Analytical Sciences

Microfluidic Paper-based Analytical Device for Quantification of Lead Using Reaction Band-length for Identification of Bullet Hole and Its Potential for Estimating Firing Distance

Supatana BUKING,*1,*2 Phoonthawee SAETEAR,*1,*2 Warawut TIYAPONGPATTANA,*1,*3 Kanchana URAISIN,*1,*2 Prapin WILAIRAT,*4 Duangjai NACAPRICHA,*1,*2 and Nuanlaor RATANAWIMARNWONG*1,*5

*1 Flow Innovation-Research for Science and Technology Laboratories (FIRST Labs)
*2 Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
*3 Department of Chemistry, Faculty of Science and Technology, Thammasat University, Pathumthani 12121, Thailand
*4 National Doping Centre of Thailand, Mahidol University, Bangkok 10400, Thailand
*5 Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukhumvit 23, Bangkok 10110, Thailand

A low-cost and user-friendly microfluidic paper-based analytical device (μPAD) was developed for identification of bullet hole from gunshot residue (GSR) on cotton fabric target. The device (25 × 82 mm) is made of filter paper with a printed pattern consisting of a circular sample loading reservoir (6 mm i.d.), a circular waste reservoir (4 mm i.d.) and a straight flow channel (3 mm wide and 60 mm long). A sticker with a ruler scale in millimeters was mounted alongside the channel. The straight channel is first impregnated with rhodizonate and dried at ambient temperature. Tartrate extract of the target fabric is loaded on the sample reservoir. If Pb(II) ions are present in the extract, pink streak of Pb(II)-rhodizonate precipitate is formed as the sample solution flows from the reservoir along the channel. The length of the pink strip is employed to estimate the firing distance.

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