J. Sep. Sci. 2003, 26, 996–1004

Irmina Zadrozna1

Kasia Połec-Pawlak2

Iwona Głuch2

Mohamed A. Ackacha3

Mirosław Mojski2

Janina Witowska-Jarosz4

Maciej Jarosz2

1Warsaw University ofTechnology, Division of OrganicChemistry, Noakowskiego 3,00-664 Warszawa, Poland

2Warsaw University ofTechnology, Department ofAnalytical Chemistry,Noakowskiego 3,00-664 Warszawa, Poland

3Sebha University, Faculty ofScience, Department ofChemistry, P.O. Box,18758 Sebha, Libya

4National Institute of PublicHealth, Mass SpectrometryLaboratory, Chełmska 30/34,00-725 Warszawa, Poland

Old master paintings – A fruitful field of activity foranalysts: Targets, methods, outlook

Natural products used by ancient artists as components of paintings on canvas andwood, on sculptures, for murals or illuminated manuscripts are presented as potentialanalytical targets. Analytical methods recommended so far for the identification of bin-ders, inorganic pigments, and organic dyestuffs are reviewed with special emphasison hyphenated techniques.

Key Words: Painting layers; Natural products; Binders; Inorganic pigments; Organic dyestuffs;Hyphenated techniques;

Received: October 16, 2002; revised: January 31, 2003; accepted: March 9, 2003

DOI 10.1002/jssc.200301483

1 Introduction

What awaits anyone trying to enter the world of the OldMasters – a world rarely visited professionally by the typi-cal analyst, a world full of unsolved problems and unan-swered questions? An answer can be formulated in thewords of Pietro Edwards concerning the nature of paint-ings. At the end of the eighteen century he pronouncedthat natural substances (of paintings) consist of heteroge-neous elements artificially held together contrary to theirnatural affinities [1]. This statement perfectly pr�cised thefar-reaching problems created by the palettes used byancient artists in creating their masterpieces.

Why is it so important to enter this world? Because withouta knowledge of the composition (chemical) of the object athand it is impossible to choose the appropriate method forits restoration – each important work of art should have itsindividual chemical and technical dossier and needs anindividually designed analytical procedure [2–5]. Only aknowledge of the materials [6–8] involved in a paintingallows a better understanding of the civilization in which itwas created and development of more efficient conserva-tion and restoration methods [9].

What is a painting layer? Somebody once said that paint-ings are made only from mud and a stick with hairs [10]. Ifthis can be accepted, the analytical target will be the mudfound on masterpieces painted on an easel or on muralmasterpieces, illuminated manuscripts, or polychromedsculptures. Defined as such, a painting is a complexmatrix, whose chemical composition changes continu-ously in the course of time, depending on several factors:specific interactions between pigment and binder; conser-vation conditions such as changes in temperature andhumidity; exposure to air pollutants; and prolonged expo-sure to natural or artificial light [11].

And what can we ultimately find in the examined mud?Since man learned to paint, artists have used a variety ofnatural substances in their efforts to create original paint-ings and achieve unique effects. Regardless of the timeand place of the origin of a painting, it usually contains nat-ural inorganic or organic materials belonging to few funda-mental classes: binders, varnishes and lining adhesives,inorganic pigments, and organic dyestuffs.

2 Natural binding mediaBinders (binding media) are, in general, fairly complexnatural products used to cover and provide cohesion inthe pigments (dyes) and protect them from deteriorationdue to passage of time and ambient conditions. Choice ofthe type of the binding medium used depended on many

Correspondence: Maciej Jarosz, Warsaw University of Tech-nology, Faculty of Chemistry, Department of Analytical Chemis-try, Noakowskiego 3, 00-664 Warszawa, Poland.Phone: +48 22 6607408. Fax: +48 22 6607408.E-mail: mj@ch.pw.edu.pl.

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i 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1615-9306/2003/1107–0996$17.50+.50/0

J. Sep. Sci. 2003, 26, 996–1004 Old master paintings 997

different factors, e.g. the location and period of the workas well as on the nature of the pigments. Natural bindingmedia [12] are classified according to their major compo-nents, and four main groups can be distinguished: poly-saccharide materials (gums), proteinaceous media, oilsand waxes, and resins.

Gums [6, 8, 12–18] form a group of non-crystalline poly-saccharide materials that can be found in vegetable mat-ter and are often exuded when a plant is damaged. Theirbinding properties are based mainly on the formation ofhydrogen bonds. They are water-soluble or water-disper-sible compounds of complex composition, usually consist-ing of a number of sugars plus their uronic acid derivatives(e.g. arabinose, fucose, galactose, galacturonic acid, glu-cose, glucoronic acid, mannose, rhamnose, xylose [8]).The plant gums: Arabic, tragacanth, and cherry havebeen used for many centuries as the principal media forwatercolors, miniatures, and manuscript illuminationsand, on occasion, as sizing materials. Honey, cane sugarsolution, and glycerin have long been used as additives inaqueous media, preventing the extreme drying thatresults in the brittleness of these particular media. Today,dextrin is more commonly used for this purpose. Karayagum, the dried exudates of the native Indian tree Sterculiaurens, has been used as a cheaper substitute for gum tra-gacanth; its alternative names include Indian tragacanth,Indian gum, and Sterculia gum. Apart those mentionedabove, also ghatti, guar, locust, plums and peach gumswere used.

Proteins [6, 12, 13, 15–35], biopolymers of amino acids(about twenty natural amino acids are commonly found inprotein hydrolysates; the most important for the identifica-tion of parent natural product are: alanine, arginine, aspar-tic acid, cysteine, glutamic acid, glycine, histidine,hydroxyproline, isoleucine, leucine, lysine, methionine,phenylalanine, proline, serine, threonine, tyrosine, valine[35]), are an important class of natural organic materialsthat have long been used as binding media and adhe-sives. Of the many proteins found in nature, thoseencountered most frequently in conservation include col-lagen glue (obtained by boiling animal skin and bones),gelatine, fish glue, size (a more purified form of glue),casein (present in milk), egg white albumin (glair), andegg yolk (tempera). This class of binders is of specialimportance, because the racemisation of amino acids canbe a basis for the age determination in archaeometry [36].

Oils [11–13, 15–17, 32, 37–40] are glycerol esters ofpredominantly C18 unsaturated aliphatic acids (e.g. lino-lenic, linoleic, myristic, oleic, palmitic, stearic acids [12,37]). Oils are liquids, fats are rather semi-solids or solids,waxes are solids which melt at elevated temperature. Ifunsaturated acid structures are present in oils, they candry thanks to polymerization process. The most frequently

used oils were: linseed oil (made from the seeds of flax),poppy-seed oil, walnut oil, sunflower oil. Waxes [41–44]consist of complex mixtures of esters of fatty acids withmonohydroxy high molecular mass alcohols, free fattyacids, high molecular mass alcohols and hydrocarbons.Natural waxes are of animal (beeswax), vegetable (car-nuba wax), or mineral (montan wax) origin.

