Tablet coloring system

Investigations, related to the photoprotection of nifedipine tablets using films containing titanium dioxide and/or tartrazine, revealed that the photoprotective effect of a film could be evaluated by using its concentration of colorant (C) and thickness (L) value. This value is the product of concentration of the colorant C and the film thickness L. Tablets coated with films having the same CL value had the same photodegradation rates. Degradation rates were found to be proportional to the CL value for every colorant system tested (18). 

Although the work is conducted in the research or formulations laboratory using small-scale processing equipment, it is important to gain early experience with colorant systems that have been selected for the finished tablet product color aids in blend-uniformity evaluation. 

I) as pale-yellow crysts and 2) as color tablets both belonging to the pinacoidal class of the tri-clinic system mp, loses its water at 120—130° and explds at 240° Easily sol in w, diff sol in aq ale, insol in abs ale and other org solvents It was first prepd by Palazzo as a by-product in the prepn of 1-hydroxytetrazole from hydrazoic... 

In a subsequent work, Raff used the CIE system to quantify the colors that could be obtained when using FD C aluminum lakes as colorants in tablet formulations [43]. He reported on the concentration dependence of the tristimulus values obtained when calcium sulfate dihydrate was compressed with various amounts of FD C Blue No. 2 aluminum lake, and one example of the reported data is found in Table 1. 

The choice of test equipment and methods has become extremely wide and, apart from large, integrated, electronic colorimetric and spectrophotometric instrumentation, field personnel can choose from miniburettes, direct-reading titrators (modified syringes), digital titrators, drop tests, tablet tests, permanent color standard comparators, indicator papers, portable colorimeters, immunoassays, etc. Today, field-test methods tend to be tailored by equipment manufacturers to their own analytical systems, and consequently the specified use of particular standard methods for the examination of water, from any one technology or official body, is probably not realistic. Rather it is the fitness-for-purpose rule that is more relevant. 

Formation of a Schiff base product of the reduction product of nimodipine (using the Zn-FICl system) and 4-dimethylaminobenzalde-hyde formed the basis of a spectrophotometric method for the determination of nimodipine in tablets [3]. A pink color exhibiting an absorption maximum at 580 nm was produced and remained stable for 30 min. The percent recovery was 99-101%, with coefficients of variation of 0.3-0.5. 

As described in the previous section, azophenol crown 4 (n = 1) shows a characteristic coloration only for Li+ ion among alkali metal ions. After extensive examinations in a number of solvent systems, lithium analytical conditions were determined as shown in Table 2 [18a]. The resulting reddish purple color is very stable and its absorbance is maintained for 10-90 min after developing color. The calibration curve for Li+, in other words, sensitivity is linear from 25-250 ppb. Na+ does not interfere, but K+, Rb+, Ca2+, Sr2+, Ba2+, and Mg2+ interfered in the determination with a similar coloration. This method was applied to the analysis of a commercial pharmaceutical preparation, a lithium carbonate tablet, since the Li2C03 tablet has been used for medical treatment of manic depressive illness [18 b]. On the other hand, the azophenol crown 4 (n = 1) is also useful as a reagent for colorimetric determination of Rb+ and Cs+ [19]. 

Color is one of the most important as well as the most eye-catching characteristics of microscopically opaque objects such as paint. Color measurements are carried out using a single-beam technique (previously measuring a standard on a perfectly white reflective object as a pure barium sulfate tablet or a polished opal glass) with microspectrophotometers fitted with image-side monochromators with geometry 4570° (like J M Tidas diode array spectrometers and the Zeiss MPM 800-system). 

---