Please cite this article in press as: J. Mazurek, et al., Investigation of cellulose nitrate and cellulose acetate plastics in museum collections using ion chromatography and size exclusion chromatography, Journal of Cultural Heritage (2018), https://doi.org/10.1016/j.culher.2018.05.011 ARTICLE IN PRESS G Model CULHER-3428; No. of Pages 8 Journal of Cultural Heritage xxx (2018) xxx–xxx Available online at ScienceDirect www.sciencedirect.com Modern and contemporary art Investigation of cellulose nitrate and cellulose acetate plastics in museum collections using ion chromatography and size exclusion chromatography Joy Mazurek ∗ , Anna Laganà , Vincent Dion , Suzanna Etyemez , Carolyn Carta , Michael R. Schilling The Getty Conservation Institute, 1200, Getty Center Drive Suite 700, 90049 Los Angeles CA, United States a r t i c l e i n f o Article history: Received 6 February 2018 Accepted 17 May 2018 Available online xxx Keywords: Cellulose acetate Cellulose nitrate cellulose esters Ion Chromatography Size Exclusion Chromatography Gas Chromatography/Mass Spectrometry a b s t r a c t One of the goals of the Preservation of Plastics Project at the Getty Conservation Institute is to inves- tigate preventative and conservation strategies for objects made of cellulose ester plastics. To achieve this goal, several analytical protocols were developed and applied to cellulose ester sculptures, design art objects and reference materials. Ion chromatography, size exclusion chromatography, and gas chro- matography/mass spectrometry were employed to measure nitric and acetic acids, molecular weight and plasticizer content. The degree of substitution and degree of polymerization for cellulose ester plastics were determined and compared to condition surveys. Cellulose nitrate sculptures by Naum Gabo and Antoine Pevsner, combs from the Harald Szeemann archival collection of the Getty Research Institute, and cellulose acetate sculptures by László Moholy-Nagy and Marcel Duchamp were included in this study. © 2018 Elsevier Masson SAS. All rights reserved. 1. Introduction The Preservation of Plastics Project at the Getty Conservation Institute (GCI) is a long-term project dedicated to advance the con- servation of plastics by studying the ageing and deterioration of these materials and investigating conservation strategies to pre- serve them [1–3]. One of the components of the project focuses on preserving and conserving objects made of cellulose esters plas- tics, such as cellulose nitrate (CN) and cellulose acetate (CA), in museum collections. Thanks to their properties such as versatil- ity and transparency, these materials have been used to produce a large variety of artifacts as well as being the first plastics utilized by artists. Among the best-known artists are the constructivists Naum Gabo, Antoine Pevsner, and László Moholy-Nagy, which used cellulose ester plastics to create sculptures currently considered icons of the 20th century. Eventually, these materials were found to be unstable, so that many of the artists observed deterioration of their objects during their lifetimes [4]. Cellulose ester plastics are prone to off gassing of acids, which results in the so-called vinegar syndrome (in CA objects), loss of plasticizers, warping, craz- ing, cracking, and brittleness. Preservation of these fragile materials usually involves cold storage, and removal from public view [5]. ∗ Corresponding author. E-mail address: Jmazurek@getty.edu (J. Mazurek). Early studies showed that CA plastics warp, buckle, and become dull due to the catastrophic effects of plasticizer loss and that hydrolysis of the polymer is affected by ultraviolet light, plasticizers and other additives [6,7]. Loss of plasticizers leads to an embrittle- ment of the material that impacts its physical properties, due to lack of compatibility as the plasticizer migrates out of the plas- tic [8]. Studies on plasticizers are conflicting, one study reported that triphenyl phosphate influenced the degradation of “Lumarith” coupons, whereas plasticizers containing aromatic rings, such as phthalates and triphenyl/tricresyl phosphates, were reported to have a stabilizing effect on Moholy-Nagy’s artwork [9,10]. In order to comprehensively study the degradation of cellulose ester plastics at the GCI, methods developed that could quan- tify nitrate, nitrite, acetate, plasticizers, and molecular weights. The degree of substitution (DS) is quantified by measuring the bound acid in the cellulose ester. Cellulose is a linear polymer composed of ß-(1→4)-glucose, and it has up to three reactive hydroxyl (-OH) sites per glucose molecule. DS is the average number of hydroxyl (-OH) sites on cellulose that is bound to an acid group or is esterified. For example, a DS of 3 indicates that, on average, all three hydroxyls sites are occupied per glucose, whereas a DS of 2 indicates two hydroxyls are occupied, and an average of 1 1/2 sites are occupied when DS is 1.5 [11]. Com- mercial CA with DS of 2.9 to 3.0 is sold as triacetate, whereas CA with DS of 2.2 to 2.7 is sold as cellulose diacetate [12]. DS values are directly related to properties of the polymer; when DS < 0.9, CA can be water soluble, while CN is highly explosive https://doi.org/10.1016/j.culher.2018.05.011 1296-2074/© 2018 Elsevier Masson SAS. All rights reserved.