Chapter 205: Simulation Lab II started

"I have a scientific research support system ( to find the latest chapter!
(Correction: There was a problem with the previous flow rate setting. Now it is 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, the thin tubes entering and exiting the silica gel column were filled with liquid, and there were no more bubbles.
At present, the sample in the sample column does not move, and does not move downward under the entrapment of the solvent. This is because the current solvent is pure petroleum ether and has very low 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 quickly increased rashly, because the instrument can only control the ratio of the solvent currently extracted.
In other words, the instrument's control of the mobile phase solvent ratio is lagging, and the actual mobile phase solvent ratio in the silica gel column may be ten seconds or ten 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 to move in the chromatographic column is different.
That is to say, once the polarity of the mobile phase is too high and the critical value of multiple components is reached 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 has failed. .
Then it is necessary to remix the sample, spin steam, fill the column, and pass the column.
This liquid chromatograph can only process one column at a time, so when 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 beside him to watch.
As time goes by, the volume fraction of B in solvents A and B slowly increases.
"Brother, I haven't responded yet, the dichloromethane is more than 20%, and I am still motionless."
"This shows that the polarity is still not in place. Slowly rise."
"I feel like the column costs a lot of solution." Seeing that the liquid level of the solvent tank next to it has dropped slightly, Han Jiaying spit out.
"Yes, and it is a mixed solvent with reaction products, it is more troublesome to reuse, at most it is used to wash bottles," Xu Qiu smiled, "but dichloromethane and petroleum ether, each is ordered Four barrels. Two barrels of ethyl acetate were ordered. It must be enough for a while."
After a while, when the software showed that the current B% was 32% in real time, a touch of red finally appeared in the blank silica gel column, and a clear signal appeared in the UV detector.
"Moved, it moved."
"Well, I'm ready to work." Xu Qiu maintained B% at 30%.
In the silica gel column, the touch of red slowly changed to a mass of red, and then to a red.
When the red head reaches the lower end of the blank chromatographic column, Xu Qiu changes the collection mode from waste liquid mode to working mode.
The light red solution is sprayed with a needle into the No. 1 test tube on the test tube rack.
After ten seconds, the No. 1 test tube is full, the needle automatically moves to the position of No. 2 test tube, and the spraying continues...
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 results of this boarding session with the results of the morning. "There is only one sample point, and it is still very shallow. From the point of view of the location, it is the main product."
Han Jiaying pointed to the needle above. "The solution here is sprayed so fast, it didn't take long for me to fill the test tube."
"We are using high-pressure liquid chromatography with a flow rate of 30 milliliters per minute. To convert, the volume of a test tube is about 10 milliliters, which is about four tubes a minute, while ordinary liquid chromatography is usually only 1 milliliters 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 puzzledly: "Will that not reduce the separation effect?"
"Because we only have two sample points, and their separation degree is relatively high, we don't have to worry about this problem." Xu Qiu explained: "If it involves more difficult to separate samples later, you can appropriately reduce the flow rate to improve the separation effect. "
...
As the solution continues to spray, the color of the liquid in the rear tube becomes more and more red.
In the first practice, Xu Qiu was more cautious. He clicked the plate 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 that it is the same product.
More than twenty minutes later.
"Brother, our test tubes are almost used up." Han Jiaying pointed to the test tube rack, which has now reached the 97th test tube.
"Wait, let's replace another set of clean test tubes." Xu Qiu also had a headache. At this time, the red color in the silica gel column had not completely disappeared. Another 100 test tubes might not be enough.
When the No. 100 test tube was filled, Xu Qiu paused the instrument, then transferred the test tube rack with the test tubes on it to a fume hood next to it, covered it with aluminum foil, and then took another test tube with 100 new test tubes. Shelf, continue to collect.
"Would you like me to go to the sample warehouse to get some test tubes." Han Jiaying actively suggested that they had only used 300 test tubes before. They thought it was enough, but now it seems that once the column is not necessarily enough, although it can be washed Net reuse, but it is bound to slow down the experiment significantly.
"It's really a problem, let me think about it..." Xu Qiu's gaze wandered, his liquid chromatograph, test tube rack, Han Jiaying, solvent bucket, and waste liquid bucket suddenly lit up, "With that, we can use waste liquid. Tube, collect the solution directly, and replace the test tube with a disposable PE cup."
"This method is good," Han Jiaying nodded repeatedly, "The capacity of a PE cup is equivalent to twenty ordinary test tubes, and it doesn't need to be cleaned after use."
"The advantages are indeed obvious, but the risks are also high. In case a little bit of other components are mixed in, then the entire 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 still 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, and rinsed it with dichloromethane solvent in a fume hood, and then simply built a solution collection device with an iron stand and a long tail clip. Put the PE cup taken by the school girl directly under the device.
Continue to collect and switch to waste liquid mode.
After more than 30 minutes, a total of seven cups of solutions were collected, and Xu Qiu tested each cup of solution. The ingredients were all single products.
At this time, the red strip in the blank silica gel column basically disappeared, and the sprayed solution was basically colorless and transparent.
Xu Qiu inserted the waste liquid tube back into the waste liquid bucket, and asked the school girl: "Do you want to collect the second product?"
"Um..." Han Jiaying thought for a while and said, "Let's collect it. This is the first time we have crossed the column. A little perfection can add more experience, in case the main product is still in the column."
