Absorption spectrophotometers are now becoming available that can record the first and second derivatives of absorbance with respect to wavelength. The advantages of this technique and its potential application to clinical analysis are discussed.

This paper reports a tunable visual color filter based on a microfluidic transmission grating. The grating lines are formed by the microflows in an array of evenly spaced straight microchannels. In experimental study, the transmission of white light measures a shift of visual color from red to blue in the zeroth order diffraction in response to a change of the refractive index from 1.3290 to 1....

This paper reports new results regarding the usefulness of colour measurements in flotation process. Colour measurements coming simultaneously from RGB-camera and a spectrophotometer (and from the same measurement point) are compared. The measured variables are used to construct a partial least squares (PLS) model and a multilinear regression (MLR) model for the prediction of the zinc content i...

Serum alkaline phosphatase estimations by the Selected Method [Clin. Chem. 21, 1988 (1975)] are very sensitive to small errors in the wavelength setting of the spectrophotometer. With a setting error as small as 3 nm, results can be too low by as much as 23%. The product of the reaction, 4-nitrophenol, can be prepared in very pure form and can be used to check both the wavelength and absorbance...

This paper describes a robust and rapid procedure for measuring chlorophyll using a microplate reader. The procedure enables direct translation of any published equation developed on a 1-cm pathlength spectrophotometer to any format microplate with any sample volume. Chlorophylls were extracted with methanol because it is compatible with cheap polystyrene plates; however, the principles apply t...