Nicomp 380 激光粒度仪系列

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Nicomp 380 ZLS 纳米激光粒度仪及ZETA电位分析仪

  • Dynamic Light Scattering

    Nicomp with AT-4.jpg

    The Nicomp 380 Submicron Particle Size   Analyzer uses the principle of   Dynamic Light Scattering (DLS) to   obtain the partcile size distribution   of colloidal systems whose sizes   range from 0.5 nanomters to 6 microns.   DLS works by illuminating a   group of particles in suspension with a   focused laser beam which gives   rise to many scattered light waves. These   waves interfere with each   other and produce a net scattered intensity   that fluctuates as a   function of time at some distant detector.   Diffusion, or Brownian   motion, of the particles causes random variations   in the phases of the   individual waves, resulting in a fluctuating light   intensity. The   particle size distribution can be obtained by analyzing   the time   behavior of these fluctuations using an autocorrelator. The     autocorrelation function for a single uniform size distribution is a     decaying exponential function where particle diffusivity is easily     obtained from the decay time. Finally the particle radius can easily be     calculated using the Stokes-Einstein relationship.

    In     general most samples are not uniform instead they are quite often     polydisperse, having a range of particle sizes. The autocorrelation     function then consists of a combination of decaying exponential     functions, each having a different decay time and the analysis of the     autocorrelation function is no longer quite simple. The instrument using     varying deconvolution algorithms must invert the raw data in order to     arrive at the best estimate of the true particle size distribution.   The   Nicomp excels at characterizing these difficult particle size     distributions by utilizing a group of unique deconvolution algorithms     ranging from a simple Gaussian approximation to a proprietary high     resolution multi-modal deconvolution analyses called the “Nicomp     Distribution".

    Some of the unique   features found on Gaussian analysis mode is a baseline adjust parameter   which provides aggregate compensation   that excedes the sensitivity   found on most other instruments which   employ a dust or dirt factor.   The Gaussian analysis mode also allows for   the user to specify a solid   or vesicle weighting mode for analysing   thin walled colloidal systems   like liposomes. The Nicomp Analysis Mode   is a proprietary   high-resolution deconvolution algorithm that was first   introduced over   25 years ago. It has historically proven its ability to   accurately   analyze even the most difficult closely spaced bimodals (e.g.   2:1   apart) and even certain trimodal distributions. This is extremely     useful in finding the native peak of the aggregate distribution.

    The standard Nicomp 380 is equipped with a 12 mW laser diode and PMT detector with an optical fiber set to 90°. Sample is introduced with drop-in cells.The 380 is the only   Dynamic Light Scattering Instrument designed using a   modular approach.   Its capabilities may be enhanced by adding one or more   modules:

    Autodilution

    This     patented module eliminates the need for manual dilution of   concentrated   sample. Autodilution makes particle size analysis quick   and easy, with   no training required. Results are highly reproducible.

    380/HPLD High Power Laser Diodes

    PSS     offers an array of high power laser diodes to meet the needs of our     most demanding applications. Higher power lasers are needed to extend     the lower limit of our instrument by providing adequate scattering from     small particles. They are also useful when measuring large particles     such as dextrans, which yield insufficient scattering intensity because     of index of refraction properties. The result is a more versatile     instrument, ideal for sizing microemulsions, surfactant micelles,     proteins and other macromolecules. It can even estimate the extent of     aggregration of biopolymers after reconstitution, without     chromatographic separation.

    Avalanche Photo Diode (APD) Detector

    The     Nicomp 380 can be equipped with various high-powered lasers as well   as a   high-gain Avalanche Photo Diode Detector (APD which provides     approximately seven times the gain of a conventional photomultiplier     tube. The APD is used to increase signal-to-noise and sensitivity in     systems that do not scatter light well. Proteins, micelles, other     macro-molecular-based systems, and nanoparticles are often dilute (1     mg/ml or less) and are made of atoms that do not scatter light well. The     Avalanche Photo Diode coupled with a nominally higher powered laser     diode module offers a low cost solution for accurately analyzing     nanoparticles in a short period of time.

    380/MA Multi-angle Goniometer

    Particles     larger than 100 nm do not scatter light isotropically in all     directions. It is possible to make DLS measurements more sensitive to     certain sized particles by changing the angle of detection. The Nicomp     380 can be equipped with a mini-goniometer that moves the optical fiber     between 12° and 175° by 0.9° increments.

    Zeta Potential

    The     Nicomp 380/ZLS is designed to measure the electrophoretic mobility   and   zeta potential of charged particles in liquid suspension. The main     reason to measure zeta potential is to predict colloidal stability.   The   interactions between particles play an important role in colloidal     stability. The use of zeta potential measurements to predict   stability   is an attempt to quantify these interactions. The zeta   potential is a   measure of the repulsive forces between particles.   Since most aqueous   colloidal systems are stabilized by electrostatic   repulsion, the larger   the repulsive forces between particles, the less   likely they will be to   come close together and form aggregates. Thus   the more stable a colloid   will be. The Nicomp 380/ZLS combines the   techniques of Dynamic Light   Scattering (DLS) and Electrophoretic Light   Scattering (ELS) to measure   both sub-micron particle size   distributions and zeta potentials in one   compact instrument.

    The     Nicomp 380/ZLS uses the method of Electrophoretic Light Scattering     (ELS) to measure Zeta potential. To make a measurement, a small aliquot     of sample is typically placed in a disposable plastic cuvette. Then the     palladium electrodes are inserted. The entire cell is placed into the     Nicomp 380. Because of the unique cell design, there is no need to   align   the cell to the stationary plane. After the cell is in place, a   simple   click of the mouse starts the measurement. Since ELS requires   the use   of heterodyned light, the scattered light must be properly   mixed with a   reference beam (split off from the incident light beam)   prior to   entering the detector. The software will begin a measurement   by   automatically adjusting the incident light intensity to optimize   the   mixing between the scattered light and the reference beam. Once   this is   completed, a reference power spectrum is measured while the   electric   field is off. Then the electric field is applied and another   power   spectrum is measured. The change in the frequency of the peak in   this   power spectrum when compared to the reference spectrum is the   Doppler   shift. The Doppler shift is used to calculate the average   mobility.   Using the Smoluchowski equation, the zeta potential is   determined.

    Autotitrator

    The     Autoitrator module gives the Nicomp 380/ZLS the ability to     automatically make multiple measurements on the same sample over a     series of different pH's or ionic concentrations. This allows     iso-electric points to be determined.

    Phase Analysis Light Scattering (PALS)

    The     use of Phase Analysis (instead of the standard amplitude analysis)     allows for the more accurate and precise measurement of small Doppler     shifts. This means that zeta potential measurements can be made in high     ionic strength or high dielectric environments (like alcohols and     organic solvents).

     


  • 详情请参考Nicomp 380 Z3000。点击跳转

  • 详情请参考Nicomp 380 Z3000。点击跳转

  • 详情请参考Nicomp 380 Z3000。点击跳转

  • 详情请参考Nicomp 380 Z3000。点击跳转

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