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Determination of Phase Equilibria of Permethrin and Dicofol with Carbon Dioxide by Capillary Method (CAT#: STEM-PPA-0048-YJL)

Introduction

Supercritical fluid extraction (SFE) has been applied to remove toxic and nonvolatile pollutants from water, plant material, and other substrates. A significant advantage of SFE over conventional handling processes is that there are no hazardous emissions. Permethrin has been chosen as a typical pyrethroid. Dicofol is an organochlorine acaricide used for control of crop-feeding mite pests. Due to the nonconventional shape of some solubility isotherms, solid-liquid transitions of pesticides under pressure of CO2 were determined using a modified capillary method.




Principle

Melting point is a characteristic property of solid crystalline substance. It is the temperature at which the solid phase changes to the liquid phase. This phenomenon occurs when the substance is heated.
The melting point measurement is usually performed in thin glass capillary tubes with an internal diameter of 1 mm and a wall thickness of 0.1 – 0.2 mm. A finely-ground sample is placed in the capillary tube to a filling level of 2 – 3 mm and introduced in a heated stand (liquid bath or metal block) in close proximity to a high accuracy thermometer. The temperature in the heating stand is ramped at a user-programmable fixed rate. The melting process is visually inspected to determine the melting point of the sample.

Applications

Chemical industry; Cosmetic/pharmaceutical industry

Procedure

1. Seal capillary.
2. Fill the sample.
3. Install the instrument.
4. Determine the melting point.

Materials

• Sample Type: crystalline compounds