一，Introduction of Shanghai Jiahang Instrument Co., LTD
Shanghai Jiahang Instrument Co., Ltd. focuses on the field of instrumentation, with profound technical accumulation and persistent pursuit of quality, in the industry to establish a good reputation. The company has a professional R & D team, continue to invest resources for technological innovation, with strong independent research and development capabilities. In the production process, we strictly follow the international quality management system standards, and introduce advanced production equipment and technology to ensure stable and reliable product quality. The company's products cover a variety of types of instruments, of which automatic digital polarimeter is one of its core products, and has been widely used in many fields.
2. Pharmaceutical industry related applications
In the 2020 edition of the Chinese Pharmacopoeia, a number of determination methods are closely related to the polarimeter, such as the 0621 spectrophotometry method. When plane polarized light passes through a liquid or solution containing optically active compounds, it produces optical rotation, and the degree of rotation is called optical rotation. At a specific wavelength and temperature, the measured rotation of polarized light through a solution of an optically active substance with a specific concentration and path length is the specific rotation. Specific rotation and rotation can be used to identify the authenticity of optically active drugs, check the degree of purity and impurity, but also to determine the content of drugs, commonly used in the detection of amino acids, proteins, alkaloids, glycosides, sugars and other drugs. Shanghai Jiahang's fully automated digital polarimeters play a key role in the quality control process of these drugs.
Three, automatic digital polarimeter introduction
3.1 Instrument Definition

Automatic digital polarimeter is a professional instrument used to accurately measure the rotation of substances. When polarized light passes through materials with asymmetric molecular structures (mirror images of each other), the plane of polarization will rotate, and the magnitude of the rotation Angle is the rotation. By measuring the rotation of the sample, it can analyze and determine the concentration, content and purity of the substance and other key parameters, which have important applications in the production, scientific research and teaching of many industries such as pharmaceutical, drug testing, sugar, food, fragrance, chemical industry and so on.
3.2 Instrument Features
Shanghai Jiahang's automatic digital polarimeter uses advanced optical systems and high-precision sensors to ensure accurate and reliable measurement results. The measurement accuracy can reach ±0.004°, which can meet the high requirements for drug detection. The instrument has the characteristics of fast response, from the sample into the measurement results, the required time is short, effectively improve the detection efficiency. In terms of operation, the user-friendly operation interface is designed, which is easy to operate, even the first time users can quickly get started. The instrument also has an automatic calibration function, which can be automatically calibrated regularly to ensure the accuracy of the measurement. At the same time, it has a variety of data output interfaces, which is convenient to connect with computers, printers and other devices to achieve data storage, transmission and printing.
3.3 Technical Specifications
The working wavelength can be selected according to the actual demand, and the optional wavelength is 589.3nm. The measuring range is 10℃ -55 ℃ (Palpatch temperature control), which can meet the detection needs of different drugs. The reading resolution of the instrument is high, up to 0.1 ° C, and the measurement results can be accurately read. The sample tank has the function of constant temperature, and the temperature control accuracy is up to ±0.1℃. It can be measured both at constant temperature and at normal temperature to adapt to different experimental conditions.
4. Application cases
4.1 Experimental purpose
Some drugs, especially new synthetic drugs, have very small rotation under the 589nm standard sodium light source. In order to meet the inspection requirements of these special drugs, it is necessary to use a polarimeter with multi-wavelength detection function to accurately measure the specific rotation of drugs to ensure that the quality of drugs meets the pharmacopoeia standards.
4.2 Provisions of Chinese Pharmacopoeia
The commonly used light source for planar polarized light is the D-line of sodium lamp in the visible light region (589nm), but for some compounds with small rotation, a short-wavelength light source is also used, such as the photoelectric polarimeter uses the filter to obtain the monochromatic light of mercury lamp at 578nm, 546nm, 436nm, 405nm and 365nm. These wavelengths of light have higher sensitivity, which can reduce the concentration of the compound under test and improve the detection accuracy.
4.3 Application Instance
Taking the detection of chloramphenicol as an example, the Chinese Pharmacopoeia stipulates the specific curl range of chloramphenicol. When using Shanghai Jiahang automatic digital politrotometer for testing, weigh a certain amount of chloramphenicol sample according to the requirements of pharmacopoeia, dissolve with a small amount of solvent, transfer to 100mL volumetric bottle, add solvent to the line, shake well for use. Turn on the instrument, select the wavelength of 365nm (in line with the pharmacopoeia's wavelength requirements for chloramphenicol detection), and preheat [preheat time]. Set the instrument test mode to the specific curl mode, set the concentration parameters according to the sample configuration concentration, and set the tube length to 100mm (standard tube length). The blank solvent is injected into the matching temperature control test tube, and the sample room of the instrument is cleared to eliminate the influence of solvent. Take out the test tube, wash the prepared sample 2-3 times, and then add the sample to the test tube with a syringe. Put the test tube after adding samples into the sample chamber, insert the temperature probe, set the temperature to 25℃, and start the temperature control. After the temperature of the sample is stable, click the test button, and the instrument will automatically read the specific rotation of the chloramphenicol sample. The measured results are compared with the specific curl range specified by the pharmacopoeia to determine whether the sample is qualified.
4.4 Experimental Equipment
Use Shanghai Jiahang automatic digital politometer (model: Digipol-P610), with a special temperature control test tube (to ensure that the sample is measured at a stable temperature), analytical balance (1/10,000 accuracy, accurate sample quality), 100mL volumetric bottle (for accurate configuration of sample solution).
4.5 Test Procedure
Sample preparation: Accurately weigh the sample according to the requirements of pharmacopoeia, dissolve it with appropriate solvent, transfer it to the volumetric bottle, shake it well at constant volume.
Instrument preheating: Turn on the instrument, select the appropriate wavelength, and preheat until the instrument is stable.
Mode setting: Set the measurement mode to specific curl mode, input sample concentration and tube length.
Background elimination: Blank solvent is injected to eliminate the effect of the solvent on the measurement.
Test tube washing: Wash test tube with sample solution to ensure measurement accuracy.
Start temperature control: Put in the sample tube, set the temperature and start temperature control.
Automatic reading: After the temperature is stable, click the test to read the specific rotation.
4.6 Test Interface
The test interface design of the instrument is simple and intuitive, and the measurement data can be displayed in real time, including the current measured rotation, specific rotation, concentration and other parameters. At the same time, there are operation buttons on the interface, which are convenient for users to select mode, set parameters, and save data. Users can choose general mode and GMP compliant mode according to actual needs to ensure that the measurement process meets relevant standards and requirements.
4.7 Calculation Formula
The formula for calculating specific curl is [a]D25 =α/(c∗L), where α is the rotatory power, [a]D25 is the specific rotatory constant at 25℃, c is the mass concentration (g/mL), and L is the length of the rotatory tube (dm). Through the measured rotatory power, combined with the sample concentration and the length of the rotatory tube, the specific rotation can be calculated, and the sample quality can be compared with the pharmacopeia standard.
4.8 Experimental Summary
The automatic digital polarimeter of Shanghai Jiahang is easy to operate, accurate and reliable in detecting the specific rotation of drugs. The multi-wavelength function of the instrument meets the special requirements of different drugs on the detection wavelength, and its high-precision measurement performance and stable temperature control system ensure the accuracy and repeatability of measurement. The instrument meets the relevant requirements of the 2020 edition of the Chinese Pharmacopoeia, and provides strong technical support to ensure the quality of drugs in the process of drug development, production and quality control, which helps to improve the overall quality level of the pharmaceutical industry.