HPLC-DAD-MS analysis of colorant and resinous components of lac-dye: A comparison between Kerria and Paratachardina genera Raquel Santos a , Jessica Hallett a , M. Conceiç ~ ao Oliveira b, * , Micaela M. Sousa c , Jorge Sarraguça d , M.S.J. Simmonds e , M. Nesbitt e a CHAM (Centre for Overseas History), Faculdade de Ci^ encias Sociais e Humanas, Universidade Nova de Lisboa and Universidade dos Açores, 1069-061 Lisboa, Portugal b Centro de Química Estrutural, Instituto Superior T ecnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal c REQUIMTE, Departamento de Química, Faculdade de Ci^ encias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Monte da Caparica, Portugal d REQUIMTE, Laborat orio de Química Aplicada, Departamento de Ci^ encias Químicas, Faculdade de Farm acia, Universidade do Porto, 4050-313 Porto, Portugal e Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK article info Article history: Received 22 June 2014 Received in revised form 27 November 2014 Accepted 25 February 2015 Available online 12 March 2015 Keywords: Dyes/pigments Liquid chromatography Mass spectrometry Lac-dye Paratachardina spp. Kerria spp. abstract A database using high performance liquid chromatography with diode array detection was created for lac-dye insects (Kerria and Paratachardina genera) in order to identify the red dye used in historical textiles. Lac from Kerria and Paratachardina species was easily distinguished by liquid chromatography coupled to negative electrospray ionization tandem mass spectrometry. Seventy-six historical lac-dye specimens and seven reference insect specimens were analyzed and compared with 41 historical car- pet samples. Using this approach, the presence of Kerria spp. was identified in three carpets, pointing to an Iranian provenance and corroborating a 16th/17th-century date for them, obtained previously with C14 analysis. Multivariate data analysis was applied to differentiate sources of Kerria and improve the lac-dye database. PCA indicates that discrimination can be obtained according to composition. Information regarding pigment and resin concentrations is recovered separately in first and second principal com- ponents, respectively, which offers a basis of separation for this type of data. The development of this lac-dye database is an important step towards improving research on lac-dye species, which can contribute to more accurate identification of the provenance of historical textiles. This work reinforces the importance of using taxonomically-verified specimens of Kerria, previously sub- mitted to molecular taxonomic studies, to construct a more reliable lac-dye database capable of iden- tifying the lac species present in historical textiles, as well as the provenance of the insect used. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction High performance liquid chromatography (HPLC) combined with sensitive and selective detection techniques such as diode array detector (DAD) and more recently mass spectrometry (MS) are widely applied to identify the colorants used in works of art [1,2]. The identification of natural dyes in historical textiles is a challenging task owing to factors such as small sample size as well as the complexity of dye degradation processes [3e5]. Extraction procedures have a direct impact on the results obtained by HPLC-DAD-MS n and other related analytical tech- niques [6,7]. Extraction of dyes from a textile fiber was usually carried out with 3 M hydrochloric acid-methanol (1:1, v/v) at boiling point. In the past few years, this traditional aggressive acidic extraction method [8,9] has been replaced by new soft extraction methods that enable the sugar derivatives of the col- orants to be extracted intact [6,7,10,11]. These extracts contain a greater diversity of compounds and therefore more complete information for differentiating samples and identifying dye sources. Indeed, sample preparation has proven to affect both the quality and quantity of the isolated colorants [7], something which is of fundamental importance for studying precious his- torical textiles. * Corresponding author. E-mail addresses: conceicao.oliveira@tecnico.ulisboa.pt, ana.rsantos@fcsh.unl.pt (M.C. Oliveira). Contents lists available at ScienceDirect Dyes and Pigments journal homepage: www.elsevier.com/locate/dyepig http://dx.doi.org/10.1016/j.dyepig.2015.02.024 0143-7208/© 2015 Elsevier Ltd. All rights reserved. Dyes and Pigments 118 (2015) 129e136