Multiplexing, labeling for multiple immunostains in the very same cell or tissue section in situ, has raised considerable interest. The methods proposed include the use of labeled primary antibodies, spectral separation of fluorochromes, bleaching of the fluorophores or chromogens, blocking of previous antibody layers, all in various combinations. The major obstacles to the diffusion of this te...

A simple and rapid method for the assay of superoxide dismutase in biological samples is described. Present method takes advantage of the inhibition of NADH-dependent-nitroblue tetrazolium reduction by the dismutase. Inhibition of the chromogen formation by superoxide dismutase was linear with increase in enzyme concentrations. The chromogen extract in butanol was stable even up to 48 hr. Super...

In connection with other studies in this laboratory (1, 2),’ it became necessary to determine the concentration of urea in the blood of individual new-born rats. In view of the small quantities of blood available and the need for a considerable number of analyses, the calorimetric method developed by Archibald (3) appeared to be particularly suitable. This method is based upon the formation of ...

A simple, sensitive and economical spectrophotometric method was developed for the determination of cefixime trihydrate in pharmaceutical formulations. This method is based on the formation of pink colored chromogen complex by the reaction of drug with ferric chloride and 2, 2 bipyridyl, which absorbs maximally at 520 nm. Beer’s law is obeyed at a concentration range of 110 mcg/ml for method. T...

The original Ellman's spectrophotometrical method for cholinesterase activity determination uses 5,5'-dithiobis-2-nitrobenzoic acid (DTNB, Ellman's reagent) as a chromogen and records the level of cholinesterase activity as an increase of absorbance at 412 nm. Although this procedure usually poses no problem, exceptions arise when the concentration of DTNB is far higher than the concentration o...

We describe a colorimetric assay for glucose determination in human serum, with use of the chromogen 2-amino-4-hydroxybenzenesulfonic acid (AHBS), glucose oxidase, and peroxidase. With this assay, glucose concentrations less than or equal to 27.8 mmol/L can be measured in serum, with a sample/reagent volume ratio as low as 0.0025. The chromogen itself is easily soluble in water and does not req...

Simple and rapid spectrophotometric & chromatographic methods have been developed and validated for the determination of Darunavir and Ropivacain in tablets and as bulk drug. The methods applied were involing use 1,2-naphthoquinone-4-sulphonate (NQS). The formar was solubilised in an alkaline medium with NQS to form an orange-colored product with λmax at 488 nm while the later gave blue colored...