(1) For security reasons.
(2) Accuracy, reliability and repeatability of the experimental results.
L standard operation runs through the whole experiment process:
① Prepare the experiment. Do the experiment in advance and have a plan. First of all, we should consult the literature, draw up the experimental plan, and then prepare the drugs and instruments used. Pay attention to the drugs used (check the basic information of drugs in advance, including melting point, solubility and toxicity? How to deal with it after use. ) Is there a laboratory and where is it? What glass instruments may be used in this experiment? Are there any glass instruments in the laboratory? Is the quantity sufficient? Is it clean? Do you want to dry it? Attention! Find all medicines and instruments in advance and put them in a fixed position for later use. For some public experimental instruments, it is necessary to negotiate in advance to solve the use.
② Experimental process. Before using the glass instrument, check it again for damage. Take the medicine according to the experimental design and start the experiment. During the experiment, people can't leave the operation site for a long time, especially in the experiment with high heating temperature. Pay attention to the phenomena in the experiment process, make records in time, and adjust your experiment plan in time according to the phenomena.
(3) After the experiment, handle the experiment in time. If it is really too late to deal with it, it should be marked to avoid being confused with other people's samples or accidentally dumped by others, and the situation should be truthfully explained in the experimental record book. Pay attention to the cleanliness of the experimental table, and the glass instruments should be cleaned and dried in time. In particular, some public appliances should not be occupied for a long time without cleaning or cleaning in time. Public drugs should be put back in time after use.
④ Analysis and summary of experimental results. After the experiment, analyze the experimental results in time. If you encounter problems that you can't solve, you can ask experienced brothers and sisters. If you still can't solve them, you should consult with the instructor in time and plan the next experiment. Summarizing the experimental results periodically in stages is convenient for finding problems and summing up the rules, which is beneficial to the next experiment.
1. Ultrasonic use
Function of ultrasonic wave: accelerate dissolution.
Cleaning instrument
Ultrasonic degassing removes bubbles in the solvent, which makes the HPLC detection baseline stable.
Precautions:
(1) First, check whether the bottle is damaged. Put the bottle in ultrasonic wave stably to avoid liquid pouring out.
② The ultrasonic water depth should be appropriate and should not be used for a long time. Pay attention to the middle stop.
③ Change the water regularly.
2. The use of constant temperature water bath:
(1) Heat the water bath to cover the material.
② The bottle should match the condenser tube.
③ Condensed water problem: the water flow is appropriate and the hose is firm. Check for aging? Can the size match? Is there something wrong?
(4) when placing the sewer pipe, be sure to put it in the sink, and finally aim at the sewer port. Be sure to put it steady, don't let the water leak to the floor, don't do it!
3. Rotating evaporator
(concentration): mainly used for continuous distillation of a large number of volatile solvents under reduced pressure. Must be connected to the circulating water pump (right)
During the running-in of the interfaces between the rotary evaporator and the circulating water pump, pay attention to lubrication and sealing, and regularly check and replace the vacuum tube, otherwise the vacuum degree will not meet the requirements.
If the vacuum cannot be drawn up or the vacuum becomes smaller, please check:
(1) Are the connectors and interfaces sealed?
(2) Whether the sealing ring and sealing surface are too worn and still effective.
(3) Whether the vacuum grease between the spindle and the sealing ring is coated.
(4) Whether the vacuum pump and its rubber tube are leaking.
(5) Whether the glass is cracked, broken or damaged.
Attention should be paid to the following issues in the process of concentration:
(1) Don't pack too much, and it is required not to exceed 1/2, otherwise it is easy to boil and pollute.
② Don't rotate too fast at first, otherwise the vacuum will not be reached and the bottle will easily fall off.
(3) Generally, the concentration process is vacuumized before heating up, and attention should be paid to timely deflation to reduce boiling. The mixture of alcohol and water is particularly easy to boil when concentrated.
(4) When turning off the pump after concentration, pay attention to the vacuum degree first, and then turn off the pump power supply, so as to avoid the reverse order, resulting in backward suction. Pay attention to protect bottles (especially large and heavy bottles) from falling into the water when unloading vacuum. Circulating water pumps generally have two suction ports, so it is necessary to observe whether the other suction port is in use when turning off the pump. Pay attention to the height of water bath when unloading bottles. If it is not suitable, lower the water level first, otherwise the bottle mouth will be immersed in water or the bottle will collide with the water bath, damaging the glass bottle and polluting the sample.
