APhA

Chart showing hierarchical relationship among a technique, methods using that technique, and procedures and protocols for one method. (Abbreviations APHA = American Public Health Association, ASTM = American Society for Testing Materials, EPA = Environmental Protection Agency)... 

Specifications and Analytical Methods. Butanediol is specified as 99.5% minimum pure, determined by gas chromatography (gc), sohdifying at 19.6°C minimum. Moisture is 0.04% maximum, determined by Kad-Fischer analysis (dkecdy or of a toluene a2eotrope). The color is APHA 5 maximum, and the Hardy color (polyester test) is APHA 200 maximum. The carbonyl number is 0.5 mg KOH/g maximum the acetal content can also be measured dkecdy by gc. 

Specifications and Analytical Methods. Purity is specified as 99.5% minimum, by gc area percentage, with a maximum of 0.1% moisture by Kad-Fischer titration. Color, as deUvered, is 40 APHA maximum samples may darken on long storage. 

Analytical Procedures. Standard methods for analysis of food-grade adipic acid are described ia the Food Chemicals Codex (see Refs, ia Table 8). Classical methods are used for assay (titration), trace metals (As, heavy metals as Pb), and total ash. Water is determined by Kad-Fisher titration of a methanol solution of the acid. Determination of color ia methanol solution (APHA, Hazen equivalent, max. 10), as well as iron and other metals, are also described elsewhere (175). Other analyses frequendy are required for resia-grade acid. For example, hydrolyzable nitrogen (NH, amides, nitriles, etc) is determined by distillation of ammonia from an alkaline solution. Reducible nitrogen (nitrates and nitroorganics) may then be determined by adding DeVarda s alloy and continuing the distillation. Hydrocarbon oil contaminants may be determined by ir analysis of halocarbon extracts of alkaline solutions of the acid. 

Name Molecular formula Hydroxyl Value Acidity, % as acetic Carbonyl, wt % 0 Boiling range, °C Color, APHA Moisture, % Plash point, °C ... 

Procedures for determining the quaUty of formaldehyde solutions ate outlined by ASTM (120). Analytical methods relevant to Table 5 foUow formaldehyde by the sodium sulfite method (D2194) methanol by specific gravity (D2380) acidity as formic acid by titration with sodium hydroxide (D2379) iron by colorimetry (D2087) and color (APHA) by comparison to platinum—cobalt color standards (D1209). 

Methanol can be converted to a dye after oxidation to formaldehyde and subsequent reaction with chromatropic acid [148-25-4]. The dye formed can be deterruined photometrically. However, gc methods are more convenient. Ammonium formate [540-69-2] is converted thermally to formic acid and ammonia. The latter is trapped by formaldehyde, which makes it possible to titrate the residual acid by conventional methods. The water content can be determined by standard Kad Eischer titration. In order to determine iron, it has to be reduced to the iron(II) form and converted to its bipyridyl complex. This compound is red and can be determined photometrically. Contamination with iron and impurities with polymeric hydrocyanic acid are mainly responsible for the color number of the merchandized formamide (<20 APHA). Hydrocyanic acid is detected by converting it to a blue dye that is analyzed and deterruined photometrically. 

The general sales specification under which maleic anhydride is sold ia the United States specifies a white fused mass or briquettes of 99.5% minimum assay and 52.5°C minimum crystallisation poiat. The melt color specification is 20 APHA maximum with a maximum APHA color of 40 after two hours of heating at 140°C. Four grams of maleic anhydride ia 10 milliliters of water are to be completely soluble. The resulting solution is to be colodess. The acidity resulting from maleic acid is allowed to be a maximum of 0.2%. 

Fumaric acid is sold as resia-grade and food-grade. The general sales specification under which resia-grade fumaric acid is sold ia the United States specifies white, crystalline granules with a minimum assay of 99.6% and maximum ash content of 0.05%. The moisture specification is 0.3% maximum with < 10 ppm heavy metals. The color of a 5% solution ia methanol is to be less than 10 APHA. Food-grade fumaric acid calls for somewhat lower impurity levels. Particle size and particle size distribution are important ia many appHcations. 

Several national organizations serve the professional needs of U.S. pharmacists. These reflect the practice milieu of members, eg, independent community pharmacies, chain dmg stores, and hospitals. The American Pharmaceutical Association (APhA), founded in 1852, is composed of the Academy of Pharmaceutical Research and Science, Academy of Pharmaceutical Practice and Management, and the Academy of Students of Pharmacy. Other organizations include the American Society of Health-Systems Pharmacists (ASHP), National Association of Chain Dmg Stores (NACDS), and National Association of Retail Dmggists (NARD). 

Analytical and Test Methods. Measurement of the sohdification point using a highly sensitive thermometer and of APHA color by comparison of molten samples to APHA standards is straightforward. Specific impurities are measured by gas chromatography. A nonaqueous titration is used to determine phthahc acid content. 

Terephthahc acid is pure white, and molten dimethyl terephthalate is colorless. Impurities or degradation products can be yellow or brown, so the darkness of either a solution of terephthahc acid in dimethylform amide or molten dimethyl terephthalate can be compared to APHA color standards. 

APHA color (269) is usually one of the specifications of PTMEG, sometimes viscosity is another (270). Melt viscosity at 40°C is often used as a rough measure of the molecular weight distribution within a narrow molecular weight range. Sometimes an empirical molecular weight ratio,... 

Compound Assay, min % Apparent equival entweight APHA colormax Water, max %... 

Apparent equivalent weight deterrnined by titration with hydrochloric acid. APHA color determined by ASTM D1209, platinum—cobalt method. 

APHA color is deterrnined using ASTM D1209 percent water is deterrnined by Kad Eischer titration following ASTM E203. Detailed analytical procedures are available in the fiterature (1) or from producers. 

Name CAS Registry Number Molecular formula Molecular weight Physical form at 25°C Boiling point, Freezing point, °C Density, g/mL Typical Assay Flash point, °C Molten color APHA... 

Contaminant by-products depend upon process routes to the product, so maximum impurity specifications may vary, eg, for CHA produced by aniline hydrogenation versus that made by cyclohexanol amination. Capillary column chromatography has improved resolution and quantitation of contaminants beyond the more fliUy described packed column methods (61) used historically to define specification standards. Wet chemical titrimetry for water by Kad Eisher or amine number by acid titration have changed Httle except for thein automation. Colorimetric methods remain based on APHA standards. 

MSA content, % appearance color, APHA freezing point, °C boiling point, °C refractive index, at 25°C density, at 25°C, g/cm ... 

Although color and turbidity of acid products are important properties, there is Httie standardization in such measurements. A ftequentiy used procedure is to determine color and turbidity by comparison with standards originally developed by the American PubHc Health Association (APHA) for examination of water (151). 

Standard Methodsfor the Examination of Water and Wastewater 17th ed., American Public Health Association (APHA), Inc., Washington, D.C., 1989,... 

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