Titrimetric Assays

A multiwavelength approach might have been considered as an alternative to chemical derivatisation. Ruddle and Wilson [62] reported UV characterisation of PE extracts of three antioxidants (Topanol OC, Ionox 330 and Binox M), all with identical UV spectra and 7max = 277 nm, after reaction with nickel peroxide in alkaline ethanolic solutions, to induce marked differentiation in different solvents and allow positive identification. Nonionic surfactants of the type R0(CH2CH20) H were determined by UV spectrophotometry after derivatisation with tetrabromophenolphthalein ethyl ester potassium salt [34]. Magill and Becker [63] have described a rapid and sensitive spectrophotometric method to quantitate the peroxides present in the surfactants sorbitan monooleate and monostearate. The method, which relies on the peroxide conversion of iodide to iodine, works also for Polysorbate 60 and other surfactants and is more accurate than a titrimetric assay. 

Volumetric apparatus invariably used in titrimetric assays, meant either to deliver a definite volume of liquid viz., burettes and pipettes, or to contain a definite volume of liquid viz., volumetric flasks and measuring cylinders, have essentially the following three cardinal general considerations, namely ... 

Classical low values for the mammalian enzyme that have appeared in the literature are the result of enzyme inactivation by hydrogen peroxide when measurements were carried out with peroxide levels in excess of 10 mM over time scales of 10 minutes or longer. The rapid sampling/titration method of Bonnichsen overcame the inactivation problem and permitted a satisfactory correlation of the overall catalytic measurements and Chance s observations on the intermediate complex (compound 1). Eventually, the introduction of the UV detector/spectrophotometer and the consequent assay based upon the UV absorbance of peroxide (35) further simplified the process by eliminating the discontinuous titrimetric assay. 

The United States Pharmacopoeia (3 1) describes the following titrimetric assay method ... 

Figure C3.1.1 Comparison of lipase activities using the titrimetric assay. The lipases used in the reaction mixture, all at 0.1 mg/ml, were from B. cepacia (diamonds), C. rugosa (triangles), and porcine pancreas (circles). Broken lines represent estimation of initial reaction rates.

Titrimetric assay method for bulk drug substance... 

Titrimetric assays based on triolein or milk fat as substrate. 

Arzoglou P, Goudoula C, Tsantili P, Lessinger JM, F6rard G, Mignot V, et al. Transferability of lipase titrimetric assays deductions from an interlaboratory study. Eur J Clin Chem Lab Med 1994 32 773-7. 

Follow-up characterization of the volatiles initially analyzed by TGA could also be conducted. Confirmation of the volatiles may be accomplished using one of several techniques thermogravimetric-infrared (TG-IR) spectroscopy, gas chromatography (GC), or thermogravimetry-mass spectrometry (TG-MS). These techniques may be able to qualitatively and quantitatively determine the content and identification of the solvents present in the material. Additionally, Karl Fisher titrimetric assays may be utilized to quantitate the water content in the material. 

The microbiological method using Lactobacillus phntarum, originally described by Snell and Wright (49), has been widely used for the determination of niacin in urine, serum, blood, foods, and tissues (16, 48,50,51,52). This organism is able to detect minute amounts of niacin (1-30 ng/mL) using a turbidimetric or titrimetric assay. 

Naphazoline hydrochloride dmg substance may be titrimetrically assayed as described in the USP monographic. The hydrochloride salt is dissolved in glacial acetic add with mercuric acetate and titrated with dilute perchloric add using crystal violet as the indicator. Also, nonaqueous titration of naphazoline hyd Uoride in acetic anhydrid gladal acetic add with dilute perchloric add and potentiometric detection h been described as an official method in the Japanese Pharmacopoeia. In addition, nonaqueous titration with dioctylsulfosucdnate sodium salt using 3 3 5 5"-tetrabromophenolph-thalein as the indicator has also been reported. ... 

A simple purpose-built fluorimeter has been constructed for the titrimetric assay of glycosaminoglycans with Acridine Orange. ... 

Titrimetric methods Titrimetric assays have been developed for acesulfame-K (titrated with sodium methoxide in benzene), aspartame, sodium cyclamate, and sodium saccharin (titrated with perchloric acid), and for saccharin (acid form) with potassium hydroxide as titrant. Precipitation, chelatometric, and redox titrations are proposed for the determination of cyclamate. The oldest methods for saccharin involve its determination by means of a Kjeldahl procedure. 

Measured by rapid titrimetric assay (71) for a catalase with approximately 3 active hemin groups per molecule. The catalase prepara tion used was not the same one as that used by Agner (19). 

In this paper the induction of lipase activity during germination of barley was studied using a titrimetric assay, with which the substrate-dependent acidification is determined. Lipase activity was already present in the quiescent barley kernel and strongly increased (up to 80-fold) during germination at 25 °C. This increase was mainly attributable to an increase in lipase activity in the embryo. Lipase activity in the embryoless grain was low and remained at a constant level. 

Lipase activity in germinating barley was determined using the titrimetric assay of Tietz Fiereck [6]. With this assay the substrate-dependent acidification of the incubation medium is determined. Similar activity values were obtained in control experiments, in which the amount of FFA liberated by lipase was measured. 

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