Various chemicals can be added to urine specimens collected for drug analysis to abnormally elevate ionic concentrations and/or interfere with either immunoassay urine drug-screening procedures or gas chromatographic-mass spectrometric confirmation techniques. One such adulterant, "Urine Luck" (formula 5.3), has been identified in our previous research to contain potassium dichromate. Screening...

A new nonlinear dimensionality reduction method for multi-spectral images was presented to solve the problem brought by high dimensionality of multi-spectral images during color reproduction. Firstly, according to the characteristics of human visual system, the CIE standard observer color matching functions were weighted to the source spectral reflectance and then a principal component analysis...

Isoniazid is an important antibiotic, which is widely used to treat tuberculosis. This study presents a colorimetric method for the determination of Isoniazid based on localized surface plasmon resonance (LSPR) property of gold nanoparticles. An LSPR band is produced by reducing gold ions in solution using Isoniazid as the reducing agent. Influences of the following relevant variables were exam...

‘J’HE MOST COMMONLY USED METHODS for the estimation of uric acid are those colorimetric procedures utilizing the reduction of phosphotungstic acid (1-7). Since these procedures are not specific for uric acid, an enzymatic procedure utilizing uricase, which oxidizes uric acid to allantoin, has been employed by a number of investigators (8-12). The enzymatic method, dependent upon the absorption ...

We developed a colorimetric and chromatographic assay for oseltamivir to assess the authenticity of Tamiflu (F. Hoffmann-La Roche Ltd., Basel, Switzerland) because of a growing concern about counterfeit oseltamivir. The colorimetric assay is quantitative and relies on an extractable colored ion-pair complex of oseltamivir with Congo red or bromochlorophenol blue. The reverse-phase chromatograph...

The implementation of colorimetric analysis within microfluidic environments engenders significant benefits with respect to reduced sample and reagent consumption, system miniaturization, real-time measurement flowing samples. That said, conventional approaches channels are hampered by short optical pathlengths single-channel configurations, which lead poor detection sensitivities low analytica...

VARIETY of methods is available for tue colorimetric determination of uric acid. In general, these are based on precipitation of proteins, followed by the reduction in an alkaline medium of phosphotungstate by the uric acid ill the protein-free filtrate. Results of colorimetric determinations may at times vary from “true” uric acid values as determined by unease methods. This is because the col...