Forensic analysis of blue ballpoint pen inks on questioned documents by high performance thin layer chromatography technique (Hptlc)

Nowadays, crimes related to forged documents are increasing. Any erasure, addition or modification in the document content always involves the use of writing instrument such as ballpoint pens. Hence, there is an evident need to develop a fast and accurate ink analysis protocol to solve this problem. This study is aimed to determine the discrimination power of high performance thin layer chromatography (HPTLC) technique for analyzing a set of blue ballpoint pen inks. Ink samples deposited on paper were extracted using methanol and separated via a solvent mixture of ethyl acetate, methanol and distilled water (70: 35: 30, v/v/v). In this method, the discrimination power of 89.40% was achieved, which confirm that the proposed method was able to differentiate a significant number of pen-pair samples. In addition, composition of blue pen inks was found to be homogeneous (RSD <2.5%) and the proposed method showed good repeatability and reproducibility (RSD