UCLA UCLA Electronic Theses and Dissertations Title Dye analysis of archaeological Peruvian textiles using surface enhanced Raman spectroscopy (SERS) Permalink https://escholarship.org/uc/item/5699m0tt Author Burr, Elizabeth Publication Date 2016 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA Los Angeles Dye analysis of archaeological Peruvian textiles using surface enhanced Raman spectroscopy (SERS) A thesis submitted in partial satisfaction of the requirements for the degree Master of Arts in Conservation of Archaeological and Ethnographic Materials by Elizabeth Burr 2016 i ii ABSTRACT OF THESIS Dye analysis of archaeological Peruvian textiles using surface enhanced Raman spectroscopy (SERS) by Elizabeth Anne Burr Master of Arts in Conservation of Archaeological and Ethnographic Materials University of California, Los Angeles, 2016 Professor Ioanna Kakoulli, Chair Surface-enhanced Raman spectroscopy (SERS) is an emerging technique for the identification of colorants at low concentrations, making it ideal for degraded and irreplaceable archaeological materials. Using silver nanoparticles (AgNPs) as the SERS platform, this research on the identification of textile dyes compares direct on-the-fiber extractionless analyses with micro- extraction methods employing hydrofluoric acid vapor, formic acid, and hydrochloric acid solutions. Seven red samples from Wari and Malena textiles from the site Huaca Malena in Peru and reference yarns dyed with Relbunium and cochineal were analyzed using individual fiber samples. Complementary analysis of archaeological samples was conducted with fiber optics reflectance spectroscopy (FORS). Carminic acid, the primary colorant of cochineal, and pseudopurpurin and purpurin, the main coloring compounds of Relbunium were detected in the reference samples. Three archeological samples provided potential matches for carminic acid and two may contain purpurin and pseudopurpurin. FORS, data indicate that all the archaeological samples contained cochineal. ii The thesis of Elizabeth Anne Burr is approved. Ioanna Kakoulli, Committee Chair Charles S. Stanish Dino DiCarlo Elena Phipps Diana Rambaldi University of California, Los Angeles 2016 iii Acknowledgements Thank you to my panel readers for their valuable comments and feedback. Thank you to the Conservation Science lab at LACMA (Diana Rambaldi, Terry Schaefer, Charlotte Eng, Laura Maccarelli, and Frank Pruesser) for allowing me to conduct research in their lab, and for all their generous teaching and assistance without which this project would not have been possible. Thank you to Vanessa Muros for sure suggestion to pursue this project, for sharing archaeological samples from Huaca Malena, for advice and support on dye analysis, and assistance in Spanish translations. Thank you to Rommel Ángeles Falcón for providing samples and information from the Huaca Malena textiles, and tour the Huaca Malena archaeological site and museum. I am greatly appreciative of the assistance and advice provided by UCLA Material Science and Engineering PhD students Xiao Ma, Yuan Lin, and Roxanne Radpour. Their interest and technical support has been crucial to completing this thesis. Also thank you to Sergey Prikhodko for assistance and training on the SEM and Raman spectrometer. Thank you to Christian Fischer, Ioanna Kakoulli and Lesley Day for feedback and assistance on FORS. Thank you to my cohort for their support. Thank you to Getty for funding the UCLA/Getty conservation program. ii Table of Contents Chapter 1 Introduction .................................................................................................................................................... 1 1.1 Background .......................................................................................................................................................... 1 1.2 Aims and scope of study ...................................................................................................................................... 2 Chapter 2 Natural Dyes and Dyeing ............................................................................................................................... 4 2.1 Natural dyes ......................................................................................................................................................... 4 2.2 Mordants .............................................................................................................................................................. 5 2.3 Natural red dye sources of Peru .......................................................................................................................... 6 2.3.1. Cochineal .................................................................................................................................................... 6 2.3.2. Rubiaceae Relbunium ................................................................................................................................. 7 2.3.3. Rubiaceae Galium ....................................................................................................................................... 9 2.3.4. Other red dyestuffs .................................................................................................................................... 10 Chapter 3 Pre-Columbian Archaeological Evidence in Peru ........................................................................................ 11 3.1 Archaeological evidence and significance of textile traditions ........................................................................... 11 3.2 Analysis of Pre-Columbian Peruvian Textiles .................................................................................................... 12 3.2.1. Early Horizon ............................................................................................................................................. 13 3.2.2. Early to Late Intermediate Periods (A.D. 200 to 1476) .............................................................................. 14 3.2.3. The rise of cochineal red ........................................................................................................................... 15 3.3 Archaeological Site of Huaca Malena ................................................................................................................ 16 Chapter 4 Dye analysis & SERS .................................................................................................................................. 18 4.1 Dye Analysis ...................................................................................................................................................... 18 4.2 Surface Enhanced Raman Spectroscopy (SERS) ............................................................................................. 18 4.3 SERS dye analysis ............................................................................................................................................ 20 4.3.1. SERS techniques and advances ............................................................................................................... 20 4.3.2. Applications of SERS for the identification of cochineal and Relbunium ................................................... 22 Chapter 5 Materials and Methods ................................................................................................................................ 22 5.1 Sample materials ............................................................................................................................................... 22 5.1.1. Chemical standards and reference materials ............................................................................................ 22 5.1.2. Archaeological materials ........................................................................................................................... 23 iii 5.2 Microscopy and image analysis ......................................................................................................................... 24 5.2.1. Optical microscopy of fiber samples .......................................................................................................... 24 5.2.2. Scanning electron microscopy of fiber samples and AgNPs ..................................................................... 