Resins [12, 13, 16, 17, 45–52] form a heterogeneousgroup of natural products composed mainly of alcohols,carboxylic acids, ketones, polycyclic hydrocarbons, andaromatic compounds (often of terpenoid origins, mainlydi- or triterpenoid). Shellac is the only animal resin thathas been used for painting purposes. It is excreted by thelac insect Coccus lacca; its drops were scratched from thetrees, washed, and purified by sieving. Resins of vegeta-ble origins are: dammar (tapped from trees of Dipterocar-paceae family) [45–47, 49–51], colophony (from differentpine trees) [53], sandarac (exuded from Callitris quadriva-lis conifers), copal (hard resin from different trees – “animmature amber resin”), elemi (from different species ofthe Bursacae family), turpentine – Venice (from Eur-opean larch) [53] and Strasbourg (from the conifer Abiesexcelsa), amber (fossil resin from pine trees), mastic(from Mediterranean shrub Pistacia lentiscus) [49, 51],Dragon’s blood (excreted by different plants growing inthe East Indies), gamboge (from East Asian tree Garniciamorella).

For the identification of binders, varnishes, and liningsmany analytical instrumental techniques were used.Among them the most important seems to be gas chroma-tography (mainly with MS detection) for analysis of gum[6, 8, 54], proteinaceous [6, 21–26, 29, 31, 32, 34, 35,40], oil [11, 25, 29, 32, 37, 39, 51], wax [41–44], and resin[50–53] species. Prior to gas chromatographic separationnatural products should be hydrolyzed [55, 56] and theresulting simple components (sugars from gums, aminoacids from proteins, fatty acids from oils) derivatized. Theother approach for preparation of the products of interestfor gas chromatographic analysis is pyrolysis [16, 57, 58](with or without simultaneous derivatization). The mostoften exploited volatile derivatives (obtained after wethydrolysis) are: trimethylsilyl (sugars [6, 8, 54], oils [59]),N-tert-butyldimethylsilyl (amino acids [22, 29], oils [11],resinous varnishes [51]), silyl or silylamine silyl esters(amino acids [6]), alkoxycarbonyl amino acid alkyl esters(amino acids [6, 21, 24, 25, 35]), alkyl esters (oils [23, 25,37]) or N-trifluoroacetyl-O-propyl esters (amino acids[23]). Derivatizing agents are: chlorotrimethylsilane andhexamethyldisilazane – HMDS (yield silyl amino acidsester and trimethylsilyl sugar derivatives – the latter inpyridine medium in the presence of trifluoroacetic acid),N-trimethylsilyldiethylamine (TMSDEA), N,O-bis(tri-methylsilyl)acetamide (BSA) (produce silylamine silylesters), N-methyl-N-tert-butyldimethylsilyl-trifluoroacet-

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998 Zadrozna et al. J. Sep. Sci. 2003, 26, 996–1004

amide (MTBSTFA), and N,O-bis-trimethylsilyl-trifluoro-acetamide (BSTFA) (form alkylsilyl esters), and alkylchloroformates (form alkyl esters or alkoxycarbonyl aminoacid alkyl esters or simple esters of fatty acids).

The alternative approach to the acid hydrolysis and thederivatization prior to the GC-MS analysis is thermal pyrol-ysis. It can be performed as a simple thermal degradationprocess (Py) [15, 16, 60] or thermally assisted hydrolysismethylation (THM) mainly with tetramethylammoniumhydroxide (proteinaceous media [61], oils [39], waxes [43,44], resinous warnishes [52, 53]), or silylation [62]. Theusefulness of this technique in art and archaeologicalanalysis was formerly questioned [23, 63] because of thecompositional complexity and very small sample size ofanalyzed materials, lack of “reference materials” (e.g.aged films of binding agents from different sources), andinsufficient chromatographic separation of degradationproducts. This technique has recently [16] gained in popu-larity.

For characterization of gum binders, thin-layer chromato-graphy [14] and ion chromatography were proposed – ICafter hydrolysis of the materials with trifluoroacetic acid[18]. High performance liquid chromatography with fluor-escence detection was successfully applied to the separa-tion of amino acids derivatized with 9-fluorenylmethylchloroformate [64], and with mass spectrometric detection(FAB, ESI, and MALDI) – for identification of small sugarsand medium-size carbohydrates derivatized by means of1-phenyl-3-methyl-5-pyrazolone [65]. Coupling of HPLCwith atmospheric pressure chemical ionization (tandem)mass spectrometry allowed identification of componentsof both fresh and aged varnishes [49]. Capillary electro-phoresis was recommended for separation of simplemonosaccharides liberated from glycoproteins or oligo-saccharides by high temperature acidic hydrolysis [66]and capillary electrochromatography – for amino acidderivatives [67]. Differences in drift time of common aminoacids determined by electrospray mass spectrometry (ESIMS) allowed development of a new method for theirseparation by ion mobility spectrometry [68].

Among spectroscopic techniques used for the identifica-tion of natural products one of the most promising seemsto be mass spectrometry, especially with atmosphericpressure chemical ionization (APCI) or electrospray ioni-zation (ESI). The first was used for characterization ofvarnishes [49] and beeswax [38]; the second one –among other applications – for analysis of oligosacchar-ides after derivatization with malononitrile [69], or aminoacids as formamidene butyl esters [70], as well as for iden-tification of hydroxyproline glycans [71]. It also allowed thedifferentiation of leucine/isoleucine [72, 73] and lysine/glutamine [74]. Matrix-assisted laser desorption/ionizationFourier transform mass spectrometry (MALDI-FTMS) has

been used for the investigation of oxidative changes inegg tempera paint strips [75].

Other spectroscopic techniques used for such studiesinclude: micro-Raman method [9, 12], Fourier transformRaman spectroscopy [76], and photoluminescence spec-troscopy (all types of binders [13]), as well as Fouriertransform-infrared spectroscopy (proteins, oils, resins [17,32]; oils and resins [77]). FT-Raman investigations aresupported by spectral libraries [78, 79].

Characterization of the natural binders in painting layers,despite many analytical methods available so far, remainsextremely difficult, mainly because of degradation pro-cesses induced by natural ageing and pollution, as well asinterferences from other components present in theobject, e.g. pigments. To date only a few papers discussthis very important problem [11, 15, 28, 49, 75].

