Enzymatic fluorometric and electrochemical determination of formaldehyde

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5730237

Weng, Juilin

Two fluorometric enzymatic methods for the determination of formaldehyde are described in chapter 1. These methods are based on the quantitative oxidation of formaldehyde with NAD{sup +}, catalyzed by the formaldehyde dehydrogenase, to form formate and NADH. In the enzymatic method 1, the NADH produced, which is proportional to the concentration of formaldehyde, was directly monitored fluorometrically. Linear calibration curves were obtained from 0.09 {mu}M to 9 {mu}M with a reproducibility of 1.8-3.3% R.S.D. For the enzymatic method 2, the resulting NADH subsequently oxidized by resazurin in the presence of second enzyme diaphorase to form resorufin, a highly fluorescent compound. Its fluorescence intensity can be used for more sensitive analysis of formaldehyde. Linearity was observed between 9 nM and 1.35 {mu}M with a R.S.D. of less than 2%. The experimental parameters of both methods were also studied. A flow-injection system for detection of formaldehyde by coupling the enzymatic method 1 with immobilized formaldehyde dehydrogenase reactor is presented in chapter 2. The system is based on the injection of liquid formaldehyde standard into a moving, nonsegmented, continuous carrier stream which contains phosphate buffer and NAD{sup +}. After sample injection, NAD{sup +} and formaldehyde flow through the enzyme reactor and react with formaldehyde dehydrogenase. The NADH produced was detected by a flow-through fluorometer. Samples with formaldehyde concentrations between 0.05 to 7 ppm have been assayed, with precision between 4.1% and 2.5% RSD. Optimal conditions for the system, as well as possible interferences, were investigated. Finally, in chapter 3, NADH has been measured by coupling it with ferricyanide (III) ion in the presence of diaphorase, followed by amperometric detection of the ferrocyanide (II) ion produced.

• Research Organization: Alabama Univ., Birmingham, AL (United States)
• OSTI ID: 5730237
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALDEHYDES
BIOASSAY
CHEMISTRY
COENZYMES
ELECTROCHEMISTRY
EMISSION SPECTROSCOPY
ENZYME ACTIVITY
ENZYMES
FLUORESCENCE
FLUORESCENCE SPECTROSCOPY
FORMALDEHYDE
LUMINESCENCE
NAD
NADH2
NUCLEOTIDES
ORGANIC COMPOUNDS
OXIDOREDUCTASES
SPECTROSCOPY