24 5.2.3. Image analysis of fiber samples and AgNPs ............................................................................................. 25 5.3 Fiber optic reflectance spectroscopy (FORS) of AgNPs and archaeological samples ....................................... 25 5.4 Surface Enhanced Raman Spectroscopy (SERS) ............................................................................................. 25 5.4.1. Sample preparation ................................................................................................................................... 25 5.4.2. Synthesis of Silver nanoparticles (AgNPs) ................................................................................................ 27 5.4.3. SERS and Raman spectromicroscopy ...................................................................................................... 28 Chapter 6 Results and Discussion ............................................................................................................................... 29 6.1 Characterization of AgNPs................................................................................................................................. 29 6.2 Characterization of archaeological textiles and fiber type .................................................................................. 31 6.2.1. Fiber and yarn type ................................................................................................................................... 31 6.2.2. Condition of archaeological fibers ............................................................................................................. 35 6.3 Characterization of reference dyes using SERS ................................................................................................ 37 6.3.1. Extractionless on-the-fiber SERS .............................................................................................................. 38 6.3.2. On-the-fiber SERS with HF micro-extraction ............................................................................................. 40 6.3.3. On-the-fiber SERS with formic acid micro-extraction ................................................................................ 42 6.3.4. Liquid micro-extraction with HCl in MeOH and H O .................................................................................. 44 2 6.3.5. Summary of findings from SERS methods ................................................................................................ 48 6.4 Dye characterization of archaeological samples using SERS and FORS .......................................................... 50 6.4.1. Extractionless on-the-fiber SERS .............................................................................................................. 50 6.4.2. On-the-fiber SERS with formic acid micro-extraction ................................................................................ 51 6.4.3. Liquid micro-extraction with HCl in MeOH and H O .................................................................................. 54 2 6.4.4. FORS analysis of archaeological samples ................................................................................................ 56 6.4.5. Summary of findings .................................................................................................................................. 57 Chapter 7 Conclusions ................................................................................................................................................. 59 7.1 SERS performance ............................................................................................................................................ 59 7.2 Future research ................................................................................................................................................. 60 iv References ................................................................................................................................................................... 61 Table of figures and tables Figures Figure 1. TOP ROW (Images and information courtesy of Rommel Ángeles Falcón) A (sample VM01): camelid warp and weft bag, eccentric tapestry technique, mountain style; B(sample T- 130A): cotton warp and camelid weft band, eccentric tapestry technique, Wari style; C (sample VM04): undyed cotton and dyed camelid polychrome band, double weave technique; D (sample 061.02.01): camelid, tapestry technique, Wari/Malena style. BOTTOM ROW (information courtesy of Rommel Ángeles Falcón): E (sample T-69): cotton warp camelid weft cloth, slotted tapestry technique, Malena style; F (sample 77.10.02):, cotton and camelid corner of cloth, brocade technique, Malena style; G (sample 119.000.029): camelid warp and weft uncu fragment, eccentric tapestry technique, Wari style. ...................................................................24 Figure 2. Secondary electron micrographs of AgNPs. Two different batches of AgNPs (right micrograph: Yuan Lin 2015) displaying round faceted particles along with rods (left image) and some wires (right image). ..........................................................................................................30 Figure 3. Raman spectra of centrifuged batch 1 AgNPs analyzed within the first few days after synthesis (A) compared to the same expired batch analyzed three months later (B). Both spectra were acquired using a 785nm laser at 0.25% laser strength for 10 seconds and 1 acquisition after using KNO to aggregate AgNPs. Raman spectra of centrifuged batch 2 AgNPs 3 analyzed within the first few days after synthesis (C) compared to the same batch analyzed one month later (D). Both spectra were acquired using 633nm laser at 0.25% laser strength for 10 seconds and 1 after using KNO to aggregate AgNPs. The large peaks at 1050 cm-1 are due to 3 the KNO added to the AgNPs. .................................................................................................30 3 v Figure 4. VM 01 photomicrographs: yarn samples images with digital microscope (A-B), cuticular scale pattern imaged with SEM (C), and interrupted medulla imaged with transmitted light (D). ....................................................................................................................................32 Figure 5. T-130A photomicrographs: yarn samples images with digital microscope (A-B), cuticular scale pattern imaged with SEM (C), and interrupted medulla imaged with transmitted light (D). ....................................................................................................................................33 Figure 6. VM 04 photomicrographs: yarn samples images with digital microscope (A-B), cuticular scale pattern imaged with SEM (C), and interrupted medulla imaged with transmitted light (D). ....................................................................................................................................33 Figure 7. 061.02.01 photomicrographs: yarn samples images with digital microscope (A-B), cuticular scale pattern imaged with SEM (C), and interrupted medulla imaged with transmitted light (D). ....................................................................................................................................33 Figure 8. T-69 photomicrographs: yarn samples images with digital microscope (A-B) and uninterrupted medulla imaged with transmitted light (C). ...........................................................34 Figure 9. 77.10.02 photomicrographs: yarn samples images with digital microscope (A-B) and interrupted medulla imaged with transmitted light (C). ...............................................................34 Figure 10. 119.000.02 images: digital microscope (top) and transmitted light image of interrupted medulla (bottom). ....................................................................................................35 Figure 11. Secondary electron micrographs of archaeological samples covered in burial contaminants both before rinsing in ethanol (A-B) and after ringing (C-D) of VM03 (A), T-130A (B), VM01 (C) and VM04 (D). ....................................................................................................36 Figure 12. SEM images of VM01 (A) T-130A (B) and VM04 (C) showing cracking and breaking in the brittle fibers. .....................................................................................................................37 vi