I Have a Research Support System

Seeing the senior sister's sly smile, Xu Qiu shook his head helplessly, picked up the phone, turned on the speakerphone, and said:

"Teacher Wei, TRPL and I have negotiated with Qiu Heming, including the detector, sample chamber and two lasers, the total price is 188,000."

"It's pretty quick, okay, let's discuss it when we come back tonight."

"By the way, there is another problem. There is not enough space in the Handan laboratory, and TRPL can't fit it. Maybe it will occupy the desk in the utility room of your office..." Anyway, sooner or later, Xu Qiu simply said Speak out on the phone.

After a few seconds of silence, Wei Xingsi said: "Okay, I understand." After speaking, he hung up the phone.

"Does Teacher Wei agree, or not?" Han Jiaying asked suspiciously.

"I don't know either." Xu Qiu shook his head and said, "If he doesn't agree, then he can only show emotion and reason."

The three of them had dinner, and after a break, they all returned to the laboratory. They wrote the review for half an afternoon, and it was time for a change.

Chen Wanqing shut down the reaction and confirmed that there were very few side reaction products by the spot plate method, so she did not separate and purify the product, and directly used the product obtained in the first step reaction as the raw material for the second step reaction to continue the reaction.

Xu Qiu and Han Jiaying planned to explore the liquid chromatograph in the laboratory, mainly wanting to test whether the instrument works well, after all, they will need it tomorrow or the day after tomorrow.

Xu Qiu has already mastered the relevant knowledge of liquid chromatography through the system:

Its main function is to separate or purify several substances mixed together, and it is usually used to separate and purify small molecule products with fixed molecular structure.

For example, for the PDI molecules that Xu Qiu and the others plan to synthesize today, after the reaction, the substances that may exist include imidazole, unreacted perylenetetracarboxylic dianhydride, amine molecules, monoamine-substituted perylenetetracarboxylic dianhydride, and diamine-substituted perylene Tetraformic dianhydride, other by-products are almost negligible.

Their target product is diamine-substituted perylenetetracarboxylic dianhydride, which mainly involves the separation of it and monoamine-substituted perylenetetracarboxylic dianhydride.

As for other imidazoles, unreacted perylenetetracarboxylic dianhydride, and amine molecules are all relatively easy to remove.

The experimental operation of liquid chromatography is also commonly known as "passing the column", where the "column" refers to the silica gel column.

When performing experimental operations, first fill the silica gel column evenly, then place the sample on the upper end of the column filled with silica gel, and then continuously inject the solvent, or mobile phase, eluent, from top to bottom with a certain pressure.

When the polarity of the solvent is enough to dissolve certain components in the sample, it will move down with these components until they are collected at the lowest end, and then the collected solution with sample components can be rotated to evaporate. Purified components were obtained.

There are three commonly used solvents, which are petroleum ether, dichloromethane and ethyl acetate according to the polarity from low to high.

The liquid chromatograph can be programmed to change the polarity of the solvent going to the silica gel column from low to high.

For example, start with 100% by volume petroleum ether, then 99:1 petroleum ether:dichloromethane, then slowly transition to 100% dichloromethane, then 99:1 dichloromethane:acetic acid Ethyl ester, and finally transition to 100% ethyl acetate.

Of course, in most cases, only two solvents are needed to separate and purify the sample.

...

"Xu Qiu, do you know how to operate the instrument?" Chen Wanqing asked after seeing them turn on the liquid chromatograph.

"There is an operating manual on the desktop of the computer. Let's check it out." Xu Qiu opened the operating manual and pretended to read it. Of course, it was mainly for Han Jiaying, and he already knew it by heart.

"Well, be careful, don't damage the instrument." Chen Wanqing said cautiously, she was in charge of this instrument.

"Sister, don't worry, she won't play badly." Xu Qiu said confidently.

The school girl read the operating instructions very carefully, while Xu Qiu was distracted by observing the equipment.

On the top of this liquid chromatograph, there is a 10 by 10 test tube rack. In the working mode, controlled by the system, after each standard is filled with about 80% of the volume of the solution, it can be automatically Replace an empty test tube and continue to receive liquid.

There is also a detector with a deuterium lamp. By testing the ultraviolet absorption spectrum of the effluent solution, the signal of the sample is detected, which is more accurate than the naked eye. Moreover, some colorless samples cannot be seen with the naked eye, but the ultraviolet absorption spectrum is can be detected.

The pipelines used in the instrument are all thin tubes with a diameter of a few millimeters, and most of the pipelines are hidden inside, and there are only six external connections.

Two of them are used to connect the upper and lower ends of the silica gel column. In the current state, the silica gel column is not connected, and the two are directly connected.

Of the other four thin tubes, two are used to extract the solvent, marked with tube A and tube B respectively. The default polarity of tube A is smaller than that of tube B, and two empty barrels are connected now; the other two thin tubes are , one leads to the test tube rack and the other leads to the waste container.

There are no samples today, so Xu Qiu mainly intends to test whether the pipeline is unobstructed, and whether the routine functions of the instrument and software are normal.

He took a 4-liter barrel of petroleum ether, a 4-liter barrel of ethyl acetate, and an empty 4-liter waste liquid barrel, and put the ends of the A pipe, B pipe, and waste liquid pipe into it respectively,

Dichloromethane is not selected, mainly because of the three solvents, dichloromethane is the most toxic, while the other two are almost non-toxic.

Then, he opened the software, entered the account password to log in, connected the instrument to the computer, and entered the operation page.

The page design is very complicated, but there are not many main functions, including start, pause, stop and switching of working/waste status.

The parameters that can be set mainly include the volume fraction ratio of the solvent extracted from tubes A and B initially, the solution flow rate, and the volume fraction ratio of the solvent extracted from tubes A and B after a few minutes, and the solution flow rate. Once the latter is set successfully, the volume fraction, The solution flow rate will vary linearly according to the number of minutes set.

Xu Qiu set the initial volume fraction ratio as 100:0, the flow rate as 30 ml per minute, and the status as waste liquid.

Everything was ready, he pressed the start button, the instrument made a low sound of "duang" and "duang", the colorless and transparent liquid was continuously sucked out from the barrel of petroleum ether, passed through the internal circulation of the instrument, and finally entered the waste water. in the liquid bucket.

After three minutes, set the volume fraction ratio to 0:100, take 0 minutes, and keep the flow rate unchanged.

After another three minutes, set it back to 100:0, 0 minutes, 30 ml per minute.

After three or two minutes, Xu Qiu pressed the stop button to turn off the instrument. 'You're done. '

Chen Wanqing was doing experiments, but she had been paying attention to Xu Qiu's movement. When she heard the movement of the instrument over there disappeared, she asked:

"The test is over, how is it?"

"Temporarily normal, there is no leakage, and the solvent extraction process of tubes A and B is also normal. Only the detector can't test because there is no sample today."

"That's good, the probability of the detector going wrong is quite small." Chen Wanqing breathed a sigh of relief:

"Mostly it's normal."