Why is a pen not used in chromatography?

Why is a pen not used in chromatography?

1) Pen ink contains colored pigments. If we use the pen to mark on the chromatography paper then these pigments will also move along with the solvent…

Why can’t a pen be used to draw the baseline on the chromatography paper?

Answer and Explanation: In paper chromatography, the starting line must be drawn with the help of pencil because the pencil lead does not dissolve in solvent, thus it will not affect the separation. The spots of the compounds are separated correctly.

Can you use pen as a marker when using TLC plate?

You can’t use a pen because the ink will travel up the TLC plate with the TLC solvent, just like your chemical samples do. You can only spot/label/mark TLC plates using a pencil. The graphite in a pencil will not run up the plate!

Why shouldn’t you use a ballpoint pen when marking the initial line and spots on the chromatography paper?

Paper Chromatography: Chromatography is a general name for a group of analytical techniques that serve to separate and identify components in a mixture.

Why is ink never used for drawing the baseline?

A baseline is drawn in pencil on the chromatography paper. (Not in ink, as the ink may get separated in the experiment and interfere with the results). A small spot of the mixture is placed on the baseline. The paper is then removed from the solvent, and marked to show where the solvent got up to.

Why are TLC plates marked with pencil and not pen?

It is important to use a pencil rather than a pen because inks commonly travel up the plate with the solvent. An example of how black ink separates is shown in the section labeled “examples”. Using TLC pipettes, apply spots of analyte to the line. Make sure enough sample is spotted on the plate.

Why is a pencil needed for the TLC experiment?

In paper chromatography, a starting line in drawn on the paper in pencil (pencil so that it does not dissolve in the solvent and affect the results). Substances in a mixture separate because they have different attractions to the stationary phase (e.g. paper) and mobile phase (e.g. solvent).

Why is water not used in TLC?

The eluent can be more polar or less polar. It should not be so polar that it would dissolve the alumina or silica. If it did, the stationary phase would not stay put, but would move with the liquid phase. For that reason, methanol and water are not normally used as the eluent.

Why is RF value important?

The Rf value allows you to compare the position of bands in your sample to the position of standards, in order to decide whether the band is made of the same thing as the standard. You can also compare your result to the results of others who have used the same solvent system.

Why should you not use ink on the coating to mark your pigment placement?

Why should you not use ink on the coating to mark your pigment placement? You should not use ink because it will move and separate in to multiple components causing confusion to interpret results. …

How do you mark a TLC plate with a pencil?

Answer: The pen ink becomes mobile on the plate and travels up the TLC plate with TLC solvent. But the solid particles of graphite in the pencil won’t get dissolved and hence can be used to mark TLC plates. To wick up liquid to fill the jar with the vapor of the eluent.

What is the difference between TLC plate and TLC chromatography?

So basically a TLC plate is to do chromatography. And what chromatography is to separate components of a dye. The reason why people use pencils instead of inks it’s just because pencils are made of carbon. Inks in pens contains dyes that might affect the chromatogram as inks has dyes that can potentially separate while doing chromatography.

How does ink travel in TLC analysis?

If you use ink it will become part of your analysis. So basically the ink will travel as the component dyes used to make it will be separated. Pencil is graphite. It will not be broken down by the solvent. In fact, TLC is a useful analytical test for the composition of inks.

How do you remove spots from a TLC plate?

The solvent level has to be below the starting line of the TLC, otherwise the spots will dissolve away. The lower edge of the plate is then dipped in a solvent.