**4. Conclusions**

In this paper, an investigation of textile samples collected from Gokstad Viking ship's grave by high performance liquid chromatography (HPLC) with diode array (DAD) and high resolution mass spectrometric detector (ESI-Q-ToF MS) was performed. The use of ESI-Q-ToF MS as a detector was paramount in order to allow us to detect not only major but also minor compounds, and to confirm the presence of analytes in sample 2. The presence of molecular markers attributable to madder-type dyestuff, most probably from *Rubia tinctorum*, was determined in all four analyzed samples. A harsh sample treatment, followed by purification by liquid/liquid extraction with ethylacetate, was needed to retrieve significant amount of analytes from most samples (only sample S1 gave satisfactory results after treatment in mild conditions). This can be attributed to the extensive degradation of the dyestuffs or the use of specific dyeing recipes which prevented the extraction with chelating agents, requiring acidic conditions.

Madder-type dyestuffs are commonly found in graves from the Viking Age and medieval Scandinavia: a number of written sources mentioned the use and export of madder and surviving trace amounts of dyes interpreted as madder have been found in a number of Scandinavian graves dating to the Viking Age [1,5,35].

With regard to the embroidery, the two samples (S3 and S4) were collected from the threads forming a polychrome pattern [14], which looked slightly redder (S3) and more yellow (S4) respective to each other. Although both extracts had a very similar composition, consisting of alizarin, purpurin, pseudopurpurin, and anthragallol, the relative alizarin and anthragallol content with respect to all other anthraquinones is much higher in the golden sample (S4) than in the redder one (S3). Thus, the HPLC data confirmed the visual observation, being alizarin and anthragallol more yellow than the other components, featuring maxima of absorbance in the visible range around 430 and 410 nm, respectively, whereas purpurin and pseudopurpurin both have maxima of absorbance higher than 480 nm. Thus, the different amounts of the components of the dyeing material suggest that different recipes were indeed employed to obtain different shades of silk thread. Finally, protein-based fiber degradation products were identified in the silk samples, confirming the animal origin of the textiles [36].

In one sample collected from the tent (S1), madder-type markers were also identified, while in S2, characterized by a yellow/white color at the time of analysis, only traces of anthraquinones were detected related to the dyestuff. It is possible that, given the purpose

of this textile material, only a small amount of dyestuff was applied, or it severely faded during the use of the fabric. On the other hand, given the different results obtained for samples S1 and S2, the tent might have been colored in two different alternating shades.

In conclusion, the application of different extraction methods along with sensitive and selective analytical techniques allowed us to detect madder-type dyestuffs used to dye both a red-and-white/undyed striped woolen cloth used as tent or sail, and for coloring a delicate embroidery of silk and gold.

These new analyses provide a small but important new piece of information about the Viking Ship grave from Gokstad, allowing us to picture the original multicolored funerary goods.

**Author Contributions:** Conceptualization, M.V. and J.J.Ł.; methodology, I.D. and J.J.Ł.; investigation, I.D. and J.J.Ł.; writing—original draft preparation, M.V., I.D. and J.J.Ł.; writing—review and editing, M.V., I.D. and J.J.Ł.; supervision, J.J.Ł. All authors have read and agreed to the published version of the manuscript.

**Funding:** Funded by the Gokstad Revitalised project, University of Oslo.

**Data Availability Statement:** All data presented in this paper can be made available by the authors upon request.

**Acknowledgments:** We thank the Museum of Cultural History, University of Oslo, for making samples of the Gokstad textiles available for our research.

**Conflicts of Interest:** The authors declare no conflict of interest.

### **References**


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