Name: separating mixtures by polarity
Uploaded: 2020-03-26T07:22:28.000Z
Duration: 3 min 7 s
Channel: JoVE

柱层析是一种利用填充柱根据化合物与固定相之间的相互作用来分离物质的技术，固定相通常以微小珠状颗粒的形式存在。颗粒间的空隙充满溶剂。打开柱子可使溶剂流经固定相。当将混合物加至填充柱顶部，随后加入更多溶剂时，混合物便进入流动相，并随溶剂流经固定相。
混合物中的每种组分与固定相的相互作用方式不同。某些组分与固定相的相互作用较弱，因此在色谱柱中移动较快，而另一些组分与固定相的相互作用较强，因而移动较慢。这使得不同的化合物分离成不同的区带，并被收集到少量的馏分中。从而实现各化合物的纯化。
那么，可以利用哪些性质来分离混合物呢？其中最常用的性质之一是极性。在此基础上，常使用硅胶（一种二氧化硅）作为固定相。硅胶通过其表面形成的羟基（-OH）与化合物发生偶极-偶极相互作用和氢键作用。因此，极性化合物会与固定相强烈相互作用，而非极性化合物则与固定相的相互作用较弱。
可用于分离的其他性质包括分子大小、电荷和疏水性。将固定相装填到色谱柱中的常用方法是使用固定相与溶剂混合形成的浆液。随后，通过让更多的溶剂流过色谱柱，使浆液压缩，从而完成固定相的装填。固定相必须均匀装填，不能有气泡、空通道或干燥区域，这一点至关重要。这些缺陷会扰乱流动相的流动，并导致区带混合。
选择色谱柱时，其直径应根据待分离样品的体积来确定。样品应在色谱柱顶部形成一层薄而均匀的覆盖层。若样品层过厚，则会导致谱带展宽。色谱柱的长度取决于化合物在固定相上的分离效果。对于与固定相具有相似亲和力的化合物，需要使用较长的色谱柱才能实现充分分离；而亲和力差异较大的化合物混合物，则可在较短的色谱柱上实现分离。
在本实验中，您将通过首先装填并制备硅胶柱来探索柱层析技术。随后，您将使用该柱分离绿色食用染料中的有色组分。

