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Monday, October 28, 2024

Scientific Method 2

 BIOLOGICAL METHOD

The scientific method in which biological problems are solved, is termed as biological method. It comprises the steps a biologist adopts in order to solve a biological problem.

Biological method has played an important part in scientific research for almost 500 years. From Galileo's experiment (in the 1590s) to current research, the biological method has contributed to the advancements in medicine, ecology, technology etc

Biological method also ensures the quality of data for public use.

BIOLOGICAL PROBLEM, HYPOTHESIS, DEDUCTIONS AND EXPERIMENTS

In solving a biological problem, biologist takes following steps:

  Recognition of biological problem

  Observations

  Hypothesis formulation

  Deductions

  Experimentation

  Summarization of results (create tables, graphics etc)

  Reporting the results

The details of these steps are as under

1.  Recognition of the Biological Problem

Biologists go for adopting biological method when they encounter some biological problem. A biological problem is a question related to living organisms that is either asked by some one or comes in biologist's mind by himself.

2.  Observations

As the first step in solving a biological problem biologist recalls his/her previous observations or makes new ones. Observations are made with five senses of vision, hearing, smell, taste and touch Observations may be both qualitative and quantitative Quantitative observations are considered more accurate than qualitative ones because the former are invariable and measurable and can be recorded in terms of numbers .

3.  Formulation of Hypotheses

Observations do not become scientific observations until they are organized and related to a question. Biologist organizes his/her and others' observations into data form and constructs a statement that may prove to be the answer of the biological problem under study.This tentative explanation of observations is called a hypothesis .It may be defined as a proposition that might be true. A hypothesis should have the following characteristics

  It should be a general statement.

It should be a tentative idea

  It should agree with available observations

  It should be kept as simple as possible.

  It should be testable and potentially falsifiable. In other words, there should be a way to show the hypothesis is false; a way to disprove the hypothesis.

4.  Deductions

In the next step, biologist draws deductions from hypotheses. Deductions are the logical consequences of hypotheses. For this purpose, a hypothesis is taken as true and expected results (deductions) are drawn from it.

Generally in biological method, if a particular hypothesis is true then one should expect

(deduction) a certain result. This involves the use of "if-then" logic

5.  Experimentation

The most basic step of biological method is experimentation Biologist perform experiments to see if hypotheses are true or not. The deductions, which are drawn from hypotheses, are subjected to rigorous testing. Through experimentations, biologis learns which hypothesis is correct

The incorrect hypotheses are rejected and the one which proves correct is accepted. A accepted hypothesis makes further predictions that provide an important way to furthe test its validity.

What is "Control" in experiments?

In science when doing the experiment it must be a controlled experiment. The scientist must contrast an "experimental group" with a "control group" The two groups are treated exactly alike except for the one variable being tested. For axample, in an experiment to test the necessity of carbon dioxide for photosynthesis, one can contrast the control group (a plant with freely available carbon dioxide) with an experimental group (a plant with no carbon dioxide available). The necessity of carbon dioxide will be proved when photosynthesis occurs in the control group and does not occur in the experimental group.

6.  Summarization of results

Biologist gathers actual, quantitative data from experiments. Data for each of the groups are then averaged and compared statistically. To draw conclusions, biologist also uses statistical analysis.

7.  Reporting the results

Biologists publish their findings in scientific journals and books, in talks at national and international meetings and in seminars at colleges and universities Publishing of results is an essential part of scientific method It allows other people to verify the results or apply the knowledge to solve other problem.

(THEORY?)

When a hypothesis is given a repeated exposure to experimentation and is not falsified. it increases biologists' confidence in hypothesis. Such well-supported hypothesis may be used as the basis for formulating further hypotheses which are again proved by experimental results. The hypotheses that stand the test of time (often tested and never rejected), are called theories Atheory is supported by a great deal of evidence.

Productive theory keeps on suggesting new hypotheses and so testing goes on. Many biologists take it as a challenge and exert greater efforts to disprove the theory.

(LAW?)

If the theory survives such doubtful approach and continues to be supported by experimental evidence, it becomes a law or principle A scientific law is a uniform or constant fact of nature. It is an irrefutable theory.

Examples of biological laws are Hardy-Weinberg law and Mendel's laws of inheritance

2.2 DATA ORGANIZATION AND DATA ANALYSIS

Data organization and data analysis are important steps in biological method Data can be defined as the information such as names, dates or values made from observations and experimentation.