3 Coloring mattersThe most important components of paints, whatever thefinal appearance of the work of art, are natural inorganicpigments and organic dyestuffs. These colored materialsare the basis of all paints, and have been used for millen-nia. Early pigments were simply ground earth or clay, andwere made into paint with spittle or fat. Modern pigmentsare often sophisticated masterpieces of chemical engi-neering. However, for art conservators and analyticalchemists working to the same end, traditional, naturalproducts are more interesting.

3.1 Inorganic pigments

Inorganic pigments, widely used in traditional color pal-ettes, do not seem to hold much fascination for analystsworking with hyphenated techniques. Identification ofcomponents of very complex species consisting of inor-ganic salts, soils, clays, often mixed with organic dye-stuffs, depends rather on spectroscopic techniques. Thereason becomes clear on considering the analytical tar-gets. They can be classified according to origin, composi-tion, color, and many other properties. The most usefulsystem seems to be based on the color of the species[78–81]. Among black pigments [32, 82, 83] the most pop-ular were carbon containing ones, e.g. ivory black, lampblack (charcoal or carbon black), and vine black; alsoblack iron oxide was used. The group of white pigments[32, 82–84] consists of: barium white (barium sulfateBaSO4), bone white (calcium phosphate Ca3(PO4)2), chalk– calcite (calcium carbonate CaCO3), gypsum (calciumsulfate dihydrate CaSO4 N 2H2O), lithopone (zinc sulfideand barium sulfate ZnS and BaSO4), lead white (basic lea-d(II) carbonate 2PbCO3 N Pb(OH)2), titanium white (tita-nium oxide TiO2), white clay (kaolin, China clay), zincwhite (zinc oxide ZnO). Blue pigments [17, 32, 82–88]:azurite – azure blue (basic copper(II) carbonate

J. Sep. Sci. 2003, 26, 996–1004 Old master paintings 999

2CuCO3 N Cu(OH)2), cerulean blue (cobalt(II) stannateCoO N nSnO2), cobalt blue (cobalt(II)-doped alumina glassCoO N Al2O3), Egyptian Blue (calcium copper(II) silicateCaCuSi4O10), lazurite – ultramarine blue (S3

– and S2– in a

sodium alumino-silicate matrix Na6[Al6Si6O24]Sn – lapislazuli), posnjakite (basic copper(II) sulfate CuSO4 N 3-Cu(OH)2 N H2O), Prussian blue (iron(III) hexacyanoferr-ate(II) Fe4[Fe(CN)6]3 N (14–16)H2O), smalt (cobalt(II) sili-cate CoO N nSiO2). Among blue pigments one of the mostfamous is Maya blue [89], composed of palygorskite clayand indigo (organic dyestuff). It was used by the ancientMaya and despite exposure to weather phenomena andchemical environmental contaminants retains its colorunaltered up to now. Green pigments [32, 82–84, 87, 90]:atacamite (basic copper(II) chloride CuCl2 N 3Cu(OH)2),chromium oxide (chromium(III) oxide, Cr2O3), cobaltgreen (cobalt(II) zincate CoO N nZnO), emerald green(copper(II) ethanoate tri-copper(II) arsenite Cu[C2H3O2] N3Cu[AsO2]2), malachite – mountain green (basic cop-per(II) carbonate CuCO3.Cu(OH)2), Scheele’s green (cop-per(II) arsenite Cu(AsO2)2), green earth – terreverte (var-iations on K[(AlIII,FeIII)(FeII, MgII)], (AlSi3, Si4)O10(OH)2),verdigris “raw” (copper(II) ethanoate Cu(CH3COO)2), viri-dian (chromium(III) oxide Cr2O3 N 2H2O). To the yellowand orange pigments [32, 82, 84, 91] belong: barium yel-low (barium chromate BaCrO4), cadmium yellow (cad-mium sulfide CdS), chrome yellow (lead(II) chromatePbCrO4), cobalt yellow (potassium cobalt nitrite K3[Co-(NO2)6] N xH2O), lead tin yellow (lead(II) stannatePb2SnO4), Mars yellow, Mars orange (synthetic iron(III)hydroxide Fe(OH)3), massicot (orthorhombic lead(II)oxide PbO), Naples yellow (lead(II) antimonatePb2Sb2O7), orpiment – King’s yellow (arsenic(III) sulfideAs2S3), pararealgar (arsenic(II) sulfide As4S4), strontiumyellow (strontium chromate SrCrO4), yellow ochre(goethite (Fe2O3 N H2O) + clay + silica), zinc yellow (zincchromate ZnCrO4). Finally, very important red pigments[32, 82–84, 90, 92, 93] are: cadmium red (cadmium sele-nide and sulfide), chrome red (basic lead chromate),litharge (tetragonal lead(II) oxide PbO), the group of rediron oxides: Mars red – (synthetic iron(III) oxide Fe2O3),English red, Venetian red, Indian red, and the mysteriouscaput mortuum [94], whose composition is still underinvestigation, realgar (arsenic sulfide As4S4), red earths –red ochre (iron(III) oxide chromophore [Fe2O3 + clay +silica]), red lead (dilead(II) lead(IV) oxide Pb3O4), vermi-lion – cinnabar (mercury(II) sulfide HgS).

The list of inorganic species used in paintings is incom-plete without metallic powders. They are of special impor-tance in manuscripts and miniature paintings. Gold wasused as a foil and paint [82] prepared by pounding metalleaf with glue, washing the obtained paste with water andmixing the dried precipitate with an appropriate glue andsaffron. Gold could be mixed with copper (to obtain a war-

mer color) or with silver (to cool its color). Silver used inancient paintings now appears black because it is tarn-ished.

The discussed inorganic species were identified in wall [9,40, 83, 89–92, 94], paper [9, 82, 85, 87, 93, 95], canvas[32, 84, 88, 96, 97], and sculpture [84, 98, 99] paintings,as well as in ceramic glazes [100–102], jewelry products[103], laboratory prepared painting layers [17], and simu-lated archaeological copper alloys [104]. As was men-tioned above, the identification is performed mainly by useof spectral methods, which allow non-destructive analysisof very small spots from the object. Among them, the mostwidely used are Fourier transform infrared (FT IR) trans-mission or (more often) reflectance [17, 32, 83, 84, 90, 94,99, 105] and Raman spectroscopy/microscopy [9, 78, 79,85, 91–98]. However, when Raman spectroscopy isused, special attention should be paid to potential laser-induced degradation of pigments (especially lead-contain-ing ones) [93]. All kinds of optical (using radiation from thevery wide spectrum) microscopy were also applied – frombinocular [82] through polarized light [82, 84] and trans-mitted polarized light [87] to scanning electron (SEM) withenergy-dispersive X-ray detectors (EDX) [32, 40, 84, 88,90, 94, 101] and high-resolution transmission electron[89] techniques. E-SEM – environmental scanning elec-tron microscope [105] was especially designed to operateat near atmospheric pressures without conductive coat-ings of the samples. Microanalysis with use of the X-rayradiation were recommended and performed in variousmodes: as energy dispersive X-ray fluorescence analysis[82, 83], X-ray absorption spectroscopy [89], X-ray diffrac-tion [82–84, 91, 94], or even proton-induced X-ray emis-sion spectroscopy (PIXE) [85, 96]. Also electrochemicalmethods: scan and cyclic voltammetry [90, 106] and clas-sical stripping voltammetry with electrodes with microsamples of examined ceramic glazes immobilized on theirsurfaces [102].

