I Have a Research Support System

(Correction: There was a problem with the previous flow rate setting. It is now changed to 30 ml per minute instead of 1 ml per minute. The laboratory uses high-pressure liquid chromatography.)

After a few minutes, the mobile phase was running smoothly, and the thin tubes going in and out of the silica gel column were filled with liquid and there were no more air bubbles.

At present, the sample in the sample column stands still and does not move down under the pressure of the solvent, because the current solvent is pure petroleum ether, which has very little polarity.

Xu Qiu turned on the UV detector and set the volume ratio of A:B to 90:10 after 5 minutes, that is, slowly increasing the polarity of the mobile phase.

The polarity of the mobile phase cannot be increased rashly and quickly, because the instrument can only control the ratio of the solvent being extracted at the moment.

In other words, the instrument's control of the solvent ratio of the mobile phase is lagging, and the actual solvent ratio of the mobile phase in the silica gel column may be the ratio of tens of seconds or tens of seconds ago.

The principle of liquid chromatography separation and purification is mainly to use substances with different molecular structures, and the critical value of solvent polarity required for moving in the chromatographic column is different.

That is to say, once the polarity of the mobile phase is too high and reaches the critical value of multiple components at the same time, these components are not completely separated, and at the same time they move down with the mobile phase and are collected at the same time, which means that the experiment fails .

Then it is necessary to re-mix the sample, spin steam, fill the column, and pass the column.

This liquid chromatograph can only handle one column at a time, so while Xu Qiu was operating, Han Jiaying went to fill the other two samples into the small sample column to complete the sample loading.

After that, she had nothing to do, so she moved a round stool and sat next to him to watch.

With the passage of time, the volume fraction of B in A and B solvents increased slowly.

Brother, I haven't responded yet. The dichloromethane is more than 20%, and I still don't move.

This shows that the polarity is still not in place, let's increase slowly.

I feel that the column is a waste of solution. Seeing that the liquid level of the solvent bucket next to it had dropped slightly, Han Jiaying complained.

That's right, and it's a mixed solvent with reaction products, so it's troublesome to reuse. It can be used to wash the bottle at most, Xu Qiu smiled, But dichloromethane and petroleum ether, each of which is ordered Four barrels, two barrels of ethyl acetate are ordered, it must be enough for a while.

After a while, when the real-time display on the software showed that the current B% was 32%, a touch of red finally appeared in the blank silica gel column.

It moved, it moved.

Well, get ready to work. Xu Qiu kept the B% at 30%.

In the silica gel column, the smear of red slowly turned into a ball of red, and then turned into a strip of red.

When the red head reached the lower end of the blank chromatographic column, Xu Qiu changed the collection mode from waste liquid mode to working mode.

The light red solution is sprayed with a needle into test tube 1 on the test tube rack.

Ten seconds later, the No. 1 test tube was filled, the needle automatically moved to the position of the No. 2 test tube, and continued to spray...

Xu Qiu was not idle either. He dipped a small amount of the solution in the No. 1 test tube with a capillary tube, and then used a 1:1 ratio of petroleum ether: dichloromethane to spot the plate.

He compared the result of this spot board with the result of the morning. There is only one sample point, and it is still very shallow. Judging from the location, it is the main product.

Han Jiaying pointed to the needle above. The solution here is sprayed so fast, it doesn't take long, and the test tube is full.

We use high-pressure liquid chromatography with a flow rate of 30 milliliters per minute. In conversion, the volume of a test tube is about 10 milliliters, about four tubes per minute, while ordinary liquid chromatography is usually only 1 milliliter per minute. The efficiency is dozens of times worse. Xu Qiu smiled and said:

The current pressure is only more than 30 atmospheres. The maximum bearing pressure of this instrument can reach 100 atmospheres, and the corresponding limit flow rate is about 60 milliliters per minute.

The gap is so exaggerated, Han Jiaying asked suspiciously, Then won't the separation effect be reduced?

Because we only have two sample points, and their separation degree is relatively high, so we don't have to worry about this problem. Xu Qiu explained: Afterwards, if it involves samples that are difficult to separate, the flow rate can be appropriately reduced to improve the separation effect.

...

As the solution continued to spray, the color of the liquid in the later test tube became more and more red.