Data organization

In order to formulate and then to test hypotheses, scientists collect and organize data .Prior to conducting an experiment it is very important for a scientist to describe data collection methods. It ensures the quality of experiment. Data is organized in different formats like graphics, tables, flow charts, maps and diagrams

Data analysis

Data analysis is necessary to prove or disprove a hypothesis by experimentation.It is done through the application of statistical methods i.e ratio and proportion.

RATIO:When a relation between two numbers e.g. a and 'b' is expressed in terms of quotient

(a/b), called the ratio of one number to the other. Ratio may be expressed by putting a division (÷) or colon (:) mark between the two numbers .For example the ratio between 50 malarial patients and 150 normal persons is 1:3. PROPORTION:

Proportion means to join two equal ratios by the sign of equality (=). For example, a:b= c:d is a proportion between the two ratios. This proportion may also be expressed as a:b::c:d. When three values in a proportion are known the fourth one (X) can be calculated.

For example, a biologist can calculate how many birds will get malaria when he allows infected mosquitoes to bite 100 healthy sparrows. In the previous experiment he noted that when he allowed mosquitoes to bite 20 sparrows, 14 out of them got malaria .

MATHEMATICS:

AS AN INTEGRAL PART OF SCIENTIFIC PROCESS

Biological method also involves the use of applied mathematics to solve biological problems .Major biological problems in which knowledge of mathematics is user include gene finding, protein structure, and protein-protein interactions etc Bioinformatics refers to the computational and statistical techniques for the analysis of biological data.

Scientific Method lecture 1

The scientific method is a systematic process used to develop and test scientific knowledgeThe scientific method plays a crucial role in scientific research, ensuring that investigations are systematic, objective, and rigorous. Here's how the scientific method is applied in scientific research:

Steps

1. Observation: Identify a phenomenon or problem.

2. Question: Formulate a specific question.

3. Hypothesis: Propose a tentative explanation.

4. Prediction: Make testable predictions.

5. Experimentation: Design and conduct experiments.

6. Data Analysis: Collect and analyze data.

7. Conclusion: Draw conclusions based on results.

8. Replication: Repeat experiments to verify findings.

Application of Scientific Method in Research

Key Scientific Terminology:

1. Variable: A factor that can change.

2. Independent Variable: The factor manipulated.

3. Dependent Variable: The factor measured.

4. Control Group: A group without manipulation.

5. Experimental Group: A group with manipulation.

6. Sample: A subset of the population.

7. Population: The entire group of interest.

8. Data: Collected information.

9. Hypothesis Testing: Statistical analysis to accept/reject hypothesis.

10. Significance: Statistical probability (e.g., p-value).

Types of Studies:

1. Experimental Study: Manipulates variables.

2. Observational Study: Observes without manipulation.

3. Survey Study: Collects self-reported data.

4. Case Study: In-depth examination of a single case.

Observation: Observation is the process of watching, listening, or recording behavior, events, or phenomena to gather information about issue.

Hypothesis is a tentative explanation or prediction based on limited evidence or observations, used as a starting point for further investigation or experimentation. Formulation of Research Question: Identify a specific research question or hypothesis.

Characteristics of a Good Hypothesis:

1. Specific: Clearly defines the predicted outcome.

2. Testable: Can be tested through experimentation or data analysis.

3. Falsifiable: Can be proven or disproven.

4. Relevant: Aligns with the research question or problem.

5. Simple: Avoids unnecessary complexity.

Best Practices:

1. Collaborate with experts.

2. Conduct thorough literature reviews.

3. Test hypotheses objectively.

4. Refine hypotheses based on results.

5. Communicate findings clearly.

5. Refine and specify the hypothesis.

How to Formulate a Hypothesis:

1. Identify the research question or problem.

2. Conduct background research.

3. Analyze existing data (if available).

4. Brainstorm potential explanations.

Examples of Hypotheses:

1. "Increasing exercise frequency will reduce blood pressure in hypertensive individuals." (Directional)

2. "There is no significant difference in academic performance between students who use digital textbooks and those who use traditional textbooks." (Null)

3. "The concentration of CO2 in the atmosphere will increase by 10% over the next decade." (Non-Directional)

Common Errors in Hypothesis Formulation:

1. Confusing hypothesis with theory.

2. Failing to specify the hypothesis.

3. Making assumptions without evidence.

4. Ignoring alternative explanations.

Literature Review:

A literature review is a comprehensive analysis and synthesis of existing research on a specific topic, issue, or phenomenon. It provides an overview of the current state of knowledge, identifies gaps, and sets the stage for further research.

