Identification Tests Sodium

Testing of phthalocyanines includes crystallization (qv), flocculation, and appHcation in paints, plastics (qv), and printing inks (1). The ASTM standard specifications include CuPc in dry powder form for various appHcations (153). The specifications cover color (qv), character or tint, oil absorption, reactions in identification tests, and dispersions and storage stabiUty. Quantitative deterrninations are possible with ceric sulfate (30) or sodium vanadate (154). Identification methods are given (155), including tests for different appHcations. 

The United States Pharmacopoeia describes the following two identification tests for procaine [31]. In one, the infrared absorption spectra of standard and sample in KBr pellets are compared, and require to exhibit maxima only at the same frequencies. In another test, 10 mg of drug is dissolved in 1 mL of water, to which is added 1 drop each of hydrochloric acid and 1 10 sodium nitrite solution. One then adds 1 mL of a solution prepared by dissolving 0.2 g of 2-naphthol in 10 mL of 1 10 sodium hydroxide solution, shakes, and obtains a scarlet-red precipitate as a positive reaction. 

The B.P, and U.S.P. also recommend the use of ultraviolet characteristics of oxyphenbutazone as an identification test. A solution of the drug in sodium hydroxide exhibits maxima and minima at the same wavelengths as that of a similar solution of a standard drug. The ultraviolet absorption characteristics of oxyphenbutazone shall be discussed later in the spectral properties of the drug. 

Identification. Triturate a quantity of finely powdered tablets, containing the equivalent of about 100 mg of dipyridamole, with 10 mL of 0.1 N hydrochloric acid, and filter. Add 0.1 N sodium hydroxide to the filtrate until the solution is basic and a precipitate forms. Heat the mixture on a steam bath for 1 min, cool, filter, and dry the residue at 105°C for 1 h. The residue so obtained responds to the identification tests for dipyridamole. 

B. The solution from Identification Test A gives positive tests for Sodium, Appendix IIIA. 

A. Add 25 mL of 1 2 hydrochloric acid to about 1.5 g of sample, and dilute to 50 mL with water. Heat to effect complete solution then cool filter on a fine-porosity, sintered-glass crucible wash the precipitate with 2 100 hydrochloric acid, saving the filtrate for Identification Test B and dry the precipitate at 105°. Add 3 mL of water and 7 mL of 1 A sodium hydroxide to 400 mg of the dried precipitate, and stir until solution is complete. Add, dropwise, 2.7 A hydrochloric acid until the solution is just acid to litmus add 1 g of p-nitrobenzyl bromide and 10 mL of alcohol and reflux the mixture for 2 h. Cool, filter, and wash the precipitate with two small portions of a 2 1 alcohol water mixture, followed by two small portions of water. The precipitate, recrystallized from hot alcohol and dried at 105°, melts at about 152° (see Melting Range or Temperature, Appendix IIB). 

B. Add 0.5 g of sodium chloride to the 1% deionized water solution prepared for Identification Test A, heat the solution to 80°, stirring constantly, and hold the temperature at 80° for 1 min. Stop heating and stirring the solution, and allow it to cool to room temperature. A firm gel forms. 

B. Portions of the filtrate obtained in Identification Test A give positive tests for Aluminum, for Magnesium, and for Sodium, Appendix IHA. 

B. Dip a clean nichrome wire into the final solution prepared in Identification Test A, and place the wire in the flame of a Bunsen burner. A bright yellow color indicates the presence of sodium. 

Aluminum Identification Test, 753 Aluminum Magnesium Silicate, 41 Aluminum Potassium Sulfate, 21 Aluminum Sodium Sulfate, 21 Aluminum Sulfate, 22 Ambrette Seed Liquid, 23 Ambrette Seed Oil, 23, 596 Aminoacetic Acid, 186 A-[4-[[(2-Amino-l,4-dihydro-4-oxo-6-pteridinyl)methyl] amino] benzoyl] -l-glutamic Acid, 157 3 - Amino-7-dimethylamino-2-methylphenazine Chloride, 861 L-2-Aminoglutaramic Acid, 175 L-2-Amino-5-guanidinovaleric Acid, 32, (S3)5... 

Cobalt(II) ion forms a deep blue solution with an excess of monothiophosphate ion in a solution made slightly alkaline with sodium acetate. This reaction can be used as a qualitative identification test for cobalt(II) ion in the presence of nickel(II) ion.8 Monothiophosphate ion reacts with lead ion in cool solution to form a white precipitate, which turns brown to black when the suspension is heated. 

