| Abstract: | CONCLUSION. Chromatographic paper Whatman 1 ˙ it is relatively easy to precisely determine the preparation of AR in W1 paper and assign it by selection of the appropriate MMMC concentration. At potentiometric determination of AR it is needed to titrate to pH 6 (range of AR1-3). In these conditions there is a good congruence between the AR determination by weight and determination by titration, ˙ it is possible to prepare a big AR, ˙ the amount of titratable substances below pH 6 is small. Newsprints A and B ˙ in modern newsprints we can relatively precisely figure out the size of AR and prepare it by means of various MMMC concentrations if the pH value in extracts is higher than 7. The analysis indicated a good congruence between the ARg determination by weight and determination by titration to pH = 6 in the range of AR1-3, ˙ at lower pH values of the extract the end-of-titration in the range of AR1-3 is reached at lower pH values and does not refer to real AR, ˙ the amount of titratable substances below pH = 6 is relatively big. ˙ the method of ARg determination by weight gives out relatively accurate results. Historic newsprints D and E ˙ it is relatively difficult to reach the calculated preparation of the amount of AR in these papers ˙ there is a big difference between AR1-3 stated by titration and ARg stated by weight ˙ even when using high MMMC concentrations, the AR reached in papers is only 1-2 % ˙ the amount of substances able to be titrated below pH = 6 or 5 is big ˙ determination of AR1-3 by titration stands for only 29-34 % of the capacity of acid-based systems in papers referring to real AR, and it just about 50 % of the ARg size stated by weight |
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