Chapter 202: Be careful, don't break the instrument

"I have a scientific research support system ( to find the latest chapter!
Seeing the sly smile of senior sister, Xu Qiu shook his head helplessly, answered 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, for a total price of 188 thousand."
"It's pretty fast, okay, we come back tonight to discuss it."
"By the way, there is still a problem. The Handan laboratory has insufficient space. TRPL can't put it down. Maybe it will take up the desk in your office utility room..." Anyway, sooner or later, Xu Qiu was just right. Speaked on the phone.
After a few seconds of silence, Wei Xingsi said: "Okay, I see." After speaking, he hung up the phone.
"Ms. Wei agreed or didn't agree?" Han Jiaying asked suspiciously.
"I don't know," Xu Qiu shook his head and said, "If he disagrees, he can only be moved with affection and understand reason."
The three of them had dinner, and after the rest, they all returned to the laboratory. They wrote a half afternoon summary, and it was time for a change of taste.
Chen Wanqing shut down the reaction and used the dot-plate method to confirm that there were few side reaction products, so the product was not separated and purified. The product obtained in the first step was directly used as the raw material for the second step to continue the reaction.
Xu Qiu and Han Jiaying plan to explore the liquid chromatograph in the laboratory. They mainly want to try whether the instrument is good or not. After all, they will use it tomorrow or the day after tomorrow.
Before Xu Qiu had mastered the relevant knowledge of liquid chromatography through the system:
Its main function is to separate or purify several mixed substances. It is usually used to separate and purify small molecular products with fixed molecular structures.
For example, Xu Qiu and his colleagues plan to synthesize PDI molecules today. After the reaction, the possible substances are imidazole, unreacted perylene tetracarboxylic dianhydride, amine molecules, monoamine substituted perylene tetracarboxylic dianhydride, and diamine substituted perylene. Tetracarboxylic dianhydride, other by-products are almost negligible.
Their target product is diamine-substituted perylene tetracarboxylic dianhydride, which is mainly related to the separation of it from monoamine-substituted perylene tetracarboxylic dianhydride.
As for other imidazoles, unreacted perylene tetracarboxylic dianhydride, and amine molecules, they are better removed.
The operation of liquid chromatography experiments is also commonly referred to as "column", where "column" refers to silica gel column.
In the experiment operation, firstly fill the silica gel column evenly, then place the sample on the upper end of the silica gel column, and then continuously inject the solvent from top to bottom under a certain pressure, or called mobile phase, eluent.
When the polarity of the solvent is sufficient to dissolve some components in the sample, it will move these components downwards until it moves to the lowest end to be collected, and then the collected solution with sample components is subjected to rotary evaporation. The purified fraction is obtained.
There are three commonly used solvents, which are petroleum ether, dichloromethane and ethyl acetate according to their polarity from low to high.
The program of the liquid chromatograph can be set to change the polarity of the solvent in the silica gel column from low to high.
For example, the first is 100% volume fraction of petroleum ether, then 99:1 petroleum ether: dichloromethane, then slowly transition to 100% dichloromethane, then 99:1 dichloromethane: acetic acid Ethyl, and finally transition to 100% ethyl acetate.
Of course, in most cases, only two solvents are needed to achieve sample separation and purification.
...
"Xu Qiu, do you know how to operate the instrument?" Chen Wanqing asked when they saw them turning on the liquid chromatograph.
"There is an operating manual on the computer desktop. Let's check it out." Xu Qiu opened the operating instructions and read it pretentiously. Of course, it was mainly for Han Jiaying. He already knew it.
"Well, you guys be careful, don't break the instrument." Chen Wanqing said cautiously. She is responsible for this instrument.
"Senior sister, don't worry, it will definitely not break." Xu Qiu said confidently.
The school girl looked at the operating instructions very carefully, while Xu Qiu was distracted to observe the instrument.
At the top of this liquid chromatograph, a 10 by 10 test tube rack is placed. In the working mode, it is controlled by the system. After each standard is filled with about 80% of the volume of the solution, it can be automatically in sequence. Replace with an empty test tube and continue to receive liquid.
There is also a detector equipped with a deuterium lamp. By testing the UV absorption spectrum of the outflow solution, the sample signal is detected, which is more accurate than the naked eye, and some colorless samples cannot be seen by the naked eye, but the UV absorption spectrum is Can be detected.
The pipes used by the instrument are thin pipes of a few millimeters in diameter, and most of the pipes are hidden inside, and there are only six pipes at the outside interface.
Two of them are used to connect the upper and lower ends of the silica gel column. The current state is that the silica gel column is not connected, and the two are directly connected.
Two of the other four thin tubes are used to extract the solvent. They are labeled A and B respectively. The default polarity of the A tube is smaller than that of the B tube, and two empty barrels are now connected; the other two thin tubes , One leads to the test tube rack and the other leads to the waste bucket.
There is no sample today. 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 barrel of 4 liters of petroleum ether, a barrel of 4 liters of ethyl acetate, and an empty 4 liters of waste liquid bucket, and put the ends of A tube, B tube, and waste liquid tube into it.
Dichloromethane was not chosen, mainly because of the three solvents, dichloromethane is the most toxic ~EbookFREE.me~ and 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 the main functions are not many, including start, pause, stop, and switch the status of work waste.
The parameters that can be set mainly include the initial volume fraction ratio of the solvent drawn by the A and B tubes, the solution flow rate, and the volume fraction ratio of the solvent drawn by the A and B tubes after a few minutes, and the solution flow rate. Once the latter is successfully set, 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 to 100:0, the flow rate to 1 ml per minute, and the state to waste liquid state.
Everything is ready, he presses the start button, the instrument emits a low sound of "duang" and "duang". The colorless and transparent liquid is continuously sucked out from the barrel of petroleum ether, circulates inside the instrument, and finally enters the waste. In the liquid bucket.
After three minutes, set the volume fraction ratio to 0:100, which took 0 minutes and the flow rate remained unchanged.
After another three minutes, set it back to 100:0, 0 minutes, and 1 ml per minute.
After another two minutes, Xu Qiu pressed the stop button to turn off the instrument. ‘That’s it. ’
Chen Wanqing was experimenting, but she had been paying attention to the movement of Xu Qiu's side. She heard the movement of the instrument there disappeared, and asked:
"The test is over, how about it?"
"It is temporarily normal, and there is no leakage. The solvent extraction process for tubes A and B is also normal. Only the detector cannot be tested because there is no sample today."
"That's good, the probability of a problem with the detector is still quite small." Chen Wanqing took a sigh of relief:
"It's probably normal."