3. Study Design: Develop a study design, including sampling strategy, data collection methods, and statistical analysis.

Prediction is the process of using data, statistical models, and machine learning algorithms to forecast future events or trends.

Experimentation research involves manipulating one or more independent variables to observe their effect on a dependent variable.

Data Collection: Collect data through experiments, surveys, observations, or secondary data analysis.

5. Data Analysis: Analyze data using statistical methods, modeling, or simulation

By applying the scientific method, researchers ensure that their investigations are systematic, objective, and rigorous, leading to reliable and generalizable findings.

 


Tuesday, October 15, 2024

Environmental Chemistry





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Monday, October 14, 2024

Introduction to natural Science contents

 

Course Code: PHY-100    Course Title: Introduction to Science              Credit Hours: 3(2-1)

Introduce students to the general science. Develop a basic understanding of everyday science and the scientific history. Understanding science across time in different civilizations and learning how to maintain the quality of science. Expected Learning outcomes: After successful completion of this course, students will be able to: 

1. Clearly articulate the development of science in various areas of human history and compare it to the modern scientific method. 

2. Describe various branches of Science, their underlying core ideas, and compare their applications. 

3. Practice applications of the Scientific methods in the natural sciences to understand various phenomena’s in nature. 

4. Determine originality of scientific work and methods for peer review. Course Contents: Theory

UNIT 1: Overview of Science 1.1 What is Science, Importance of Science 1.2 Difference in Fact, hypothesis, theory, and law  1.3 Important areas and branches of Science

UNIT 2: History and evolution of Scientific civilization  2.1 Ancient Greek history and inventions 2.2 Egyptian history 2.3 China history and achievements 2.4 Scientific history of south Asia region 2.5 Contributions of renowned Muslims scientists in various branches of science

UNIT 3: Modern Scientific method  3.1 Scientific Method and Terminology 3.2 Advantages, Methods, and Limitations 3.3 Understand nature and environment with science 

UNIT 4: Introduction to Main Areas of Science  4.1 Physics: Sub-branches of Physics: Mechanics, Thermodynamics, Optics, Modern and Nuclear Physics 4.2 Important theories and laws of Physics  4.3 Biology: Sub-branches of Biology; Cell structure and cell cycle  4.4 Important theories and laws of biology (three laws of biology, cell theory, gene theory, evolution) biological interactions.  4.5 Chemistry: Sub-branches of Chemistry  4.6 Important theories and laws of Chemistry (atomic theory, kinetic theory of gases)

UNIT 5: Quality and Standards of Science Physics Department 5.1 What is Pseudoscience and how to avoid fake science 5.2 Approaches to maintain quality and standards of science 

UNIT 6: Scientific Communication 6.1 What is peer review? 6.2 Differentiate between good and poor quality research work  6.3 Control and replications in science experiments 

PRACTICAL 

UNIT 7: Physics  7.1 Working of simple pendulum and calculation of its time period. 7.2 To find the area and volume of various objects. The students will be able to apply simple formulas for calculating area/volume. 7.3 Demonstration of open and closed circuits. Practical observation of everyday physics around us. 

UNIT 8: Biology 8.1 Seed germination and growth: To observe and understand the process of seed germination, imbibition, and early plant growth stages (e.g., wheat, beans, sunflower). 8.2 Leaf Structure and Function: To explore the structure and function of different types of leaves. Students will observe and compare leaf shapes, margins, venation patterns, and structures like stomata using hand lenses or microscopes.

UNIT 9: Chemistry 9.1 To determine the melting and boiling point of certain liquids. 9.2 Students will understand and observe distillation, solvent extraction, crystallization process in various chemistry experiments.

Assessment Method

MID Exam: 12 Marks

 Assignment/Quiz: 8 Marks

Final Exam: 20 Marks Practical Exam: 20 Marks

Recommended Books:

1. Carey, S., 2011. A Beginner's Guide To Scientific Method. 4th ed. Boston: Clark Baxter, pp.1-7, 29-45.

2. Chalmers, A., 2015. What Is This Thing Called Science? 4th ed. Indianapolis: Hackett Publishing Company, Inc., pp.24-47.

