I decided to talk to Dr. Robert Mustacich, one of the world's experts on chromatography. He was able to answer some of my questions as well as tell me some things about his job.
Dr. Mustacich owns and works at RVM Scientific here in Santa Barbara. There they work with gas chromatography. They have applied for a patent to develop smaller chromatographs than the ones used today. In the photo, Dr. Mustacich is holding a prototype of the miniature chromatograph he is working on.
While I was there, I got to see several different chromatographs and the different types of tubing that are used as the stationary phase in gas chromatography. There is very small diameter tubing and very large diameter tubing. You can buy tubing that is thirty meters long with an inside diameter of only 50 microns! Inside of this tubing is a thin layer of a polymeric substance that, when the gas is pumped through, absorbs the gas. The different gases used will be absorbed at different levels and will go through the tube at different rates. This is how you can tell what kind of gas it is.
I took with me some of the results from my experiments and showed them to Dr. Mustacich. He said that my results were very good, even though the results from the candy test were very light and hard to see. He told me that sometimes thin-layer chromatography cells are made so that when you shine ultra-violet light on them you can see where the different spots of the solute are. This comes in handy when testing invisible substances such as helium gas or hydrogen gas. He said that without looking he could not tell whether the thin-layer cells that I was using were meant to reflect ultra-violet light but, when I got home, if I could, I might want to try it because the yellows were very faint and light. I tried this at home with my younger sister's black light but unfortunately, the thin-layer cells that I was using are not made to reflect the light, so his suggestion did not work.
Dr. Mustacich showed me some of the different kinds of tubing that he is using and even gave me a small sample to take home. He showed me the latest kind of tubing which is made out of glass, with the thin polymeric coating on the inside. The glass tube is coated in steel. This is useful because it won't break if dropped and still works the same. Unfortunately, it is very expensive and only made by one company on the East Coast. I also was able to see one of the most common kinds of tubing used. This was made out of glass and had the thin polymeric coating on the inside. This tubing comes in all different sizes. The sample I have is a very common size with an inner diameter of 250 microns.
I also asked some questions about the solvent that I was using with my thin-layer chromatography and if it was the best choice for my experiment. Using his library, I was able to get the molecular structure for F.D.&C. Yellow Dye #5. After looking at the ingredients of the solvent, we discussed possible solvents that I might want to try if I had time. He said that changing the solvent might actually make the results worse since the solvent I was using came with the thin-layer chromatography set and was probably designed for those specific thin-layer cells. Therefore, if I changed the solvent I was using, it might not work with my thin-layer cells. He suggested that I stay with the solvent that I was using for the rest of my project and only if there was time, change it. He suggested that since F.D.&C. Yellow Dye #5 was slightly acidic, I might want to try vinegar as a solvent. By using vinegar, I might be able to protonate some of the Yellow #5 and therefore it might show up better on the paper.
We also talked about extracting the dye from the shells of the candy bits. I told him about the process that I was using now and he suggested that I might want to use rubbing alcohol instead of the vinegar to extract the dye off of the candy. The rubbing alcohol would evaporate faster leaving me with a somewhat more concentrated amount of the dye. He also suggested that since my process was working well, this technique might only work a small amount better and therefore may not be worth the time.
Talking to Dr. Mustacich was really helpful to me. He was able to answer all
of my questions about chromatography. By going to RVM Scientific, I was able to
see several different chromatographs first hand and I also got to see several
different types of tubing. My experience with Dr. Mustacich was a great one and
I was able to learn many things about chromatography.
Project researched and
documented by Ann VanBlaricum
Disclaimer: These pages were written in 1997 while the author was a sophomore in high school taking AP Chemistry. Hence, the author is not an expert on this subject, she cannot vouch for the accuracy or currency of these data or the links.