OptiMelt Automated Melting Point System - Stanford Research ...

72 Maintenance and Calibration Chapter 4Recommendations and Tips• The accuracy of the melting point determinations performed with your OptiMelt isonly as good as the last temperature calibration and ultimately only as good as theaccuracy of the standards used.• Calibrating the temperature readings against CRSs accounts not only for inaccuraciesin the thermometer but also for the unique heat conducting properties of each metaloven/capillary assembly. Alternative calibration methods relying on the use ofreference thermometers or calibration baths, though adequate for checking thetemperature accuracy of the thermometer by itself, are static measurements that donot take into consideration the thermal lag between the thermometer and the capillarysamples during the heating process.• Password protection is built into the Calibration menu to prevent accidental changesto any calibration data by inexperienced or unauthorized personnel.• No reliable CRSs with melting points above 300 °C are available.• An important advantage of WHO traceable standards (such as the O100MPS CRSKit) is that their assigned melting point temperatures are clear points with accuraciesthat closely match the accuracy specifications of OptiMelt.• The offset corrections (TOCs) from an Acceptability Test become obsolete as soon asthey are entered into the calibration menu and calibration is successfully completed.Do not enter the results of an Acceptability Test more than once!• It is not unusual to see differences between the results obtained for the samecompound from liquid bath and metal ovens. This discrepancy is generallyunderstood and accepted, and rarely exceeds the uncertainty of the measurement. Aslight difference is to be expected, and is rarely beyond the accuracy of the standards.• Whenever possible, use the MeltView software package to visualize the melts and tostore a record of the melt process. Being able to replay a melt not only improves theaccuracy of your visual melting point determinations, but also provides completedocumentation conforming to GLP requirements.• A list of compounds commonly used as Melting Point Standards is included inAppendix B of this manual.OptiMelt Automated Melting Point System