1. What type of silica is used in FlashTubes?

2. Can I use a polar solvent with FlashTubes?

3. Is there is a possibility of mixing the flourescence indicator with compounds inside of tubes, so that the compounds are not completely pure after separation?

4. Can you pack FlashTubes with different silica types?

5. Approximately what is the ratio of compounds visible in UV-light compared to the number of compounds invisible in UV-light which cannot be purified by FlashTube chromatography?

6. What are the tube dimensions?

7. Can FlashTube chromatography be used to obtain high purity individual isoflavones?

8. Do you have information/examples on flash tubes application for obtaining high purity polar compounds?

9. I'm working with with larger samples - 100mg or more. Compound is diffusing inside the tube, and the band is becoming too big. How do I solve the problem?

10. Are you planning to make larger tubes (larger than 2008 FlashTubes) ?

11. Do you have a procedure to separate free fatty acids from mono- di- and triglycerides with flash tubes?

Detailed Questions and Answers

Q: What type of silica is used in FlashTubes?
A: TLC silica 6-35µm (micrometers)

Q: Can I use a polar solvent with FlashTubes?
A: Some combinations of polar and non-polar solvents may be difficult to use. An example could be chloroform with 5% of methanol which is very useful for TLC. With FlashTubes however, the methanol gets stuck on top of the column so the eluting solvent will be only chloroform. For TLC methanol is always present in the atmosphere of the TLC-chamber. Some other combinations can however be very useful. One example is chloroform/methanol/water/triethylamine (6:3:1:0,5) which can be used to isolate polar amines.

Q: Is there is a possibility of mixing the flourescence indicator with compounds inside of tubes, so that the compounds are not completely pure after separation?
A: The fluorescence indicator is an inorganic material which is insoluble in all solvents and will not be an impurity as a result of extraction. When filtering it is however important to use a filter (often <10µm) which does no allow the small particles of the fluorescent material to pass through.

Q: Can you pack FlashTubes with different silica types?
A: No. At this time FlashTubes are packed with only one type of silica TLC silica 6-35µm

Q: Approximately what is the ratio of compounds visible in UV-light compared to the number of compounds invisible in UV-light which cannot be purified by FlashTube chromatography?
A: Most compounds, and especially drug like molecules, absorb UV-light and are
visible on the FlashTube. We believe that the ratio absorbing/non-absorbing
compounds would be greater than 9:1, that is >90% of the compounds people
work with can be purified by FlashTube chromatography.

Q: What are the tube dimensions?
A: FT2002 - Length 125mm; Diameter 12mm FT2008 - Length 200mm;Diameter 17mm

Q: Can FlashTube chromatography be used to obtain high purity individual isoflavones?
A: FlashTube chromatography is a general method for purification of all compounds which separate on TLC. For isoflavones we believe that solvent systems used for TLC can be used for FlashTubes as well. Probably minor modifications may be needed. One advantage with FlashTubes may be with polar compounds with very low Rf values. Since they are isolated by cutting the column they need not be forced all the way through it.

Q: Do you have information/examples on flash tubes application for obtaining high purity polar compounds?
A: We have used FlashTube chromatography for purification of different polyamines. The solvent system we used was chloroform, methanol, water, triethylamine (6:5:1:0,5). A useful procedure for extraction of the silica plug was using a solvent mixture of 1M NaOH and chloroform. In this case the compounds were lipophilic enough to be extracted into the chloroform. If the compounds have no basic groups it should be possible to use for example ethyl acetate/water for extraction. The silica could also be extracted with solvent combinations like methanol, water, triethylamine (9:1:0,5) optionally adding some chloroform when less polar extraction media could be used.

Q: I'm working with with larger samples - 100mg or more. Compound is diffusing inside the tube, and the band is becoming too big. How do I solve the problem?
A: One problem with larger samples is that they are dissolved in relatively large volumes and that polar solvents are added to improve solubility. If then the column is eluted with non-polar solvents this may cause problems. In general the sample should be dissolved in a small volume and in the eluting solvent. Please provide us with more details regarding a particular separation; type of compound, eluting solvents etc. so that we will provide a specific advice.

Q: Are you planning to make larger tubes (larger than 2008 FlashTubes) ?
A: We have considered making larger tubes but we have no immediate plans for this. An alternative solution for large samples is to divide the sample in e.g. three portions and use three FlashTubes for the separation.

Q: Do you have a procedure to separate free fatty acids from mono- di- and triglycerides with flash tubes?
A: A problem with fatty acids, mono-, di- and triglycerides is that they have no UV-absorption so that they can not be detected visually on the FlashTube. However, it should be quite simple to establish a procedure where each component could be isolated at a known distance from the top of the column. You can try a TLC-system you are using and with the same volume of solvent to be used for FlashTubes. The column can be cut in 1-1.5 cm pieces and each piece analyzed for its constituents.

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