In the first practical operation, Xu Qiu was more cautious, spotting plates every five test tubes to judge whether the components in the test tubes were pure.

Fortunately, there is only one sample point, and the climbing position on the silica gel plate is also consistent, indicating the same product.

Twenty minutes later.

Brother, we are almost running out of test tubes. Han Jiaying pointed to the test tube rack, and it has now run to the 97th test tube.

Let's replace it with another set of clean test tubes later. Xu Qiu also had a headache. At this time, the red line in the silica gel column hadn't completely disappeared, and another 100 test tubes might not be enough.

When the 100th test tube was filled, Xu Qiu paused the instrument, then transferred the test tube rack together with the test tubes above it to the fume hood next to it, covered it with aluminum foil, and then took another test tube containing 100 new test tubes rack, continue to collect.

Do you want me to go to the sample warehouse to get some test tubes again? Han Jiaying offered to suggest that they only got 300 test tubes before, and they thought they would be enough, but now it seems that the columns may not be enough even though they can be washed. Net reuse, but bound to slow down experiments considerably.

It's indeed a problem, let me think about it... Xu Qiu's eyes wandered, liquid chromatograph, test tube rack, Han Jiaying, solvent barrel, waste liquid barrel, his eyes suddenly lit up, Yes, we can use the waste liquid tubes, collect the solution directly, and use disposable PE cups instead of test tubes.”

This method is good, Han Jiaying nodded repeatedly, The capacity of a PE cup is equivalent to 20 ordinary test tubes, and there is no need to wash it after use.

The advantages are indeed obvious, but the risk is also great. If a little bit of other components are mixed in, the whole cup of solution will have to be separated again. Xu Qiu smiled and said:

Of course we can't give up eating because of choking, we should apply this method first.

Okay, I'll go find the PE cup.

Xu Qiu paused the instrument again, took out the waste liquid tube from the waste liquid bucket, rinsed it with dichloromethane solvent in the fume hood, and then simply built a solution collection device with an iron stand and long tail clips. Put the PE cup taken by the school girl directly under the device.

To continue collecting, switch to waste mode.

After more than 30 minutes, a total of seven cups of solution were collected, and each cup of solution was tested by Xu Qiu, and the ingredients were all single products.

At this time, the red line in the blank silica gel column basically disappeared, and the sprayed solution basically returned to colorless and transparent.

Xu Qiu reinserted the waste tube into the waste bucket, and asked the school girl, Do you think we should collect the second product?

Hmm... Han Jiaying thought for a while and said, Let's collect it. This is the first time we have passed the pillar. If it is perfect, we can gain more experience. What if the main product is still in the pillar.

Xu Qiu was amused, These 100 test tubes and seven cups can also be by-products?

Hey, just in case.

Okay, I'll listen to you. Xu Qiu didn't insist. Anyway, he did it for more than an hour, and he didn't care about adding another hour.

He continued to slowly increase the content of component B, and collected the second product in a similar manner.

This time the amount was relatively small, so I collected it directly in test tubes. I used 16 test tubes in total, and all of them were collected.

Spot the plate to test it, and it really is the component with less content.

After the two products were collected, Xu Qiu removed the sample column, leaving only the blank silica gel column, then rinsed the pipeline with pure dichloromethane for three minutes, and finally idling for three minutes to remove the solvent in the pipeline , shut down the instrument.

‘Although it is a disposable blank silica gel column, it should be reusable if it is rinsed clean. '

My God, we used so many solvents. Han Jiaying suddenly said with emotion.

After all, there are a lot of samples, about 5 grams. Xu Qiu responded. He glanced at the two solvent barrels next to him. Now less than half of the 4 liters of petroleum ether is left, and the dichloromethane has been used up almost quickly. For a quarter, I reminded again, Don't forget to replace the petroleum ether later, otherwise the column will dry out and there will be big problems.

Hmm, Han Jiaying nodded, and took out the sample column and a new blank silica gel column, Then I will purify my sample.

Go. Xu Qiu carefully transferred the more than 100 test tubes and seven cups to the rotary evaporator next to it.

Because he had confirmed the purity of the sample by spotting the plate before, he directly combined several test tubes with adjacent numbers into the same eggplant-shaped bottle. After confirming the purity again by spotting the plate, he began to spin evaporate.

