Medical chemistry experiments.

, chemical reagents and related knowledge there are many kinds of chemical reagents, the world's chemical reagents classification and classification standards are different. China's chemical reagent products have national standards (GB), the Ministry of Chemical Industry standards (HG) and enterprise standards (QB) three levels.(i) Chemical reagent classification chemical reagents thousands of products, according to their use can be divided into - reagents, standard reagents, high-purity reagents, special reagents, indicators and papers, organic synthetic reagents, biochemical reagents, clinical reagents and so on. Here are a few of them:
1. General reagents General reagents are the most commonly used reagents in the laboratory and can be divided into four grades according to the amount of impurity content. The level, specifications, markings and scope of application of general reagents are set out in Table 28-1.
2. Standard reagents Standard reagents are standard substances that measure the chemical amount of other substances (to be measured) and are characterized by high subject content and accuracy and reliability. Standard reagents are generally produced by large reagent plants and tested in strict accordance with national standards.
3. The main body content of high purity reagents high purity reagents is equivalent to that of superior pure reagents, but the impurity content is lower than that of superior pure and benchmark reagents, and the specified impurity items tested are 1 to 2 times more than the same excellent grade pure or benchmark reagents. High purity reagents are mainly used for the decomposition of samples in trace or trace analysis and the preparation of test fluids. High purity reagents are also common reagents, such as HCl, HF, HClO4, HNO3, H2SO4, etc.
4. A special reagent is a reagent with a special purpose. Similar to high-purity reagents, specialized reagents not only have a high subject content, but also a low impurity content, unlike high-purity reagents, impurity components that interfere with a particular use need only be controlled below the limits that do not cause significant interference, and reagents used in various instrument analyses such as
chromatography
analysis standard reagents, gas chromatography carriers and fixation fluids, liquid chromatography fillers, thin layer analysis reagents, ultraviolet and infrared
spectral
pure reagents, magnetic resonance spectrometry analysis reagents, etc. are all special reagents.(ii) The selection of chemical reagents inexperiments, according to the requirements of the experiment, such as the sensitivity and selectivity of the analytical method, the content of the analytical object and the accuracy of the analysis results, etc. , reasonable selection of the corresponding level of chemical reagents. Because the price of the same reagent of different specifications varies greatly, the level of reagent selection should be low and not high, so as not to cause waste under the premise of meeting the experimental requirements. The selection of reagents should consider the following points:
1. Standard solutions commonly used in titration analysis, generally first with A. R. The reagents are roughly matched and then marked with the working reference reagents. G. can also be used in experiments that are not very demanding on the results of the analysis. R. Or A. R. Reagents replace work baseline reagents. Other reagents used in titring analysis are generally pure.
2. In terms of body content, G. R. And A. R is the same or similar, but the impurity content is different. If the experiment requires a high subject content of the reagent used, such as constant chemical analysis, A. R. Reagents, if the content of reagent impurities is strict, G. should be used. R. Reagents.
3. G is generally used in instrument analysis experiments. R, A. R. or special reagents, high purity reagents should be used when determining trace components.
4. If the purity of existing reagents does not meet certain experimental requirements, it is often used once to more than once before purification. Common purification methods are distillation (liquid reagents) and recrystration (solid reagents).
5. Organic chemical experiments can not be separated from organic solvents and reagents, solvents not only as a reaction medium, in the product purification and reprocessing is also often used. Commercially available organic solvents, reagents have industrial grade, chemical purity and analytical purity and other specifications, the higher the purity, the more expensive.
in organic synthesis, solvents and reagents of appropriate specifications are often selected according to the characteristics and requirements of the reaction in order to enable the reaction to go smoothly. Some organic reactions have high requirements for solvents and reagents, and even the presence of trace impurities or moisture can affect the rate, yield, or even success or failure of reactions. Therefore, it is also important to understand the properties and purification methods of solvents and reagents commonly used in organic reactions.(iii) Storage of chemical reagents storage of chemical reagents is also an important work of laboratory personnel. It is not appropriate to store too many flammable, explosive and toxic chemical reagents in a general laboratory and should be requisitioned at any time according to the dosage. In order to prevent chemical reagent failure and even cause accidents, general chemical reagents should be stored in well-ventilated, clean,
driding
rooms, and pay attention to prevent moisture, dust and other substances pollution. At the same time, according to the nature of the reagent to take the corresponding storage method:
1. See light-prone reagents such as AgNO3, KMnO4, CHCl3, CCl4, H2O2, etc.
2. Easy-to-oxidize reagents in contact with air, such as SnCl2, FeSO4, etc.
3. Volatile reagents such as ethanol, ether, acetone, ethyl acetate, etc. should be stored in brown bottles and placed in a dark place.
