A summary of the key points of the thin-layer chromatography experiment.

related topicsAbout the preparation of CMC-Na: 1. First add the called CMC to 8/10 of the required amount of water, let it dissolve fully, bring to the boil at
heating
, then slowly add the remaining water. This is not easy to form particles in the boiling process, boiling time is short..2. The concentration of CMC solution 0.3-0.7% is more appropriate, in practice 0.4% to 0.5% most practical, the concentration is high in the future color display if there is a heating process slightly careless plate easy to blacken, the concentration is low paved out of the plate is not strong, a touch on the slag, not good to save, and point will be very tense, easy to hole..3. 0.5% CMC-Na and water bath dissolved to a full stirring solubility, if not soluble, can be added a few drops of ethanol before swelling, better soluble, but as far as possible, because after adding ethanol to make CMC-Na adhesion reduced. After full swelling, use a skimmed cotton pad to pump on the cloth funnel. Seal and refrigerate for use..4. (1) CMC-Na solution can no longer be boiled with cold water, otherwise, after a few days will turn green, moldy. Note that CMC-Na solutions that have been placed for too long may yellow and may have mold that can never be used again.(2) If you have a filtering device you can filter the CMC-Na solution directly, you don't have to wait for it to precipitate and then take the liquid (hey hey, I'm an acute son), there are two benefits one is to save the CMC-Na solution, and the other is to reverse the filtered CMC-Na solution without having to worry about pouring out the insoluble of the lower layer!) There is a way

filter the CMC solution, in the cloth funnel tile thin layer of skimmed cotton, do not make sure that every hole has not been missed Oh! Wetting degreased cotton with distilled water, starting the
spoulation pump
, after pumping can rest assured that the bold inverted CMC solution, to ensure that the filtered solution clear and transparent, and long-term placement does not precipitate..5. CMC-Na is a polymer material, and the dissolution of polymeric materials will inevitably have a process of dissolution, dissolution, so when preparation, should be called a good CMC-Na a small amount of sprinkled on the surface of water, so that its natural Subsidence, pay attention to spread out tiles, so that it can be fully soaked, so that it can be dissolved, and then can be placed in a water bath pot heating dissolved, of course, if you are not in a hurry to use the words can also be completely, directly soaked with water put that, estimated ten and a half days can also be used..6. . CMC-Na preparation, you also said a lot, I just want to say that in the CMC-Na dissolution process, you can use a heating operation of the magnetic mixer, about 5 hours, should be able to get satisfactory results. And this allows THEC-Na to dissolve and the solution to be more clarified.
CMC-Na reprocessing, a lot of people say filtering, or filtration, I think it may be slow, and easy to waste. My approach is centrifugation, 5000rpm centrifugation 20min. Pour out the upper liquid (very clear, but also eliminate the possible contamination during the filtration process.) Even more valuable is that I can collect CMC-Na below that is not fully dissolved. Continue to add to the water, you can also make!! Why not?.7. Spread CMC-Na thin sheet, first the CMC-Na dissolved completely, can be dissolved into the desired concentration after heating ultrasound treatment, and then filtering, can quickly get the liquidrequirements for thin sheet: 1. the plate requires smooth cleaning, no scratches, before use can be washed with washing liquid or soapy water, and then rinsed clean with water, dry. . 2. What kind of glass is clean: is soaked with cleaning essence is also good, soaked with acid is also good, when you feel washed clean, take it in your hand stand up, if you find that the water is not a stream, but a waterfall state, then your glass has been washed clean. In fact, the real clean glass, will soon be able to dry. . 3. How to clean the thin sheet after use, I tried to use washing powder, washing clean, repeatedly washed several times, still hanging water beads. Laying thin laminates requires glass plates to be clean, tidy and do not hang water drops. It is recommended to use lotion foam. If it can not be solved then had to give up this glass plate, some say can use hydrochloric acid. on grinding and paving requirements: 1. Thin layer analysis silicone weight and CMC-Na volume ratio of 1:4 ratio (this ratio can make the silicone plate spread out a better effect not to drop slag or too hard board) fully mixed milling, to pick up the hammer can see the mixture and hammer have a certain adhesion. That's good. Thin sheet must be smooth and oil-free, take a certain amount of solution on the board, with a thin rod guide it to cover the surface of the plate, one hand to lift the silicone plate the other hand under a gentle tap, turn the plate evenly knock. . 2. Silicone grinding, of course, is a direction, can be appropriate to add a certain amount of waterless ethanol or acetone to de-foam, can also be properly stirred and placed in a clean container ultrasound, the effect is good. The amount of hand-paved silicone is generally 10 x 20 of about 3 to 4 grams, silicone and CMC-Na dosing is generally 1:2.8 to 3, depending on the thickness of the plate to be laid and the concentration of CMC-Na. . 3. According to the use of thin sheet needs, the appropriate amount of well-developed adsorbent poured into the thin sheet, first with a small hammer to absorb the adsorbent, tilt the laminate, so that the adsorbent flow to the side of the laminate, to the adsorbent accumulation of a certain amount, and then reverse tilt the laminate, so that the adsorbent reflow; . 4. Place the slide on the platform and spoon the paste silicone and spread it evenly over the surface of the slide. When paving the board, you can fall down the middle of the plate, you can also fall down an edge, you can also use a glass rod to lead the solution tiled on the glass plate, when you should also pay attention not to introduce small bubbles.