柱层析

Column Chromatography

柱层析
在有机化学实验室中，存在多种用于纯化和分离化合物的技术。当待分析化合物的量少于10克时，最可靠的微型分离技术之一是柱层析。该技术根据混合物中各化合物的物理性质（如溶解度、极性、疏水性、分子大小和电荷）进行分离。
<h4>色谱法基础</h4>
任何色谱系统的三个主要组成部分是固定相、流动相以及待分析的样品混合物。在柱色谱中，固定相通常是微米级的微珠，这些微珠均匀地填充在一根垂直的柱子中。流动相（也称为溶剂）持续从柱子顶部加入，并在重力作用下或通过泵控制的流速流经固定相。
将样品溶解于少量溶剂中，然后加至色谱柱顶部。加入更多溶剂以推动样品流经固定相。混合物中的各组分因其性质不同，在流动相与固定相之间发生分配，形成不同的区带。
与固定相相互作用强的化合物将比与固定相相互作用弱的化合物移动得更慢。因此，与固定相相互作用弱的化合物会比相互作用强的化合物更早从色谱柱中流出，即更早洗脱。化合物与固定相相互作用的强度由滞留因子（Rf）定义，该因子是组分迁移距离与流动相迁移距离的比值。滞留因子需首先通过薄层色谱法测定。
<img src="/CDNSource/lm/labs/63/63_Concepts_1.jpg" alt="色谱方程 Rf=距离比，公式。" data-altupdatedat="1761830439000" />
较高的滞留因子值表明样品与固定相之间有较强的相互作用，因而需要较长时间才能洗脱。较低的滞留因子值表明样品与固定相之间的相互作用较弱，因而洗脱速度较快。由于不同化合物因具有不同的Rf值而在色谱柱中分离成独立的区带，并在不同时间依次洗脱，因此可通过在色谱柱下方分段收集流出溶剂，从而实现各组分的单独分离。
<h4>柱层析注意事项</h4>
色谱柱是一种垂直放置的玻璃或塑料管。其尺寸可从几厘米（例如巴斯德移液管）到数米（例如工业用色谱柱）不等。色谱柱的直径取决于待分离样品的量，而长度则取决于分离的难易程度。实现样品在柱中高效地分离成清晰条带的关键在于形成较薄的样品层，因此确定合适的柱直径是至关重要的一步。相对于色谱柱直径而言，若上样体积过大，则会产生比相同上样体积在更大直径柱中更宽且分辨率更低的条带。
选择色谱柱长度时，必须考虑各组分的 Rf 值。对于滞留因子相近的组分，分离可能较为困难，需要使用更长的色谱柱以分辨出各个独立的谱带。而滞留因子差异较大的化合物则可能无需长柱，因其较易实现分配分离。在选择固定相时，应选用能使各组分具有不同滞留因子的固定相。
装填色谱柱是进行柱色谱分离过程中最关键的步骤。装入柱中的固定相质量应至少为样品质量的20倍。如果色谱柱底部没有多孔筛板，则应使用棉花和一层薄沙进行填充，以防止固定相从柱出口流失。
装填色谱柱有两种方法：干法装柱和湿法装浆法。在干法装柱中，固定相以粉末形式直接转移至色谱柱中。随后用流动相/溶剂多次洗涤色谱柱，以确保溶剂充分渗透硅胶柱的每一部分。如果操作不当，该方法可能增加柱内出现干燥斑块、沟流和气泡的风险。这些缺陷将影响色谱柱对混合物各组分的分离能力。
浆液法可制备出更均匀的填充柱，且不会产生气泡、干燥区域和沟流。该方法需将固定相与溶剂混合，形成均匀的浆液。然后将浆液转移至色谱柱中，同时轻敲柱壁以去除形成的气泡。在此步骤中，若色谱柱带有活塞，应保持其开启，以便溶剂顺利排出。
<h4>硅胶色谱法</h4>
分离化合物混合物时可利用多种不同的性质，例如分子大小、电荷和疏水性。在有机化学中，用于分离化合物的一种性质是极性。其中，硅胶和氧化铝胶是最常用的固定相。硅胶具有极强的极性，能与极性化合物形成强烈的偶极-偶极相互作用。此外，由于硅胶表面含有羟基（-OH），还能与待分析物形成氢键。
混合物中极性最强的组分与硅胶结合紧密，在柱中移动较慢；而非极性组分在流动相中溶解度更高，在柱中移动较快。因此，混合物各组分必须具有不同的极性。与固定相相互作用较强的组分，可通过让极性流动相流经色谱柱而被洗脱出来。
<h4>参考文献</h4>
<ol>
	<li style="font-size:17px">Shuler, M.L., Kargi, K., DeLisa, M. (2017). 生物工艺工程：基本概念。新泽西州上萨德尔河：Prentice Hall。</li>
	<li style="font-size:17px">Harris, D.C. (2015). 定量化学分析。纽约：W.H. Freeman and Company。</li>
</ol>

柱层析  
在有机化学实验室中，存在多种用于纯化和分离化合物的技术。其中最可靠的分离方法之一……

Education

教育

JoVE Lab Manual

Chemistry

化学

层析柱

separating mixtures by polarity

Column chromatography separates compounds in an organic chemistry lab by using differences in physical properties. It is especially useful for microscale separations when less than 10 grams of material is available for analysis. The method can separate a mixture based on solubility, polarity, hydrophobicity, size, and charge.

Any chromatography system has three main parts: the stationary phase, the mobile phase, and the sample mixture. In column chromatography, the stationary phase is usually made of microscale beads packed into a vertical column. The mobile phase is a solvent that flows through the column by gravity or at a controlled rate with a pump. The sample is first dissolved in a small amount of solvent, added to the top of the column, and then pushed through with more solvent.

As the mixture moves through the column, its compounds partition between the two phases. They form separate bands because each compound interacts differently with the stationary phase. Compounds that interact strongly move more slowly. Compounds with weaker interactions elute, or leave the column, earlier. The retardation factor, or Rf, describes this interaction by comparing how far a component travels with how far the mobile phase travels. A high Rf means strong interaction and slow elution. A low Rf means weaker interaction and faster elution. The Rf is determined first with thin layer chromatography, and the separated compounds are collected in fractions as they leave the column.

