We purchased the following compounds from Sigma: adenine, adenosine, 2-deoxyadenosine, 2-deoxyguanosine, inosine, 2-deoxyinosine, xanthine, hypoxanthine, orotic acid, uric acid, thymine, uracil, dihydrothymine, dihydrouracil, N-carbamyl-[beta]-aminoisobutyric acid, N-carbamyl-[beta]-alanine, thymidine, uridine, pseudouracil, 5-hydroxymethyluracil, and 2-deoxyuridine.
Dihydrouracil is quantifiable at 100-600 mmol/ mol creatinine.
For 2-deoxyinosine, adenosine, 2-deoxyadenosine, guanosine, 2-deoxyguanosine, succinyladenosine, orotic acid, thymine, dihydrouracil, dihydrothymine, uridine, 2-deoxyuridine, and 5-hydroxymethyluracil, sample concentrations were below the lower limits of quantification, as were the concentrations of inosine and N-carbamyl-[beta]-aminoisobutyric acid for children older than 1 year and N-carbamyl-[beta]-alanine for children older than 4 years of age.
In the sample from the patient with DHP deficiency, there were unidentifiable peaks in the chromatograms of dihydrouracil and dihydrothymine.
Optimal peak shapes were achieved for all analytes except for dihydrouracil and N-carbamyl-[beta]-alanine, which were characterized by broader and split peaks.
For xanthine, adenosine, 2,8-dihydroxyadenine, uracil, thymine, dihydrouracil, dihydrothymine, N-carbamyl-[beta]-amino-isobutyric acid, N-carbamyl-[beta]-alanine, uridine, and pseudouridine, the detection limit was between 1 and 10 [micro]mol/L.
The interference of 5,6-dihydrouridine could be eliminated by use of the transition m/z 132 [right arrow] 115 for the detection of dihydrouracil (see Fig.
Correlation between uracil and dihydrouracil plasma ratio, fluorouracil (5-FU) pharmacokinetic parameters, and tolerance in patients with advanced colorectal cancer: a potential interest for predicting 5-FU toxicity and determining optimal 5-FU dosage.
Simple liquid chromatographic method for the determination of uracil and dihydrouracil plasma levels: a potential pretreatment predictor of 5-fluorouracil toxicity.