Nuclear magnetic resonance

64問 • 1年前

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transitions between energy levels may be generated by radiant energy if the molecules are first placed in a magnetic field.

investigate the properties of organic molecules, like sructure/ identity, and molecular configuration

Nuclear magnetic resonance

an energy transfer is possible between the base energy to a higher energy leve

Nuclear magnetic resonance

energy transfer takes place at a wavelength that corresponds to radio frequencies

Nuclear magnetic resonance

The signal that matches this transfer is measured in many ways and processed in order to yield an NMR spectrum for the nucleus concerned. (T/F)

True

the plot of radio frequency applied against absorption

NMR Spectrum

signal in the spectrum

Resonance

form of electromagnetic radiation to pump the excess alpha oriented nuclei into the beta state.

Nuclear magnetic resonance

exploits the magnetic properties of certain atomic nuclei. ... Thus, in organic chemistry practice, NMR analysis is used to confirm the identity of a substance. (T/F)

True

frequency of the signal expressed with reference to a standard Computed as the difference between the resonance frequency of the nucleus and a standard, relative to the standard.

Chemical shift

as a fraction of the nominal resonance frequency or parts-per-million (ppm) are used.

Chemical shift

a phenomenon that takes place due to the neighboring proton

Spin-spin couple

peaks are split into multiplets which depend upon the groups on adjacent nuclei.

Spin spin coupling

difference between the adjacent sub-peaks in a split signal

J coupling

The basic instrumentation needed to measure NMR spectra includes (

magnet with strong, stable homogenous field, radio receiver and detector, radiofrequency transmitter:, coil of wire, cell containing the sample

It is an instrumental method for identifying the chemical constitution of a substance by means of the separation of gaseous ions according to their differing mass and charge.

Mass spectrometry.

generates multiple ions from the sample under investigation, it then separates them according to their specific mass-to-charge ratio (m/z), and then records the relative abundance of each ion type.

Mass spectrometry

For producing gaseousionsfrom the substance being studied

Ion source

For resolving the ionsinto their characteristicsmass components according to their mass-to-charge ratio.

Analyzer

For detecting the ions and recording the relative abundance of each of the resolved ionic species.

Detectors systems

Mass spectrometer always work with positive ions (T/F)

True

The ions are then deflected by a magnetic field according to their masses. The lighter they are, the more they are deflected

Deflected.

The ions are accelerated so that they all have the same kinetic energy

Accelerated.

is a process in which a solution of mixture containing inert materials, drug principles and impurities is separated into its components while moving through a bed of fixed porous solid having different and reversible affinities for the substance being separate

Chromatography

a fixed bed core of large surface area.

Stationary phase

a fluid which moves through or over the surface of the stationary phase.

Mobile phase

Whar are the 2 types of chromatography

Stationary phase, Mobile phase

It brings about the separation of a mixture through a competitive process in which the molecules of the mobile phase compete with the analyte molecules for polar adsorption site on the adsorbent.

Adsorption Chromatography

The chromatographic process is known as where the mobile phase is liquid.

liquid-solid chromatography

The chromatographic process is known as when the mobile phase is a gas

gas – solid chromatography

Chromatographic technique in which the mobile and stationary phases are liquids referred to as liquid-liquid chromatography (LLC)

Partition Chromatography

Separation in partition elution chromatography is based upon

Nernst’s law.

According to this law, when two practically immiscible solvents are in contact with each other and substance which is soluble in each is added, the substance distributes itself in such a way that at equilibrium and at a given temperature the ratio of the concentrations of the two solutions is constant.

Nernst’s law.

it is the activity ratio rather than the concentration ratio which remains constant

Nernst’s law.

the ratio of the distance travelled over the paper sheets by a given compound to the distance travelled by the front of the mobile phase, from the point of application of the test substances.

Retardation Factor (Rf)

the ratio between the distances travelled by a given compound and a reference substance.

Retardation Reference (Rr)

The materials used to pack column for use inion-exchange chromatography are either cationic or anionic exchange resins.

Ion-Exchange Chromatography

These substances are insoluble in water and as the name implies, exchange cations or anions in solution in the mobile phase which come in contact with the active sites of exchange resins

Ion-Exchange Chromatography

Contains either sulfonic acid (-SO3H) or carboxylic acid

Cationic exchangers

Resin contain either quaternary ammonium or amino functional group in the Y position.

Anionic exchange

stationary phase consists of a polymeric matrix onto the surface of which ionic functional groups, e.g. carboxylic acid or quaternary amines have been chemically bonded

Ion exchange chromatography

As the mobile phase passes over this surface, ionic solutes are retained by forming electrostatic chemical bonds with the functional groups. The mobile phase used in ion exchange chromatography are always liquid.

Ion exchange chromatography

This is also known as gel filtration or gel permeation chromatography, and maybe defined as a separation procedure in which differential migration of solute molecules is based on molecular size

Molecular Exclusion Chromatography

Column material consists of a network-like structure of polymer material having pores of various sizes which exclude some molecules but permit the passage of other smaller molecules.

Molecular Exclusion Chromatography

The simplest type of chromatographic column consists of a separation flask and a cylindrical glass tube constricted at one end.

Column chromatography

The material placed in the column to absorb the drug is referred to as the .

Adsorbent

Purified siliceous earth, activated alumina, silica gel and calcium carbonate are examples of adsorbents commonly used. (T/F)

True

The adsorbent is uniformly and firmly packed into the tube so that the solvent called will pass through it.

Mobile phase

The column adsorbent is treated with fresh portions of solvent referred to as ________ to bring about the separation of the components as each drug progress down the column at a characteristic rate in a chromatogram.

Developer

used in highpressure liquid chromatography and gas chromatography

Column chromatography

Ether is used as

Eluant

When the separated compounds are colored or fluoresce under UV light the adsorbent column is forced, intact from the tube and the fractions are easily divided into segments with a knife.

Column Chromatography

When the compounds are radioactive, their position on the column may be determined by the use of a

Geiger-Muller counter.

Another procedure commonly used to develop chromatogram is known as

Elution chromatography

The column is washed with suitable solvent referred to as

eluants

until each compound is successively obtained in the effluent liquid known as the

Eluate

The basic principle of separation in the partition chromatography is that of difference in partition coefficients of substances between two immiscible liquids.

Paper-Partition Chromatography

One of which is a stationary phase supported on a solid adsorbent with the other mobile liquid phase flowing through it.

Paper-Partition Chromatography

which is accomplished by allowing the mobile phase to flow downward on the paper strip.

Descending Chromatography

An which the mobile phase is allowed to rise upward on the paper by capillary attraction

Ascending Chromatography

in which the mobile phase moves out in concentric circles from the center of a circular piece of paper.

Radial Chromatography,

When the compounds are colorless they may be visualized painting or spraying the extruded column with a

color-forming agent.

It involves the spotting of a sampler of a mixture of components at one end of an adsorbent-coated glass plate or other suitable support followed by passage of solvent through the adsorbent for the purpose of separating components of the sample

Thin-Layer Chromatography

are the most widely used adsorbents

Silica Gel G, Alumina

Cell structure.

Quinn Karylle Fuentes · 28問 · 2年前

Cell structure.