Assigned purity

Assigned Purity = [100%—(% moisture content + % residual solvents)] 

Assigned Purity = [100%—(% moisture content -I- % residual solvents + % counter ion)] x [purity/100]. 

Other equations may be used for calculating assigned purity and documented in the raw data, depending on 

---

As discussed earlier, the assignment of purity is ideally done by a relative method, comparing analyte peaks in chromatograms of sample solutions with analyte peaks in chromatograms of a reference standard of assigned purity. The difficulty that arises when no suitable reference standard exists has already been alluded to. Purity then has to be assigned on a 100% detected impurities basis. The nature of the difficulties that arise in assigning purity in this way is discussed in the next section. 

It is therefore necessary to evaluate impurities utilizing a variety of techniques and instruments, prior to assigning purity values to the drug substance. 

When assigning purity and assay values, some general considerations include ... 

Characterization data—Full characterization data should be supplied for the primary reference standard, including the results from analytical testing and spectral characterization. The assigned purity of the reference standard should be clearly designated. 

Documentation of preparation of stock and sub-stock solutions must start with receipt of the reference standard, its Certificate of Analysis, assigned purity (and possibly chiral purity) and its history of storage and use after receipt (Section 9.4.4). Procedures for preparation and subsequent dilution of stock solutions are described in Section 9.5.4 and stability testing for these solutions in Section 10.4.Ih. Some of the relevant documentation might be included in general laboratory SOPs but full documentation of all study-specific procedures and data regarding preparation, storage and validation of stock solutions is required. 

In a patent assigned to Mitsubishi, air oxidation is carried out in the presence of copper salts to avoid the formation of complicating impurities in the oxidation of dihydrovitarnin to vitamin (33). In other work, high yields of vitamin were obtained by performing the oxidation in an alkaU medium (34). High purity vitamin can also be obtained by an oxidation in dimethyl sulfoxide (35). 

Two distinct sesquiterpenes exist in the essential oil of Santalum album, known as a-santalene and /3-santalene. 8-santalene is probably a bicyclic and a-santalene a tricyclic sesquiterpene. These sesquiterpenes were discovered by Guerbet. From the method of their preparation it is doubtful whether they have been obtained in a state of purity, so that the characters assigned to them must be accepted with some reserve, and as probably being only approximate. 

Structure of Oxy-F Compound F is extremely unstable and is difficult to obtain at a level of purity suitable for NMR studies. However, an oxidation product, Oxy-F, formed when F is left standing at — 20° C, is considerably more stable than F and can be purified to a sufficiently high level of purity. Oxy-F is nonfluorescent and shows absorption maxima at 237 nm and 275 nm (shoulder). The high-resolution FAB mass spectrum indicated the molecular formula of Oxy-F to be C33H3809N4Na2 [m/z 703.2363 (M + Na)+ and 681.2483 (M + H)"1"]. The H and 13C NMR data allowed the assignment of structure 7 to oxy-F (Fig. 3.2.6 Nakamura et al., 1988). 

Tables Assignment and wavenumbers (cm ) of the external and torsional vibrations of a-Ss based on polarization dependent studies [106, 107]. In the first two columns the type and symmetry classes of the molecular and crystal vibrations, respectively, are given. The wavenumbers of the vibrations are listed in the columns infrared and Raman corresponding to the order of symmetry species given in the second column (crystal). " S means orthorhombic Sg with natural isotopic composition, while stands for isotopically pure Sg crystals (purity >99.95%)... 

The proton magnetic resonance spectrum of the product in trifluoroacetic acid shows that the isomeric purity is greater than 90%. The proton magnetic resonance spectral properties for the isomeric amino ketones in both trifluoroacetic acid and chloroform-d are as follows (solvent) 8 (multiplicity, number of protons, assignment, coupling constant J in Hz.) 1-... 

Cycloamylose forms inclusion complexes stereoselectively with the enantiomers of isopropyl methylphosphinate (124) from which it was possible to isolate one enantiomer with an optical purity of 66%. The absolute configuration of menthyl methylphosphinate has been revised to the opposite of that previously assigned. 

---