Zhejaing Sealand Technology Co., Ltd. is a trustworthy manufacturer of Mass Flow Meter, Mass Flowmeter, Mass Meter, Flow Meter, Flowmeter, ATEX, IECEx & CE approved. The product range covers different size from DN03 to DN150, and bigger sizes are being developed.
Sealand mass flow meter is designed and produced according to world`s latest Coriolis technology with exelent appearance, stability and accuracy to measure mass flow rate of a fluid traveling through a tube, widely applied to alternative energy, oil & gas, chemical, food & beverage, industrial energy, marine, power, pulp & paper, water & wastewater industries, etc.
Mass flow meter measures the mass based on Coriolis effort. The operating principle involves inducing a vibration of the tube through which the fluid passes. The vibration, though not completely circular, provides the rotating reference frame that gives rise to the Coriolis effect. While specific methods vary according to the design of the flow meter, sensors monitor and analyze changes in frequency, phase shift & amplitude of the vibrating flow tubes. The changes observed represent the mass flow rate and density of the fluid.
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Introduction to High Performance Liquid Chromatography
High-performance liquid chromatography (HPLC) is a widely used analytical technique for separating, identifying, and quantifying compounds in a mixture. Its fundamental principles are similar to those of classical liquid and gas chromatography, allowing the application of plate theory and kinetic theory to understand and optimize the separation process.
The basic HPLC system consists of three main components: the pumping system, the chromatographic column, and the detection system. The mobile phase is delivered under high pressure using a precision pump, which plays a critical role in maintaining consistent flow rates and minimizing pulsations. This pump must be capable of operating over a wide range of flow rates, resist solvent corrosion, generate high pressure (typically 15–300 bar, with some systems reaching up to 800 bar), and have minimal dead volume to ensure efficient and accurate separations.
For gradient elution, two high-pressure pumps are often used—one to deliver a strong solvent and the other a weak solvent. These pumps are controlled by a computer, enabling precise control over the composition of the mobile phase. This flexibility enhances resolution and allows for better separation of complex mixtures.
Sample injection is typically done via a micro-syringe or a six-way valve, ensuring accurate and reproducible introduction into the system. Detection is commonly performed using UV absorbance detectors, which offer sensitivity down to the nanogram level. Other detection methods include fluorescence, refractive index, electrochemical, and mass spectrometry detectors, depending on the nature of the analytes.
Types and Applications of HPLC
1. **Liquid-Solid Adsorption Chromatography**
In this method, the stationary phase is an adsorbent such as silica gel, alumina, or polyamide. The mobile phase can be classified into two types: the "eluent" and the "prime." The prime helps determine the general shape of the chromatogram, while the eluent adjusts the retention time of specific components, providing selectivity for certain compounds. Common primes include non-polar solvents like hexane or cyclohexane, while eluents may consist of polar solvents like alcohols or esters. This technique is suitable for separating isomers, antioxidants, and vitamins.
2. **Liquid-Liquid Partition Chromatography**
This type of chromatography uses a stationary phase composed of a bonded liquid. It includes normal-phase and reverse-phase chromatography. In normal-phase, the stationary phase is polar, and the mobile phase is non-polar, making it ideal for separating polar compounds. Reverse-phase, on the other hand, uses a non-polar stationary phase (such as C18) and a polar mobile phase (like water or acetonitrile), making it particularly effective for small molecules such as peptides, nucleotides, and amino acid derivatives.
Another variant is ion-pair chromatography, where ions form neutral pairs in the mobile phase, improving separation of charged species. This method is especially useful when dealing with ionizable compounds.
3. **Ion Exchange Chromatography**
This technique relies on the exchange of ions between the sample and the stationary phase. The stationary phase is usually an ion-exchange resin, and the mobile phase is an aqueous solution with a pH close to the pKa of the target compound. This method is commonly used for separating charged molecules such as proteins, nucleic acids, and amino acids.
For more information on HPLC equipment and applications, visit Shanghai Qite Analytical Instrument Co., Ltd.: http://
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