Reichert ABBE MARK III

The Reichert Abbe Mark III Refractometer is a state-of-the-art optical instrument designed for precise refractive index measurements in various quality control applications, including food and beverage, medical, pharmaceutical, industrial fluids, chemical, and petrochemical industries. Its advanced features and user-friendly interface make it a versatile and widely used instrument.

Function Description

The primary function of the Abbe Mark III is to measure the refractive index of transparent and translucent liquid or solid samples. It is programmed to directly display the refractive index, percent solids (Brix), and sample temperature. The percent solids scale is based on ICUMSA conversion tables for sucrose solutions. For non-sucrose solutions, measurements can be taken in refractive index mode or, if the conversion value is known, in percent solids mode.

The instrument also supports custom channels, which can be programmed to provide product-specific measurements in refractive index or percent solids, with temperature compensation. This allows for direct readouts of values corrected to a predetermined temperature, eliminating the need for complex manual conversions and facilitating comparisons against specific formulas or process specifications.

Usage Features

The Abbe Mark III is designed for ease of use, with several features to ensure accurate and consistent measurements:

Sample Analysis: The process begins by raising the upper prism, applying the sample to the clean measuring surface, and gently lowering the upper prism to spread the sample evenly and eliminate air bubbles. Allowing the sample to reach temperature equilibrium with the instrument is crucial for accuracy.
Optical Alignment: Users view the image through a focusing eyepiece. If the shadowline is indistinct or colored, the Color Dispersion Correction Wheel is rotated to reduce color dispersion and achieve a sharp, clear shadowline. The Shadowline Adjustment Knob is then used to center the shadowline within the "X" pattern. For consistent measurements, the shadowline should always be approached from below. Once centered, the READ key is pressed to capture the measurement.
Reading Modes: The instrument offers multiple reading modes, including Refractive Index (Index), Temperature Corrected Refractive Index (Index-TC), Percent Concentration (Solids), and Temperature Corrected Percent Concentration (Solids-TC). These modes can be selected via the menu or by using the Up/Down keys on the display.
Solid Sample Measurement: The Mark III can measure transparent or translucent plastic or glass solid samples, as well as thin pliable solids like contact lens material. For solid samples, a contact fluid with a higher refractive index than the sample (e.g., Bromonaphthalene) is applied to the polished sample surface, which is then placed on the measuring prism. The upper illumination prism should not be lowered onto solid samples to prevent damage.
Calibration: Routine calibration is essential for maintaining accuracy. The instrument offers two calibration options:
- Set Point Calibration: Performed daily using distilled water as the standard. The shadowline is adjusted to the center of the "X" pattern, and the READ key is pressed to calibrate.
- Span Point Calibration: Allows for up to six additional calibration points using NIST-certified calibration fluids. This ensures accuracy across the instrument's full reading range or a specific range relevant to the samples being analyzed. Set Point calibration must be completed before performing Span Point calibration.
Editing Calibration Points: The instrument allows users to edit stored calibration values to match new calibration standards, which may be necessary if calibration fluid lot numbers change or alternate fluids are used.
Automatic Temperature Correction (TC): This feature mathematically corrects refractive index values to a specific temperature (commonly 20°C) based on refractive index, temperature, and temperature coefficient. This is particularly useful for comparing readings at varying ambient temperatures.
Automatic Temperature Equilibration: This option detects when the sample and prism have reached thermal stability, ensuring accurate measurements. Users can set the desired temperature stability range, and the instrument will prompt them to align the shadowline and press READ once stability is achieved.
Custom Channels: The Mark III supports user-programmable custom channels (Channels 2-15) for specific product measurements, including units like specific gravity, % protein, or g/ml. These channels can be uploaded from a PC and activated through the instrument's menu.
Computer and Printer Interface: Two RS232 serial ports allow for data download to a computer and custom channel file upload/deletion. The instrument can also connect to an external printer for outputting text strings, which can be customized to include various data points like temperature, index, channel, time, and date.
Password Protection: A password feature limits user access and protects critical settings from unauthorized alteration.
Language Options: The instrument supports English, French, Spanish, and German languages.

Maintenance Features

Proper care and cleaning are crucial for the longevity and accuracy of the Abbe Mark III:

Prism Cleaning: The prism surfaces must be cleaned thoroughly before and immediately after each sample application to prevent residue buildup, which can adversely affect readings. Distilled water, diluted soapy water, isopropyl alcohol, or methanol can be used, followed by rinsing with distilled water and drying with a lint-free cloth. Abrasive materials should never be used on the optical surfaces.
Instrument Body Cleaning: The body and display areas can be cleaned with a soft cloth and a mild soap and water solution or a typical household glass cleaning product.
Chemical Precautions: Certain strong solvents (e.g., N,N-Dimethylformamide, Tetrahydrofuran, cresols, phenols, tar acids, and some lacquer thinners) can damage the sealant between the prism and the stainless steel block. Reichert Analytical technical support should be consulted if there are concerns about sample or solvent compatibility.
Thermal Shock Prevention: When using a water bath circulator, the prism temperature should be adjusted gradually to avoid thermal shock.
Water Bath Attachment: The instrument is equipped with four water ports for connecting to a water bath circulator, allowing for temperature control of the prisms above or below ambient temperature. Tubing should be flexible enough to allow the upper prism assembly to open and close freely.