Summary: Three methods for determination of ammonia in saliva are reported. The indophenol method on diluted saliva has the best precision (coefficient of Variation 0.8%) and the lowest reagent cost. The ammonium electrode method is the quiekest, but it requires simultaneous determination of the potassium content of the specimen. The enzymatic method gives the same result äs the electrode method, but is more expensive. Deproteinisation proved not to be necessary. In one hour 10, 20 or 40 determinations can be performedVith the enzymatic, indophenol-or the electrode method, respectively. Bestimmung von Ammoniak im Speichel mit der Berthelot-Reaktion, einer Ammonium-Elektrode und einer enzymatischen Methode: Eine vergleichende Untersuchung Zusammenfassung: Drei Methoden zur Bestimmung von Ammoniak im Speichel wurden geprüft. Die Methode nachBerthelot für verdünnten Speichel hat die beste Präzision (VK -0,8%) und die geringsten Reagenzienkosten. Die Messung mit der Ammoniak-Elektrode ist die schnellste, erfordert jedoch die gleichzeitige Kalium-Bestimmung. Die enzymatisehe Methode ergibt die gleichen Resultate wie die potentiometrische, ist jedoch teurer. Enteiweißung ist nicht erforderlich. In einer Stunde können mit der enzymatischen Methode 10 ? mit der Berthelot-Reaktion 20 und mit der potentiometrischen Methode 40 Bestimmungen durchgeführt werden.

A simple and fast HPLC method for the determination of ροφΗγπηβ in bile without extraction is described. ΡθφΗγΗη8 were determined in bile from control subjects and from patients after orthotopic liver transplantation, ineluding three patients with eiythropoietic protoporphyria. It was found that: 1) coproporphyrin I is the predominant porphyrin in bile of controls, accompanied by some coproporphyrin III and protoporphyrin, whereas protoporphyrin mostly but not always is the predominant porphyrin in the bile of erythropoietic protoporphyria patients. In two of the three erythropoietic protoporphyria patients, the bile contained a hundred times more protoporphyrin than that of ήοη-porphyric orthotopic liver transplantation patients. The third erythropoietic protpporphyria patient remained cholestatic and was unable to excrete sufficient amounts of protoporphyrin.2) All investigated bile samples contained no secondary porphyrins derived from protoporphyrin, i. e. no deutero-, pempto-, or mesoporphyrin. Even when extracts of bile and serum were concentrated fifty to a hundred times, no traces of deutero^, pempto-and mesoporphyrin were detected. This complete absence of secondary porphyrins suggests that an enterohepatic circulation of dicarb xylic porphyrins from the distal gastrointestinal tract does not exist.3) The HPLC chromatqgfarns contain peaks from unknown compounds. No correlation between ροφ!^τίη8 and these compounds was found.Porphyrin profiles were followed in the bile of some orthotopic liver transplantation patients. Three episodes are recognizable. D ring the first three days after orthotopic liver transplantation there is a very high οορΓοροφΙ^ιίη excretion. There is then a lag of one to three weeks, in which no or very low ρoφhyrin concentrations are detectable, followed by the restoration of normal biliary ροφίιγιίη patterns. IntroductionThe poφhyric diseases can be identified by profiling of urine, faeces or blood (1-3), and detecting the ροφίν/-Determination of ροφίι^η profiles in biological sain-rins that are ffQ^y elevated. Thus, together with their plesbyrneansofHPLChasprovedvaluableinthediag-clinical presentation, congenital erythropoietic pornosis and treatment of patiemts suffering from currently phyria, poφhyria cutanea tarda and attacks of acute inknownforms ofpoφhyria, allcausedby adeficiency or termittent poφhyria can be identified by analysis of Inhibition of enzymes involved in the synthesis of haem. urine, whereas stool analysis is needed to identify at-

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