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CHEMISTRY : Chromatography


PROJECT TITLE: Solvents Characteristics : METHANOIC ACID (Formic Acid)
LAST UPDATE: 2 Sep 2009
VERSION HISTORY: 1.0 - First release
1.1 - 07 Feb 1999
1.2 - Revision of text and formatting. (2-Sep-2009)


Here are the chromatography characteristics of Formic Acid as a solvent on the standard refernce ink under test. This was tested at various concentrations by diluting it with water. Concentrations used were: Absolute, 90%, 80%, 70%, 60%, 50%.

Chromatography characteristics that are tested include the speed , solubility and separation of the two dyes from the refernce ink.
  1. Solubility and Separation score is out of 10 were 0 is the worst and 10 is excellent
  2. Flow Rate is the portion (expressed as percent) of solvent that had moved along the 12cm strip of chromatography paper. For example if the solvent moved 6cm from the origin, the flow rate is given as 50%


Table of Results using the solvent METHANOIC ACID(Formic Acid) at various concentrations in Paper Chromatography
Solvent: Methanoic Acid (Formic Acid) - CH.COOH
Concentration Absolute (100% c. ) 90% 80% 70% 60% 50%
Flow Rate: 19% in 5mins
38% in 15mins
50% in 30 mins
72% in 60mins
Not calculated 17% in 5mins
30% in 15mins
46% in 30 m ins,

69% in 60mins
Not Calculated 21% in 5mins
39% in 15mins
56% in 30 m ins,

80% in 60mins
Not calculated
Solubility: 9
Very little was left on the application spot.
Faint blue application spot, and intensely coloured zones on the strip.
Very good solubilty, dark zones are produced
Very good solubilty, dark zones are produced
Very good solubility, cyan maybe slightly fainter from 70%
There is a sudden drop in solubilty, the violet dye is faint and there is no or minimal cyan dye. Point of application quite dark.
Separation of dyes: 1
No separation
Two touching zones, of which the violet zone is the upper one, which consists of a deep and concentrated line with the level of the solvent edge, while just beneath is the rather circular cyan zone, which is more dispersed.
Same as 90% Conc.
Two distinct zones are formed, with the violet dye as a semi-oval zone with the flat surface with the level of the solvent in the strip, and just beneath an ovala zone of the other cyan dye.
Two distinct roundish zones seperated by about 2-4mm
Only the violet dye can be seen here
Allocated Time: 45 mins 60 mins 60 mins 75 mins 75 mins 90 mins
Score: 15% 70% 72% 84% 90% 34%
Concentration Absolute (100% c. ) 90% 80% 70% 60% 50%
Comments: An intense blue coloured (ink colour) line at the edge of the solvent on the strip. It seams to leave a trailing cyan tail, which gives the 1 point in the separation score. Actually it is not bad to demostrate the two colours on their own, but there is no clear cut separation. It's a fast solvent and has very good solubility. Very similar to 90%, perhaps slightly improved separation A wider separation would be more desirable, however an overall good solvent (diluted) both in terms of speed and solubility. The wider separation makes this diluted solvent gain more marks from the 70% Meehanoic acid, however it can be seen that the zones were slightly less intense in colour. Slow, very faint, and cyan component is absent.


BEST Separation: 60% Methanoic Acid - 80-90mins.
Note: The solvent makes both zones appear as green/pistaccia colour. However as the strip is let to dry in air, the green colour changes back to the original violet and cyan dye. Similarly, on adding this ink to a solution of Formic acid, a green solution is produced.

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