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Nanotechnology Particle Size Measurement Solutions
Microtrac has been a pioneer in particle sizing technology for over 35 years! In 1990 Microtrac released the Ultrafine Particle Analyzer incorporating the Controlled Reference Method of analysis of dynamic light scattering particle sizing. The Nanotrac is the latest generation of dynamic light scattering sub-micron analyzers from Microtrac. The enhanced Nanotrac design features 20 times faster measurements, smaller particle size capability, higher precision, higher accuracy and advanced software capabilities all in a small robust package. Fixed optics design with no moving components ensures long term stability with highly repeatable results from day to day as well as instrument to instrument.
Nanotrac complies with the ISO 22412 standard for Dynamic Light Scattering.
The main features of the Nanotrac:
- Technology - Dynamic Light Scattering incorporating the patented Controlled Reference Method for advanced power spectrum analysis of Doppler shifted scattered light.
- Range - Measurement capability from 0.8 to 6500 nanometers.
- Sample Size - Typically less than 3ml in standard cell, or 0.2ml with small cell option.
- Rapid Analysis - 15 to 30 second analysis times in most cases.
- Analysis Simplicity - No "A Priori" or advance knowledge of the particle size distribution is required. Nanotrac will accurately report monomodal, multimodal, broad and narrow distributions without the need to select special calculation algorithms.
- Accuracy - Measures using Mie scattering calculations for spherical particles and proprietary Modified Mie calculations for non-spherical particles. This feature is unique to Microtrac.
- Repeatability - Better than 1% from instrument to instrument for 100nm polystyrene.
- Traceability - Particle Size measurements traceable to NIST standards.
- Concentration - Capable to measurements up to 40% reducing the need to dilute samples which may affect particle size or colloid stability. Low concentration measurements down to 100ppb possible due to high signal level from Controlled Reference Method.
- Temperature Control - Precise temperature monitoring and compensation eliminates the need for temperature control baths or devices.
- Versatility - Nanotrac probe can be external for use in autosamplers (NAS), Dip-N-Run configuration or in-line applications.
- Validation - Full IQ/OQ support documentation is available
- Security - Nanotrac FLEX software meets or exceeds FDA 21 CFR Part 11 protocols.
Nanotrac: The Options
Nanotrac ULTRA
A key feature of Nanotrac throughout its history has been the ability to measure samples at significantly higher concentrations than conventional Photon Correlation Spectroscopy. However, there are many applications where materials are produced in very low concentrations and typically in sizes less than 50nm. The Nanotrac ULTRA has been designed to address this market need and measure such samples without sacrificing any of its tried and true capabilities from the past. The unique Nanotrac ULTRA Probe design is optimized to detect particle size distributions in low concentration suspensions and is particularly sensitive to size ranges below 50 nm but without any loss of sensitivity to larger sizes up to 6.5 um and high concentrations.
Nanotrac NPA151 - Internal Probe
The Nanotrac 151 features an internal probe embedded in a stainless steel sample cell. The standard sample cell has a sample volume of 3mls and the small volume option is available with a 0.2ml minimum volume. Temperature and viscosity compensation is achieved through the use of a high accuracy temperature sensor embedded in the sample block. The sample chamber can be maintained at a selected temperature by connecting it to an external circulating constant temperature bath. Nanotrac is controlled by the Microtrac FLEX operating software package. Data can be stored, retrieved, exported, trended and statistically analyzed.
Nanotrac NPA251 - External Probe
The Nanotrac NPA251 features an external probe. This allows the user to immerse the probe in a sample vessel or process bypass. The probe cable is available in various lengths. Temperature compensation is facilitated through a sensor embedded in the probe tip. When combined with the NAS35 Autosampler, a robot arm automatically moves the probe to as many as 35 sample vials mounted in its carousel.
Nanotrac NPA253 - Combination
Nanotrac NPA253 combines an external probe with an internal sample cell offering users the flexibility of measuring samples in-line, in-vials, or in-the-unit. Both cell options available with model NPA151 are also available with the combination model which now also includes the internal cell fluid circulation feature for temperature control.
Nanotrac NPA150, NPA250, NPA252 - Legacy Products
Nanotrac's legacy models are still in production and available to help our customers maintain precise product consistency with existing process and quality control equipment.
