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Unit Code 8707:
Valproic Acid, Total, Serum

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Method Description

Enzyme-multiplied immunoassay technique (EMIT) is performed using

the Olympus analyzer. EMIT offers an alternative to the traditional

spectroscopic and chromatographic method for quantitating blood

concentrations of drugs. The technique for drugs is based upon an

enzymatic assay for glucose-6-phosphate dehydrogenase, using

spectral properties at 340 nm, in which the reduction of nicotinamide

adenine dinucleotide (NAD) substrate is monitored. The basis of the

drug detection technique is an immunological reaction between the

drug and a specific antibody. The reagent contains the enzyme

(glucose-6-phosphate dehydrogenase) to which the drug is covalently

bound and antibody-specific to the drug. The antibody binds most of

the drug-bound enzyme, rendering the enzyme inactive. This results

in a baseline enzymatic activity. In the presence of free drug, antibody

equilibrates between free drug and enzyme-bound drug leaving

some of the drug-bound enzyme uncomplexed and able to catalyze

the reaction. If more free drug is introduced, either as standard or

sample, then competition for the antibody takes place between the

drug in the sample and the drug attached to the enzyme. This results

in more drug-bound enzyme being left uncomplexed and able to

catalyze the enzyme reaction at a greater rate as compared to the

baseline activity. The observed enzyme activity increases with the

amount of total free drug in the sample. (Package insert:  EMIT 2000

Valproic Acid Assay. Olympus. Melville, NY. October 2005)

Performing Laboratory Location

Rochester

Key