Chemistry: Thin Layer Chromatography

994 Words2 Pages
bulb-icon

Recommended: Thin layer chromatography separation scheme

Introduction
Thin layer chromatography is a classical case of adsorption or solid/liquid chromatography or planar chromatography. In planar chromatography, the stationary phase is applied on a flat surface and movement of mobile phase is due to the capillary action. The stationary phase is normally a polar absorbent and the mobile phase can be a single solvent or combination of solvents. Adsorption is a concentration dependent process and adsorption coefficient is not constant, in contrast to partition coefficient (liquid/liquid chromatography). Hence, if the concentration of sample is more than the absorptive capacity of stationary phase, the separation of components of the mixture will be poor. TLC is a useful tool for separating and identifying …show more content…

The covalent network of these adsorbents creates very polar material. Silica gel is acidic in nature and thus offers poor separation of basic samples. However, Alumina is available in all forms (neutral, basic, or acidic). However, it cannot separate large sample sizes unlike silica gel under a given layer thickness. Alumina being more reactive than silica gel also limits its use. Fig.1: Structure of silica (www.ecompounds.com) …show more content…

In addition, the coated plate must be physically stable to ensure consistent chromatographic properties. Stability of the layer of stationary phase both in the dry and wet form is achieved by the use of a binder. Binders facilitate the adsorbent sticking to the support. Common binders are Gypsum (G) or Plaster of Paris (CaSO4.2H2O). It is used in about 10-15% by weight of gel. However, due to high solubility of the gypsum binder in aqueous solutions, they are not recommended for use with mobile phase containing water more than 20%. Silica gel plate with gypsum binder is given the designation "silica gel G". Some organic binders like carboxy methyl cellulose, starch (1-2%), and polyvinyl alcohol (1-5%) are also used. These give a stronger binding but get charred on treatment with strong sulphuric acid solutions and

Show More
Related

  • Aromatic Substitution Lab

    953 Words  | 2 Pages

    Therefore, it is expected that the methyl meta-nitrobenzoate would be the product formed faster and in greater quantities because it has the more stable intermediate. Thin layer chromatography uses a solvent (in this case 85% hexane–15% ethyl acetate) to separate different products based on differences in polarity of the molecules. Typically more polar compounds will have more interaction with the stationary phase, and will not move as from the solvent front. This means that the less polar a substance is, the farther it will move. Using the mechanism of electrophilic benzylic substitution, it can be determined at where each step of the mechanism is occurring, and at what procedure it is occurring at.

    Read More

  • Substrate Concentration Lab Report

    592 Words  | 2 Pages

    Thorough analysis of the graph displayed enough evidence suggesting that an increase in substrate concentration will increase the height of bubbles until it reaches the optimum amount of substrate concentration, resulting in a plateau in the graphs (figure 2). Hence; supported the hypothesis.

    Read More

  • The Pilot Pen Company: Pilot G2 Gel Pen Gel Ink

    716 Words  | 2 Pages

    Schwartz, Debra A. "Just for the Gel of It." The Last Word:. N.p., n.d. Web. 03 Apr. 2014.

    Read More

  • Caffeine Extraction Experiment

    1054 Words  | 3 Pages

    The objective of this experiment was to perform extraction. This is a separation and purification technique, based on different solubility of compounds in immiscible solvent mixtures. Extraction is conducted by shaking the solution with the solvent, until two layers are formed. One layer can then be separated from the other. If the separation does not happen in one try, multiple attempts may be needed.

    Read More

  • Styles And Experiences Of Albrecht Durer And Jan Van Eyck

    1052 Words  | 3 Pages

    -creates a strong surface and can be used as a thin layer for glazes or a thick layers for impasto

    Read More

  • Countercurrent Chromatography Essay

    698 Words  | 2 Pages

    Separations are important techniques in chemistry that are used to separate various components of a mixture. They are carried out by mixing two immiscible liquids containing certain solutes together in a separatory funnel, allowing them to separate, then extracting the distinct layers that form. The ratio of the concentration of solute present in the upper layer to the concentration in the lower layer is called the partition coefficient. The efficiency of a separation is described by this partition coefficient. If the coefficients for the two layers are largely different, then the separation can be carried out in a single step. If they aren’t, a more complex process is necessary.1,2 Countercurrent chromatography is a technique used carry out separations in these kinds of cases. It uses a continuous liquid-liquid partitioning process to streamline the usual extraction procedure.