3. Douglas J Futuyma and Mark Kirkpatrick (2005) Evolution, 4th Edition. Sinauer Press, Unit 1 4. Ernst Mayr (1997) This is Biology: The Science of the Living World. Harvard University Press, Cambridge, Massachusetts: C h 1-4, Ch 6.

 5. Hawking, S, Mlodinow, L (2008). A Briefer History of Time. Bantam Books, - Chapter 3: Nature of a Scientific Theory  Physics Department

6. H. Eugene, Bruce. E, Patrick Woodward, Chemistry: The Central Science, 2017, Pearson, 14th Edition.

7. James E McClellan and Harold Dorn (2016) Science and Technology in World History: An Introduction. Second Edition. Johns Hopkins University Press – pp 39- 45, 55-62. 8. Raymond Chang, General Chemistry: The Essential Concepts, 2008, McGraw Hill, 5th Edition.

Suggested Resources:

 World’s Oldest Calendar - https://www.ancient-origins.net/newshistoryarchaeology/lunar-calendar-001234 Bone - https://www.naturalsciences.be/sites/default/files/Discover%20Ishango.pdf • Kalokol Pillar’s Site - http://www.chaz.org/Arch/Turkana/Namoratunga/ASI_Kalokol.html

 Beginning of a scientific revolution in Europe - https://youtu.be/vzo8vnxSARg6

 Brahe and Kepler, a revolution in astronomy - https://youtu.be/-FYvy3_egHw

 The scientific methods of Galileo, Bacon, and Descartes https://youtu.be/UdQreBq6MOY

 Newton and Leibinz - https://youtu.be/9UKGPOwR-iw

Thursday, October 10, 2024

Distillation

 


Distillation is one of the most very process for separation the components of a solution. The solution is heated to form a vapor of the more volatile components in the system, and vapor is then cooled, condensed, and collected as pure liquid. By repeating vaporization and condensation, individual components in the solution can be recovered in a pure state. Essences and many pure products from the oil refinery industry are processed via distillation.

Principles

Distillation is a technique by which a liquid mixture is separated into fractions with higher concentrations of certain components by using differences in relative volatility. The mechanism involved in distillation is the differences in volatility between individual components. With sufficient heat applied, vapours are formed from the liquid solution. The liquid product is subsequently condensed from the vapour phase by removal of the heat. Therefore, heat is used as the separating agent during distillation. In general, distillation can be carried out either with or without reflux involved. For the case of single-stage differential distillation, the liquid mixture is heated to form a vapour that is in equilibrium with the residual liquid. The vapour is then condensed and removed from the system without any liquid allowed to return to the still pot. This vapour is richer in the more volatile component than the liquid removed as the bottom product at the end of the process. However, when products of much higher purity are desired, part of the condensate has to be brought into contact with the vapour on its way to the condenser and recycled to the still pot. This procedure can be repeated many times to increase the efficiency of separation of mixture. This  process is called as rectification.

 Objectives

Distillation is used to separate the liquid mixture into two or more separated components. In a basic distillation column, a feed stream enters in the middle of the column and two fractions leave, one at the top and other at the bottom. Component with lower boiling points will be concentrated in the fraction leaving the top while component with higher boiling point will be concentrated in the stream at the bottom. Separation is achieved by controlling the column temperature and pressure to take advantage of differences in the relative volatility of the components of mixture and therefore has tendency to change phase. The lighter and lower boiling point components evaporate and travel up the column to form the top product and the heavier, higher boiling point components condense and travel down the column to form the bottom product.

Principle of Separation

Distillation takes advantage of the difference in relative volatility of the feed mixture components. Generally for two or more compounds at a given pressure and temperature, there will be a difference in the vapour and liquid compositions at equilibrium due to component partial pressure. Distillation exploits this by bringing liquid and gas phases into contact at temperatures and pressures that promote the desired separation. During this contact, the components with the lower volatility (typically lower boiling point) preferentially move into the liquid phase while more volatile components move into the vapour phase. A distillation column may use either trays or a packed bed to bring the gas and liquid into contact. For a column using trays, we can consider the changes to gas and liquid phase compositions as they both enter and exit a single tray. The liquid entering the tray will contact the gas exiting the tray, Fig.2. The hotter vapour phase heats the incoming liquid phase as it bubbles through the tray, evaporating the light components which then leaves the tray with the vapour phase. Conversely, the cooling of the vapour phase by the liquid phase will cause the heavier components of the vapour phase to condense and exit the tray with the liquid phase.