Xu Qiu was amused, "Can these 100 test tubes and seven cups be by-products?"
"Hey, just in case."
"Okay, it's up to you." Xu Qiu didn't insist. Anyway, he did it for more than an hour, and he didn't care about adding another clock.
He continued to slowly increase the content of component B, collecting the second product in a similar way.
This time the amount was relatively small, so I collected it directly with test tubes. Once 16 test tubes were shared, all the collections were completed.
I checked it with the board, and it turned out to be 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 the pipeline was rinsed with pure dichloromethane for three minutes, and finally it was left idling for three minutes to remove the solvent in the pipeline. , Shut down the instrument.
‘Although it is a disposable blank silica column, if it is rinsed, it should be reusable appropriately. ’
"God, we used so many solvents." Han Jiaying said with emotion suddenly.
"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 there are less than half of the 4 liters of petroleum ether left, and methylene chloride has been used almost quickly. One quarter again reminded him, "Don't forget to replace the petroleum ether later, or the column will dry out and a major problem will occur."
"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 100 test tubes and seven cups to the rotary steamer next to him.
Because he had already confirmed that the sample was pure by tapping the plate before, he directly merged several test tubes with adjacent numbers into the same eggplant-shaped bottle. After tapping the plate again to confirm the purity, he started rotary steaming.
There are more than 2 liters of solvent in total, and the rotary steaming time is very long.
In the case of rotary steaming operation, there is generally no risk in controlling the vacuum degree.
So Xu Qiu watched the experiment progress of the school sister and her sister while spinning steaming, and occasionally chatted.
The school girl walked the column in an orderly manner, taking samples with test tubes or PE cups, ordering a board from time to time, and sometimes Xu Qiu would also go to help.
The senior sister also worked continuously, first after processing two reactions, and then casting two more reactions.
However, after finishing all these things, she was free. Chen Wanqing talked to him and the school girl for a while, and Xu Qiu also shared with her the problems encountered when crossing the pillar today.
After the rotary steaming, Xu Qiu used a stainless steel spatula to scrape the bright red powdery product on the wall of the eggplant-shaped bottle and transfer it to a glass bottle. A total of 4.8 grams of product was obtained. The preliminary judgment was PDI-2, which was very pure.
After that, Xu Qiu and Han Jiaying had almost no rest, using the liquid chromatograph and the rotary steamer alternately, even eating meals in rotation.
The high-intensity experimental life of six or seven hours of continuous work is back.
No way, on the one hand, the high-pressure liquid chromatography experiment cannot be suspended for a long time, because the sample column may dry out, thereby forming a fault, causing the experiment to fail;
On the other hand, someone must watch it during operation, otherwise, in case of an accident, such as liquid leakage, the injection volume of 30 ml per minute is no joke.
Fortunately, they successfully purified today's three reaction products, and the yield and purity were very good.
As for Han Jiaying's other reaction, after she added a new amine molecule and increased the reaction temperature, the result of the dot pattern changed to 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.
Of course, the experiment was not all smooth sailing, and some small accidents occurred:
For example, there are two dots in a cup of solution when you tap the plate, and you have no choice but to pour it into the waste bucket.
Another example is accidentally breaking two empty test tubes.
...
On the school bus back to Handan, Han Jiaying found a vacant seat for the Second Company, then got inside, and Xu Qiu sat on the outside with him.
Chen Wanqing smiled meaningfully towards them, and chose a back seat to sit down.
Not long after getting in the car, the school girl looked blurred and looked tired.
After a while, Xu Qiu, who was closing his eyes, suddenly felt a head on his shoulder leaning over. He turned his head and looked at it. The school girl pouted her little mouth, and her sleeping face was quite cute.
He adjusted his sitting posture and closed his eyes again. Today's experiment of this intensity is really overwhelming.
When Xu Qiu opened his eyes again, he found that he was asleep just now. At this time, he and Han Jiaying became dependent on each other~EbookFREE.me~ However, the school girl seemed to be sleeping relatively deep, no Signs of waking up.
He looked out the window and was almost at school, so he gently woken her up.
"Um... brother, did I just sleep?"
"I'm almost at school, so I won't go to the laboratory today. I'll take you back to the bedroom directly later."
"Good~"
...
Xu Qiu returned to the bedroom, took a shower, and got a lot of energy, and then entered the simulation laboratory II.
I got this feature more than two months ago, and it can finally be launched today.
The ability of the simulation experimenter is equivalent to Xu Qiu's experimental ability, and all the experimental characterization methods involved, Xu Qiu has reached the fourth order before.
Most of them are accumulated during his own practical operation, and a small part of the practical operation is insufficient. He also specially 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 the routine tests such as nuclear magnetism, elemental analysis, and mass spectrometry of the three products they separated and purified today.
Although these data cannot be directly used in reality, they can be used to judge the molecular structure and the purity of the sample, which is instructive for subsequent work.
In addition, he also arranged the preparation of organic solar cell devices, performance testing, and performance optimization.
When he was reviewing the manuscript, he had an idea that was 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 too many kinds of donor materials for him to try, so I still find the opportunity to talk to Teacher Wei and purchase another batch.
If you synthesize by yourself, whether it is real synthesis or analog synthesis, it is too much trouble.