3.2 Organic dyestuffs

Knowledge concerning organic dyestuffs [107] and meth-ods suitable for their separation and identification in artobjects is very limited to date. At all times and locations,the quality and colors of the fabrics indicated the socialstatus of their owners. The more brilliant, vivid and strikingthe colors of the dyes, the more expensive, exclusive, andprecious they were. Fabrics in dyes reproducing colors ofthe most precious gemstones were diplomatic gifts, a signof leadership and imperial power. The history of fabricdyeing abounds in regulations concerning the production,trade, and use of dyes, often protected by secret informa-tion. Artists in particular regions and times (e.g. in Meso-america over a thousand years ago [89], pre-ColumbianPeru during the Inca period, 300–1532 AD [108], duringthe colonial period in the Peruvian Andes [88], in New

1000 Zadrozna et al. J. Sep. Sci. 2003, 26, 996–1004

Spain – Mexico [87], or in Cuba [109], as well as in medi-eval Persia [82] and India [110]) used various dyes, whichare now very difficult to identify. And ultimately, dyes pop-ular in specific regions were often replaced by others,when new routes, especially to India or America wereopened, e.g. for this reason Indian indigo displaced woad(European source of indigo) and American cochineal sup-planted European kermes.

Organic dyes are traditionally divided into several groupsof different color, e.g.: blue, violet and red, yellow, orangeand brown. Among the blue pigments of organic origin themost important is indigo [82, 86–88, 108, 111], one of themost ancient blue dyes used by man. The dyeing species,indigo(tin) is present in the leaves of a number of Indigo-fera species, of which the Asian Indigofera tinctoria is themost important for commercial production. As was men-tioned above, it almost completely replaced indigo-(tin)obtained from European woad (Isatis tinctoria). The otherreported blue dyes are of local importance, e.g. texotli ormatlali [87], and even their active components are veryoften unknown.

Active color components of violet and red dyes are mostlyanthraquinone derivatives. These pigments are extractedfrom animals or vegetables. The most famous ancient Tyr-ian purple [82, 87] – violet pigment – was made from thefluid secreted from specific mollusks. The other animal reddyes of great importance are: cochineal [82, 87, 107, 108,111–113] (in which the active substance is carminic acid)prepared from dried pregnant females of Coccus cacti,kermes [82, 107, 108, 112] (dyeing component is ker-mesic acid) extracted from dried females of other insectsfrom the same family (Coccus ilicit) and Lac-dye [82, 107,112, 113] (colored thanks to the presence of laccaic acidsin its composition) – resinous excretions of Coccus lacca.

Lichens [114], shrubs, or trees (their heartwood, wood,roots, seeds, or florets) are source of other red dyes usedso far mostly in paintings (but also as natural coloringagents of food products [42]): logwood [86, 87, 112]obtained from the heartwood of the Mexican tree Haema-toxylum brasiletto, archil [107, 112] (coloring constituent:orcein) from different lichens of the Rocella family, alkanet[107, 115] (alkannin, anchusin) from roots of species thatbelong to the genuses Lithospermum, Echium, Onosma,Anchusa, Arnebia, Macrotomia, and Cynoglossum of thefamily Boraginaceae, madder [82, 107, 108, 111, 112,116–119] (alizarin, purpurin, and their derivatives) fromroots of Rubia tinctoria, safflower [107, 112] (activecarthamin and useless safflor yellows) from dried florets ofCathamus tinctorius, brazilwood [107, 112, 120] (brazi-lein) from the wood of Caesalpinia curcas, Caesalpiniaechinata, Caesalpinia sappan, Haematoxylum brasiletto,and Haematoxylum campechianum and the family of “redwoods” [107, 112]: Sandalwood (santalin), Barwood,

Caliaturwood, Camwood, and Narrawood. As examplesof more exotic red dyes Cuetlaxocitl (from poinsettiaplants) and Cuauhy-ohuachtli (from seeds of the shrubJatropha cucrcas) can be mentioned [87].

The yellow color of pigments from the next group is veryoften due to the presence of different flavones in parentplant material: weld [107, 108, 112] (color components:luteolin, apigenin; obtained from leaves and stem ofReseda luteola), Persian berries [107, 108] (rhamnetin,rhamnazin, and quercetin; dried unripe berries of variousshrubs of the buckthorn family), old fustic [107, 108](morin and maclurin; wood of Chlorophora tinctoria Gard),young fustic [107, 108] (fisetin; heartwood of Rhus coti-nus), quercitron [107, 108] (quercitrin and quercetin; innerbark of Quercus tinctoria), dyer’s broom [107] (genistein;extract from leaves and branches of Genista tinctoria).

Tannins [107, 108, 112, 121–123] (active components:gallic acid and ellagic acid, but also grandinin/roburin E,castalagin/vescalagin, valoneic acid bilactone, mono-, di-and trigalloyl glucose, ellagic acid rhamnose, quercitrinand others) present in plant or animal dyeing agents areresponsible for their different brown shadows. Tannic pig-ments are obtained from many sources; in many countriesthere are various plants, which contain a high percentageof tannin. For instance sumach can be extracted both fromleaves and fruits (Rhus coriania bushes) and heart wood(Rhus cotina). Galls are the morbid excretions resulting onpuncture by insects Cynips gallae-tinctoria living on theleaves of some oak trees.

Another subgroup form dyes containing derivatives ofphenol or naphthol as chemical components: turmeric[107, 108, 124–126] (active substances: curcumin,demethoxycurcumin, bisdemethoxycurcumin, ar-turmer-one, curlone, and others; obtained from undergroundstem or rhizome of Curcuma longa or various species ofCurcuma), cutch [107, 108] (catechin; isolated by steepingin water the leaves from various bushes and trees anddepending of its origin known as Gambir Catechu, BengalCutch, or Mangrove Cutch), black walnut [107, 108, 127](a-juglone; from leaves and shells of black walnut), mari-gold (palmitic and myriastic esters of lutein – obtainedalso from algae [128]; dried powdered golden flowers ofTagetes erecta herbs), henna [107, 108] (lawsone; pow-dered dried leaves of Lawsonia alba).

