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.
Maind
S D
SD
Neutron Activation Analysis Unit of Central Forensic Science Laboratory, Hyderabad, Analytical Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
Kumar
S A
SA
Chattopadhyay
N
N
Gandhi
Ch
Ch
Sudersanan
M
M
D002244:Carbon; D005607:Fraud / Q000517:prevention & control*; D006801:Humans; D008674:Metals, Rare Earth / Q000737:chemistry*; D009501:Neutron Activation Analysis / Q000379:methods; D011237:Predictive Value of Tests; D013054:Spectrophotometry, Atomic / Q000379:methods; D013804:Thenoyltrifluoroacetone / Q000737:chemistry*
D008674:Metals, Rare Earth; C028433:chinese ink; D013804:Thenoyltrifluoroacetone; D002244:Carbon