Browsing by Author "Cody, Robert B."

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Creating a searchable chromatographic database with the NIST mass spectral search program
    (American Chemical Society , 2022-03-09) Cody, Robert B.; Sparkman, O. David; Moore, Hannah
    The NIST Mass Spectral Search Program can be used to create a searchable database of chromatograms. This approach was tested for a small database of chromatograms for gin volatiles and for a database of insect cuticular hydrocarbons with retention times and reconstructed total ion current chromatographic peak areas substituted for m/z values and abundance. The In-source HiRes Identity search permitted matching of randomly selected chromatograms against the database with good results. This approach is not intended to replace commercial software for chromatographic database management as it does not address the problems of chromatographic alignment or chromatographic deconvolution, but it does provide a method to manage a simple chromatographic database if other options are not available.
  • Thumbnail Image
    ItemOpen Access
    Cuticular hydrocarbons for identifying Sarcophagidae (Diptera)
    (Nature Publishing Group, 2021-04-08) Moore, Hannah E.; Hall, Martin J. R.; Drijfhout, Falko P.; Cody, Robert B.; Whitmore, Daniel
    The composition and quantity of insect cuticular hydrocarbons (CHCs) can be species-specific as well as sexually dimorphic within species. CHC analysis has been previously used for identification and ageing purposes for several insect orders including true flies (Diptera). Here, we analysed the CHC chemical profiles of adult males and females of eleven species of flesh flies belonging to the genus Sarcophaga Meigen (Sarcophagidae), namely Sarcophaga africa (Wiedemann), S. agnata Rondani, S. argyrostoma Robineau-Desvoidy, S. carnaria (Linnaeus), S. crassipalpis Macquart, S. melanura Meigen, S. pumila Meigen, S. teretirostris Pandellé, S. subvicina Rohdendorf, S. vagans Meigen and S. variegata (Scopoli). Cuticular hydrocarbons extracted from pinned specimens from the collections of the Natural History Museum, London using a customised extraction technique were analysed using Gas Chromatography–Mass Spectrometry. Time of preservation prior to extraction ranged between a few weeks to over one hundred years. CHC profiles (1) allowed reliable identification of a large majority of specimens, (2) differed between males and females of the same species, (3) reliably associated males and females of the same species, provided sufficient replicates (up to 10) of each sex were analysed, and (4) identified specimens preserved for up to over one hundred years prior to extraction.
  • Thumbnail Image
    ItemOpen Access
    Cuticular hydrocarbons for the identification and geographic assignment of empty puparia of forensically important flies
    (Springer, 2022-02-26) Moore, Hannah; Lutz, Lena; Bernhardt, Victoria; Drijfhout, Falko P.; Cody, Robert B.; Amendt, Jens
    Research in social insects has shown that hydrocarbons on their cuticle are species-specific. This has also been proven for Diptera and is a promising tool for identifying important fly taxa in Forensic Entomology. Sometimes the empty puparia, in which the metamorphosis to the adult fly has taken place, can be the most useful entomological evidence at the crime scene. However, so far, they are used with little profit in criminal investigations due to the difficulties of reliably discriminate among different species. We analysed the CHC chemical profiles of empty puparia from seven forensically important blow flies Calliphora vicina, Chrysomya albiceps, Lucilia caesar, Lucilia sericata, Lucilia silvarum, Protophormia terraenovae, Phormia regina and the flesh fly Sarcophaga caerulescens. The aim was to use their profiles for identification but also investigate geographical differences by comparing profiles of the same species (here: C. vicina and L. sericata) from different regions. The cuticular hydrocarbons were extracted with hexane and analysed using gas chromatography-mass spectrometry. Our results reveal distinguishing differences within the cuticular hydrocarbon profiles allowing for identification of all analysed species. There were also differences shown in the profiles of C. vicina from Germany, Spain, Norway and England, indicating that geographical locations can be determined from this chemical analysis. Differences in L. sericata, sampled from England and two locations in Germany, were less pronounced, but there was even some indication that it may be possible to distinguish populations within Germany that are about 70 km apart from one another.