Polymethine long-chained dicarboxylic acids make skele-tons of yellow pigments present in saffron and annatto.Saffron [107, 129, 130] is the dried stigmas of crocus (Cro-cus sativus) flowers. Its major active components are fourcrocin species, crocetin, picrocrocin, and their metabo-lites. The same substance can be obtained from fruits ofthe Cape jasmine shrub (Gardenia jasminoides Ellis).However, the extracts are not used interchangeably in allapplications since saffron is valued both for its coloring

J. Sep. Sci. 2003, 26, 996–1004 Old master paintings 1001

properties and as an aroma and flavor (it is also used ascolorant for food) and, moreover, it is the world’s mostexpensive pigment. Annatto [87, 107, 108], the orange-red dye, is not so popular because its light-fastness is notvery good. Its active component is bixin and it is derivedfrom fruits of the Brazilian shrub Bixa orellana. Amongorganic dyes also asphalt [131] should be mentioned. Ithas been used by painters since the 17th century, but isextremely rare as a pigment material with a known pre-19th century provenance.

The pigment of animal origin, Indian yellow [82] (magne-sium salt of euxanthic acid, MgC19H16O11 N 5H2O), is apathological component of urine of cows fed with mangoleaves.

Various conventional methods have been proposed forthe identification of organic dyestuffs: e.g. acid digestionof threads, extraction of the resulting solution with methyl-ene chloride, and colorimetric investigation of both phases[86, 88], or boiling samples of textile with aqueous solu-tions of tin, aluminum, iron, copper or uranium in order toobtain series of mordant lakes of different shades andcompare them with known dyes [112]. The former proce-dures [86, 88] were recommended for blue pigments, thelatter one for a wide range of products. Optical and spec-troscopic techniques have been used for dye characteri-zation: traditional microscopy [82, 119], transmitted polar-ized light microscopy [87], scanning electron microscopy[119], fibre optics reflectance spectroscopy [95, 132],image spectroscopy mapping [133], UV-Vis spectropho-tometry and spectrofluorometry [134, 135], nuclear mag-netic resonance [136], Fourier-transform infrared [99,119, 137] and Raman spectroscopy [95, 120, 134], X-raypowder diffraction [119], total reflection X-ray fluores-cence [138] and mass spectrometry with electron ioniza-tion [126], laser desorption ionization [114, 139, 140], andmatrix-assisted laser desorption/ionization [115].Because of the complex composition of the paintinglayers, chromatographic techniques were also involved intheir analysis: pyrolysis gas chromatography-mass spec-trometry [131, 141–143] and thermally assisted hydroly-sis and methylation GC-MS [111], thin layer chromatogra-phy [144], as well as high performance liquid chromato-graphy with diode-array detection [108, 116, 117, 127,129, 130, 145–147] (high-speed counter-current chroma-tography [122, 128, 148] was used for dyes isolation andpurification) and thermospray [124] or electrospray [118,121, 123, 125] mass spectrometric detection.

4 ConclusionsAnalysis of objects of art, especially ancient paintings,constitutes a great challenge to the analyst. The sheervariety of natural products of unknown origin and compo-sition mixed together in the analytical samples makes

their identification extremely difficult. It creates the needto develop a unique procedure for almost every individualobject. Fortunately, very similar or even the same naturalproducts can be found in food and much valuable informa-tion is available from papers discussing this field of analy-sis [149–154]. The pronounced complexity of the exam-ined matrices and the very small amounts of sample avail-able force the analyst to look for extremely sensitive andselective analytical methods. Hyphenated techniques[155–159] (especially coupling of high performance liquidchromatography or, even better, capillary electrophoresis,with mass spectrometers with atmospheric pressure ioni-zation), very rarely used so far, could play a cruciallyimportant role.

AcknowledgmentsKasia Połec-Pawlak is grateful to the Foundation for Pol-ish Science for financial support. Mohamed Abduelrah-man Ackacha is grateful to the Ministry of Education ofLibyan Jamaheria for a PhD grant. This work was finan-cially supported by Polish State Committee for ScientificResearch within the grant no. 3 T09A 089 18.

References[1] C.K. Keck, J. Am. Inst. Art. Conserv. 1977, 17, 45–52.[2] J.S. Mills, R. White, The Organic Chemistry of Museum

Objects. Butterworths, London 1994.[3] A.M. Pollard, C. Heron, Archaeological Chemistry, RCS

Paperbacks, Royal Society of Chemistry, Cambridge 1996.[4] H. West FitzHugh, Artists’ Pigments. A Handbook of Their

History and Characteristics. Oxford University Press, 1997.[5] E. Ciliberto, G. Spoto, Modern Analytical Methods in Art and

Archaeology, Wiley-Interscience, New York 2000.[6] S.L. Vallance, Analyst 1997, 122, 75R–81R.[7] S.L. Vallance, B.W. Singer, S.M. Hitchen, LC-GC Intern.

1997, 10, 48–53.[8] S.L. Vallance, B.W. Singer, S.M. Hitchen, J.H. Townsend, J.

Am. Inst. Art. Conserv. 1998, 37, 294–311.[9] C. Coupry, Analusis 2000, 28, 39–46.

[10] Pigments Through the Ages, http://webexhibits.org/pig-ments/intro/paintings.html.

[11] M.P. Colombini, F. Modugno, R. Fuoco, A. Tognazzi, Micro-chem. J. 2002, 73, 175–185.

[12] P. Vandenabeele, B. Wehling, L. Moens, H. Edwards, M. DeReu, G. Van Hooydonk, Anal. Chim. Acta 2000, 407, 261–274.

[13] L.J. Larson, K.-S. Kim Shin, J.I. Zink, J. Am. Inst. Art. Con-serv. 1991, 30, 89–104.

[14] K.V. Kharbade, G.P. Joshi, Stud. Conserv. 1995, 40, 93–102.

[15] R. Stevanato, M. Rovea, M. Carbini, D. Favretto, P. Traldi,Rapid Commun. Mass Spectrom. 1997, 11, 286–294.

[16] P. Bocchini, P. Traldi, J. Mass Spectrom. 1998, 33, 1053–1062.

[17] M. Bacci, M. Fabbri, M. Picollo, S. Porcinai, Anal. Chim.Acta 2001, 446, 15–21.

[18] M.P. Colombini, A. Ceccarini, A. Carmignani, J. Chroma-togr. A 2002, 968, 79–88.

1002 Zadrozna et al. J. Sep. Sci. 2003, 26, 996–1004

[19] S.M. Halpine, Stud. Conserv. 1992, 37, 22–38.

[20] F. Ronca, Stud. Conserv. 1994, 39, 107–120.

[21] M.R. Schilling, H.P. Khanjian, L.A.C. Souza, J. Am. Inst. Art.Conserv. 1996, 35, 45–49.

