Ion suppression; a critical review on causes, evaluation, prevention and applications.

The consequences of matrix effects in mass spectrometry analysis are a major issue of concern to analytical chemists. The identification of any ion suppressing (or enhancing) agents caused by sample matrix, solvent or LC-MS system components should be quantified and measures should be taken to eliminate or reduce the problem. Taking account of ion suppression should form part of the optimisation and validation of any quantitative LC-MS method.

Development of a nano-electrospray MSn method for the analysis of serotonin and related compounds in urine using a LTQ-orbitrap mass spectrometer.

Serotonin, its key metabolite hydroxyindole acetic acid (5-HIAA) and dopamine have been shown to be potential biomarkers whose levels in serum and urine can be correlated with certain psychiatric and physiological disorders and illness, including depression, schizophrenia, anxiety and dementia. Recently we have published elsewhere that 5-HIAA has been identified as a potential biomarker for Attention Deficit Hyperactivity/Hyperkinetic Disorder (AD-HKD). This study describes a versatile and validated method for the analysis of these three compounds in urine using a nanoelectrospray-MS(n) method interfaced with an LTQ Orbitrap mass spectrometer.

Development of an LC-MS/MS method for the analysis of serotonin and related compounds in urine and the identification of a potential biomarker for attention deficit hyperactivity/hyperkinetic disorder.

Serotonin is a major neurotransmitter and affects various functions both in the brain and in the rest of the body. It has been demonstrated that altered serotinergic function is implicated in various psychiatric disorders including depression and schizophrenia. Serotonin has also been implicated along with dopamine in attention deficit-hyperkinetic disorder (AD-HKD).