Arginine and methylated arginines in human plasma and urine measured by tandem mass spectrometry without the need for chromatography or sample derivatisation

Quantification of arginine and its mono- and dimethylated analogs NMMA, ADMA and SDMA in biological fluids by LC–MS/MS: Is LC superfluous?

“…In our opinion, this study [9] suffers from many analytical and non-analytical shortcomings. In the present article, we discuss the article by Weaving et al [9] from the analytical point of view, especially focusing on the importance of the HPLC step in quantitative analysis of l-arginine and its methylated derivates in biological samples and on issues closely related to the LC-MS/MS technique including matrix effects.…”

“…The authors concluded that their method "requires neither sample derivatization nor the need for chromatographic separation of analytes, shows good precision and accuracy and is suited for both research purposes and implementation in the busy, routine clinical laboratory" [9]. In our opinion, this study [9] suffers from many analytical and non-analytical shortcomings. In the present article, we discuss the article by Weaving et al [9] from the analytical point of view, especially focusing on the importance of the HPLC step in quantitative analysis of l-arginine and its methylated derivates in biological samples and on issues closely related to the LC-MS/MS technique including matrix effects.…”

“…Recently, Weaving et al [9] reported the synthesis of d 2 -SDMA, d 2 -ADMA and d 2 -NMMA and their use as internal standards (IS) for the simultaneous quantification of the endogenous counterparts in human plasma and urine by MS/MS without preceding HPLC separation, i.e., by directly injecting the eluate of SPE extracts into the mass spectrometer. l-Arginine was quantified by the same method using a commercially available d 7 -l-arginine as the IS [9].…”

“…l-Arginine was quantified by the same method using a commercially available d 7 -l-arginine as the IS [9]. The authors concluded that their method "requires neither sample derivatization nor the need for chromatographic separation of analytes, shows good precision and accuracy and is suited for both research purposes and implementation in the busy, routine clinical laboratory" [9]. In our opinion, this study [9] suffers from many analytical and non-analytical shortcomings.…”

Simultaneous quantitative determination of NG,NG-dimethyl-l-arginine or asymmetric dimethylarginine and related pathway's metabolites in biological fluids by ultrahigh-performance liquid chromatography/electrospray ionization-tandem mass spectrometry

“…Recently Weaving [48] reported simultaneous quantification of the endogenous compounds in human plasma and urine by MS/MS without preceding HPLC separation, only by directly injecting the eluate of SPE extracts into the mass spectrometer. However, as comments Martens-Lobenhoffer [49], this is not suitable because this bring to loss of selectivity and accuracy in the quantitative determination and it is necessary to minimize matrix-associated effects.…”