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Models Nanotrac |
NPA 150 Internal sample cell and probe
Nanotrac NPA 151 ULTRA, optimized for low concentration measurements
Nanotrac NPA 250 External probe option
Nanotrac NPA 252 Combination unit with both internal and external probe capabilities |
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External probe options |
1.5 meter cable is standard
Also available at 0.75, 1.5, 3.5, 5.5, 10, 15, 20 Meters |
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Internal Sample Cell Volumes |
3 ml (Standard), 0.2 ml
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Measurement Range |
0.8 to 6500 nanometers (0.0008 to 6.5 microns) |
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Measurement Angle |
180 Degrees |
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Repeatability |
1% for 100nm Polystyrene |
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Concentration limits |
High up to 40% by solids in some cases
Low 0.1ppm for 200 nm polystyrene
ppb range in Nanotrac ULTRA |
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Optical Components |
Laser Diode - 780 nm wavelength, 3 mW nominal, Class lllB
Laser and detector fixed in place- no alignment required |
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Solvent Compatibility |
Wetted surfaces are stainless steel and sapphire. Compatible with most organic and inorganic solvents. |
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Power Requirements |
Instrument powered via PCI bus.
90 to 240 VAC
47 to 63 Hz
5 Amps |
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Water circulator fittings |
5/16” OD Swagelock Tube Fittings |
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Temperature |
10 to 50 Degrees C |
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Humidity |
up to 90% non condensing |
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Sample Temperature |
10 to 82 Degrees C |
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Temperature measurement |
Accurate to +/- 0.1 Degree C |
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Dimensions
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Width 10.2 cms (4 inches)
Depth 38.1 cms (15 inches)
Height 15.2 cms (6 inches)
Weight 3.2 kgs (7 pounds) | |
Nanotrac Technology
How dynamic light scatter works to accurately measure nano size particulates
The Controlled Reference Method
Particles suspended in a dispersing fluid are subject to random collisions with the thermally excited molecules of the dispersing fluid resulting in Brownian motion. The velocity and direction of the resulting motion are random but the velocity distribution of a large number of mono-sized particles averaged over a long period will approach a known functional form, in this case the size distribution of the particles.
In the Nanotrac, light from a laser diode is coupled to the sample through an optical beam splitter in the Nanotrac probe assembly. The interface between the sample and the probe is a sapphire window at the probe tip. The sapphire window has two functions! Firstly, it reflects the original laser back through the beam splitter to a photodetector. This signal which has the same frequency as the original laser acts as a reference signal for detection, offering Heterodyne detection.
Secondly, the laser passes through the sapphire window and is scattered by the particles which are in suspension but moving under Brownian motion. The laser is frequency shifted according to the Doppler effect relative to the velocity of the particle. Light is scattered in all directions including 180 degrees backwards. This scattered, frequency shifted light is transmitted through the sapphire window to the optical splitter in the probe to the photodetector. These signals of various frequencies combine with the reflected signal of un-shifted frequency (Controlled Reference) to generate a wide spectrum of heterodyne difference frequencies. The power spectrum of the interference signal is calculated. The power spectrum is then inverted to give the particle size distribution.
As particle size is determined from the velocity distribution of the particles moving under Brownian motion it is necessary to compensate for the physical parameters that directly affect the particle velocity. If the dispersing fluid molecules have a higher average thermal energy they will impart higher velocities to the particles with which they collide. Median particle velocity is directly proportional to the absolute temperature of the fluid. A viscous fluid slows the energized particles.
Particle velocity is inversely proportional to fluid viscosity. The Nanotrac incorporates a highly accurate temperature sensor in the sample cell. By describing the fluid temperature and viscosity characteristics in the Nanotrac algorithm, these parameters can be included in determining accurate particle size distributions. Also, because the laser light needs only to penetrate approximately 100 microns into the sample to generate a power spectrum, the Nanotrac can accurately determine particle size distributions at significantly higher concentrations than other methods.
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Nanotrac Autosampler Carousel (NAS35) |
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Nanotrac Automatic Sampling System
When combined with a Nanotrac external probe model particle size analyzer, the Nanotrac Auto-Sampler (NAS 35) provides a convenient means of measuring, unattended up to 35 samples. Each sample position on the NAS 35 carousel is controlled by independent sample measurement setup parameters. Therefore each sample location can have very different samples for measurement than any other sample position. Automated, on board ultrasonic dispersion is also provided and can be individually controlled for each position. Cleaning of the Nanotrac optical and ultrasonic probes is also automated.
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