[22] M. Carbini, R. Stevanato, M. Rovea, P. Traldi, D. Favreta,Rapid Commun. Mass Spectrom. 1996, 10, 1240–1242.

[23] A. Casoli, P. Musini, G. Palla, J. Chromatogr. A 1996, 731,237–246.

[24] M.R. Schilling, H.P. Khanjian, J. Am. Inst. Art. Conserv.1996, 35, 123–144.

[25] R. Mateo Castro, M.T. Dom�nech-Carb�,V. Peris Mart�nez,J.V. Gimeno Adelantado, F. Bosch-Reig, J. Chromatogr. A1997, 778, 373–381.

[26] M.P. Colombini, R. Fuoco, A. Giacomelli, B. Muscatello,Stud. Conserv. 1998, 43, 33–41.

[27] A. Casoli, G. Palla, J. Tavlaridis, Stud. Conserv. 1998, 43,150–158.

[28] M.P. Colombini, F. Modugno, A. Giacomelli, J. Chromatogr.A 1999, 846, 101–111.

[29] M.P. Colombini, F. Modugno, M. Giacomelli, S. Francesconi,J. Chromatogr. A 1999, 846, 113–124.

[30] M.A. Fadrigo, M. Favaro, P. Traldi, Rapid Commun. MassSpectrom. 2000, 14, 2203–2209.

[31] E. Manzano, A.G. Bueno, A. Gonzales-Casado, M. delOlmo, J. Cultur. Heritage 2000, 1, 19–28.

[32] M.T. Dom�nech-Carb�, M.J. Casas-Catal�n, A. Dom�nech-Carb�, R. Mateo-Castro, J.V. Gimeno-Adelantado, F.Bosch-Reig, Fresenius J. Anal. Chem. 2001, 369, 571–575.

[33] B. Ram�rez-Barat, S. de la Vi�a, Stud. Conserv. 2001, 46,282–288.

[34] L. Castellani, P. Ferrantelli, M. Sinibaldi, G. Vigliano, J. Cul-tur. Heritage 2001, 2, 209–215.

[35] J.V. Gimeno-Adelantado, R. Mateo-Castro, M.T. Dom�-nech-Carb�, F. Bosch-Reig, A. Dom�nech-Carb�, J. de laCruz-Ca�izares, M.J. Casas-Catal�n, Talanta 2002, 56,71–77.

[36] J. Csap�, Zs. Csap�-Kiss, J. Csap� Jr., Trends Anal. Chem.1998, 17, 140–148.

[37] J.V. Gimeno-Adelantado, R. Mateo-Castro, M.T. Dom�-nech-Carb�, F. Bosch-Reig, A. Dom�nech-Carb�, M.J.Casas-Catal�n, L. Osete-Cortina, J. Chromatogr. A 2001,922, 385–390.

[38] K. Kimpe, P.A. Jacobs, M. Waelkens, J. Chromatogr. A2002, 968, 151–160.

[39] F. Cappitelli, T. Learner, O. Chiantore, J. Anal. Appl. Pyroly-sis 2002, 63, 339–348.

[40] L. Rampazzi, F. Cariati, G. Tanda, M.P. Colombini, J. Cultur.Heritage 2002, 3, 237–240.

[41] A.G. Giumanini, G. Verardo, P. Strazzolini, H.R. Hepburn, J.Chromatogr. A 1995, 704, 224–227.

[42] R. Naß, C. Markst�dter, V. Hauke, M. Riederer, Phytochem.Anal. 1998, 9, 112–118.

[43] L. Wang, S. Ando, Y. Ischida, H. Ohtani, S. Tsuge, T.Nakayama, J. Anal. Appl. Pyrolysis 2001, 58–59, 525–537.

[44] A. Asperger, W. Engewald, G. Fabian, J. Anal. Appl. Pyroly-sis 2001, 61, 91–109.

[45] E.R. de la Rie, Stud. Conserv. 1988, 33, 53–70.

[46] E.R. de la Rie, Stud. Conserv. 1988, 33, 109–114.

[47] E.R. de la Rie, C.W. McGlinchey, Stud. Conserv. 1989, 34,137–146.

[48] C. Vieillescazes, J.L. Larice, S. Coen, Anal. Chim. Acta1995, 317, 65–73.

[49] G.A. van der Doelen, K.J. van der Berg, J.J. Boon, N. Shi-bayama, E.R. de la Rie, W.J.L. Genuit, J. Chromatogr. A1998, 809, 21–37.

[50] G.A. van der Doelen, K.J. van der Berg, J.J. Boon, Stud.Conserv. 1998, 43, 249–264.

[51] M.P. Colombini, F. Modugno, S. Giannarelli, R. Fuoco, M.Matetini, Microchem. J. 2000, 67, 385–396.

[52] K.J. van der Berg, J.J. Boon, I. Pastorova, L.F.M. Spetter, J.Mass Spectrom. 2000, 35, 512–533.

[53] D. Scalarone, M. Lazzari, O. Chiantore, J. Anal. Appl. Pyro-lysis 2002, 64, 345–361.

[54] J. Bleton, P. Mejanelle, J. Sansoulet, S. Gorsaud, A. Tcha-pla, J. Chromatogr. A 1996, 720, 27–49.

[55] M. Weiss, M. Manneberg, J.F. Juranville, H.W. Lahm, M.Fountoulakis, J. Chromatogr. A 1998, 795, 263–275.

[56] M. Fountoulakis, H.W. Lahm, J. Chromatogr. A 1998, 826,109–134.

[57] T.P. Wampler, J. Chromatogr. A 1999, 842, 207–220.

[58] J.M. Challinor, J. Anal. Appl. Pyrolysis 2001, 61, 3–34.

[59] J. Eras, F. Monta�es, J. Ferran, R. Canela, J. Chromatogr. A2001, 918, 227–232.

[60] J. Douda, V.A. Basiuk, J. Anal. Appl. Pyrolysis 2000, 56,113–121.

[61] X. Zang, J.C. Brown, J.D.H. van Heemst, A. Palumbo, P.G.Hatcher, J. Anal. Appl. Pyrolysis 2001, 61, 181–193.

[62] G. Chiavari, D. Fabbri, S. Prati, J. Chromatogr. A 2001, 922,235–241.

[63] A.M. Schedrinsky, T.P. Wampler, N. Indictor, N.S. Baer, J.Anal. Appl. Pyrolysis 1989, 15, 393–412.

[64] K. Ou, M.R. Wilkins, J.X. Yan, A.A. Gooley, Y. Fung, D.Sheumack, K.L. Williams, J. Chromatogr. A 1996, 723,219–225.

[65] X. Shen, H. Perreault, J. Chromatogr. A 1998, 811, 47–59.

[66] A. Guttman, J. Chromatogr. A 1997, 763, 271–277.

