Polarimeter Tubes

Precision Engineered Polarimeter Tubes

Bellingham + Stanley polarimeter tubes (sometimes referred to as “Polarimeter Sample Cells”) are manufactured to high quality standards conforming to ICUMSA recommendations and are compatible with most makes of polarimeter from manufacturers around the world. Made with quality materials from a manufacturer with over 100 years’ experience in polarimetry, these sample cells stand up to repeated use time and time again. To see our selection of polarimeter tubes please click here. 

The Importance of Sample Tube Length

Optical rotation (the result from measuring with a polarimeter) is a linear function of the concentration of both the test substance and the path length of the solution (i.e. the tube length). Specific rotation is the angular rotation obtained under standard measuring conditions: concentration, tube length, temperature and wavelength. 

Calculation of Specific Rotation (optically active liquids/solutions)

Where: 
a                      is the corrected optical rotation
[a]tl                  is the specific rotation at t °C in the polarised light of wavelength 
l. l                     is the length of the polarimeter tube in metres
d                      is the relative density of the liquid or solution at 20 °C
c                      is the concentration of the solute expressed in grams per mL of solution 
p                      is the concentration of the solute expressed in gram per gram solution

Tube length and, importantly, the accuracy of the tube length is critical to the result whether results are declared as optical or specific rotation. To learn more about polarimeters, optical rotation, specific rotation and how tube length affects the experimental reading, please read our Technical Bulletin P001.

Polarimeter Tube Shapes & Sizes

Polarimeter tubes come in a variety of shapes, sizes and styles of sample inlet and outlet to suit the sample being tested.  

• 30 mm collar
• 5, 10, 25, 50, 100 and 200 mm tube lengths
• Choice of sample interface styles
• Silica Windows for 300-900 nm operation
• Glass or stainless steel tubes
• Plastic, metal or PEEK ends
• Spare parts available

Standard Glass Polarimeter Tubes

Standard glass tubes feature nylon (plastic) end caps with a choice of filling style and are ideal for non-volatile or corrosive samples in food, sugar, chemical, and academic applications.   

• Bubble tubes: To remove any bubbles from the light path
• Centre fill tubes: For easy filling of samples from a beaker or pipette
• Cup fill tubes: For easy filling of viscous samples

Special Glass Polarimeter Tubes

Special polarimeter sample tubes such as those with metal (stainless steel) end caps are available. These tubes have replaceable seals between the glass tube and end cap making them ideal for applications where the sample may degrade the adhesive used with standard tubes.   

Glass polarimeter tubes with replaceable PEEK end caps are commonly used in the chemical and pharmaceutical industries where Hydrochloric Acid (HCl) forms part of the sample under test.

• Centre fill tubes with metal or PEEK end caps
• Cup fill is available on tubes with metal end caps only

XPC Tubes for use with Peltier Controlled Polarimeters

If you are seeking the best temperature response during measurement, we offer metal (stainless steel) polarimeter tubes which work in harmony with the XPC Peltier Temperature Control of the ADP600 Series and ADP450 Digital Polarimeters. These tubes have removable filler cups so that sample may be introduced easily. Temperature sensors may also be applied to the sample itself by using special collars that prevent the probe from disturbing the light path.

• Removable filler cups
• Perfect for temperature sensors

Low Volume Sample Tubes

For those looking to measure extremely small amounts of rare or valuable sample with a digital polarimeter, these Low Volume metal polarimeter tubes are available in 5, 10, 25, and 50 mm variants. Suitable for 0.1 ml of sample up to 1.0 ml of sample. These 10, 25, and 50 mm specialist sample tubes feature sample entry and exit via UNF 28 female threads and PTFE pipe connectors, whilst the 5 mm has a Luer taper nozzle fitting for sample application using a syringe. 

Low volume tubes are especially suited to “closed systems” where the prevention of sample loss through evaporation is imperative, or for when working with automated workflows. 

• UNF female threads (10, 25 & 50 mm)
• UNF 28 pipe adaptors included (10, 25 & 50 mm)
• Serrated nozzle adaptors available
• Luer taper female nozzles (5 mm only)