OptiMelt Automated Melting Point System - Stanford Research ...

86 Melting Point Certified Reference Standards Appendix Bit is best to obtain CRSs directly from the US Pharmacopeia Convention in order todetermine the usability of the OptiMelt according to US Pharmacopeia protocols.• Beware of Standards Laboratories offering CRSs compatible with multiplepharmacopeias. Ask for samples of Certificates of Measurement before orderingstandards to assure the compatibility of their records with the pharmacopeia protocolyou plan to follow. Contact the Laboratory director whenever in doubt. A reputableaccreditation center will always be very helpful and forthcoming.• Occasionally, accreditation centers will run out of stock of some CRSs. In that rareevent, the standards lab should be able to recommend alternative sources for CRSswhile they restock their supplies. It is always a good idea to have an emergencysecond source of standards identified in case a backup supplier is required.• Some CRSs have expiration dates. Following strict GLP and GMP guidelines, QAlabs must keep track of those dates, and never use expired CRSs for calibration ordetermination of acceptability of their melting point equipment.• A slight drift in melting point results is expected when the melting point temperaturesobtained with a liquid bath oven are compared to those obtained with a metal blockoven under the same ramping conditions. This difference is to be expected andgenerally ignored since it generally falls within the intrinsic uncertainty of themeasurement.• Use capillary tubes of the same kind, and from the same supplier, to performcalibrations and to carry out all subsequent measurements. Beware that somepharmacopeia protocols include specific capillary requirements.• Failure to clean the tubing before making capillary melting tubes is one of the mostcommon causes of low melting points and broad melting point ranges. Wheneverpossible buy pre-made tubes from reputable sources, to assure the bestreproducibility of results.• Dry CRS samples carefully and store them in a vacuum dessicator between meltingpoint determinations. Forty eight hours over P 2 O 5 is a very common recommendationfor drying standards. Follow all standard-specific recommendations.Accreditation CentersThe following table is a list of accreditation centers which stock melting point CRSs.Notice that the scope of the centers ranges from local to worldwide.Keep in mind that certification protocols are constantly being revised and modified. Usethis table as reference only and access the Internet to update the records on this table ifnecessary.OptiMelt Automated Melting Point System