Examiner of Questioned Documents, Wisconsin State Crime Laboratory, Milwaukee, WI
(Received 16 April 1991; accepted 5 February 1996)
Quality control procedures for thin-layer chromotrography (TLC) are offered to increase reproducibility and dependability of results. During preparation of a TLC ink standard library, several types of inconsistencies were observed. Observations of more than 100 chromatograms of writing inks indicated the need for the institution of quality control procedures. Procedures were developed to ensure proper solvent selection, TLC plate selection, and proper photographic recording of TLC plates. Implementing quality control procedures in TLC enables the document examiner and forensic chemist to achieve these results.
Paper ID: JFS14015J