Quantitative evaluation of europium in blue ballpoint pen inks/offset printing inks tagged with europium thenoyltrifluoroacetonate by spectrofluorometry and ICP-AES.

Tagging of writing/printing inks with suitable inorganic taggants such as rare-earth chelates has the potential to help document examiners identify fraud in sensitive written/printed documents. Selection of rare-earth chelates as taggants primarily depends on the satisfactory sensitivity of analytical determination and the absence of the taggants in normal varieties of inks used for document writing/printing. Spectrofluorometric determination of trace amounts of europium in blue ballpoint pen inks and offset printing inks tagged with europium thenoyltrifluoroacetonate was carried out with sodium tungstate solution. Sodium tungstate acts as a specific reagent that enhances the fluorescence intensity of the Eu3+ ion. The excitation and emission wavelengths are 270 nm and 605 nm respectively. The results were compared with the data obtained with ICP-AES. Satisfactory recoveries were observed with precision better than 5% RSD and comparable accuracy. Under the optimized experimental conditions, detection limits and quantitation limits were determined. The detection limits obtained by spectrofluorometry and ICP-AES were 0.01 microg/mL and 0.006 microg/mL respectively whereas the limits of quantitation were about 0.03 microg/mL and 0.018 microg/mL respectively. The spectrofluorometric method is rapid, selective, sensitive and accurate for the determination of europium in blue ballpoint pen ink and offset printing inks and may be suitable for application in the examination of sensitive documents to aid in document related crime investigation. The advantages and limitations of the tagging approach and proposed analytical techniques are discussed.

Analysis of Indian blue ballpoint pen inks tagged with rare-earth thenoyltrifluoroacetonates by inductively coupled plasma-mass spectrometry and instrumental neutron activation analysis.

Characterization and assessment of inks on sensitive documents for absolute/relative age determination is the challenging forensic problem in spite of practical difficulties. Tagging of ballpoint pen ink with suitable taggant(s) is a unique method to come out with definitive inferences on the detection of forgery in documents written with ballpoint pens. Selection of a proper taggant primarily depends on sensitivity of analytical determination and their absence in normal varieties of ink used for document writing. Rare-earth elements, from all technical considerations can be potential taggant(s) for inks. To ensure more compatibility with ink, 13 rare-earth thenoyltrifluoroacetonate chelates were prepared and characterized. The ballpoint pen inks were tagged with rare-earth thenoyltrifluoroacetonate chelates individually at about 1-100 ppm level depending on sensitivity of element under suitable optimized experimental conditions and instrumental sensitivity. Aliquots of such tagged ink having varying amounts of taggants were analyzed by ICP-MS and INAA. Satisfactory recoveries and a good linear relationship of intensity (signal) against concentrations/amounts were observed. Under the optimized experimental conditions, the detection limits were worked out. This study of tagging metal ions in combination with ICP-MS and NAA as an analytical tool can allow to draw various combination options based on different rare-earth chelates as suitable materials for tagging of ballpoint pen inks for absolute/relative age determination to aid in document related crime examination. The advantages and limitations of proposed analytical techniques are discussed.