Determination of endogenous concentrations of N1-methylnicotinamide in human plasma and urine by high-performance liquid chromatography.
A high-performance liquid chromatographic assay for the determination of endogenous plasma and urine concentrations of N1-methylnicotinamide was developed. N1-Methylnicotinamide and N1-ethylnicotinamide (internal standard) are reacted with acetophenone in a strong base at 0 degree C, formic acid is added, and the reaction mixture is heated in a boiling water bath, resulting in the formation of fluorescent derivatives. These derivatives were chromatographed on a C18 reverse-phase column using a mobile phase of acetonitrile-triethylamine and 0.01 M heptanesulfonic acid adjusted to pH 3.2. Fluorescent detection was achieved using 366-nm excitation and 418-nm emission filters. Precision and accuracy were generally greater than 90%, interfering peaks did not cochromatograph, and the limit of quantification was 2 ng/ml in plasma using a 0.2-ml sample. The method was used to examine the concentrations of endogenous N1-methylnicotinamide in the plasma of 36 subjects with various pathology. The mean concentration was 18 ng/ml and the range was 6.2 to 116.7 ng/ml. The assay represents a marked improvement on previous methods and is suitable for routine clinical monitoring.
Somogyi
A
A
Department of Clinical and Experimental Pharmacology, University of Adelaide, Australia.
Siebert
D
D
Bochner
F
F
D000098:Acetophenones / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005260:Female; D005456:Fluorescent Dyes; D006801:Humans; D007674:Kidney Diseases / Q000097:blood; D008103:Liver Cirrhosis / Q000097:blood; D008297:Male; D008875:Middle Aged; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D015203:Reproducibility of Results
D000098:Acetophenones; D005456:Fluorescent Dyes; D009536:Niacinamide; C038699:acetophenone; C008472:N-methylnicotinamide