4. Easy to erode the glass reagents, such as hydrofluoric acid, fluorinated salts, caustic alkalis, etc. should be stored in plastic bottles, alkali bottles should be rubber plugs, not abrasive plugs.
5. Water-absorbing reagents, such as waterless sodium carbonate, sodium hydroxide, potassium hydroxide, calcium chloride, sodium peroxide, sulfuric acid and other bottles should be strictly sealed.
6. Interacting reagents, such as volatile acids and ammonia, oxidants and reducers, should be stored separately.
7. Flammable and explosive reagents, such as benzene, ether, acetone and other flammable reagents should be stored in a cool and ventilated place, not direct sunlight, explosive reagents such as bitter acid, perchloric acid and perchlorate, hydrogen peroxide and high-pressure gases, etc., should be stored at low temperatures, not with flammable materials, when moving or activated must not be violent vibration, high-pressure gas vents are not allowed to face people.
8. Highly toxic reagents, such as cyanide, antimony, mercury, chlorpyure, etc., should be placed in a safe, set up a two-door special custody, access must be two people present, and make a good record to avoid accidents.
9. Special reagents should adopt special storage methods. Reagents that need to be stored at low temperatures must be stored in the refrigerator, work benchmark reagents that have been dried or burned to constant weight should be stored in dryers, sodium metal should be sealed in liquid paraffin, white phosphorus should be immersed in water, etc. (iv) The use of chemical reagents when the chemical reagents are divided into laboratories, they are usually solid reagents in wide-mouth bottles, liquid reagents or preparation solutions are placed in fine-mouthed or drip bottles, and light-easy-to-decompose reagents (e.g. AgNO3, KMnO4, H2O2, CH3Cl, etc.) should be placed in brown bottles. Each reagent bottle should be labeled with the name, specification or concentration of the reagent and the date.
and apply a thin layer of wax to the outside of the label to protect it. During the experiment, various reagents can be obtained as needed. Before using reagents, you should clear the label to avoid using the wrong reagents. When using, open the cap (plug) and place it back on the test bench. If the stopper is not flat but flat, it can be clamped with the index and middle fingers or placed on a clean surface dish, and it must never be placed on a horizontal platform to avoid contamination.
after taking the reagent should be timely cap (plug), absolutely prohibit the cap (plug) Zhang Guan Li Dai, and then put the reagent bottle label out to the original place. It is worth pointing out that you should not touch chemical reagents by hand, pay attention to savings when using reagents, how much to take, and how much to use, and that recycling value should be put into recycling bottles. 1. The use of solid reagents (1) should be obtained with a clean, dry spoon. The two ends of the spoon are the size of two spoons, take a large number of solids with a large spoon, take a small amount of solids with a small spoon. Special keys should be used. Used spoons must be washed and dried before they can be used again to avoid staining the reagents.
(2) take care not to take more, multi-take reagents can not be reversed back to the original bottle, can be placed in a designated container for others to use.
(3) When adding solid reagents to the test tube (especially the wet test tube), a small spoon may be used or the medicine may be placed on a folded note, and then extended into the test tube 2/3, and then the test tube vertical, the drug can all fall to the bottom of the test tube. When adding a block solid, tilt the test tube so that it slides slowly down the tube to avoid breaking the bottom of the test tube.
(4) If the particles of solids are large, they can be studied in a clean, dry study. Note that the amount of solids in the research should not exceed 1/3 of the research capacity.
(5) If a certain mass of solid reagents are used, the solids can be weighed on a scale or analyzed on a scale or analysis of
tensions
according to the nature of the solids and the required quality accuracy, such as the solids placed in clean paper, surface dishes, small beo bowls or weighing bottles.
(6) toxic drugs should be taken under the guidance of teachers. 2. The use of liquid reagents (1) when taking liquid reagents from a drip bottle, use a dropper in the drop bottle. When using, first remove the dropper from the liquid surface, pinch the rubber head with your fingers to drain the air, and then insert the dropper into the reagent, relax your finger to inhale the reagent.
