Colorimetric determination of free and total cholesterol by flow injection analysis with a fiber optic detector.
A flow injection method for the determination of total and free cholesterol is presented. Cholesterol esterase and cholesterol oxidase are immobilized on aminoalkyl glass beads. The beads are packed into a tubular glass reactor. The cholesterol esters traversing through the esterase reactor are cleaved to cholesterol and fatty acids. The oxidase reactor converts cholesterol to cholest-4-en-3-one and hydrogen peroxide is generated. The sample stream is merged with reagent streams consisting of a peroxidase solution and a solution of 2,2'-azino-bis-(3-ethyl-benzthiazoline-6-sulfonic acid) diammonium salt, and a hydrogen peroxide-dependent color reaction takes place in a short coiled reactor. The signal is monitored by means of fiber optic instrumentation. Cholesterol concentration can be related to the absorption of the oxidized dye form at a wavelength of 425 nm. The working range is 0.5-0.8 mmol l-1, and the sample throughputs are 60 and 30 h-1 for free and total cholesterol, respectively.
University of Technology, Institute of Analytical Chemistry, Vienna, Austria.
A
A
Krug
A A
AA
Suleiman
G G
GG
Guilbault
R
R
Kellner
D002784:Cholesterol / Q000032:analysis*; D003124:Colorimetry / Q000379:methods*; D005336:Fiber Optic Technology / Q000379:methods*; D055100:Optical Fibers; D012680:Sensitivity and Specificity
D002784:Cholesterol