Reference measurement procedure for Δ9-tetrahydrocannabinol in serum
An isotope dilution gas chromatography/mass spectrometry (ID-GC/MS) reference measurement procedure for Δ9-tetrahydrocannabinol (THC) in serum was developed and validated. The method complies with the concept of a ratio primary reference measurement procedure. The uncertainty was determined for two concentrations of THC in serum (1 ng/mL and 2.4 ng/mL). The calculation procedure is based on the Guide to the Expression of Uncertainty in Measurement (GUM). The relative expanded uncertainty was found to be less than 2% for both concentration levels, corresponding to a 95% confidence interval. For the reference method, it was shown that the measurement of THC within the concentration range covered by the current threshold values is very accurate. The method has the potential to provide traceability for the methods used in practical forensics.
Primary methods for the measurement of amount of substance
Primary methods of measurement play an important role in metrology because they provide the essential first link in the chain of traceability from the abstract definition of a unit of the International System of Units (SI) to its practical use in measurement. A definition of a primary method of measurement has been developed by the Consultative Committee for Amount of Substance (CCQM) that distinguishes between those methods that measure a quantity directly and those that measure the ratio of two quantities. Methods that do not fulfil the definition of being primary also play an important role in measuring amount of substance. In some cases, it is appropriate to refer to these as secondary methods.
Catalytic removal of tert-butyldimethylsilyl (TBS) ether by PVP-I
Abstract A mild, efficient and rapid protocol the deprotection of alcoholic TBDMS ethers using PVP-1 as catalyst in methanol, the procedure of deprotection of various TBDMS ethers were found to be very convenient, easy work-up, high yielding.