Methoden der direkten Blutammoniakbestimmung ohne Destillation

Abstract

Methods for the direct determination of blood ammonia without disfilia/ionIn the present scries of investigations the following methods were used for the direct determination of ammonia in whole blood: colorimetric determination by 2 modifications of the phcnol-hypochloritc reaction and the cnzymic determination with 2-Oxoglutaratc, NADH and glutamic acid dchydrogcnasc. The chief sources of error in all determinations of blood ammonia are located in the stages from the sampling of the blood to the analytical reaction mixture. Amino acids react to varying extents in the phenol-hypochloritc reaction. Quantitatively measurable reactions arc only given by glycinc, leucine and by very high concentrations of glutamine. A modification of the reaction with increased concentrations of reagents gave higher blood ammonia values than the modification of MÜLLER-ÜEISSENI-IIRTZ and KHLLBR, using the same blood samples. There were positive correlations between the cnzymic and the phcnol-hypochloritc methods, and between the two modifications of the latter. The colorimctric method showed a 89-100% recovery for NH 3 -N added to whole blood. There was a strict linear relationship between the extinction at 578 nm and the NH 3 -N concentration of the standard solution, The rcproducibility of the two phcnol-hypochlorite methods was tested by multiple determinations in series and by double measurements from day to day. V% in the series for the two methods was 1.83 and 2.01%, and for the double determinations 2.2% and 2.71%. Within the normal range, single determinations showed good agreement between values obtained by the phenolhypochloritc method and the values of MÜLLER-BEISSENHIRTZ and KELLER.