The stationary phase in HPLC normally will be the silica gel. The silica gel will help to separate the components in the liquid sample as its particle size, surface properties and pore structure will lead to good separation results of solvent by minimize the length of diffusion path. The silica gel is also inert to most solvent so it can separate various type of chemical compound with high reproducibility. During the separation, the component in sample will interact with the adsorbent material within the pores of the stationary phase. This will cause the different flow rates for the different components and leading to the separation of the components as they released from the column.
Aromaticity can be termed as a chemical property of conjugated cycloalkenes. Aromaticity deals with the uncommon stability of benzene and its derivatives, which is caused by the ability of the electrons in the p-orbitals to delocalize and act as a framework to generate planar molecules. A molecule is only considered aromatic due to the fact that it is cyclic, that it follows the Huckel’s Rule and lastly that each element must have a p-orbital. Antioxidants play and important role in health. It can be defined as a group of organic chemicals and have been used to hinder the process of oxidative degradation of food products, fats and oils and polymers.
These are prepared by dispersing the drug in polymeric base solution. There are some polymers used in preparation of Transdermal patches: Natural polymers: such as, cellulose derivatives, Zein, Gelatin, Shellac, Waxes, Proteins, Gums and their derivatives, Natural rubber, Starch etc. Synthetic Elastomers: e.g. polybutadiene, hydrin rubber, polyisobutylene, silicon rubber, nitrile, acrylonitrile, neoprene, butyl rubber etc. Synthetic Polymers: such as, polyvinyl alcohol, polyvinylchloride, polyethylene, polypropylene, polyacrylate, polyamide, polyurea, polyvinylpyrrolidone, polymethylmethacrylate etc
Polyactic Acid Is plastic bad for the earth? We use plastic to create items that make our lives easier everyday. Plastic has been molded into bottles, chairs, toys, and almost anything one can imagine. Over time the items created can potentially be more harmful for the planet than helpful. Plastic cannot just disappear, and everyday millions of plastic items are being used, a lot for only one day before being thrown out.
Solvent used in the elution process would be the mobile phase and solvents of different polarity would have a significant impact on the separation due to the varying solubility of compounds in different solvents. Hexane, being the less polar solvent, interacts mainly with the less polar analytes but very slowly with polar analytes. Therefore using hexane at the start of the elution process allows the less polar compound to be eluted out first. After the complete collection of less polar analyte, the mobile phase was changed to the more polar hexane/ethyl acetate solvent, which has stronger interaction with the more polar component, allowing it to be eluted out faster. The change in solvents throughout the elution process would allow for an effective and efficient separation of the compounds β-carotene and chlorophyll in the crude extract of green leaves.
The chemistry of epoxides is dominated by the reactions that involve opening of the strained three-membered heterocyclic ring by nucleophiles. Such reactions yield valuable bifunctional compounds. In nature, epoxide ring opening is catalysed by the phenolic proton of a tyrosine moiety . But in laboratory, the cleavage usually occurs in non-aqueous media in presence of a Lewis acid catalyst like Al2O3, Li+, Mg2+ etc. Additionally often elevated temperature and excess of nucleophiles are required.
There is strong covalent bonds between these atoms but weak Van der waals force (dipole-dipole force) between Polypropylene molecules. Isotactic Polypropylene forms a somewhat tetrahedral arrangement and its molecules are asymmetrical. These molecules form a long polymer chain.
1.1. Polyesters Polyesters are the polymers that contain ester functional group in their main chain. The polyesters can be classified according to the composition of their main chain as aliphatic and semi-aromatic in addition to aromatic polyesters. Also can be thermoplastic or perhaps thermoses. All common polyesters are thermoplastics (Rosato, L. et al.
Heat resistant. Investigating how the composition and the structure affect the parent material of polymers: We are using Plastics widely everywhere and so many types of plastics we have. The additives change the structure and the composition of the polymer.
Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. There are many different types of plastics such as: • Polyester (PES) – Fibers, textiles. • Polyethylene terephthalate (PET) – Carbonated drinks bottles, peanut butter jars, plastic film, microwavable packaging. • Polyethylene (PE)