What is Porapak Q?
Porapak Q (ethylvinylbenzene-divinylbenzene polymer) is a substance used to pack the column in gas chromatography (GC). The Porapak Q column method (PQM) was recently developed to concentrate volatile components in foods (1).
What is a plot column?
Porous Layer Open Tubular (PLOT) GC columns contains an immobilized porous layer of a solid adsorbent, such as alumina, or polymers. PLOT columns are ideal for efﬁcient, reproducible analyses of volatile compounds.
How are GC columns made?
Gas chromatography (GC): Older columns were made of glass or metal packed with particles of a solid stationary phase. More recently, narrower diameter (capillary) columns have been made using fused silica coated on the inside with a film of the stationary phase material.
What is Scot in chromatography?
General description. Capillary columns are basically of two type wall-coated open tubular (WCOT) and support-coated open tubular (SCOT). WCOT columns consist of a capillary tube, where the walls of the tube are coated with liquid stationary phase.
What are the 4 types of column chromatography?
Column chromatography can be classified into four classes: adsorption column chromatography, partition column chromatography, gel column chromatography and ion-exchange column chromatography.
Which gas is used in GC?
The mobile phase used in GC is an inert gas, such as nitrogen, helium, or hydrogen. The mobile phase is usually referred to as a carrier gas; when a mixture of substances is injected at the column inlet, each component is carried toward the detector by the mobile carrier gas.
What is the tailing factor?
Symmetry factor (S, also called “tailing factor”) is a coefficient that shows the degree of peak symmetry.
What is Rf value?
The Rf (retardation factor) value is the ratio of the solute’s distance travelled to the solvent’s distance travelled. The word comes from chromatography when it was discovered that a given component will always travel the same distance in a given solvent under the same conditions.
Why C18 column is used in HPLC?
Because of the extra carbons, C18 has a larger surface area that the mobile phase has to travel across. This offers more interaction time between the bonded phase and the elutes. Thus the sample elutes more slowly and has more separation.
What is GC principle?
Principle of gas chromatography: The sample solution injected into the instrument enters a gas stream which transports the sample into a separation tube known as the “column.” (Helium or nitrogen is used as the so-called carrier gas.) The various components are separated inside the column.
What is DB 5 column?
Agilent J&W DB-5 is nonpolar and low bleed, and is available in a range of column dimensions. DB-5 is also bonded, crosslinked, and solvent-rinsable, and has a high temperature limit. It is equivalent to USP phase G27.
What is the dead volume in HPLC?
The dead volume is the volume of an HPLC system between the point of injection to the point of detection, excluding the column.
What is polar and nonpolar in HPLC?
Reverse Phase HPLC
The stationary phase is nonpolar, like C18 bonded silica. The mobile phase is polar, usually being water and polar organic solvent. Compounds with the most hydrophobicity elute later in the chromatogram and those with the least hydrophobicity elute earlier.
What is a good Rf value?
A desirable Rf value lies between 0.3 and 0.7, since it is likely that other compounds present in the mixture will be visible on the TLC plate when the Rf is in this range.
What is Rf formula?
Retention/retardation factor (Rf) can be calculated by the relative migration values of solute (analyte) and the solvent front. Rf = Migration of analyte / Migration of solvent front. The calculation of the Rf value is basically the calculation of relative affinities of a solute with the stationary and mobile phases.
Is C18 polar or nonpolar?
A C18 column is an example of a “reverse phase” column. Reverse phase columns are often used with more polar solvents such as water, methanol or acetonitrile. The stationary phase is a nonpolar hydrocarbon, whereas the mobile phase is a polar liquid.
Why is acetonitrile used in HPLC?
Acetonitrile is often used because of its low UV cutoff, lower viscosity (methanol forms highly viscous mixtures with water at certain concentrations), and higher boiling point.
Why is GC used?
Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture.
Which gas is used in gas chromatography?
In Gas Chromatography there are three gases that are commonly used as a carrier gas: nitrogen, helium and hydrogen.
What is C18 column in HPLC?
C18 columns are HPLC (high performance liquid chromatography) columns that use a C18 substance as the stationary phase. C18 HPLC columns are used in environmental sciences and chemical analysis, as well as industries such as pharmaceutical and environmental sciences, to analyze individual parts of chemical mixtures.
Which column is used in GC?
Two types of columns are used in gas chromatography: packed columns and capillary columns. Short, thick columns made of glass or stainless steel tubes, packed columns have been used since the early stages of gas chromatography.
What is the peak purity?
Peak Purity is an analysis of absorbance spectra across the peak to determine if they are all similar or there are differences. If there are spectral differences, it implies there are two or more compounds eluting in that chromatographic peak each being spectrally different.
What is tailing factor in HPLC?
What is RRT and RRF in HPLC?
Relative retention time (RRT) is used to know where peaks apart from main compound elutes in HPLC analysis (RRF) : Relative Response factor (RRF) comes into picture when our compound and impurities have different wavelength maxima.
Is high or low Rf better?
The lower the frequency, the better the range.
All else being equal (RF power, antenna gain, etc.) lower frequencies propagate better than higher frequencies. Thus, range is better, and signals pass through objects more readily at lower frequencies.