When dropping reagents into the test tube, clamp the dropper with your thumb, index finger and middle finger, suspend it above the test tube mouth, and never put the dropper into the test tube or touch the pipe wall, so as not to stain the dropper. Put the dropper back into the original drop bottle after use and do not misplace it. The dropper containing the reagent shall not be flat or tilted upward to prevent the reagent from flowing into the rubber head, corroding the rubber head and contaminating the reagent.
pouring method when using liquid reagents from the fine-mouthed bottle at the same time (2). First remove the stopper, place it on the countertop, hold the container (e.g. test tube, tube, etc.), hold the labeled side of the reagent bottle in your right hand (so as not to get the label dirty when pouring liquid), pick up the bottle and gradually tilt it so that the mouth of the bottle rests against the wall of the container, slowly pour the reagent into the container, or inject it into the berrotted cup along a clean glass rod.
pour out the desired amount, lean the reagent bottle against the container and slowly lift the bottle. To prevent droplets left at the mouth of the bottle from flowing to the outer wall of the bottle. Over-taken reagents must never be reversed back to the original bottle.
(3) quantify liquid reagents, a tube or piped pipe can be used. If you do not need to take accurate quantities, you do not need to use a tube or pipet, as long as you learn to estimate the amount of liquid removed from the bottle. Such as qualitative analysis experiments using dropper to take liquid, lml quite a few drops, 5 ml solution accounted for a few parts of the test tube volume and so on. It is generally required that the amount of solution poured into the test tube does not exceed 1/3 of its volume. (v) Classification of chemical hazardous substances Toxic and harmful substances such as hazardous chemicals are a very important and internationally controlled special commodity in China, according to customs
statistics
, each year China's dangerous chemicals and other toxic and harmful substances import and export types of more than 3000 kinds, amounting to more than 40 billion U.S. dollars, a large number of dangerous chemicals and other toxic and harmful substances imported into China's environment and people's health has brought more and more serious impact.
of various reasons, China's hazardous chemicals at home and abroad every year occurred in various types of safety accidents as many as hundreds. Therefore, it is very important to know and chemical dangerous goods safety knowledge. According to the national standard (GB13690-92), China will be chemical dangerous goods divided into eight categories (data are divided into nine categories, the addition of the ninth category, that is, miscellaneous):
1 categories: explosives, such as TNT, trinitrophenol and so on.
2: compressed or liquefied gases, such as hydrogen, ethylene oxide, etc.
3: flammable liquids, such as ether, acetone, petroleum ether, ethanol, etc.
4 categories: flammable solids, self-igniting articles and wet flammable articles, such as white phosphorus, sodium metal, etc.
categories: oxidants and organic peroxides such as H2O2, KMnO4, etc.
categories: poisons and infected substances, such as cyanide, arsenic, etc.
7 categories: radioactive substances, such as 60Co, 3H, etc.
8 categories: corrosion products, such as strong acids, strong alkalis and so on.
, acid-base standard solution preparation and acid-base titration . The preparation of acids and alkalis and the determination of their concentration are the most basic operations in chemical and biological laboratories and are often carried out in various types of research. This experiment is divided into two parts: (i) the preparation and comparison of acid-base standard solution (Experimental Purpose
1. Master the method of indirect method of making acid and alkali solution;
2. Learn the operation method of acid (alkali)-type titration tube.
"Experimental Principles"
. NaOH absorbs water vapor and CO2 from the air easily. Hydrochloric acid is easy to wave out HCl gas so they can not use direct method to make standard solution, can only be used indirect method to make, and then use the reference substance to determine its exact concentration. When the acid-base reaction reaches the theoretical end point, CNaOHVNaOH-CHClVHCl usually calculates the exact concentration of the other solution, depending on the volume ratio of the acid-base solution, as long as the concentration of any one of the solutions is determined.
the "Experimental Content"
. 1. Indirect method of preparation of acid-base solution;
2. acid-base standard solution is relatively titration.
Reagents and Equipment
1. Instrument 500mL glass plug fine mouth bottle, 10mL measuring tube, 500mL rubber plug fine mouth bottle, 250mL berries, bench scales, 50mL acid titration tube, 50mL alkaline titration tube, 250mL conical bottle.
2. Reagent NaOH solids, thick HCl, 0.1mol/L HCl, 0.1mol/L NaOH, 0.05% methyl orange, 0.1% phenolic.
"Experimental Methods and Steps"
1. The preparation of HCl solution with a clean volume of 3.5mL thick HCl, diluted with distilled water to 500mL, into the abrasive reagent bottle, cover the plug, shake well, label spare.
2. Preparation of NaOH solution.