Identification by RP-HPLC-DAD, FTIR, TGA and FESEM-EDAX of natural pigments prepared from Datisca cannabina L Ozan Deveoglu a, b, * , Emrah Cakmakcı a , Turan Taskopru c, d , Emine Torgan e , Recep Karadag e, f a Department of Chemistry, Faculty of Science and Letters, Marmara University, 34722 Goztepe, Kadıkoy, Istanbul, Turkey b Department of Chemistry, Faculty of Science, Cankırı Karatekın University, 18100 Cankırı , Turkey c Department of Physic, Faculty of Science, Cankırı Karatekın University, 18100 Cankırı , Turkey d Department of Physic, Faculty of Science, Anadolu University, Eskisehir, Turkey e Turkish Cultural Foundation, Research and Development Laboratory for Natural Dyes, 34775 Umraniye, Istanbul, Turkey f Laboratory of Natural Dyes, Faculty of Fine Arts, Marmara University, 34718 Acıbadem, Kadıkoy, Istanbul, Turkey article info Article history: Received 27 May 2011 Received in revised form 26 January 2012 Accepted 2 February 2012 Available online 15 February 2012 Keywords: Natural pigment RP-HPLC FTIR TGA FESEM-EDAX Hemp abstract In this study, natural pigments from the hemp (Datisca cannabina L.) dye plant were prepared by using KAl(SO 4 ) 2 $12H 2 O (alum), FeSO 4 $7H 2 O and SnCl 2 $2H 2 O mordants. A reversed-phase high performance liquid chromatography (RP-HPLC) with diode array detection (DAD) method was utilized for the iden- tification of dyestuffs in the natural pigments. The dyestuff extractions from the pigments were carried out with 37% HCl/MeOH/H 2 O (2:1:1 v/v/v) mixture. The pigments were further characterized by ATR- FTIR analysis. It was found that all metals precipitate datiscetin and carbonates. Also results show that the datiscetineiron complex co-precipitates with glycosides. Thermal degradation of the pigments was determined by thermogravimetric analysis. High char yields were found for all pigments. These char yields are attributed to the high metal chelating capacity of datiscetin. The microstructure and chemical homogeneity of obtained natural pigments were studied by field emission scanning electron microscopy equipped with energy dispersion spectroscopy. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction The hemp (Datisca cannabina L.) plant is also known as “gence” in Turkey [1]. It is a robust, glabrous perennial plant that grows up to 1e2 m high in the Black Sea region, West and South Anatolia [1e3]. All aerial parts of this plant are used for dyeing. The hemp plant is mainly native to Turkey, North India, Western Asia. In the past, this plant was used by nomads in north-west Turkey as a dye plant. At the present time as in the past, it has been used for carpet and plain weaves. In addition, it is also used to yellow fibers in Van, Turkey. The aerial parts of hemp are dried and granulated, then the dyeing is accomplished by the mordant dyeing method. Hemp has been used to dye silk, wool and cotton in combination with an alum mordant. It yields a beautiful golden yellow with good fastness to washing but is not so fast to light. The plant is very rich in flavonols: datiscetin is present in the form of a rutinoside, datiscin (amounting to 10% of the weight of the fresh leaves). Kaempferol, quercetin and galangin are also present [2]. The natural pigments are prepared by the reaction of metal salts like aluminum (III) (KAl(SO 4 ) 2 $12H 2 O), tin(II) (SnCl 2 $2H 2 O) and iron(II) (FeSO 4 $7H 2 O) with the dyestuff compounds (flavonoids, anthraquinones, etc.) present in the dye sources and an alkaline solution (mostly K 2 CO 3 ) is used to adjust the pH. [4e10]. The yellow compounds obtained from plants have been used throughout history, both as textile dyes and to prepare natural pigments used in historical paints [9]. Many historical sources refer to the prepara- tion of yellow pigments from flavonoid-rich plants [10]. The mordant links to specific functional groups of the dye molecule by covalent and coordination bonds and the pigments are precipitated as in-soluble metaledye complexes in alkaline solution [11]. Flavonoids constitute a group of natural antioxidant substances which have been studied because of their properties such as anti- bacterial, anti-inflammatory, antiallergic, antimutagenic, antiviral and anticancer [12e15]. Also, interestingly it was found previously that the flavonoidemetal complexes are more effective antioxi- dants than the free flavonoids [16,17]. The natural dyestuffs * Corresponding author. Department of Chemistry, Faculty of Science and Letters, Marmara University, 34722 Goztepe, Kadıkoy, Istanbul, Turkey. Tel.: þ90 216 3384474/124; fax: þ90 216 3367468. E-mail addresses: ozan.deveoglu@marmara.edu.tr, odeveoglu@yahoo.co.uk (O. Deveoglu). Contents lists available at SciVerse ScienceDirect Dyes and Pigments journal homepage: www.elsevier.com/locate/dyepig 0143-7208/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.dyepig.2012.02.002 Dyes and Pigments 94 (2012) 437e442