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GC-MS quantification of urinary symmetric dimethylarginine (SDMA), a whole-body symmetric l-arginine methylation index
- Bollenbach, Alexander, Hanff, Erik, Beckmann, Bibiana, Kruger, Ruan, Tsikas, Dimitrios
- Analytical biochemistry 2018 v.556 pp. 40-44
- anhydrides, arginine, chemical structure, derivatization, ethyl acetate, gas chromatography-mass spectrometry, humans, ionization, ions, methylation, monitoring, quantitative analysis, risk factors, urine
- Circulating and excretory Nᴳ,N´ᴳ-dimethyl-l-arginine (symmetric dimethylarginine, SDMA) and Nᴳ,Nᴳ-dimethyl-l-arginine (asymmetric dimethylarginine, ADMA) are cardiovascular risk factors. Despite close chemical structures, the gas chromatography-mass spectrometry (GC-MS) measurement of SDMA is remarkably more difficult than that of ADMA for as yet unknown reasons. Here, we describe an improved GC-MS method for the quantitative determination of SDMA in human urine using commercially available Nᴳ,N´ᴳ-di-[²H3]methyl-l-arginine (d6-SDMA) as internal standard. The method is based on a single derivatization step with pentafluoropropionic anhydride (PFPA) in ethyl acetate (30 min, 65 °C) to N,N,N,O-tetrakis-pentafluoropropionyl derivatives, electron-capture negative-ion chemical ionization and selected-ion monitoring of the mass-to-charge (m/z) ions of m/z 456 for SDMA and m/z 462 for d6-SDMA.