The size and shape of the column affect how well the separation works. A chromatography column is a vertical glass or plastic tube that can range from a few centimeters, such as a Pasteur pipette, to meters in industrial systems. The column diameter depends on the amount of sample, and the length depends on how difficult the separation is. Thin sample layers give the best band separation, so using the right diameter is important. If too much sample is loaded for the column diameter, the bands become broader and less defined. When components have similar Rf values, a longer column may be needed to separate them. If their Rf values are very different, a shorter column may still work well. The stationary phase should also be chosen so the components have different Rf values.

Packing the column correctly is one of the most important steps. The stationary phase should weigh at least 20 times more than the sample. If there is no porous disk at the bottom, cotton and a thin layer of sand are used to stop the stationary phase from leaving the column. The column can be packed by a dry method or by a slurry method. In the dry method, the powder is added directly and then washed with solvent so the mobile phase can move through the silica gel. If this step is not done well, dry patches, channels, and air bubbles can form. These defects reduce how well the mixture separates. The slurry method mixes the stationary phase with solvent first, then transfers it into the column while tapping the sides to remove bubbles. If the column has a stopcock, it should be open so the solvent can drain.

Silica gel chromatography is a common way to separate compounds by polarity. Silica gel and alumina gel are the most used stationary phases for this purpose. Silica gel is very polar and can form dipole-dipole interactions and hydrogen bonds because of its -OH groups. Polar components bind more strongly to silica gel and move slowly through the column. Non-polar components stay more soluble in the mobile phase and move faster. Because of this, the mixture must contain components with different polarities. More polar compounds are eluted by using a polar mobile phase through the column.

Separating Mixtures by Polarity

lab techniques

Measuring with Accuracy in the Lab

Measuring with accuracy in the lab starts with careful records, the right tools, and correct reading of data. Scientists use lab notebooks to record how an experiment was done. These notes include the amounts of materials used and each step of the procedure. Without that record, an experiment cannot be repeated in the same way. Balances and glassware are used to measure solids and liquids for experiments. The precision of a measurement depends on the equipment used. Digital balances show the...

scientific measurement and lab skills

Graphs, Curve Fit, and Standard Deviation

Two-dimensional graphs help students compare an independent variable with a dependent variable in science data. In a chemistry example, temperature is the independent variable and volume is the dependent variable. After data are collected, the relationship between the two measurements must be quantified so it can be evaluated and compared with other relationships. A graph can also show when no relationship exists between the two variables. To make a two-dimensional graph, each data point needs...

stoichiometry, product yield, and limiting reactants

stoichiometry-product-yield-and-limiting-reactants

Balancing Equations and Reactant Limits

Chemical equations show how reactants change into products during a reaction. Stoichiometry is the study of the relative amounts of reactants and products. It is based on the Law of Conservation of Mass, which says matter is neither created nor destroyed. Because atoms are only rearranged, the number and identity of atoms must match on both sides of a reaction. That is why a chemical equation must be balanced. A balanced equation has the same number of atoms for each element in the reactants...

redox reactions

Oxidation States in Redox Reactions

Oxidation states help identify redox reactions. In a redox reaction, oxidation is the loss of one or more electrons, and reduction is the gain of one or more electrons. These reactions are often tracked by changes in oxidation state, also called oxidation number. Each atom in a molecule has an oxidation state. This number shows how oxidized an atom is compared with its free elemental form. It is written as the charge an atom would have if every bond were purely ionic. In that model, bonding...

ideal gas law

Gas Laws Behind the Ideal Gas Equation

The ideal gas equation brings together the main gas laws used in chemistry. Gases have molecules that are far apart, so their behavior is described with four measurable variables: pressure, volume, number of moles, and temperature. The ideal gas law links these variables with the gas constant, R, which equals 8.314 J·K−1 mol−1. Boyle’s law describes the link between pressure and volume. When temperature and the number of moles stay constant, pressure and volume change in opposite directions.

acid and base concentrations

Acids, Bases, and pH in Titration

Acids, bases, and pH explain how acidic or basic a solution is. An Arrhenius acid releases hydrogen ions when it dissolves in water, while an Arrhenius base releases hydroxide ions. These reactions also create conjugate partners: an acid forms a conjugate base after losing hydrogen, and a base forms a conjugate acid after losing hydroxyl. Every acid has a conjugate base, and every base has a conjugate acid. pH measures the amount of hydrogen ions in a solution. The pH scale runs from 0 to 14...

