double-beam spectrophotometer

double-beam spectrophotometer

[¦dəb·əl ¦bēm spek·trō·fə′täm·əd·ər]
(spectroscopy)
An instrument that uses a photoelectric circuit to measure the difference in absorption when two closely related wavelengths of light are passed through the same medium.
References in periodicals archive ?
ACE enzyme (100 [micro]l of 30 mU enzyme), 200 [micro]l of cryptide solutions, and substrate (2 ml of 0.5 mM FAPGG substrate) were mixed, and the absorbance at 340 nm was continuously monitored with a double-beam spectrophotometer in kinetic mode option.
The absorbance was measured at 517 nm using a double-beam spectrophotometer. Lower absorbance of the reaction mixture indicated higher free radical-scavenging activity.
The solution was incubated for 10 min, and the absorbance was measured at 700 nm using a double-beam spectrophotometer. Higher absorbance of the reaction mixture indicated higher reducing power.
In a double-beam spectrophotometer, the light beam is split in half.
"You have two double-beam spectrophotometers for the price of one," says Gomez.