Color reaction

About: Color reaction is a research topic. Over the lifetime, 1194 publications have been published within this topic receiving 19579 citations.

A new spectrophotometric method for determination of furfural and pentoses

Abstract: A spectrophotometric method for determination of furfural and pentoses based on their color reaction with sulfuric acid in the presence of mercury(II) was developed.

Anisaldehyde-4-phenyl-3-thiosemicarbazone as an analytical reagent for the extractive spectrophotometric determination of gold

Abstract: The synthesis, spectral characteristics and analytical applications of anisaldehyde-4-phenyl-3-thiosemicarbazone (APT) are described. A simple, rapid, selective and sensitive spectrophotometric method for the determination of microgram amounts of gold, alone or in the presence of associated metals, is developed, based on the colour reaction between the metal ion and anisaldehyde-4-phenyl-3-thiosemicarbazone. The yellow-brown complex (λmax.= 365 nm) is extracted into ethyl acetate. Gold(III) reacts with the reagent in the ratio 1 : 1 (metal to ligand) over the pH range 4.0–7.0. Beer's law is obeyed over the concentration range 0.1–12.3 µg ml–1 of gold. The molar absorptivity and Sandell's sensitivity of the method are 2.12 × 104 l mol–1 cm–1 and 0.0092 µg cm–2, respectively. The relative standard deviation for ten replicate determinations of 45 µg of gold(III) was 1.71%. The interference of various ions has been studied and conditions were developed for the determination of gold in some synthetic samples.

Direct colorimetric determination of formaldehyde in textile fabrics and other materials

Abstract: A colorimetric method for direct determination of formaldehyde in textile fabrics and other materials is described. Color development and breaking formaldehyde bonds of the analyzed material occur simultaneously in the same reaction mixture without destruction of the material. The method is based on the color reaction of formaldehyde with indole-3-acetic acid or tryptophan. Common inorganic salts, higher aliphatic aldehydes, carbohydrates, amino acids (except tryptophan), and many other organic compounds do not react and do not interfere with the color reaction. Some interferences have been exhibited by acetaldehyde and glyoxal. The method was simple, accurate, and relatively insensitive to the reaction conditions. Only very small amounts of material are needed, and the reaction proceeds at room temperature. Different kinds of polymeric materials have been analyzed successfully (cotton, wool, plastics, collagen, wood, and furs). Most of the dyed fabrics or other materials could be analyzed in the same manner because under the reaction conditions the dyes were not extracted in the reaction mixture.