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Quartz Control Plate (QCP) FAQ: Calibration, Use, Handling, Cleaning, and Certification
Learn what a Quartz Control Plate (QCP) is, how it is used, how calibration works, what the certificate means, and how to handle and store a QCP properly.
What is a Quartz Control Plate (QCP)?
A Quartz Control Plate (QCP) is a Certified Reference Material (CRM) used to verify the optical rotation performance of polarimeters and saccharimeters. It provides a stable, traceable reference value that helps confirm an instrument is operating correctly and producing reliable measurements.
What is a QCP used for?
A Quartz Control Plate is commonly used for:
- Verifying optical rotation performance
- Evaluating instrument linearity
- Supporting routine performance verification
- Supporting calibration verification and quality assurance activities
Is a QCP used to verify temperature accuracy?
No. A Quartz Control Plate is designed to verify optical rotation performance only. It is not intended to verify or calibrate the temperature accuracy of a polarimeter or saccharimeter.
Can handling affect QCP performance?
Yes. Although Quartz Control Plates are durable, improper handling can affect their performance. Physical damage—including scratches, chips, mechanical stress, contamination, or impact—may alter optical characteristics and prevent the QCP from meeting certification requirements.
How should a QCP be handled?
To help maintain accuracy and extend the life of your Quartz Control Plate:
- Handle the QCP only by the mount or assembly.
- Avoid touching the optical quartz surfaces.
- Minimize handling whenever possible.
- Protect the QCP from mechanical shock, contamination, and chemical exposure.
- Allow the QCP to stabilize to ambient temperature before performing measurements.
How should a QCP be stored?
When not in use, store the Quartz Control Plate in its supplied protective storage container. Proper storage helps protect the optical surfaces from dust, scratches, and accidental damage.
How do I clean my Quartz Control Plate?
Clean the QCP only when necessary.
- Remove loose dust using clean, dry compressed air whenever possible.
- If additional cleaning is required, gently wipe the quartz surface using a soft, lint-free optical cloth or an optical-grade cleaning swab intended for precision optics.
- Use only light pressure. Excessive force may scratch the optical surface and affect measurement performance.
Cleaning: Can I use alcohol or solvents to clean my QCP?
Avoid using solvents whenever possible.
If compressed air or a dry optical cloth is insufficient and a solvent appears necessary, contact Rudolph Standards Laboratory before cleaning. Using an improper solvent may damage the optical surfaces or affect measurement performance.
Calibration: Is the quartz physically adjusted during calibration?
No. The quartz is not physically adjusted, repaired, or altered during calibration. It is measured and certified in its existing condition. The certified values represent its performance at the time of calibration.
What does recalibration include?
Recalibration consists of precise measurement and certification of the Quartz Control Plate. No physical adjustments or modifications are made during the process.
Is the calibration date the same as an expiration date?
No. The calibration date indicates when the Quartz Control Plate was calibrated. It is not an expiration date.
Does a QCP expire?
No. A Quartz Control Plate is an artifact reference material and does not have a fixed expiration date. Its continued suitability depends on:
- Physical condition
- Proper handling
- Storage practices
- Frequency of use
- Successful recalibration
How often should a QCP be recalibrated?
A typical recalibration interval is every 2 to 3 years. However, the appropriate interval depends on:
- Frequency of use
- Application requirements
- Internal quality procedures
- Regulatory or accreditation requirements
- Risk assessment
Users should establish recalibration intervals that align with their quality management system.
Who is responsible for establishing recalibration intervals?
The user is responsible for determining appropriate recalibration intervals based on internal procedures, regulatory requirements, accreditation standards, and the level of measurement risk associated with the application.
For a new QCP, should the recalibration interval begin on the calibration date or the first use date?
For newly purchased Quartz Control Plates, many organizations establish the recalibration interval beginning on the date the QCP is first placed into service rather than the calibration date. This practice should follow the organization's internal quality procedures and applicable regulatory requirements.
Where is QCP recalibration performed?
Quartz Control Plate recalibration is performed exclusively at the Rudolph Research Analytical Standards Laboratory, where the QCP is measured and certified using traceable reference standards and established calibration procedures.
Can Rudolph recalibrate non-Rudolph Quartz Control Plates?
No. Rudolph Research Analytical recalibrates only Rudolph-manufactured Quartz Control Plates.
If you have a non-Rudolph QCP, trade-in or replacement options may be available. Contact Rudolph Standards Laboratory for additional information.
Certification: How do I know if my QCP meets specifications?
If your Quartz Control Plate meets all applicable certification requirements, an official Calibration Certificate is issued.
If the QCP does not meet certification criteria, a certificate is not issued, and Rudolph will provide supporting information regarding the results.
What do the values on the Calibration Certificate represent?
The Calibration Certificate reports the certified optical rotation values measured at specified wavelengths, along with the associated measurement uncertainty.
These certified values are used to compare your instrument's readings during routine performance verification.
Why doesn't my Calibration Certificate include "As-Found" and "As-Left" values?
"As-Found" and "As-Left" values are typically reported only when an item is physically adjusted during calibration.
Because a Quartz Control Plate is measured but not adjusted, these values are not applicable. The certified values represent the QCP's condition at the time of calibration.
What happens if my QCP does not meet certification criteria?
If a Quartz Control Plate does not meet certification requirements:
- A Calibration Certificate is not issued.
- Rudolph Standards Laboratory will provide supporting information regarding the calibration results.
- Available options, including replacement or trade-in (when applicable), will be discussed.
Additional Questions
Can I use one QCP on multiple polarimeters?
In most cases, yes. A Quartz Control Plate may be used on multiple compatible instruments, provided it is appropriate for the instrument design, measurement range, and operating procedures. Refer to your instrument documentation or contact Rudolph Standards Laboratory if you have compatibility questions.
Why is using a Certified Reference Material important?
Certified Reference Materials provide traceable, documented reference values that help:
- Verify instrument performance
- Support ISO and GMP quality systems
- Increase confidence in measurement results
- Demonstrate traceability during audits
- Improve long-term measurement consistency
Need Additional Assistance?
Our Standards Laboratory team is happy to answer your questions regarding Quartz Control Plates, recalibration services, certification, or replacement options.
Rudolph Standards Laboratory
Phone: (973) 584-1558
Business Hours: Monday–Friday, 8:30 AM–5:00 PM EST
Email: standards@rudolphresearch.com
Need a new QCP or recalibration service? Contact us to request a quotation for a new Quartz Control Plate or recalibration of your existing Rudolph QCP.