    Read More

  • Pigment Chromatography Lab

    396 Words  | 1 Pages

    The distance of the initial extract line to a pigment band was divided by the distance of the marked solvent front to the initial extract line both were measured in cm. The RF (relative to front) was calculated for each pigment band, indicating the travelled distance between the pigment and the front (solvent line) on the chromatography

    Read More

  • Chromatography: History, Introduction, and Classification

    863 Words  | 2 Pages

    Chromatography has been developed over the past century and has an important contribution in many areas of modern science. However the main original work of M.S.Tswett was published in a book Chromatographic Adsorption Analysis.

    Read More

  • Applications and Future of Teflon

    1186 Words  | 3 Pages

    due to its high resistance to oils and grease, and its slippery and wax-like properties, it is used to coat various cookwares2

    Read More

  • Surface Chemistry of Silica

    1273 Words  | 3 Pages

    ...ussion: Adsorption sites for salt as well as for alcohol are polar silanol groups (Fig 1c). As discussed earlier, alcohol is not adsorbed on all silanol groups (prefers isolated silanol group) and alcohol is more preferentially adsorbed than salt. So, anchorage of salt on the silica surface must be very distinct, reducing the possibility of irreducible mixed metal support formation. Also for substantial adsorption, silica gel has to be contacted with very concentrated salt-alcohol solution. In our opinion small amount of water cause ionization of alcohol which further induce ionization at silanol surface creating anionic sites suitable for esterification of ethoxy group. On the other hand, salt is mostly “associated” if the water is around 1-2% in the solution and the adsorbed salt will act as nucleation site for salt present mainly because of physical interaction.

    Read More

  • Aluminum

    1227 Words  | 3 Pages

    The oxide of aluminum is amphoteric—showing both acidic and basic properties. The most important compounds include the oxide, hydroxide, sulfate, and mixed sulfate compounds. Anhydrous aluminum chloride is important in the oil and synthetic-chemical industries. Many gemstones—ruby and sapphire, for example—consist mainly of crystalline aluminum oxide.

    Read More

  • Lambda DNA: Restriction Endonuclease And DNA Crease

    1149 Words  | 3 Pages

    During the incubation, in an Erlenmeyer flask, 1X Tris Acetate EDTA (1 mL) and powder agarose (0.4 g) were dissolved in dH2O (49 mL). Then the solution was microwave for 2 minutes and allowed to cool to room temperature. Then SafeRed concentrate (2.5 µL) was added to the solution and it was poured into the gel box and allowed to solidify.

    Read More

  • Hplc Essay

    1175 Words  | 3 Pages

    Stationary phase is of extreme importance in an HPLC analysis, as the chemical nature of the same and its compatibility with the analyte of interest is extremely significant for efficient separation. The most commonly used stationary phase is silica packed column which acts as a adsorbent. Each component in the sample interacts with these silica particles and gets eluted out in different time intervals. These silica columns may be of C14 or C18 type depending on the component of interest and also the columns themselves come in various dimensions each with a specific purpose of analysis.

    Read More

  • Analytical Chemistry

    1122 Words  | 3 Pages

    is impossible to specify a single best method to carry out a given analysis in

    Read More

  • Exploring the Langmuir and Freundlich Adsorption Models

    1053 Words  | 3 Pages

    Langmuir adsorption model assumesthat adsorption occurs at specific homogeneous adsorption sites onthe adsorbent surface and intermolecular forces decrease rapidlywith the distance from the adsorption surface. The model further basedon the assumption that all the adsorption sites are energeticallyidentical and adsorption occurs on a structurally homogeneousadsorbent. The Langmuir (Hadi et al., 2010) non-linear form is pre-sented in Eq. (6).which may be unfavourable (RL > 1), linear (RL = 1), favorable (0 < RL< 1) or irreversible (RL = 0) [31,32]. It has been found from Fig. 8 that the values of RL for TG range from 0.0068 to 0.039 and for ATG was 0.02 to 0.13. The lower RL values at higher BG concentration indicate that adsorption is more favourable at higher concentrations. The degree of favourability tended toward zero (the completely ideal irreversible case) rather than unity (which represent a completely reversible case). Thus the adsorp-tion of BG on to both gels is confirmed to be a favourable process.

    Read More

More about Chemistry: Thin Layer Chromatography

Open Document