[67] Q.-H. Ru, J. Yao, G.-A. Luo, Y.-X. Zhang, C. Yan, J. Chrom-togr. A 2000, 894, 337–343.

[68] G. Reid Asbury, H.H. Hill Jr., J. Chromatogr. A 2000, 902,433–437.

[69] Y.H. Ahn, J.S. Yoo, Rapid Commun. Mass. Spectrom. 1998,12, 2011–2015.

[70] D.W. Johnson, Rapid Commun. Mass. Spectrom. 2001, 15,2198–2205.

[71] S. Kilz, S. Waffenschmidt, H. Budzikiewicz, J. Mass Spec-trom. 2000, 35, 689–679.

[72] A.G. Hulst, C.E. Kientz, J. Mass Spectrom. 1996, 31, 1188–1190.

[73] P. Krishna, S. Prabhakar, M. Vairamani, Rapid Commun.Mass. Spectrom. 1998, 12, 1429–1434.

[74] U. Bahr, M. Karas, R. Kellner, Rapid Commun. Mass. Spec-trom. 1998, 12, 1382–1388.

[75] O.F. van der Brink, J.J. Boon, P.B. O’Connor, M.C.Duursma, R.M.A. Heeren, J. Mass Spectrom. 2001, 36,479–492.

[76] P. Vandenabeele, F. Verpoort, L. Moens, J. Raman Spec-trosc. 2001, 32, 263–269.

[77] M.T. Dom�nech-Carb�, F. Bosch-Reig, J.V. Gimeno Ade-lantado, V. Periz Mart�nez, Anal. Chim. Acta 1996, 330,207–215.

[78] I.M. Bell, R.J.H. Clark, P.J. Gibbs, Raman SpectroscopicLibrary of Natural and Synthetic Pigments (pre-ca. 1850AD), http://www.chem.ucl.ac.uk/resources/raman/speclib.html.

J. Sep. Sci. 2003, 26, 996–1004 Old master paintings 1003

[79] L. Burgio, R.J.H. Clark, Spectrochim. Acta A 2001, 57,1491–1521.

[80] Alchemia malarstwa, http://alchemiamalarstwa.republi-ka.pl/index.html.

[81] Pigmenty malarskie, http://www.astercity.net/lasfodel/ogrod/pigmenty.htm.

[82] N. Purinton, M. Watters, J. Am. Inst. Art. Conserv. 1991,30, 125–144.

[83] M.C. Edreira, M.J. Feliu, C. Fern�ndez-Lorenzo, J. Mart�n,Anal. Chim. Acta 2001, 434, 331–345.

[84] A. Dom�nech-Carb�, M.T. Dom�nech-Carb�, M. Moya-Moreno, J.V. Gimeno-Adelantado, F. Bosch-Reig, Anal.Chim. Acta 2000, 407, 275–289.

[85] C. Andal�, M. Bicchieri, P. Bocchini, G. Casu, G.C. Galletti,P.A. Mand�, M. Nardone, A. Sodo, M. Plossi Zappal�,Anal. Chim. Acta 2001, 429, 279–286.

[86] A. Cordy, K.-N. Yeh, J. Am. Inst. Art. Conserv. 1984, 24,33–39.

[87] M.E. Haude, J. Am. Inst. Art. Conserv. 1998, 37, 240–270.

[88] A.M. Seldes, J.E. Burucffla, M.S. Maier, G. Abad, A. J�ure-gui, G. Siracusano, J. Am. Inst. Art. Conserv. 1999, 38,100–123.

[89] L.A. Polette, G. Meitzner, M.J. Yacaman, R.R. Chianelli,Microchem. J. 2002, 71, 167–174.

[90] A. Dom�nech-Carb�, M.T. Dom�nech-Carb�, J.V.Gimeno-Adelantado, F. Bosch-Reig, M.C. Sauri-Peris,M.J. Casas-Catal�n, Fresenius J. Anal. Chem. 2001, 369,576–581.

[91] H.G.M. Edwards, L.F.C. de Oliveira, P. Middleton, R.L.Frost, Analyst 2002, 127, 277–281.

[92] R.L. Frost, H.G.M. Edwards, L. Duong, J.T. Kloprogge,W.N. Martens, Analyst 2002, 127, 293–296.

[93] G.D. Smith, L. Burgio, S. Firth, R.J.H. Clark, Anal. Chim.Acta 2001, 440, 185–188.

[94] L.F.C. de Oliveira, H.G.M. Edwards, R.L. Frost, J.T. Klo-progge, P.S. Middleton, Analyst 2002, 127, 536–541.

[95] S.P. Best, R.J.H. Clark, M.A.M. Daniels, C.A. Porter, R.Withnall, Stud. Conserv. 1995, 40, 31–40.

[96] L. Bussotti, M.P. Carboncini, E. Castellucci, L. Giuntini,P.A. Mand�, Stud. Conserv. 1997, 42, 83–92.

[97] L. Burgio, K. Melessanaki, M. Doulgeridis, R.J.H. Clark, D.Anglos, Spectrochim. Acta B 2001, 56, 905–913.

[98] M. Castillejo, M. Mart�n, D. Silva, T. Stratoudaki, D. Anglos,L. Burgio, R.J.H. Clark, J. Cultur. Heritage 2000, 1, S297–S302.

[99] F. Casadio, L. Toniolo, J. Cultur. Heritage 2001, 2, 71–78.

[100] D.A. Scott, M. Schilling, J. Am. Inst. Art. Conserv. 1991, 30,35–40.

[101] G.M. Ingo, G. Bultrini, T. de Caro, C. Del Vais, Surf. Inter-face Anal. 2000, 30, 101–105.

[102] A. Dom�nech-Carb�, M.T. Dom�nech-Carb�, L. Osete-Cortina, J.V. Gimeno-Adelantado, F. Bosch-Reig, R.Mateo-Castro, Talanta 2002, 56, 161–174.

[103] L.E. Garc�a-Ayuso, J. Amador-Hern�ndez, J.M. Fern�n-dez-Romero, M.D. Luque de Castro, Anal. Chim. Acta2002, 457, 247–256.

[104] I. Constantinides, M. Gritsch, A. Adriaens, H. Hutter, F.Adams, Anal. Chim. Acta 2002, 37, 189–198.

[105] M.R. Derrick, E.F. Doehne, A.E. Parker, D. C. Stulik, J. Am.Inst. Art. Conserv. 1994, 33, 171–184.

[106] A. Dom�nech-Carb�, M.T. Dom�nech-Carb�, J.V.Gimeno-Adelantado, F. Bosch-Reig, M.C Sauri-Peris, S.S�nchez-Ramos, Analyst 2001, 126, 1764–1772.

[107] J.H Hofenk-de Graaff, Natural Dyestuffs; Origin, ChemicalConstitution, Identification, ICOM, Committee of Conserva-tion, Amsterdam, 1969.