if necessary, you can hold 10 fingers in both hands on the glass plate, rhythmic bumps, so that the paste silicone distribution is balanced. Especially the four corners of the carrier plate, easy to be higher than the other parts of the glass plate, so pay special attention. Upside down the plate, the surface should look smooth and flat, no pores. After the thin sheet is laid, it must be placed on a flat countertop, otherwise it is difficult to ensure that the thickness of the silicone on the board is uniform. . 5. Paved thin sheet first let it dry a little, that is, do not see a clear watermark, put in the oven with a temperature below 50 degrees and open the wind
dry
30 minutes, and then heat up dry to dry, pay attention to heat up too fast in the process of use may occur layering phenomenon is not conducive to separation, the above method by my more than two years of practice effect is better and time-consuming and not too long. . 6. 10g adsorbent adds 3 drops of 95% ethanol to drive away bubbles; About the expander: 1. The isolated sample is relatively acidic, generally added acid in the expander 2. Added methicillin because the sample is acidic, the amount of acid and the acidity of the substance is in a positive relationship, water may be because your sample is a nucleotide with acid water to do a buffer, the purpose is to make the spot smooth, not off the tail, spread well. . 3. Saturation is also very important, the edge effect is very serious may wish to use the lower end immersed in the expander filter paper attached to the inner wall of the expander cylinder, so that the saturation effect will be better 4. 1) in the layer tank port to apply the appropriate amount of Vraslin, increase the sealing; 2) to expand the size of the edge effect of the agent, determine the length of the expander balance time, the general balance time in 30 minutes can be. . 5. The polarity of organic solvents, methanol>chloroform, so in chloroform: methanol: ammonia (10:1:0.6) this expander, if the polarity is slightly larger, the proportion of methanol can be appropriately reduced; chloroform: methanol: ammonia 10:1:0.6 and 20:2:1.2 polarity is certainly the same, is that a problem? there is also a problem, in this expander, methanol dosage is small, and methanol is volatile, easy to produce edge effects, pay special attention to the balance of the expander and the sealing of the analyzer. . 6. Different unfolding systems mean that there should be at least one solvent (preferably a solvent in different groups) rather than a different proportion. Or use a different fixed phase. about unfolding: 1. What is the cause of sample trailing in TLC? How do I fix it? . 2. TLC samples run into almost a line, spots do not have a clear separation, would like to ask what is the cause of this? How should this be resolved in general? the cause of problem 1 is basically the same: a, for some chemical components with acid and alkaline, partial ionization in the solution, in fact, there are molecules, ions when unfolding, with neutral organic
reagement
development is bound to appear two types of layering behavior, resulting in de-tailing or even a line. b, the expander selection is not appropriate c, the sample sample is too large, sample overload solution: a, add a few drops of foriconic acid or ice acetic acid to the expander; b, when expanding with ammonia saturation c, reduce the amount of sample d, references, adjust the type of expander, proportion 2. I would like to ask, about TLC secondary unfolding, is the first start of color display and then continue to expand a second time, or after the first unfolding, another expander then unfolded ah? asked which big man to point out the secondary unfolding of TLC. The secondary unfolding is determined according to the sample, but certainly after the first unfolding, the plate is dried or blow-dried, and then put into another unfolder to expand, some samples are expanded in a different direction, and the original direction is vertical. So it depends on the actual separation of the sample. Generally because of the sample composition, polarity differences are large, some about color: 1. In the work of the study of the use of sulfuric acid ethanol color for quantitative analysis of varieties, but where the addition of CMC plate is easy to paste, especially when the temperature is above 100 degrees, after the use of water plate without CMC auxiliary, there will be no baking phenomenon, so it can also be inferred that CMC easy to paste with sulfuric acid.
Feel the key to the auxiliary water board is silicone G and water ratio to reach about 1:3.5, and after grinding to be coated as soon as possible, can not be easily solidified and difficult to coat, I am a hundred people can not solve, CMC also has a similar
stabilizer
role 2. "0.5% of the plate heating time will be black for a long time", is after the layering, color display bar, I have encountered the same situation, this only strictly control the heating color time. This question should be answered this way: but where the CMC plate is easy to bake, especially when the temperature is above 100 degrees, if you switch to water plate without CMC auxiliary to do, there will be no baking phenomenon, but not CMC auxiliary plate is too soft, dotting easy to point out holes, there is a good way to adjust the concentration of CMC to 0.1%, so it is not easy to blacken. Don't believe you try, our side of the drug testing office have done this 3. About the thin sheet heating blackened problem, in fact, it is easy to solve: when sprayed after the color agent does not have to bake in the oven, you can use an electric hair dryer blowing on the back of the board can show color. We generally use this method in our laboratory, simple and clean. If you do not want to use the oven baking, must use with glass windows, when you see the color display will be taken out, otherwise it is not good to control the coloring time, time is too long, CMC easy to carbonize black In my experience, the blackening of the thin-layer version is associated with an over-concentration of CMC-Na, and if you look, you will find that when there is a strong sulphuric acid in the color agent, the heating time becomes slightly longer (other color agents are fine), My teacher said this is because the thick sulfuric acid carbonized CMC-Na, in fact, you just need to reduce the concentration of CMC-Na . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
generally I am color-showing after the electric blowing wind, to blow evenly, the hair dryer away from the board distance is farther, to prevent parts will be black. also pay attention to color agent, if the color agent contains sulfuric acid, heating time must be mastered, not too long. . 5.CP2000 in 277 pages of suline TLC
amino acids
appear to be problematic: ... With "positive butanol butanone-enriched ammonia solution water" as the expander, after unfolding, dry, sprayed with tritone acetone solution (1-50) ,... . throne and ammonia solution to show color reaction, make the whole plate color, tritone oxidation suline and then with the release of ammonia gas reaction generated points can still be seen in the whole board, other amino acids do not want to see. Amino
acids
thin layer identification process, before the color display will be the finished plate baked in the oven for a period of time, to ensure that the expander swing clean, the effect is good about the cracking plate: 1. plate.