![]() ![]() ![]() Precautions for Using the Automatic Melting Point Meterġ) The test sample is dried in advance and ground into powder by mortar. Before the instrument is used, check whether the tube sleeve is assembled with the furnace body Check whether the light source output is good. During the test, avoid contacting the heating part to prevent scalding ģ) After the instrument is used, the temperature drops to room temperature. If the sample to be tested generates toxic gas after decomposition, the instrument shall be put in the ventilation kitchen for testing. The principle of the instrument is acid, alkali, and other corrosive liquids Ģ) During capillary sampling, pay attention to avoid capillary fracture and hand injury. Precautions for Use of Melting Point Meterġ) The melting point meter shall be placed in a dry, dust-free, and ventilated laboratory environment to avoid excessive humidity and dust pollution and reduce the service life of the melting point meter. The reference materials commonly used in the calibration of melting point meter are naphthalene (final melting 80.6 ℃), adipic acid (final melting 152.9 ℃), and anthraquinone (final melting 285.7 ℃). Due to the large error caused by long-term use and seasonal temperature difference, the verification is also performed once a year. The melting point meter needs to be verified when it is turned on for use or has been used for one year. Test Accuracy, Repeatability of Test Results, and Test Range Are the Reference for Selecting a Melting Point MeterĪccording to the actual needs, the higher the accuracy and repeatability, the better after meeting the measurement range. For sheet or block samples, a micro melting point meter can be used. The melting point meter based on the capillary melting point measurement method can be used for powder samples, and the visual melting point instrument or automatic melting point meter can be determined according to specific indicators such as whether the sample is transparent after melting, the initial melting of the sample, and the melting range. Polarimeters & Refractometer & Melting Point Meter Expand.Electronic Balance-TD & YP Balance (0.01g/0.1g ).Elisa Microplate Reader & Microplate Washer.Constant Temperature & Humidity Chamber.GCMS (Gas Chromatograph and Mass Spectrometry).Inductively Coupled Plasma Mass Spectrometer (ICP-MS). ![]() Full Spectrum Direct Reading Spectrometer.ICP Emission Spectrometer (ICP-AES/ICP-OES).Atomic Absorption Spectrophotometer (AAS).Do not heat so vigorously that the entire sample boils away. The purpose of this step is to expunge the air originally present in the capillary tube and replace it with the sample's vapor. Continue heating until a vigorous stream of bubbles emerges from the tip of the capillary tube (Figure 6.25d), such that individual bubbles can barely be distinguished.Studies of this method\(^7\) have determined that it is best to heat the oil gently and in a continual manner, as stopping and starting have caused the results to suffer.It is okay to continue heating a Thiele tube if bubbles are seen. If the oil is not subsequently changed, the sample may boil when heated in the tube. In this method, the rubber band occasionally breaks causing the sample to fall into the oil and contaminate it. Although bubbles should not be seen in the Thiele tube as it warms, they commonly are seen if the tube had been used previously for boiling point determinations.This method is an excellent way to indirectly and slowly heat the sample. The cooler, denser oil will sink, thereby creating a current as shown in Figure 6.25c). As the oil warms and becomes less dense, it will rise and travel up the triangular portion of the tube. Heat the oil gently on the side arm of the Thiele tube with a microburner if available, or Bunsen burner using a back and forth motion (Figure 6.25c).The thermometer should not touch the sides of the glass, and if it does it should be clamped in such a way that it no longer touches. The rubber band should be higher than the top of the mineral oil (Figure 6.25b), keeping in mind that the oil may expand somewhat during heating. Place the rubber stopper and thermometer assembly into the Thiele tube, adjusting the height so that the sample is midway (if possible) inside the tube (Figure 6.25a).Insert a capillary tube into the sample (the same type that is used for melting points), open end down and sealed end up (Figure 6.24d).įigure 6.25: a) Insertion of the assembly into the Thiele tube, b) Rubber band is above the oil, c) Heating, d) Vigorous bubbling of sample.\( \newcommand\) of sample (Figure 6.24c). ![]()
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