buffers

Buffer pH and the Common Ion Effect

Buffer solutions help keep pH steady when acids or bases are added. In water, an Arrhenius acid (HA) dissociates into hydrogen ions, H+, and a conjugate base, A-. More hydrogen ions make a solution more acidic and lower its pH. An Arrhenius base (BOH) dissociates into a conjugate acid, B+, and hydroxide ions, OH-. Strong acids and strong bases usually change pH a lot because they react completely in water and raise the amount of H+ or OH-. Buffers reduce those pH changes. A buffer usually...

enthalpy of reaction

Reaction Heat, Hess’s Law, and Calorimetry

Reaction heat is explained through enthalpy, Hess’s law, and calorimetry. These ideas show how heat moves during chemical reactions and how scientists measure it. Thermodynamics is the study of heat energy and other forms of energy, such as work. Its laws are used across science, from biology to physics. The first law says energy is conserved in an isolated system. Energy can change form, such as thermal energy becoming work, but it cannot be created or destroyed. The second law of...

solubility

Solubility in Water and Other Solvents

Solubility describes how much of a solute can dissolve in a specific solvent. It is usually reported as solute mass per solvent volume or as solute mass per solvent mass. For example, sodium chloride has a solubility of 36 g per 100 mL of water at room temperature. If solubility is given by solvent mass, that mass must be converted to volume for later calculations. Temperature changes solubility. Sodium carbonate dissolves at about 7 g per 100 mL of water at 0 °C, 22 g per 100 mL at room...

metal flame emission

Flame Test Metal Color Clues

Flame testing uses a metal sample and a flame to identify a substance by its color. Each element gives off a characteristic light emission in the flame, so the color can help distinguish one element from another. This same idea appears in fireworks, where different metal components create different colors. The color comes from energy absorbed by the metallic component. When a species absorbs energy, that energy can go into translation, vibration, rotation, or electron excitement. Electron...

balmer series

Hydrogen Emission Lines

Hydrogen emission lines show how electrons move between fixed energy levels in the Bohr model. Niels Bohr proposed this model for the hydrogen atom in 1913. In this model, an electron can only occupy certain orbits, and it cannot exist between them. These energy states are labeled with the quantum number n. The ground state is n = 1. Higher values, such as n = 2, 3, 4, and so on, are excited states. An electron changes state only by absorbing or emitting energy equal to the difference between...

beer's law

Absorbance Spectra and Beer-Lambert Analysis

Absorbance spectra and the Beer-Lambert Law show how light can be used to study molecules in solution. When light hits a substance, it may be absorbed, transmitted, or reflected. A substance often interacts with a range of wavelengths, and each wavelength can affect the molecules or atoms in a different way. When a molecule absorbs light, that energy can be used for translation, vibration, rotation, or electron excitement. Electron excitement is especially important in spectroscopy because it...

concentration dependence

Reaction Order and Rate Constants

Chemical kinetics describes the speed of a chemical reaction. The rate depends on the reaction mechanism, the complexity of the reaction, and the number of reactants involved. Reactant concentration also affects how fast a reaction happens. The rate law is the experimental relationship that connects these factors to reaction rate. In the rate law, each reactant contributes through a reaction order. The general form is r = k[A]^m[B]^n for aA + bB + ... → cC. Here, r is the reaction rate, k is...

temperature dependence

Reaction Rate, Arrhenius, and Catalysts

Chemical kinetics explains how fast a reaction happens and why that speed changes. The reaction rate is the speed of a chemical reaction. It is defined as the change in concentration of a reactant or product over time. Reaction speed depends on several factors, including the concentration of the reactants and the temperature of the reaction. Each reactant affects the rate in a specific way. That relationship is described by the rate law. The rate law is an equation that connects the...

galvanic cells

Battery Power from Redox Reactions

Electrochemistry studies how chemical change and electrical energy are linked. In this branch of chemistry, electrons move from one species to another. That movement can either produce current or be driven by an applied current. The main reaction in electrochemistry is the oxidation-reduction, or redox, reaction. A redox reaction has two half-reactions. Oxidation is the loss of electrons, and reduction is the gain of electrons. These changes also shift the oxidation state of each substance. The...

