United States Pharmacopoeia impurities

The fermentation-derived food-grade product is sold in 50, 80, and 88% concentrations the other grades are available in 50 and 88% concentrations. The food-grade product meets the Vood Chemicals Codex III and the pharmaceutical grade meets the FCC and the United States Pharmacopoeia XK specifications (7). Other lactic acid derivatives such as salts and esters are also available in weU-estabhshed product specifications. Standard analytical methods such as titration and Hquid chromatography can be used to determine lactic acid, and other gravimetric and specific tests are used to detect impurities for the product specifications. A standard titration method neutralizes the acid with sodium hydroxide and then back-titrates the acid. An older standard quantitative method for determination of lactic acid was based on oxidation by potassium permanganate to acetaldehyde, which is absorbed in sodium bisulfite and titrated iodometricaHy. 

In this chapter we describe characteristic validation procedures of the Heavy Metals Limit Test in the Japanese Pharmacopoeia (JP) [1]. Although an equivalent test is commonly listed in both the United States Pharmacopoeia and the European Pharmacopoeia, there are differences in the color reagents and conditions of sample preparation of the JP procedure. Heavy metals are defined in the JP as poisonous metallic impurities such as Pb, Bi, Cu, Cd, Sn, and Hg that form colored colloidal precipitates with sodium sulfide TS in a slightly acidic solution of pH 3 to 4. The level is expressed as the equivalent quantity of lead. 

United States Pharmacopoeia Rev. 25 and National Formulary Rev. 20. 2002 General Test (467) Organic Volatile Impurities, p. 1943. 

The United States Pharmacopoeia deals with impurities under several sections ... 

Whereas the European pharmacopoeias describe the method of NMR spectroscopy only in principle, the United States Pharmacopoeia 23 gives detailed information about the procedures of qualitative and quantitative applications. In the section on qualitative application, the correlation between chemical shifts and coupling constants on the one hand and the structure of a molecule on the other hand is stressed. For quantitative applications, an absolute method, utilizing an internal standard, and a relative method are given. Consequently, NMR spectroscopy is used in the USP for identification of drugs and their impurities (see test section) and for quantification (see assay section of a monograph). 

---