How can we detect small molecules using ECD?
Many clinical analytes can be detected using electrochemical detection due to the -OH and decentralized ring structures which many of them possess. For example, see figure 1 of how a dopamine molecule can be oxidized.
If we use a column to separate out a sample containing dopamine, we can pass the eluted band of dopamine through an electrode which can oxidize the dopamine. This will cause a signal to be read by an electrochemical detector and the chromatogram will indicate a peak. Using known peak sizes from known concentrations we can calculate concentration of unknown peak sizes.
Fig. 1. Dopamine molecule being oxidized
Metanephrines & Catecholamines in Urine – HVA, VMA / Dopamine, Norepinephrine
HPLC with electrochemical detection has been established as a fast and reliable method for the determination of urinary metanephrines. Clinical kits are available from several suppliers that contain all the necessary chemicals and materials for sample preparation and analysis. The biological samples are processed by an SPE step, followed by a wash and elution step, prior to injection onto the HPLC system. The ALEXYS Clinical Analyzer together with a commercially available sample prep kit is a proven solution for routine analysis of catecholamines. The chromatogram is an overlay of 10 analyses and shows the repeatability of the system for both metanephrines (fig 2 – left) and catecholamines (fig 2 -right).
Fig. 2. 10 overlaid chromatograms of the same metanephrines analysis.
What Verulam Scientific can offer
Verulam scientific offer application specific set-ups covering a very large range of clinical, environmental and research needs, utilizing the bespoke ALEXYS™ system which can be configured for the most complex of needs.
For those looking for an alternative, Verulam can offer any of the decade detectors set up with an ECOM™ system (as shown below). We can also tailor your needs with second hand-equipment or building a system out of what instruments you currently have