Development of a low cost gas diffusion device for ammonia detection in the vitreous humor and its preliminary application for estimation of the time since death
| Autor: | Giacomo Musile, Ksenia Shestakova, Franco Tagliaro, Elio Franco De Palo, Rossella Gottardo, Covadonga Palacio, Dario Raniero |
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| Rok vydání: | 2019 |
| Předmět: |
Adult
Materials science vitreous humour genetic structures Pathology and Forensic Medicine gas diffusion analysis low cost analytical devices Young Adult chemistry.chemical_compound Ammonia Capillary electrophoresis Limit of Detection pH indicator Humans Gaseous diffusion Ammonium Coloring Agents Aged Aged 80 and over Detection limit post mortem interval Vitreous humour Chromatography Reproducibility of Results Thymol blue Middle Aged eye diseases Vitreous Body chemistry Postmortem Changes ammonia Colorimetry Smartphone sense organs Thymolphthalein Law |
| Zdroj: | Forensic Science International. 295:150-156 |
| ISSN: | 0379-0738 |
| DOI: | 10.1016/j.forsciint.2018.12.012 |
| Popis: | A simple and low cost analytical device is described for the determination of ammonium in the vitreous humor suitable for inferring the post mortem interval in forensic cases. The device is based on ammonia formation from ammonium ion by means of NaOH addition to the vitreous humor sample and its detection with a pH chemical indicator in the gas phase above the vitreous humor sample. From the gas phase, ammonia diffuses through a polymeric membrane and it is trapped and detected with a droplet of pH indicator thymol blue. The color change of the droplet is measured using a smartphone camera. Under optimal conditions, the device showed a limit of detection of 0.2mM, with between days precision of ≤ 15% expressed as relative standard deviation, and an accuracy between days from 88.3% to 114.5%. This homemade gas diffusion analytical device was successfully used for the determination of ammonia in vitreous humor samples from forensic autopsies. The results obtained with the proposed method, although for a limited number, showed a close correlation with the data obtained with an instrumental analysis based on capillary electrophoresis. Moreover a significant correlation was also found between the results of the present method and the time elapsed since death by a simple evaluation of the color intensity. In conclusion, this preliminary study showed that the proposed device, after adequate validation, could be a promising tool for a presumptive estimation of the time since death directly at the crime scene. |
| Databáze: | OpenAIRE |
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