Hidrológiai Közlöny 1967 (47. évfolyam)

7. szám - A „Szervesanyag meghatározási problémák édesvizekben” című 1966. szeptember 25–28. között Tihanyben rendezett Szimpózium előadásai - Bidlo, Zdenek: Megjegyzések a vízben levő rezorcinol kimutaásához

Bidlo, Z.: A vízben levő rezorcinol Hidrológiai Közlöny 1967. 7. sz. 319 dilution of the residue on evaporation. Maintaining standard conditions, we obtained inspite of it reproducible Rf-values. The detection of cliromatographic spots was quite simple because the compounds used were sufficient coloured. A really simple detection is performed by spraying the chromatogram with a diluted mineral acid (e.g. sulphuric acid, nitric acid. hydrochloric acid etc.), but we found that a previous spraying of the chromatogram with an ethanol solution of phloroglucinol followed by drving at 100°C is more advisable; when we then spray the chromatogram with the already mentioned dilute mineral acid, the pink colour of spots changes into blue enabling a better identification of not so well coloured spots. Procedure A) Quantitative determination 25,0 ml of resorcinol solution with the concentration 0.5—5.0 ml/g is pippetted into a 100 mlErlenmeyer flask and lieated on the water bath 5 minutes with 0.2 ml of 1% solution of ANBN in ethanol. After 5 minutes 0.5 ml of concentrated nitric acid is added, the solution is cooled under tap-water and in a separating funnel extracted twice with 10 ml and 5 ml of benzene respectively. The collected benzene layers are reextracted again twice with 10 ml of 50% sulphuric acid and after filling up to 25 ml in a graduated flask it is measured at 550 m/u against the blank. B) Paper chromatography The already measured fenoxazine solution in 50% sulphuric acid is in a 250 separating funnel diluted with 100 ml of distilled water and extracted into 10 ml of chloroform. The reddish coloured lower layer is then discharged into a test tűbe and the chloroform is evaporated on a water bath at 40—50°C by bubbling through nitrogén. The residue on evaporation is diluted with 0.5 ml of a 50% solution of formamide in ethanol and this solution is used for paper chromatography on Whatman No. 4. The chromatogram is run with petrol b. p. 107—130°C; when the solvent has run to a distance of 25—30 cm, the chromatographic paper is withdrawn from the chamber, air-dried and then spray ed with the 1% solution of phloroglucinol in ethanol. The chromatogram is then dried for 5 minutes at 100°C in an oven. The final spraying is performed with diluted hydrochloric acid (1:1). Evaluation o! results In the introduction of this paper different views were discussed as to the constitution of the product which is förmed in the reaction of resorcinol, its derivatives or p-substituted phenols with ANBN. According to Ring and Newall by the reaction of ANBN with p-cresol, two products ofphenoxazine structure are supposed to be förmed; the difference between these products was in the position of the oxo-groups attached on the phenoxazine nucleus. Alsó our results support this point of view. The paper chromatography of the reaction product förmed by the reaction of resorcinol derivatives with ANBN always reveals two spots different both in colour and in Rf-values. The first spot is blueviolet and has a lower Rf-value, the second is pink-red and the Rf-value is higher, as it is seen from the Tab. 4. Tab. 4. Paper eliromatoKraphy Substance RfColour of spotvalue Colour of spotResorcinol 0.06 blue—violet 0.45 red—pink 4-ethylresorcinol .... 0.22 blue—violet 0.64 red—pink 5-methylresorcinol . . . 0.00 blue—violet 5-methylresorcinol . . . 0.39 red—pink • The existence of two reaction products, however, does not diminish the possibility applying this reaction for the determination of resorcinol and its derivatives in water. As it is shown in Tab. 3, other polyhydric phenols do not interfere with this determination, with the exception when they are present in more than 10 times excess. On the other hand we have to point out that the calibration curves for resorcinol, 4-ethyl resorcinol and 5methyl resorcinol differ from each other as it is shown in Fig. 3 which is quite common for all compounds forming homologous series. In this case as well as other analogical ones it is very valuable to combine the quantitative determination with the qualitative identification; only then are we sure about the correct calibration curve to be used for the evaluation of the measured absorbance. The described determination of resorcinol and its derivatives is applicable for samples, where the concentration of the mentioned compounds is from 0.5 to 5.0 mg/l. This concentration rangé is alsó the lower concentration limit for the successful performance of paper chromatography; lower concentration would leave residues on evaporation with very little colour. In such cases we must use a greater initial sample volume as already mentioned, or we must use somé sort of preconcentration as e. g. vacuum evaporation. LITERATURE [1] Gerngross 0. et al. (1933): Ber. (i(i, 435. [2] Mlodecka J. (1959): Ghem. analit. 4, 45. [3] Nicolas L., BurelB. (195(5):Chim. anal. 38, 316. [4] Umeda M. (1964): Yalcugaku Zasshi 84, 9, 836. [5] Anger V., Ofri S. (1964): Z. anal. Ghem. 203, 352. [6] King T. ./., Newall C. E. (1965): J. chem. soc. p. 480. Megjegyzések a vízben levő rezorcinol kimutatásához Bidlo, Zdenék Amíg a vízben levő egyértókű fenolok meghatározását nagy részletességgel tanulmányozták, csak igen kevés a többértékű fenolok meghatározására alkalmas módszer. Ezek közül a módszerek közül csak egy volt általában ajánlott, a katechol meghatározás ferrovegyületekkel.