⑤ Pay attention to the replacement of water in water bath and circulating pump. It is suggested to change the water of circulating pump once a week, and the water change cycle should be shortened when the frequency of use is high. Or connect the condensate outlet with the circulating water pump to realize the timely water change of the circulating water pump.
4. Use of the suction filtration device: connected with the circulating water pump.
Filtering and degassing of solvents used in HPLC: filtering to remove some particulate impurities, using microporous membranes with pore diameters of 0.45um and 0.22um, which are divided into water phase membrane and oil phase membrane.
Matters needing attention in vacuum filtration of solvents? Suction bottle, check it first. Is it damaged? Align so as not to leak? Can't suck backwards? It is forbidden to leave the work site for a long time when filtering the solvent, so that the vacuum pump can be emptied for a long time and the service life can be shortened.
5. Use of electronic balance
(1) Precision instruments shall be leveled, and it is forbidden to move at will.
② Pay attention to the range of the balance. Usually, there is a maximum value and a minimum value on the balance.
③ Pay attention to cleaning. Be careful not to spill the weighing paper of solid samples on the weighing plate, especially some corrosive samples, and be especially careful when weighing. When it overflows, turn off the power supply of the balance, gently take out the tray, clean up the spilled articles with soft paper in time, and wipe it with cotton balls dipped in anhydrous ethanol if necessary. When weighing liquid samples, special attention should be paid to ensure that the liquid samples are not spilled on the tray, the gap between the switch doors or the LCD screen. If corroded, the balance will be inaccurate, the door will not close or it will be difficult to open and close the door. After the balance is used for a period of time, it should be calibrated with the attached calibration weight to ensure accurate weighing.
(4) Clean it up in time after use. This cleaning work includes waste weighing paper, handling spilled objects around the balance and cleaning the remaining items on the medicine spoon. If necessary, clean the medicine spoon, inorganic salts can be washed with water, organic drugs can be washed with corresponding organic solvents, and the medicine spoon should be cleaned in time and put back in place.
6. Use of oven
Drying samples: ① Pay attention to the setting of temperature. For samples with special requirements and easy deterioration at high temperature, they must be put into the oven after the temperature is stable. Otherwise, when the oven heats up, it will exceed the set temperature by 5 ~ 10 degrees for a period of time.
(2) Try to dry the samples during the day and avoid staying overnight. Pay attention to check whether there is any abnormality in time when drying samples at high temperature.
(3) When using a Petri dish or beaker, it is forbidden to fill the sample too much, and pay attention to the liquid level, especially some extract or viscous substances.
Drying equipment: ① Cleaning the glass equipment, first draining most of the water, and then sending it into the oven for drying.
② When drying the instrument, remove the rubber band and rubber plug, and try to remove the label paper.
(3) Fill in the upper layer first, and then put down the next layer. When there are dry instruments on the lower floor, you must take them out first, and then stack the wet instruments on the upper floor, otherwise the dry instruments on the lower floor will be easily cracked by the water drops of the wet instruments.
7. Reasonable use of refrigerator
Purpose: to store some medicines or personal samples that need refrigeration or low temperature freezing, such as biological samples.
Precautions for storing samples:
(1) Don't put any drugs or samples in the refrigerator, (this is a wrong idea: samples are easier to store in the refrigerator than at room temperature, and so on. ) Use them when you need to store them. Arrange neatly and smoothly, and avoid random stacking. Gently open and close the refrigerator door, otherwise the liquid sample stored on the door cabinet will easily tilt or pour out, polluting the refrigerator or other people's samples.
(2) Remember to label the sample when saving it, indicating who the sample belongs to? What are the numbers and contents? Especially for the important samples made by individuals, it must be noted that the label paper is best wrapped with plastic tape, otherwise the repeated freezing and thawing of the samples will easily lead to the label falling off and the handwriting being blurred.
(3) If the sample is sensitive to wet water vapor, pay attention to carefully wrap the bottle seal with waterproof tape to isolate it from water vapor as much as possible.
(4) Personal samples should be cleaned regularly, and useless samples should be handled in time. Don't take out, move or discard other people's samples without permission.