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A. Mochizuki, A. Tamaoka, A. Shimohata, Y. Komatsuzaki and S. I. Shoji, “Ab42-Positive Non-Pyramidal Neurons around Amyloid Plaques in Alzheimer’s Disease,” Lancet, Vol. 355, No. 9197, 2000, pp. 42-44. doi:10.1016/S0140-6736(99)04937-5

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• TITLE: A New Metal Tag for Highly Selective and Sensitive Analyses of Amino Acids and Dipeptides by HPLC/ICP-MS

  AUTHORS: Daigo Iwahata, Kazuki Nakamura, Rie Yamada, Hiroshi Miyano, Naoyuki Yamada

  KEYWORDS: Metal Tag; HPLC/ICP-MS; Amino Acid; Dipeptide; Derivatization; Speciation

  JOURNAL NAME: Journal of Analytical Sciences, Methods and Instrumentation, Vol.3 No.2, May 31, 2013

  ABSTRACT: We have developed a novel metal tag, bis(ethylenediamine)-4'-methyl-4-carboxybipyridine-ruthenium N-succinimidyl ester (ECRS) for sensitive analysis of amino acids using high performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICP-MS). ECRS is a functional reagent, containing an ester group at one end that can be activated to bind to amino group and a chelated ruthenium at the other. The activated ester was reacted briefly with amino groups under weakly alkaline conditions. The ruthenium was detected sensitively by ICP-MS. ECRS was reacted with 17 proteinogenic amino acids in borate buffer. The derivatives were separated by reversed phase HPLC and identified by quadrupole-based ICP-MS. ECRS was suitable for speciation; low molecular weight compounds containing amino groups. We have thus established a quantitative analytical method for amino acids and dipeptides. The detection limits of branched amino acids (signal-to-noise ratio of 3) were 1.5 nmol·L-1 in the standard solution (100 amol per injection).