Simplify Grasp of HPLC by Relating it to Human Body Functions

Chromatographic analysis has made innumerable contributions in research and quality control laboratories. The versatility and acceptance of the chromatographic techniques is showing an outstanding acceptance in sectors covering fundamental and applied research and in industrial sectors covering quality control in pharmaceuticals, foods, environmental monitoring, clinical diagnostics monitoring, forensic samples analysis, etc.

Applications involving HPLC analysis have seen remarkable growth in recent years. This has been possible because of availability of options in choice of separation columns, detectors, scale of analysis (pg to gm. level determinations) and modes of operation such as reverse phase, normal phase, ion chromatography and gel permeation chromatography.

HPLC is a modular system and the reliability of results depends greatly on the performance of each and every module. In a way similarities can be drawn with the functioning of organs of the human body. We shall see the comparison in the next few sections.

Mobile Phase- the Blood lifeline

In the human system the blood stream serves transportation of the nutrients and oxygen to each and every organ to promote healthy function and growth of cells. Likewise the mobile phase serves the purpose of transferring the injected sample through the HPLC system- first through the separation column and next to the detector. Like the blood stream the mobile phase flows through the tubes and column inside the HPLC system in a defined path. The reproducibility of results depends on the pre-defined flow rate without any restrictions or leakages. The mobile phase should be prepared fresh before start of analysis, degassed to free it from dissolved gases and filtered. Filtration under vacuum of the mobile phase helps remove any solid suspensions which can result in blockages and damage delicate components of the system.

Sample- The food that you eat

The sample should be fully soluble in the mobile phase and filtered to remove any solid suspensions. This is comparable to food which should be chewed properly for easy and thorough digestion. The sample needs to be fully compatible with the mobile phase solvents and the column packing material and not lead to any side reactions. The amount of sample injected should not exceed the recommended amount otherwise it can lead to overloading of the column and lead to flat-topped or broad peaks. This can be considered to be akin to indigestion when food is taken in excess of stomach’s processing capacity.

Column-The Stomach

Stomach is the key organ for assimilation and digestion of foods. Likewise in HPLC the column facilitates interaction of sample with the packed stationary phase. The sample components get attached to the stationary phase and subsequently eluted in a sequence. The elution rate is temperature dependent so it is essential to place the column inside a thermos tatted column oven for stabilization and maintenance of constant column temperature.

Pump- The Heart

Heart is the principal organ responsible for pumping blood throughout the body in continuous and consistent flow rate throughout your life-time. Similarly, the HPLC pump or set of pumps are required to deliver the mobile phase at set or variable rates depending on the mobile phase delivery program. The pump requires regular inspection and maintenance to replace worn-out components such as pistons, seals and O-rings. This is necessary to prevent leaks in the systems which affect the flow rates.

Detector-Eyes and Brain

Eyes and brain help us identify the objects that we see and transmit the signals to the brain to help determine the number of objects or to estimate the quantity of material. Similarly the detector identifies the individual separated components separated by the column and produce electrical signals which help the detector quantify them through the application software. The detector should be free of any leftover components of previous analysis before the start of fresh analysis.

The objective of comparing the human body to the HPLC system was to make its understanding much more easy and interesting so that you do not get scared by the sight of complex tubings, wires and different modules once you come across such systems and are able to relate it to your body organs for an easy understanding of its operation.