Die polarimetrische Bestimmung der Äpfelsäure

Auerbach, Friedrich; Krüger, Deodata

doi:10.1007/bf02107844

Cited by 6 publications

(3 citation statements)

References 14 publications

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confidence: 70%

Aerobic oxidation of aromatic hydrocarbons in the presence of ascorbic acid

Warren

1943

Biochemical Journal

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1. Citrate increases the rotation ofthe molybdate complexes of malic acid (as already observed by Auerbach & Kruger [1923]), of citramalic acid and of isocitric acid. The increase can amount to more than 100 %. The magnitude of the effect under varying conditions is investigated.2. The effect of citrate must be taken into account when the above acids are determined polarimetrically by the molybdate method. Isocitric acid concentrations calculated from polarimetric readings by previous investigators who were unaware of the citrate effect require revision.3. Preliminary experiments show that the equilibrium mixture of isocitrate, 6i8-aconitate and citrate in the presence of liver or muscle aconitase contains 6*2 % isocitrate, 4*3 % cis-aconitate and 895% citrate (380; pH 6-8; 0-025M phosphate buffer). The effect of pH is small between 6-& and 7-4. MgCl2 shifts the equilibrium in favour of citrate.4. A modified polarimetric method is suggested for the determination of malic and isocitric acids, applicable to solutions containing citrate.

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supporting

confidence: 70%

Aerobic oxidation of aromatic hydrocarbons in the presence of ascorbic acid

Warren

1943

Biochemical Journal

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“…I943 SUMMARY 1. Citrate increases the rotation ofthe molybdate complexes of malic acid (as already observed by Auerbach & Kruger [1923]), of citramalic acid and of isocitric acid. The increase can amount to more than 100 %.…”

Section: Polarimetric Determination Of Malic and Isocitric Acidsmentioning

confidence: 88%

The effect of citrate on the rotation of the molybdate complexes of malate, citramalate and isocitrate

Krebs

Eggleston

1943

Biochemical Journal

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“…The method most commonly used in recent years is based upon the high optical rotation of malic acid in the presence of uranium (£) or of molybdenum (1) salts. This method is specific only in the absence of other optically active acids; furthermore, the possibility that dlmalic acid may sometimes be present in plant tissues (8) introduces an element of uncertainty into the result as a measurement of the total quantity of malic acid present.…”

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confidence: 99%