Substances with Similar Structural Units

Antibiotic hjB/-values with solvent 3 3 4 Ref. With iodine vapour Colour in UV light 

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Solid solutions can also be formed to a limited extent with substances that have a similar formula but a different crystal structure. One of the substances imposes its structure upon the other. In lattices which are stable even if some sites in the unit cell are unoccupied, substances with different formulae can form solid solutions (anomalous mixed crystals). The incorporated ions must be of similar size, but do not need to have the same valency because electroneutrality is ensured by the presence of a compensating valency elsewhere in the lattice. Changes in the relative concentrations in the solid solutions lead to continuous variation of their properties. 

Some universal HPLC detectors will give a response for nearly any compound, but that response is not always related to weight or concentration. For example, ELSD allows detection of most non-volatile substances, but the response depends on the quantity and nature of the particles produced upon drying. For compounds of similar structures and vapor pressures, one can expect similar responses per unit mass by ELSD ( 10-20%) (16). Under such circumstances, the ELSD can be used in conjunction with a UV detector to determine RRF values by peak area ratios ... 

Some strains of Streptomyces are able to produce a series of antibiotics of similar activity they are designated streptothricines (StTs) (54JA566). Six substances with a similar behaviour were separated from different antibiotics of streptothridne group and were indexed as A-Fourth varying repeating units. The structure and properties of these antibiotics were extensively studied. 

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