A specific identification test for urea is the enzymatic reaction with urease. 50 mg of powdered resin or 0.1 ml of the resin solution is carefully heated in a test tube with a Bunsen burner until all formaldehyde has been removed (check odor ). After cooling and neutralizing with 10% sodium hydroxide using phenolphthalein as an indicator, 1 drop of 1 N sulfuric acid and 0.2 ml of a freshly prepared 10% urease solution are added. A moist piece of litmus paper is then attached to the upper rim of the test tube. After a short time, the blue coloration of the indicator paper demonstrates the presence of ammonia which is formed only by urea-containing resins and not by melamine resins. Hexamethylene tetramine is the only substance that may interfere with this reaction. 

The methods for measuring impurities in samples should be sensitive. In contrast identification tests should be rather insensitive. For example the flame test for sodium ions will give a positive even with trace amounts present hence the use of the precipitation method with zinc uranyl acetate in pharmacopoeias. 

Chemical Tests. Several tests may be run to assist in the identification of this material. Does the ignition test confirm the presence of the aromatic ring system Does the soda Hme or sodium fusion test indicate that nitrogen is present Is the material soluble in 10% hydrochloric solution ... 

Sodium copper chlorophyllin, approved by the FDA as a color additive in citrus-based dry beverage mixes, should have a ratio of absorbance (SoretQ band) not less than 3.4 and not more than 3.9. In Europe, purity criteria of the food additives E141[i] and E141[ii], which are copper complexes of chlorophyll and chlorophyllin, respectively, are set out in the EC color specifications that include identification and spectrophotometric assay tests. ... 

Fig. 3.130. HPLC chromatograms of the test mixture detected by DAD (270 nm, upper lane) by APCI-MS-TIC (middle) and by ESI-MS-TIC (lower lane). Peak identification l=benzene sulphonic acid sodium salt 2=2-naphtalene sulphonic acid sodium salt 3=2-anthraquinone sulphonic acid sodium salt 4 = sulphorhodamine D sodium salt 5=crocein orange G 6=eriochrome black T 7=2,6-anthraquinone disulphonic acid disodium salt 8 = 1,5-naphtalene disulphonic acid disodium salt 9 = azophloxine 10 = 1,2-benzene disulphonic acid dipotassium salt. Reprinted with permission from G. Socher et al. [178].

The scheme that is shown in Figure 9.9 is very simple. More complex qualitative analyses involve many more steps of isolation and identification, including some steps that are not precipitation reactions. For example, some ions, such as sodium, Na", and potassium, K, cannot he precipitated out of an aqueous solution, because the ionic compounds that contain them are always soluble. Instead, chemists identify these ions using a flame test. In the following ThoughtLab, you will simulate a qualitative analysis that includes a flame test. 

Seliwanoff s test analy chem A color test helpful in the identification of ketoses, which develop a red color with resorcinol in hydrochloric acid. s3 liv3,nofs, test sellite liNORG chem A solution of sodium sulfite (Na2S03) used in the purification of 2,4,6-trinitrotoluene to remove unsymmetrical isomers. se,lTt ... 

For years the iodoform test was a laboratory method for the identification of a methyl ketone (a ketone where one of the R groups is a methyl group). A positive test produced the compound iodoform. Iodoform, CHI3, is a yellow precipitate with a characteristic odor. The oxidation utilizes sodium hypoiodite, which is generated in situ by the reaction of iodine with sodium hydroxide. Figure 10-35 shows an example of the iodoform test. 

Amines are easily identified because they re readily soluble in dilute acid. Sodium fusion converts the cimine to the cyanide ion, which is detectable by a Vciriety of methods. The ready formation and decomposition of diazonium salts (discussed in the earlier section Reactions with nitrous acid ) leads to the identification of primary amines. The Hinsberg test (see the nearby sidebcir) is useful in identifying amines. 

This assay is a recently published modification of the alkali resistance test.11 Sodium hydroxide (NaOH) is strongly keratolytic and rapidly introduces structural defects in the horny layer. Burckhardt introduced the alkali resistance test in 1947.12 His goal was to develop a procedure that would enable the identification of individuals at increased risk of chemical injury to skin. In some European centers the alkali resistance test subsequently became an accepted screening procedure, in the United States the test never caught on. Researchers after Burckhardt largely found the alkali resistance test to be unreliable and irreproducible.13,14 Attempts to improve the method failed15 and therefore the alkali resistance test fell into disuse. However, NaOH has been used as an irritant in other tests.16,17... 

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