Polarimeters are generally zero calibrated using air or distilled water. However, in some cases it is desirable to use an active blank solvent to zero the instrument, allowing further measurement to reflect any optically active component that is later added to the solvent.
Bellingham + Stanley do not supply any materials for zero calibration.
SPAN Calibration – Sucrose Solutions
Sucrose Solutions of known concentration may be used to verify the upper scale of a polarimeter operated in either the angular or sugar scale. Sucrose Solutions are primarily used in the sugar and food industries but are considered too time consuming to prepare, requiring a new sample to be made for each calibration as its optical rotation is affected by time. Sucrose Solutions are also temperature dependent so it is desirable to control the temperature of the sample or employ temperature compensation if available.
SPAN Calibration – Quartz Control Plates
Most commonly, Quartz Control Plates (QCP) are used for verifying and calibrating polarimeters, as they are inert and have a relatively low temperature co-efficient, making them easy to handle. QCPs also offer extremely good traceability to internationally recognised standards. Bellingham + Stanley manufacture three types of Quartz Control Plates to the highest standard and are supplied with a Certificate of Conformity showing values in angular rotation (°A) and ISS (°Z) at sodium (589nm) and NIR (850nm) wavelengths at 20 °C.
In addition, QCPs may be supplied with an optional UKAS Certificate of Calibration, showing traceability to PTB. UKAS Certificates are preferred when working in controlled environments such as the food or pharmaceutical industries, where GLP is essential.
When used with an ADP polarimeter manufactured by Bellingham + Stanley, a thermal block should be used to provide mechanical contact to the instrument’s external temperature sensor to ensure that the measured temperature fully represents the actual temperature of the QCP for both stabilisation and compensation objectives.
Certification of QCPs at wavelengths other than 589/850nm is available as part of Certification Service detailed below.
|Order Code||Nominal Value||Description|
|34-20||+100 °Z||+34.6 °A||Standard Quartz Control Plate supplied in soft protective cover, Certificate of Conformity showing optical rotation in ° A & °Z for sodium and NIR wavelengths (only).|
|34-21||+15 °Z||+5.2 °A|
|34-241||Thermal Block for use with ADP/S|
Quartz Control Plates may be supplied from new with a traceable certificate, as an optional service. Additionally, as part of GLP, it is often required to have existing Quartz Control Plates recalibrated at regular intervals.
Bellingham + Stanley, a UKAS accredited Calibration Laboratory number 0834, offer a certification service whereby Quartz Control Plates may be issued with a UKAS Certificate of Calibration at sodium (589.44nm) wavelength and additionally at any other wavelength specified by the customer between 546-900nm, with traceability shown to ICUMSA and PTB. QCPs outside of the ranges below may also be certified within the UKAS laboratory to an uncertainty of ±0.05 °Z (±0.017 °A)
|1||13 to 17 °Z||4.5 to 5.9 °A|
|2||95 to 105 °Z||32.9 to 36.4 °A|
|3||-26 to -34 °Z||-9.0 to -11.8 °A|
|Ranges 1-3: Uncertainty: ±0.017 °Z
and ±0.006 °A
In the Range -34 °Z to 105 °Z but outside of ranges 1-3: Uncertainty: ±0.05 °Z and ±0.017 °A
|90-803||Calibration, quartz control plate at 20.0 °C & 589.44nm.|
UKAS Certificate of Calibration for
Quartz Control Plate at 20.0 °C
Must be ordered in addition to Certificate of Calibration at sodium wavelength (589nm – Code 90-803)
Manufacturers Certificate of Calibration* for Quartz Control Plate at 20.0 °C
Must be ordered in addition to UKAS Certificate of Calibration at sodium wavelength (589nm – Code 90-803)
*Values below 546nm are not currently within the Bellingham + Stanley scope of UKAS accreditation and so are supplied as a separate Manufacturers Certificate of Calibration.
Best Measurement Capability (Uncertainty):
The reported expanded uncertainty of measurement is stated as the standard uncertainty of measurement in units of °Z multiplied by the coverage factor k = 2, which for a normal distribution corresponds to a coverage probability of approximately 95%. The standard uncertainty of measurement has been determined in accordance with publication EA-4/02.
FAQTechnical Bulletion TB-003 – Calibration of Polarimeters using sucrose.