1.     Applications

Distillation has been used widely to separate volatile components from non-volatile compounds. In industrial settings such as oil refineries and natural gas processing plants, this separation process is undertaken using a distillation column. 

Di  Distillation is used in industries to proceed many commercial processes; Production of gasoline,  , xylene, alcohol, paraffin, kerosene,  distilled water and many other liquids. Distillation is used for purification of solvents and liquid products from there reaction mixture.

3.      It is used in the manufacturing of distilled water, double distilled water used in laboratories and pharmaceutical industries. toxic and expensive organic solvents that are extensively used in the extraction, synthesis and analysis can be recovered by distillation for economic benefits as well as for  protection of environmental.

5.      Distillation is used in the separation of volatile oils such as clove oil, cardamom oil, anise oil,  eucalyptus oil etc. from the plant extracts.

6.      It can also be used in the isolation of volatile components from a mixture of two or more volatile liquids. It can be used as a quality control method for alcohol content in liquid formulations. The alcohol is separated from formulations by distillation and alcohol content is determined.

8.      It can be used to liquefy and separate gases from the air. For example: nitrogen, oxygen, and argon are distilled from the air.

9.      Distillation is used in crude fermentation broths to separate alcoholic spirits.

10.  It can also be used in the fractionation of crude oil into gasoline and heating oil.

7.    





Thursday, October 3, 2024

Column Chromatography

 

Column Chromatography

Adsorption chromatography in biochemical applications usually consists of a solid stationary phase and a liquid mobile phase. The most useful technique is column chromatography, in which the stationary phase is confined to a glass or plastic tube and the mobile phase (a solvent or buffer) is allowed to flow through the solid adsorbent. A small amount of the sample to be analyzed is layered on top of the column. The sample mixture enters the column of adsorbing material and the molecules present are distributed between the mobile phase and the stationary phase. The various components in the sample have different affinities for the two phases and move through the column at different rates. Collection of the liquid phase emerging from the column yields separate fractions containing the individual components in the sample.

Specific terminology is used to describe various aspects of column chromatography. Poured or packed: When the actual adsorbing material is made into a column, it is said to be poured or packed.  Loading is Application of the sample to the top of the column. Developing or eluting: Movement of mobile phase through the loaded column is called developing or eluting the column. The bed volume is the total volume of solvent and adsorbing material taken up by the column. The void volumeis the volume taken up by the liquid phase in the column is the void volume. The elution volume is the amount of solvent required to remove a particular analyte from the column. This is analogous to Rf values in planar chromatography. In adsorption chromatography, solute molecules take part in specific interactions with the stationary phase. Herein lies the great versatility of adsorption chromatography.

Adsorbing material: A specific sorbent can be chosen that will effectively separate a mixture. from a large variety of available sorbing materials,  There is still an element of trial and error in the selection of an effective stationary phase. However, experiences of many investigators are recorded in the literature and are of great help in choosing the proper system.  Adsorbing materials come in various forms and sizes. The most suitable forms are dry powders or a slurry form of the material in an aqueous buffer or organic solvent. Alumina, silica gel, and fluorisil do not normally need special pretreatment. The size of particles in an adsorbing material is defined by mesh size. This refers to a standard sieve through which the particles can pass. A 100-mesh sieve has 100 small openings per square inch. Adsorbing material with high mesh size (400 and greater) is extremely fine and is most useful for very high resolution chromatography. For most biochemical applications, 100 to 200 mesh size is suitable.

Operation of A Chromatographic Column

A typical column setup is shown in Figure 5.4. The heart of the system is, of course, the column of adsorbent. In general, the longer the column, the better the resolution of components. However, a compromise must be made because flow rate decreases with increasing column length. The actual size of a column depends on the nature of the adsorbing material and the amount of chemical sample to be separated. For preparative purposes, column heights of 20 to 50 cm are usually sufficient to achieve acceptable resolution. Column inside diameters may vary from 0.5 to 5 cm.

