Metabolic analysis of body fluids by capillary electrophoresis using noncovalently coated capillaries

The potential of capillaries noncovalently coated with charged polymers for the metabolic analysis of body fluids by CE is illustrated. Firstly, the usefulness of a coating consisting of a triple layer of polybrene–dextran sulfate–polybrene for the fast analysis of organic acids is described. The CE system allowed direct injections of CSF, plasma and urine samples, yielding good separation efficiencies. RSDs for migration times and peak areas of organic acids in plasma were <3% and <5%, respectively. The usefulness of the system is illustrated by the profiling of organic acids in plasma and urine samples. Secondly, a CE system comprising a bilayer coating of polybrene–poly(vinylsulfonate), which provides a considerable EOF at low pH is described. This system was combined with TOF-MS and used for the fast analysis of amino acids in cerebrospinal fluid (CSF) and urine with minimal sample pretreatment. RSDs for migration times and peak areas of amino acids in CSF and urine were <2% and <10%, respectively. The applicability of the system is demonstrated by the profiling of endogenous low-molecular weight metabolites in CSF from a healthy individual and a patient with complex regional pain syndrome.