Top 250+ chromatography interview questions and answers – best chromatography interview questions wisdom jobs 3 gases that cause acid rain


The most commonly used detector is the flame ionize detector. The sample is combusted with the help of fuel gas and oxidant in the detector body. Combustible sample components burn and produce ions and electrons which can conduct electricity through the flame. A large potential difference is applied at the burner tip and the collector electrode located above the thitima electricity sound effect flame and the current between the electrodes is measured. The detector is mass sensitive and response is not affected by carrier gas flow rate changes. However, the detector is not responsive to inorganic electricity dance moms gases such as C O, O 2, NH 3, N 2, CS 2, CO 2, etc.

Isothermal operation is useful when high resolution is required for separating compounds having narrow boiling range. Temperature is set to around mid range of boiling points of constituents. This results in good resolution of low boiling components but band broadening of higher boiling components can result due to their longer retention in the column.

Paper chromatography is a form of liquid chromatography where the components of a mixture of organic nyc electricity cost per kwh compounds get separated as unique spots by unidirectional flow of the developing liquid mobile phase solvent mixture over the filter paper to which a spot of the sample is applied. The distance travelled by each component is specific under the given set of operational conditions.

The samples should have a medium solubility in the developing solvent q mart gas station mixture.Too high a solubility will lead to transfer of the component alongwith the solvent front and on the other hand if the solubility is too low the component will not be carried by the solvent mixture and will remain close to the initial applied spot. In either case the resolution of the mixture components will be low. Thus reasonably good resolution can be obtained for medium solubility of compounds in the solvent mixture.

Rf is a unit less quantity and lies between 0and 1.A value of 0 indicates no separation has taken place and electricity kwh cost uk 1 represents that the component has moved entire length alongwith the solvent front. In case two spots have same value of Rf it indicates that they are not resolved. At least a difference of 0.05 is necessary to discern the separation between two spots.

Chromatographic technique of analysis has seen an impressive growth over time. Such advances have increased laboratory throughputs lowered limits of detection and has made forays into new areas of applications. Paper chromatography has retained its ground till date and is popular in laboratories across the world. Some of the reasons for electricity flow diagram this are:

Reverse phase Chromatography has the widest range of applications. The stationary phase comprises non polar organic chains bound to inert silica surface and mobile phase comprises of aqueous or aqueous-organic mixtures comprising of polar solvents of varying degrees of polarity. The elution sequence is polar followed by less polar and least polar or non polar compounds eluting gas near me cheap last through the column.

In size exclusion chromatography the separation does not involve chemical interactions between eluting molecules and stationary phase. The separation takes place on the basis of molecular size with larger molecules eluting first and electricity lessons 4th grade small molecules in the end. Small molecules are retained longer in the pores of the stationary phase therefore they get eluted last.

A bulk property detector responds to some property of mobile phase and sample combination passing through it at any point of time such a Refractive index or Electrochemical detector whereas a specific property detector is responsive only to the characteristic property of the eluting molecule and is independent of changes in mobile phase composition such as UV-Vis and Fluorescence detectors.

When the composition of the mobile phase is not changed through the chromatographic run the operation is termed as isocratic. It can involve a single solvent or a mixture of two or more solvents mixed in a fixed proportion. In gradient operation the composition at start of run is programmed to change at a predetermined rate gas house gorillas and the composition at the end of run is different from the composition at the start.

Plate theory concept was introduced to explain efficiency of columns. The concept assumes that a state of instantaneous equilibrium exists between the concentration of solute in stationary phase and the mobile phase and further the column is imagined to be divided into a number of theoretical plates. Any analyte electricity per kwh calculator spends a finite time in each plate and this is the equilibrium time. Smaller the plate height the greater is the number of plates in a given length (HETP) and better monroe la gas prices is the column resolution.

During chromatography, if the components to be separated are colourless, then these separated components on chromatogram are not visible. Their presence is detected by development, which involves spraying a suitable reagent (called developing reagent) on the chromatogram, or placing the chromatogram in iodine chamber when various components become visible. This process is called developing of chromatogram.