Modified electrodes provide efficient pre-adsorption of cellular metabolites and their sensitive detection using anodic square-wave voltammetry.
We developed and validated the workflow using synthetic mixtures of 20 common metabolites, defined the limits of detection using current technology, and compared the peak lists generated using both C and H data to those generated using H data alone.
Briefly, phthalate metabolite determination in urine involved enzymatic deconjugation of the metabolites from the glucuronidated form and then solid-phase extraction followed by detection using reversed-phase high-performance liquid chromatography isotope dilution tandem mass spectrometry.
-Epicatechin and its related metabolites were analysed in plasma by HPLC-FLD/UV and electrochemical detection using authentic standards provided by Mars Inc., as previously described.
Concentrations of gemcitabine and its inactive metabolite difluorodeoxyuridine were determined in human plasma samples by HPLC and MS/MS detection using 2-deoxyuridine as an internal standard.
Immunochemical methods may vary due to differential detection of D3 and D2 molecules (conventional analytical measurement of serum or plasma 25-OH D level reflects the sum of 25-OH D3 plus 25-OH D2), interference by detection using polyclonal antibodies, and nonspecific detection of other vitamin D metabolites including degradation products [ 22, 23].
As metabolites were speciated using HPLC separation of arsenobetaine (AsB), arsenocholine (AsC), arsenate, arsenite, MMA, and DMA, followed by detection using ICP-MS.
Arsenic metabolites were speciated using HPLC separation of arsenobetaine (AsB), arsenocholine (AsC), AsV, AsIII, MMA (MMAIII + MMAV), and DMA (DMAV), followed by detection using ICP-MS.
As metabolites were speciated using HPLC separation of arsenobetaine (AsB), arsenocholine (AsC), arsenate (InAsV), arsenite (InAsIII), MMA, and DMA followed by detection using ICP-MS.
Urinary As (uAs) metabolites were speciated using HPLC separation of arsenobetaine (AsB), arsenocholine (AsC), arsenate (AsV), arsenite (AsIII), monomethylarsonic acid (MMAIII + MMAV), and dimethylarsinic acid (DMAV), followed by detection using ICP-MS (Vela et al. 2001).
