It is a sterol (or modified steroid), a lipid molecule and is biosynthesized by all animal cells because it is an essential structural component of all animal (not plant or bacterial) cell membranes that is required to maintain both membrane structural integrity and fluidity. Cholesterol enables animal cells to dispense with a cell wall to protect membrane integrity and cell viability, thus allowing them to change shape and move about (unlike bacteria and plant cells which are restricted by their cell walls).

In addition to its importance for animal cell structure, cholesterol also serves as a precursor for the biosynthesis of steroid hormones and bile acids. Cholesterol is the principal sterol synthesized by all animals. In vertebrates the hepatic cells typically produce greater amounts than other cells. It is absent among prokaryotes (bacteria and archaea), although there are some exceptions such as Mycoplasma, which require cholesterol for growth.

Reversed-Phase HPLC Determination of Cholesterol in Food Items.

Some Facts about Cholesterol

Cholesterol is a soft, waxy substance found among the lipids or fats in the bloodstream and in all cell membranes. It is a non-saponifiable lipid essential in maintaining good health, as it is used to form cell membranes, several hormones, vitamin D, and bile acids needed to digest the fats present in our foods (1). Cholesterol is the major sterol in the human body and belongs to the class of molecules called steroids, which are derivatives of the perhydrocyclopentanophenanthrene ring system (2). Its chemical structure.

METHODS OF CHOLESTEROL ANALYSIS

Spectrophotometric Methods

Spectrophotometry refers to the measurement of absorption and emission of light by materials. This section reviews some of those methods involving an optical end-point reaction.

Mass Spectrometric Method

An isotope dilution/ mass spectrometric (ID/MS) method for total serum cholesterol cholesterol served as labeled internal standard and primary standard respectively. Calibration curves were made from the averages of two single independent molecular-ion ratio measurements on the unlabeled and the labeled cholesterols separately and on four such standard mixtures. Aliquots of the same solution of labeled cholesterol were used for the serum sample analyses. After saponification using alcoholic potassium hydroxide and extraction, ratios of the molecular-ions at m/z 390 and 386 from the two forms of cholesterol were independently measured twice by gas Chromatography-mass spectrometry

METHODOLOGY OF HPLC

The detector is the most complex and expensive piece of equipment in the HPLC instrument. Several types of detectors are in use and available commercially. Some of these detectors are ultraviolet-visible absorption, refractive index, fluorescence, heat of adsorption, electrical conductivity, and flame ionization (26). The performance criteria such as sensitivity, detection limit, linearity, repeatability, peak shape and spreading, ease of operation and maintenance, as well as applicability, are to be considered in the choice of any kind of detector. UV-Visible Absorption Detector.