Documents are frequent targets of fraud and adulteration. Sometimes it is not enough to determine the document's authenticity or authorship, but it is also necessary to demonstrate when the document was signed or written. Determining the age of a document, also known as ink dating analysis, is still a challenge for the forensic examiners. There are two main approaches for the dating of ballpoint pen inks: the static method, which is based on the characterization and identification of the ink composition and comparison to a reference collection, and the dynamic method, which involves the study of ink's processes and alterations that occur with time, considering environmental aging factors such as light and humidity. This article aims to provide a comprehensive systematic review of the studies regarding ballpoint ink characterization and dating, in the last ten years. There are several methods, destructive and non-destructive, which are capable of characterizing and differentiating blue and black ballpoint pens that have shown applicability to the static approach. Regarding the dynamic dating methods, most studies quantified the loss of 2phenoxyethanol (2-PE) solvent over time using GC-MS, or studied the dyes degradation through different methods. Although ink dating approaches offer relatively good accuracy, there is still more research to be done, such as the documents' storage conditions evaluation, the influence of initial ink quantity variation between different pen brands and writing fists, and the type of paper.

In Forensic Documentoscopy, it is frequently questioned if a particular document was written with one or more pens. Different methods have been developed to distinguish pen inks from each other, but some of these techniques require the ink extraction, destructing the document, and other techniques uses high cost instruments. PhotoMetrix PRO ® , an app for mobile devices, is a qualitative and colorimetric analysis tool that applies uni-and multivariate analysis. Amongst them, Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA) and Partial Least Squares Discriminant Analysis (PLS-DA) can be obtained from digital images' decomposing data. It is a non-destructive and a simple method, of easily use and low cost. Chemometric knowledge is important for results interpretation. This study aims to evaluate the PhotoMetrix PRO ® capacity on blue ballpoint pens differentiation. Three experiments were performed with different ballpoint pens, including colorful pens as an app functionality control. The results showed appropriate differentiation between colorful ballpoint pens, and there was a satisfactory tendency of separation for different brands of blue ballpoint pens, most used in Brazil. This method is interesting to confirm subjective results, eliminating visual differences, intrinsic for each observer, which can be useful in places with an instrument deficiency, like the Video Spectral Comparator ® . New studies to evaluate writing pressure's