Used machines for sale

Refractometry benchtop refractometers

Main brands:

Leica, Reichert

Refractometry benchtop refractometers

BENCHTOP REFRACTOMETRY
COMPLETE TECHNICAL GUIDE – EXPANDED VERSION

ADVANCED OPERATING PRINCIPLES

Snell’s Law and Refractive Index (nD)

The refractive index is a physical property characteristic of each substance when temperature and pressure are constant.

For solutions, the refractive index varies according to concentration.

The refractometer measures light deviation at the interface between:

Prism (higher refractive index)

Sample (lower refractive index)

This difference generates a critical angle that allows precise refractive index calculation.

Importance of Wavelength – Sodium D Line (589.3 nm)

The refractive index varies depending on the wavelength of light.

For international standardization, the sodium D line (589.3 nm) is used.

Digital models:
Use an LED with an interference filter to simulate this exact wavelength.

Abbe models:
Use Amici prisms for chromatic compensation.

MODERN OPTICAL PRINCIPLE

Total Internal Reflection

In digital models:

Light strikes the prism.

Part of the light is refracted and part undergoes total internal reflection above the critical angle.

A CCD or CMOS sensor detects the light/dark boundary.

An algorithm calculates the refractive index with high precision.

This system eliminates operator subjectivity.

METROLOGICAL PARAMETERS

Measurement Range

Refractive index (nD): 1.30000 to 1.72000
Brix scale: 0 to 95%

Typical Accuracy:

Premium models: ±0.00002 nD
Industrial models: ±0.1% Brix

Resolution:

0.00001 nD
0.01% Brix

Repeatability:

±0.00001 nD
±0.02% Brix

Important:
Resolution does not mean accuracy. An instrument may display many decimal places and still lack precision.

TEMPERATURE CONTROL – CRITICAL FACTOR

Temperature is the main source of error in refractometry.

A variation of 1 degree Celsius may change the reading by 0.1% Brix.

Example:

20% Brix solution at 20°C
May indicate 19.8% Brix at 25°C

Types of Temperature Control

Basic ATC
Automatic temperature compensation
Stabilization time: 30 to 60 seconds

External circulating water bath
Water circulation around the prism
High thermal stability

Peltier technology
Electronic heating and cooling system
Stabilization in 10 to 30 seconds
Allows programmable temperature curves
Higher market value

PRISM MATERIALS

Optical glass
General use

Synthetic sapphire
High abrasion resistance
Ideal for fruit pulp and sugar

Quartz
Special UV applications

Sapphire prisms significantly increase resale value.

INDUSTRIAL APPLICATIONS

Chemical and Petrochemical Industry

Use:
Measurement of solvents, polymers, resins and lubricating oils

Technical requirements:
Seals resistant to aggressive solvents (FFKM or Teflon)
Measurement in nD with five decimal places

Pharmaceutical and Cosmetic Industry

Use:
Identification of essential oils
Purity control of glycerin and alcohol

Requirements:
GLP and GMP compliance
21 CFR Part 11 compatibility
Electronic records and audit trail

Food and Beverage Industry

Use:
Determination of total soluble solids
Sugar concentration control

Technical needs:
Wide Brix range (0 to 95%)
Easy cleaning
Sapphire prism for mechanical resistance

REFERENCE MANUFACTURERS

ATAGO
RX Series
Industrial robustness

ANTON PAAR
Abbemat Line
High precision for R&D and pharmaceutical labs

METTLER TOLEDO
Excellence Series
Integration with density meters and pH meters

BELLINGHAM + STANLEY
RFM Series
Highly resistant prisms

REICHERT
AR Series
Durable Abbe and digital models

FACTORS THAT INCREASE RESALE VALUE

Integrated Peltier control
Traceable calibration (NIST or equivalent)
Valid calibration certificate
Premium brand
Original licensed software
Prism in perfect condition

FACTORS THAT REDUCE VALUE

Scratched prism
No temperature control
Discontinued model
Missing accessories

STRATEGIC TECHNICAL KEYWORDS

Scale linearity
Traceable calibration
High resolution CCD sensor
Total internal reflection
Automatic temperature compensation
21 CFR Part 11 compliance
LIMS integration
Metrological repeatability
Electronic temperature control

Equipment for analytical laboratory R&D in the food industry.

Machine code: 266-218

Brand: Agilent HP, Anton Paar, Horiba, Hunter Lab, Kyoto Electronics, Leica, Merck, Mettler Toledo, Miele Professional, Millipore, Parker, Reichert, Thermo Fisher Scientific

Headspace Sampler

Manufacturer: Agilent Technologies

Model: G1888

Year: Not specified

Technical Description: Automated static headspace sampling system designed for volatile compound introduction into gas chromatographs. Features a 70-via...