There are more than 2 liters of solvent in total, and the rotary evaporation time is very long.

In the case of rotary evaporation, the vacuum degree is well controlled, and there is generally no risk.

So Xu Qiu was spinning and steaming, while paying attention to the experimental progress of the junior and senior sisters, chatting occasionally.

The school girl is walking around the pillars in an orderly manner, taking samples with test tubes or PE cups, ordering boards from time to time, and sometimes Xu Qiu will help when she is too busy.

The senior sister also did continuous homework, first post-processing two responses, and then submitting two responses.

However, after finishing all this, she was free, and Chen Wanqing chatted with him and her school girl for a while, and Xu Qiu also shared with her the problems she encountered when passing the pillars today.

After the rotary steaming was completed, Xu Qiu used a stainless steel scraper to scrape off the bright red powdery product on the wall of the eggplant-shaped bottle and transferred it to a glass bottle. A total of 4.8 grams of the product was obtained, which was preliminarily judged to be PDI-2 with a very high purity.

Afterwards, Xu Qiu and Han Jiaying barely rested, they used the liquid chromatograph and the rotary steamer alternately, and even ate meals in rotation.

The high-intensity experimental life of six or seven hours of continuous work, it came back.

No way, high-pressure liquid chromatography experiments, on the one hand, cannot be suspended for a long time, because the sample column may dry out, thereby forming faults and causing the experiment to fail;

On the other hand, someone must be watching during the operation, otherwise in case of accidents, such as liquid leakage, the injection volume of 30 ml per minute is no joke.

Fortunately, they successfully purified the three reaction products today, and the yield and purity are very good.

As for Han Jiaying's other reaction, after she newly added amine molecules and increased the reaction temperature, the result of spotting became one deep and one shallow.

However, due to time constraints, there was no time for separation and purification, and only the step of mixing samples was carried out.

Of course, it was not all smooth sailing during the experiment, and there were some small accidents:

For example, if there are two spots in a glass of solution when spotting the plate, it has no choice but to pour it into the waste liquid bucket.

Another example is the accidental breaking of two empty test tubes.

...

On the school bus back to Handan, Han Jiaying found a vacant seat in Erlian, and got inside, while Xu Qiu sat on the outside.

Chen Wanqing smiled meaningfully at them, and chose a seat near the back to sit down.

Not long after getting in the car, the junior girl's eyes were blurred and she looked tired.

After a while, Xu Qiu, who was closing his eyes, suddenly felt a head leaning over his shoulder. He turned his head and looked.

He adjusted his sitting posture and closed his eyes again. Today's experiment of this intensity is really too much for him.

When Xu Qiu opened his eyes again, he realized that he had also fallen asleep just now. At this moment, he and Han Jiaying had become leaning on each other.

However, the school girl seemed to be in a deep sleep and showed no sign of waking up.

He looked out the window, and he was almost at school, so he gently shook her awake.

Hmm... Senior Brother, I fell asleep just now?

It's almost time for school, so I won't go to the laboratory today, I'll take you back to the dormitory later.

Okay~

...

Xu Qiu returned to the dormitory, took a shower, refreshed a lot, and then entered the simulation laboratory II.

Got this feature a little over two months ago and it's finally up and running today.

The ability of the simulated experimenters is equivalent to Xu Qiu's experimental ability, and all the experimental representation methods involved, Xu Qiu has already reached the fourth level or above.

Most of them are accumulated during his own practical operation, and a few of them are insufficient in practical operation. He also brushed to the fourth level in the simulation laboratory I.

Therefore, this tool is very stable.

The work he arranged for the simulation experimenters included routine tests such as NMR, elemental analysis, and mass spectrometry on the three products they separated and purified today.

Although these data cannot be directly used in reality, they can judge the molecular structure and the purity of the sample, which is of guiding significance for the follow-up work.

In addition, he also arranged organic solar cell device preparation, performance testing, and performance optimization.

When he was reviewing the manuscript before, he came up with an idea, which is to use simulation experimenters to help him explore the device performance under different combinations of donor and acceptor materials.

Simply put, it is to help trial and error.

However, there are not many kinds of donor materials for him to try now, so he still needs to find an opportunity to mention it to Mr. Wei and buy another batch.

If you synthesize it yourself, whether it is real synthesis or simulated synthesis, it is too troublesome.