Matrix-assisted laser desorption/ionization tandem mass spectrometry for identification of organic tattoo pigments in inks and tissue samples.

With regard to the increasing number of tattooed people, legal regulations for tattoo inks were implemented across Europe-aiming for higher consumer safety. To control the laws' abidance, analytical methods are needed to identify banned ingredients from the given negative lists. Since specific organic pigments are often associated with tattoo side effects, their identification in tattoo inks as well as in biological samples is of great importance. Particularly, poorly soluble organic pigments are challenging to detect. In the past, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was reported as a promising tool for organic pigment identification. Here, we present a MALDI tandem mass spectrometry (MS/MS) approach to increase identification specificity and sensitivity in the process based on pigment fragment ions which is of special importance in tissue samples. For further verification of pigment identities, alkali metal cation attachment was used. Sample preparation was optimized and included mechanical disruption followed by the application as dried droplets with the matrices α-cyano-4-phenylcinnamic acid and sinapinic acid as well as ethanol. Pigments were identified by spectral comparison to reference libraries containing 40 pigments and following a decision tree. Additionally, successful pigment identification in biological samples was carried out. The implemented automated MALDI-MS and -MS/MS acquisitions make the hereby proposed pigment identification suitable for routine application.

The mitochondrial genomes of the caddisflies Sericostoma personatum and Thremma gallicum (Insecta: Trichoptera).

The mitochondrial genomes of the caddisfly species Sericostoma personatum and Thremma gallicum were sequenced on a 454 FLX and Illumina MiSeq platform, respectively. Reads were assembled de novo and remaining gaps in the S. personatum mitogenome closed by Sanger sequencing. The lengths of the assembled mitogenomes were 15,260 bp and 15,343 bp for S. personatum and T. gallicum, respectively. Both mitogenomes contained all 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and the control region. The mitochondrial gene order of both caddisflies is identical with the typical insect gene order. These are the third and fourth published mitogenomes of the order Trichoptera of two formerly unexplored families and thus will be useful in future phylogenetic analysis.