403
Lipid classes may be identified by their reaction with specific chemical reagents,
by spectroscopic techniques, or by their chromatographic behaviour relative to
authentic standards, and the amounts of each determined by appropriate methods.
The fatty acid composition of each lipid class can then be determined by gas chromatography (GC). Simpler molecular species of lipids can be isolated by some form
of partition or complexation chromatography. It is a very powerful tool for lipid
analysis. Complete lipid profiling of a given sample is possible by this method.
Different components of lipid are separated in fractions by chromatography. The
various fractions are then subject to spectrometric analysis to assess the molecular
identity and their relative concentration. IR, NMR and Mass Spectrometry are most
commonly used (McClements 2003). In spite of their reliability, chromatographic
analysis is done only when complete molecular identification of the lipid is required.
Factors like high cost of the instrument and reagent also limit the usage of this
method (Greenfield and Southgate 2003).
Methods for the analysis of lipids are therefore essential for many research, clinical and quality control applications. Lipid analysts have been at the forefront in the
development of gas chromatography (GC) (or gas-liquid chromatography (GLC)),
thin-layer chromatography (TLC), and high-performance liquid chromatography
(HPLC), Mass spectroscopy. Chromatography is the most frequently used method
of separating lipids into groups.
Chromatographic Analysis of Lipids
Chromatography technique is the powerful analytical procedures for separating and
analyzing the properties of lipids, especially when it is combined with techniques
like mass spectrometry or NMR which can analyse the chemical structure of the
peaks. In chromatographic analysis mixture of the molecules to be separated is
passed through a column that contains a matrix capable of selectively retarding the
flow of the molecules. Based on their differing affinities for the matrix in the column
the molecules in the mixture are separated because of. The stronger the affinity
between a specific molecule and the matrix, its movement is more retarded, and
passes through the column at a reduced rate. Based on the strength of their interaction with the matrix different molecules can be separated. After being separated by
the column, suitable detectors like UV-visible, fluorescence, or flame ionization can
be utilized to analyse the concentration of each molecules. Chromatography helps
in complete lipid profiling, by which lipid characteristics such as the amount of
saturation, cholesterol and other factors such as adulteration, presence of antioxidants could also be determined. The various types of chromatography that are available for lipid analysis of foods are thin layer chromatography (TLC), gas
chromatography (GC), and high pressure liquid chromatography (HPLC).
Lipid samples obtained from natural sources are complex mixtures of individual
lipid classes. In most of the cases a combination of techniques are required to separate and analyse all of these rather than a single technique. Chromatography is one
of the most preferred method by lipid analysts. There are six main modes of
Lipids and Oils: An Overview
Lipid classes may be identified by their reaction with specific chemical reagents,
by spectroscopic techniques, or by their chromatographic behaviour relative to
authentic standards, and the amounts of each determined by appropriate methods.
The fatty acid composition of each lipid class can then be determined by gas chromatography (GC). Simpler molecular species of lipids can be isolated by some form
of partition or complexation chromatography. It is a very powerful tool for lipid
analysis. Complete lipid profiling of a given sample is possible by this method.
Different components of lipid are separated in fractions by chromatography. The
various fractions are then subject to spectrometric analysis to assess the molecular
identity and their relative concentration. IR, NMR and Mass Spectrometry are most
commonly used (McClements 2003). In spite of their reliability, chromatographic
analysis is done only when complete molecular identification of the lipid is required.
Factors like high cost of the instrument and reagent also limit the usage of this
method (Greenfield and Southgate 2003).
Methods for the analysis of lipids are therefore essential for many research, clinical and quality control applications. Lipid analysts have been at the forefront in the
development of gas chromatography (GC) (or gas-liquid chromatography (GLC)),
thin-layer chromatography (TLC), and high-performance liquid chromatography
(HPLC), Mass spectroscopy. Chromatography is the most frequently used method
of separating lipids into groups.
Chromatographic Analysis of Lipids
Chromatography technique is the powerful analytical procedures for separating and
analyzing the properties of lipids, especially when it is combined with techniques
like mass spectrometry or NMR which can analyse the chemical structure of the
peaks. In chromatographic analysis mixture of the molecules to be separated is
passed through a column that contains a matrix capable of selectively retarding the
flow of the molecules. Based on their differing affinities for the matrix in the column
the molecules in the mixture are separated because of. The stronger the affinity
between a specific molecule and the matrix, its movement is more retarded, and
passes through the column at a reduced rate. Based on the strength of their interaction with the matrix different molecules can be separated. After being separated by
the column, suitable detectors like UV-visible, fluorescence, or flame ionization can
be utilized to analyse the concentration of each molecules. Chromatography helps
in complete lipid profiling, by which lipid characteristics such as the amount of
saturation, cholesterol and other factors such as adulteration, presence of antioxidants could also be determined. The various types of chromatography that are available for lipid analysis of foods are thin layer chromatography (TLC), gas
chromatography (GC), and high pressure liquid chromatography (HPLC).
Lipid samples obtained from natural sources are complex mixtures of individual
lipid classes. In most of the cases a combination of techniques are required to separate and analyse all of these rather than a single technique. Chromatography is one
of the most preferred method by lipid analysts. There are six main modes of
Lipids and Oils: An Overview