electrolytic cells

Electroplating with Electrolytic Cells

Electrochemistry links electrical energy with chemical change, and electrolytic cells show how electricity can drive a nonspontaneous reaction. In these reactions, electrons move from one species to another. The key chemistry is a redox reaction, or oxidation-reduction reaction, which happens in two half-reactions. Oxidation is the loss of electrons, and reduction is the gain of electrons. The substance that loses electrons is the reducing agent, and the substance that gains electrons is the...

proper lab notebook keeping

Recording a Reproducible Lab Experiment

Accurate lab notebook records are essential in science and organic chemistry labs. Without clear notes, descriptions, quantities, and observations, an experiment cannot be repeated or checked. Good record keeping supports reproducibility, which means other people can follow the same work and get similar results. A laboratory notebook is useful in school labs, research settings, and industry. It can also become a legal record when an idea, process, substance, or technique is patented and...

basic organic chemistry techniques

Organic Lab Glassware and Safe Handling

Organic chemistry labs use specific glassware, careful weighing steps, and controlled heating to keep reactions safe and accurate. Beakers and Erlenmeyer flasks are often used for mixing or holding solvents, but they are not meant for measuring volume unless only an approximate amount is needed. Volumetric glassware is used when a precise volume matters. This group includes graduated cylinders, volumetric pipettes, and volumetric flasks. A graduated cylinder is commonly used in the organic lab...

melting points

How Impurities Change Melting Points

Melting point helps identify an organic compound by showing the temperature where a solid turns into a liquid at 1 atmosphere of pressure. It is a physical property, like solubility, density, color, and electronegativity. Because the exact start of melting is hard to measure, the result is reported as a range. The lower end is when the first drops of liquid appear. The upper end is when the last solid has melted. Scientists compare this range with literature values to help identify a compound. <br...

boiling points

Boiling Point and Vapor Pressure

Boiling point and vapor pressure are key physical properties of a liquid. For a pure compound, the boiling point can help identify the substance. In experiments, the boiling point is usually recorded as a range because exact values are hard to measure and may differ by a few degrees from the literature value. Vapor pressure explains why a liquid boils. In a sealed container, some molecules at the liquid surface gain enough energy to escape into the gas phase. At the same time, some gas...

recrystallization

Purifying Crystals by Solubility

Purifying crystals by solubility is a key organic chemistry technique. Recrystallization uses differences in solubility to separate a desired solid product from starting materials, solvent, and impurities. It is one of the three standard purification methods, along with distillation and extraction. Solubility is the maximum amount of a substance that can dissolve in a fixed volume of solvent at a given temperature. Different solutes dissolve in different solvents, and their behavior can vary...

extraction

Separating Mixtures with Solvent Extraction

Solvent extraction is a common way to separate and isolate a target compound in organic chemistry. In this process, a solute moves from one phase to another so it can be separated from unreacted starting materials or impurities. Extraction is also useful when a product is dissolved in a reaction solvent that is hard to remove by evaporation, such as a solvent with a high boiling point. There are three main types of extraction. In solid-liquid extraction, the solute moves from a solid phase...

simple distillation

Separating Liquids by Boiling Point

Separating liquids by boiling point is the goal of distillation. A miscible mixture contains liquids that mix evenly, and it can be heated so that the more volatile liquid evaporates first. Volatility is a liquid’s tendency to vaporize, and boiling begins when bubbles form in the liquid phase. In a closed container, liquid and vapor can reach equilibrium, which means the rate of vaporization equals the rate of condensation. The pressure from the vapor above the liquid is called vapor pressure.

steam distillation

Steam Distillation and Low-Boiling Separation

Steam distillation is a separation method for temperature-sensitive organic compounds. It works best when the organic compound is immiscible in water, meaning the two liquids do not mix. The method helps remove the organic molecule from a non-volatile contaminant without using the higher temperatures needed for many other separations. In steam distillation, the immiscible mixture is heated until both water and the volatile organic compound distill together. The vapor rises to a condenser,...

thin-layer chromatography

TLC Separation by Polarity

Thin-layer chromatography (TLC) separates compounds in a mixture by polarity. It uses the same basic parts as other chromatography methods: a stationary phase, a mobile phase, and the solute. In TLC, the stationary phase is a thin coating on a plate instead of material packed into a column. The stationary phase in most TLC systems is polar silica gel, a form of silicon dioxide. Its surface has OH groups that can form hydrogen bonds. The sample is first spotted on a pencil start line with a...

