Identity tests infrared spectrum

Test 1 Infrared absorption. This test must be carried out according to the general procedure <197K>. The spectrum obtained from the sample of primaquine phosphate should be identical with that spectrum obtained from USP Primaquine Phosphate RS. 

In many pharmaceutical companies, quality control departments already use NIRS to identify formulations. Figure 23 illustrates a PLS calibration for the active content determination in a low-dose tablet. Once identity testing is passed, it is straightforward to consider as a next step the determination of active content in intact tablets. Thus, qualitative and quantitative analysis can be performed by acquiring a single NIR spectrum per sample. Two analytical techniques are replaced by one—nondestructive—NIR measurement. For this purpose near-infrared spectroscopy is a fast and powerful alternative to traditional analysis, which only remains necessary as reference analytics. 

The infrared spectrum of a sample in a potassium bromide pellet may be used as an identity test. In such cases, the infrared spectrum of the sample should compare favorably with the moxalactam disodium reference spectrum over the range of 2.5 to 16 microns. 

The ultraviolet-visible spectra of most compounds are of limited value for qualitative analysis and have been largely superseded by the more definitive infrared and mass spectroscopies. Qualitative analytical use of ultraviolet-visible spectra has largely involved describing compounds in terms of the positions and molar absorptivities of their absorption maxima, occasionally including their absorption minima. Indeed, some organic compounds are still characterized in terms of the number of peaks in the UV-visible spectrum and their absorbance ratios. This is usually the case in phytochemistry and photodiode array chromatography and when the analyst has a limited range of compounds to work with whose spectra are known to differ. In the pharmacopeias, however, absorbance ratios have found use in identity tests, and are referred to as Q-values in the U.S. Pharmacopia (USP). 

Some allylic and benzylic alcohols give this test result because the reagent can oxidize them to aldehydes and ketones, which subsequently react. Some alcohols may be contaminated with carbonyl impurities, either as a result of their method of synthesis (reduction) or as a result of their becoming air-oxidized. A precipitate formed from small amounts of impurity in the solution will be formed in small amounts. With some caution, a test that gives only a slight amount of precipitate can usually be ignored. The infrared spectrum of the compound should establish its identity and identify any impurities present. 

Write out a complete procedure by which you synthesized and isolated Compounds 1 and 2. Describe the results of your experiments to determine a good crystallization solvent for both compounds. Draw the structures of Compounds 1 and 2. Give all melfing-point data and results of other tests used to identify the two compounds. Identify significant peaks in the infrared spectrum and proton/carbon NMR spectra. Show clearly how all these results confirm the identity of the two compounds. Write a balanced equation for the synthesis of Compounds 1 and 2. What type of reaction is this Propose a mechanism for the reaction. Determine the percentage yield of each of the compoimds. 

The dibasic acid of wilforine has an ultraviolet spectrum almost identical with that of the dibasic acid obtained from wilfordine, and in fact the latter appears to be the hydroxy derivative of the former. The infrared absorption spectra of wilfordine and wilfortrine show peaks in the hydroxyl region (3534 cm." ) that are absent in the spectra of wilforine and wilforgine. The dibasic acid of wilfordine gives a positive test for an a-hydroxy acid, whereas the dibasic acid of wilforine does not. The hydroxy acid is, therefore, thought to have structure (X IX. 

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