Serum methylmalonic acid by capillary zone electrophoresis using electrokinetic injection and indirect photometric detection.
Elevated methylmalonic acid (MMA) is a superior marker for cobalamin (vitamin B12) deficiency. A rapid assay for serum MMA suitable for clinical specimens has been developed. The specimen is injected electrokinetically after a simple extraction. MMA is measured using indirect photometric detection at 210 nm, based on the displacement of phthalic acid in the running electrolyte; no derivatization is needed. The detection limit is 0.2 mumol/L, well below 0.4 mumol/L, which defines elevated concentrations. The assay is linear up to 100 mumol/L, although specimens above 10 mumol/L are diluted to maximize resolution. The CV is < 10% at 0.30 mumol/L and 0.80 mumol/L. The assay gives results that are comparable to more traditional methods.
Franke
D R
DR
Department of Pathology, University of Utah, School of Medicine, Salt Lake City 84132, USA.
Marsh
D B
DB
Nuttall
K L
KL
D015415:Biomarkers / Q000097:blood; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008764:Methylmalonic Acid / Q000097:blood*; D010783:Photometry / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000175:diagnosis*
D015415:Biomarkers; D008764:Methylmalonic Acid