column chromatography

Column chromatography separates compounds in an organic chemistry lab by using differences in physical properties. It is especially useful for microscale separations when less than 10 grams of material is available for analysis. The method can separate a mixture based on solubility, polarity, hydrophobicity, size, and charge. Any chromatography system has three main parts: the stationary phase, the mobile phase, and the sample mixture. In column chromatography, the stationary phase is usually...

hydrolysis of an ester

Soap Formation from Triglycerides

Triglycerides are lipids made of a glycerol backbone linked to three fatty acids. They are common in vegetable oils and animal fats. Plant lipids are the basis of vegetable oils, while animal lipids are used as lard or general sources of fats. A fatty acid has a long carbon chain, usually between 12 and 20 carbons, with a weak organic acid at one end. Some fatty acids contain double bonds. These are unsaturated fats. The double bond usually gives the chain a bent, cis shape. As a result,...

synthesis of luminol

Luminol Chemiluminescence in Forensics

Luminol chemiluminescence shows how a chemical reaction can produce light and help with blood detection. Chemical reactions may be endothermic or exothermic, depending on whether they absorb or release heat as reactants become products. The enthalpy of a reaction is the energy difference between reactants and products, or ΔH. A positive ΔH means the reaction is endothermic. A negative ΔH means it is exothermic. Many reactions do not happen in a single step. They can pass through intermediates...

esterification

Ester Formation and Everyday Fragrances

Esters are organic compounds with a carbonyl group attached to an oxygen that connects to another alkyl or aryl group. Their general formula is RCOOR'. They are often made by reacting a carboxylic acid with an alcohol in an esterification reaction. In this process, the hydroxyl group of the acid is replaced by an alkyl or aryl group. Many simple esters have familiar fruit and flower smells because their structures are small and less complex. Formic acid and methanol can combine to form methyl...

identification of unknown aldehydes and ketones

identification-of-unknown-aldehydes-and-ketones

Carbonyl Tests for Aldehydes and Ketones

Aldehydes and ketones are carbonyl compounds, which means they contain a C=O functional group. A ketone has two alkyl or aryl groups attached to the carbonyl carbon. Acetone is the simplest ketone, with two methyl groups. An aldehyde is similar, but it has at least one hydrogen attached to the carbonyl carbon. Formaldehyde is the simplest aldehyde, and acetaldehyde has one hydrogen and one methyl group. The carbonyl carbon in both aldehydes and ketones is electrophilic because the oxygen atom...

uv-vis spectroscopy of dyes

How Dyes Absorb Visible Light

Dyes absorb visible light because their molecular structure lets them interact with specific wavelengths. When light hits a substance, some light is absorbed and the rest is reflected or transmitted. The color we see depends on the wavelength that is reflected. A blue substance reflects blue light, around 430 to 480 nm, and absorbs the complementary orange region, around 590 to 630 nm. Compounds that do not absorb in the visible range appear colorless to the human eye. Light also has energy and...

identifying alcohols

Alcohol Tests for Primary, Secondary, and Tertiary

Alcohol tests can help sort alcohols by structure and reactivity. Alcohols are organic molecules with a hydroxyl group attached to an alkyl or aryl group, written as ROH. If the carbon with the hydroxyl group has one R group, the alcohol is primary. If it has two R groups, it is secondary. If it has three R groups, it is tertiary. Alcohols can also be aromatic when they contain a benzene ring. Phenol is the simplest aromatic alcohol. To identify an alcohol, chemists can use its chemical...

chemistry

Comprehensive, curriculum-focused videos for both instructors and students in introductory chemistry lab courses.

https://cloudfront.jove.com/files/banners/scicat/labbio.jpg

Learn how column chromatography separates mixtures by polarity, Rf values, and band movement through a packed column using silica gel and solvents.

Separating Mixtures by Polarity | JoVE K12

通过这段 3 分钟的教师指南，准备教授 柱层析。涵盖 JoVE Lab Manual 上 Chemistry 实验的关键准备步骤。

Chemistry 中的 柱层析 教师准备 - 993+ 观看次数 | JoVE Lab Manual

在这段 9 分钟的学生实验流程视频中，逐步学习 柱层析 的操作步骤。属于 JoVE Lab Manual 上的 Chemistry 系列。

Chemistry 中的 柱层析 学生实验流程 - 3.9K+ 观看次数 | JoVE Lab Manual

Separating Mixtures by Polarity

Description

Transcript