Towards a new conservation method for ancient manuscripts by inactivation of iron via complexation and extraction

The aim of this work was to study the efficiency of extraction of iron from model paper samples by use of different ligands (deferoxamine mesylate, the potassium-magnesium salt of phytic acid and diethylenetriaminepentaacetic acid) at varied concentrations (0.01, 0.005, and 0.001 mol L(-1)) and pH (7, 8, 9). Graphite furnace atomic absorption spectrometry (GFAAS) was used to monitor the total amount of iron in solutions of the respective ligands. Two types of model were used to investigate the behaviour of various iron species present in ancient iron-gall ink. Requirements for the optimal procedure, which could possibly be used in the conservation of ancient manuscripts, included high effectiveness of iron extraction from samples which modelled free iron ions (samples "Fe"), while iron deposited in the form of ink (samples "A") should remain without any visible change of the ink's intensity. The best results were achieved with the solution of 0.005 mol L(-1 )diethylenetriaminepentaacetic acid (pH=9), which allowed extraction of 97+/-1% of iron from "Fe" model samples and only 64+/-1% from "A" samples.