 3.0%. A metrological approach was undertaken to examine all possible biases that contributed to the combined measurement uncertainty of the method. This high-accuracy method can serve as a reference method for techniques commonly applied in routine testing laboratories. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Koh G.,Chemical Metrology Laboratory | Chia R.S.C.,Chemical Metrology Laboratory | Lin Q.,Chemical Metrology Laboratory | Cheow P.-S.,Chemical Metrology Laboratory | And 2 more authors.
Journal of Separation Science | Year: 2011

A GC-high-resolution isotope dilution MS (IDMS) method for the quantification of melamine in milk powder is described. The developed technique is compared to the LCIDMS/MS technique, typically used for the determination of melamine in various matrices. The accuracy of the GC-high-resolution IDMS method was demonstrated when a small degree of equivalence was obtained in a regional comparative study involving the determination of melamine in milk powder. © 2011 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim.

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