Packing of Column

Once the adsorbing material and column size have been selected, the column is poured. If the tube does not have a fritted disc in the bottom, a small piece of glass wool or cotton should be used to support the column. Most columns are packed by pouring a slurry of the sorbent into the tube and allowing it to settle by gravity into a tight bed. The slurry is prepared with the solvent or buffer that will be used as the initial developing solvent. Pouring of the slurry must be continuous to avoid formation of sorbent layers. Excess solvent is eluted from the bottom of the column while the sorbent is settling. The column must never run dry. Additional slurry is added until the column bed reaches the desired height. The top of the settled adsorbent is then covered with a small circle of filter paper or glass wool to protect the surface while the column is loaded with sample or the eluting solvent is changed. Sometimes it is necessary to pack a column under pressure (5 to 10 psi). This leads to a tightly packed bed that yields more reproducible results, especially with gradient elutions sections).

Loading Of Column

The sample to be analyzed by chromatography should be applied to the top of the column in a concentrated form. If the sample is solid, it is dissolved in a minimum amount of solvent; p. 74. After the sample is loaded onto the column with a graduated or disposable pipet, it is allowed to percolate into the adsorbent. A few milliliters of solvent are then carefully added to wash the sample into the column material. The column is then filled with eluting solvent.

Eluting The Column

The chromatography column is developed by continuous flow of a solvent. Maintaining the appropriate flow rate is important for effective separation. If the flow rate is set too high, there is not sufficient time for complete equilibration of the analytes with the two phases. Too low a flow rate allows diffusion of analytes, which leads to poor resolution and broad elution peaks. It is difficult to give guidelines for the proper flow rate of a column, but, in general, a column should be adjusted to a rate slightly less than “free flow.” Sometimes it is necessary to find the proper flow rate by trial and error. One problem encountered during column development is a changing flow rate. As the solvent height above the column bed is reduced, there is less of a “pressure head” on the column, so the flow rate decreases. This can be avoided by storing the developing solvent in a large reservoir and allowing it to enter the column at the same rate as it is emerging from the column.
Adsorption columns are eluted in one of three ways. All components may be eluted by a single solvent or buffer. This is referred to as continual elution. In contrast, stepwise elution refers to an incremental change of solvent to aid development. The column is first eluted with a volume of one solvent and then with a second solvent. This may continue with as many solvents or solvent mixtures as desired. In general, the first solvent should be the least polar of any used in the analysis, and each additional solvent should be of greater polarity or ionic strength. Finally, adsorption columns may be developed by gradient elution brought about by a gradual change in solvent composition. The composition of the eluting solvent can be changed by mixing two different solvents to gradually change the ratio of two solvents.
Alternatively, the concen tration of a component in the solvent can be gradually increased. This is most often done by addition of a salt (KCl, NaCl, etc.). Devices are commercially avail able to prepare predetermined, reproducible gradients.

Collecting the Eluent

The separated components emerging from the column in the eluent are usually collected as discrete fractions. This may be done manually by collecting specified volumes of eluent in Erlenmeyer flasks or test tubes. Alternatively, if many fractions are to be collected, a mechanical fraction collector is convenient and even essential. An automatic fraction collector  directs the eluent into a single tube until a predetermined volume has been collected or until a preselected time period has elapsed; then the collector advances another tube for collection. Specified volumes are collected by a drop counter activated by a photocell, or a timer can be set to collect a fraction over a specific period.

Detection of Components

The completion of a chromatographic experiment calls for a means to detect the presence of analytes in the collected fractions. The detection method used will depend on the nature of the analytes. Smaller molecules such as lipids, amino acids, and carbohydrates can be detected by spotting fractions on a thin-layer plate or a piece of filter paper and treating them with a chemical reagent that pro duces a color. The same reagents that are used to visualize spots on a thin-layer or paper chromatogram are useful for this. Proteins and nucleic acids are conveniently detected by spectroscopic absorption measurements at 280 and 260 nm, respectively. Enzymes can be detected by measurements of catalytic activity asso ciated with each fraction. Research-grade chromatographic systems are equipped with detectors that continuously monitor some physical property of the eluent and display the separation results on a computer screen . The newest advance in detectors is the diode array . Most often the eluent is directed through a flow cell where absorbance or fluorescence characteristics can be measured. The detector is connected to a recorder or com puter for a permanent record of spectroscopic changes. When the location of the various analytes is determined, adjacent fractions containing identical components are pooled and stored for later use.

  SURFACE TENSION AND CHEMICAL CONSTITUTION PARACHOR Surface tension to due to an inward force acting on the molecules at the surface of a...