A review of polysorbate quantification and its degradation analysis by liquid chromatography coupled with charged aerosol detection.

Polysorbates (PS), as non-ionic surfactants, contribute significantly to the stability of proteins in formulations. However, their lack of chromophore groups makes them difficult to detect with high sensitivity and simplicity. The charged aerosol detector (CAD) is an emerging and universal detector that can provide highly sensitive response signals to non-volatile or semi-volatile substances, such as esters, acids, oxidized aldehydes, and contaminant ions in PS.

Determination of oxidized and reduced CoQ10 and CoQ9 in human plasma/serum using HPLC-ECD.

This chapter describes the use of reversed-phase HPLC with multichannel coulometric electrochemical detection for the routine, sensitive, and simultaneous measurement of oxidized and reduced CoQ10 and CoQ9 in human plasma and serum. Analytes are first resolved chromatographically prior to electrochemical detection using three serially placed flow-through coulometric sensors set for oxidation-reduction-re-oxidation. Such electrochemical manipulation of analytes not only improves selectivity and specificity (decreasing the likelihood of co-elution), but also leads to improved sensitivity and decreased noise.

Metabolomic applications of electrochemistry/mass spectrometry.

Analytical techniques used for multivariate analysis of endogenous metabolites in biological systems (e.g., metabolomics, metabonomics) must be capable of accurately and selectively monitoring many known and unknown molecules that span a diverse chemical spectrum and over extremely large dynamic concentration ranges.