Development and validation of an LC–MS/MS method for quantification of cyclic guanosine 3′,5′-monophosphate (cGMP) in clinical applications: A comparison with a EIA method

Improved method for the determination of cyclic guanosine monophosphate (cGMP) in human plasma by LC–MS/MS

“…We found values of 3.92 ± 1.17 nM. This is comparable to results obtained by other [13]). The applicability of the method can therefore be regarded as proven.…”

“…The solid phase sample extraction and concentration and the tandem mass spectrometric detection resulted in high sensitivity and selectivity with peak shapes uncompromised by endogenous substances. Compared to a previously published method for the determination of cGMP from human plasma [13], the here-described method showed slightly better sensitivity (limit of quantification 1 nM vs. 1.5 nM) and improved R.S.D. 's (intra-day 1.6-1.7% vs. 6.0-10.1%, inter-day 3.0-5.6% vs. 5.6-8.1%).…”

“…Zhang et al [13] described a simple protein precipitation as sample preparation. In our experience, such a sample preparation leads to very impure extracts, which can result in reduced chromatographic performance and reduced sensitivity, due to ion suppression effects.…”

“…As cGMP is a very polar molecule, retention on reversed phase columns is difficult and requires a nearly 100% aqueous mobile phase [12], ion pairing [10] or reversed phase columns with hydrophilic endcapping [13]. On the other hand, porous graphitic carbon columns provide good retention behavior with polar compounds such as cGMP.…”

“…Recently, a method quantifying cGMP from human plasma utilizing an isotope labeled analogue of cGMP as I.S. has been published [13]. The authors describe a very straightforward sample preparation and short chromatography, but have to revert to the less sensitive negative ionization electrospray (ESI) mode because of interferences in the positive mode.…”