[108] J. Wouters, N. Rosario-Chirinos, J. Am. Inst. Art. Conserv.1992, 31, 237–255.

[109] A.A. Tagle, H. Paschinger, H. Richard, G. Infante, Stud.Conserv. 1990, 35, 156–159.

[110] B.V. Kharbade, O.P. Agraval, Stud. Conserv. 1998, 33, 1–8.

[111] D. Fabbri, G. Chiavari, H. Ling, J. Anal. Appl. Pyrolysis2000, 56, 167–178.

[112] H. Schweppe, J. Am. Inst. Art. Conserv. 1979, 19, 14–23.

[113] J. Wouters, A. Verhecken, Stud. Conserv. 1989, 34, 189–200.

[114] W. Van Roy, A. Mathey, L. Van Vaeck, Rapid Commun.Mass. Spectrom. 1996, 10, 562–572.

[115] V.P. Papageorgiou, A.S. Mellidis, A.N. Assimopolou, A.Tsarbopoulos, J. Mass Spectrom. 1998, 33, 89–91.

[116] O. Raatikainen, T. Naaranlathi, S. Auriola, J. Chromatogr.A 1993, 630, 423–428.

[117] G.C.H. Derksen, T.A. van Beek, Æ. De Groot, A. Capelle,J. Chromatogr. A 1998, 816, 277–281.

[118] G.C.H. Derksen, H.A.G. Niederl�nder, T.A. van Beek, J.Chromatogr. A 2002, 978, 119–127.

[119] G.A. Mazzochin, F. Agnoli, S. Mazzochin, Anal. Chim. Acta2003, 475, 181–190.

[120] H.G.M. Edwards, L.F.C. de Oliveira, M. Nesbitt, Analyst2003, 128, 82–87.

[121] J.-P. Salminen, V. Ossipov, J. Loponen, E. Haukioja, K.Pihlaja, J. Chromatogr. A 1999, 864, 283–291.

[122] G. Tian, T. Zhang, F. Yang, Y. Ito, J. Chromatogr. A 2000,886, 309–312.

[123] P. M�mmel�, H. Savolainen, L. Lindroos, J. Kangas, T.Vartiainen, J. Chromatogr. A 2000, 891, 75–83.

[124] R. Hiserodt, T.G. Hartman, H. Chi-Tang, R.T. Rosen, J.Chromatogr. A 1996, 740, 51–63.

[125] X.-G. He, L.-Z. Lin, M. Lindenmaier, J. Chromatogr. A1998, 818, 127–132.

[126] B.L.M. van Baar, J. Rozendal, H. van der Goot, J. MassSpectrom. 1998, 33, 319–327.

[127] M. Grzu, D. Fraisse, A.P. Carnat, A. Carnat, J.L. Lamai-son, J. Chromatogr. A 1998, 805, 315–318.

[128] H.-B. Li, F. Chen, T.-Y. Zhang, F.-Q. Yang, G.-Q. Xu, J.Chromatogr. A 2001, 905, 151–155.

[129] P. Lozano, M.R. Castellar, M.J. Simancas, J.L. Iborra, J.Chromatogr. A 1999, 830, 477–483.

[130] N. Li, G. Lin, Y.-W. Kwan, Z.-D. Min, J. Chromatogr. A1999, 841, 349–355.

[131] G.M. Languri, J. van der Horst, J.J. Boon, J. Anal. Appl.Pyrolysis 2002, 63, 171–196; 2002, 64, 123–124.

[132] M. Leona, J. Winter, Stud. Conserv. 2001, 46, 153–162.

[133] A. Casini, F. Lotti, M. Picollo, L. Stefani, E. Buzzegoli, Stud.Conserv. 1999, 44, 39–48.

[134] B. Guineau, Stud. Conserv. 1989, 34, 38–44.

[135] C. Miliani, A. Romani, G. Favaro, J. Phys. Org. Chem.2000, 13, 141–150.

[136] E.L. Ghisalberti, I.M. Godfrey, Stud. Conserv. 1998, 43,215–230.

[137] R.D. Gillard, S.M. Hardman, R.G. Thomas, D.E. Watkin-son, Stud. Conserv. 1994, 39, 187–192.

[138] W. Devos, L. Moens, A. Von Bohlen, R. Klocken�mper,Stud. Conserv. 1995, 40, 153–162.

1004 Zadrozna et al. J. Sep. Sci. 2003, 26, 996–1004

[139] J.J. Boon, T. Learner, J. Anal. Appl. Pyrolysis 2002, 64,327–344.

[140] D.M. Grim, J. Alison, Int. J. Mass Spectrom. 2003, 222,85–99.

[141] N. Sonoda, Stud. Conserv. 1999, 44, 195–208.[142] S. Nakamura, T. Masahiko, S. Daishima, J. Chromatogr. A

2001, 912, 329–334.[143] T. Learner, Stud. Conserv. 2001, 46, 225–241.[144] L. Masschelein-Kleiner, Mikrochim. Acta 1967, 6, 1081–

1085.[145] S.M. Halpine, Stud. Conserv. 1996, 41, 76–94.[146] W. Metzger, K. Reif, J. Chromatogr. A 1996, 740, 133–

138.[147] P. Novotn�, V. Pac�kov�, Z. Bos�kov�, K. Stulik, J. Chro-

matogr. A 1999, 863, 235–241.[148] F. Yang, T. Zhang, G. Tian, H. Cao, Q. Liu, Y. Ito, J. Chro-

matogr. A 1999, 858, 103–107.[149] M. Careri, A. Mangia, M. Musci, J. Chromatogr. A 1998,

794, 263–297.

[150] T. Watanabe, S. Terabe, J. Chromatogr. A 2000, 880,311–322.

[151] R. Aparicio, R. Aparicio-Ru�z, J. Chromatogr. A 2000, 881,93–104.

[152] I. Moln�r-Perl, J. Chromatogr. A 2000, 891, 1–32.

[153] T. Cserh�ti, E. Forg�cs, J. Chromatogr. A 2001, 936, 119–137.

[154] M. Careri, F. Bianchi, C. Corradini, J. Chromatogr. A 2002,970, 3–64.

[155] W.M.A. Niessen, A.P. Tinke, J. Chromatogr. A 1995, 703,37–57.

[156] J. Cai, J. Henion, J. Chromatogr. A 1995, 703, 667–692.

[157] W.M.A Niessen, J. Chromatogr. A 1999, 856, 179–197.

[158] K. Pawlak, M. Mojski, M. Jarosz, Chem. Inz. Ekol. 2002, 9,1135–1155.

[159] K. Połec-Pawlak, M. Jarosz, Chem. Anal. 2002, 47, 783–805.