European history is filled with tales of heroic knights who fought on behalf of kings and queens—and the romance of these legends surely grows when backed by scientific fact. For centuries, helmets, swords and other artifacts with purported links to past heroes have been on display in museums across the continent. In recent years, historians and archaeologists have been turning to analytical technologies such as mass spectrometry to test the age and origin of items in museum collections.

One example is an ornamented sword called the Tizona, which was carried by the Spanish hero El Cid in the late 11th Century. Rodrigo Diaz de Vivar was the medieval knight who came to be known as El Cid, shortened from mio Cid el compëador—"my lord the champion." After battling the invading Moors on behalf of two Castilian kings, El Cid was forced into exile by a subsequent regent who distrusted him. His exile propelled him into the life of a mercenary who eventually came to rule the kingdom of Valencia—a reign that lasted until his death in 1099.

Scholars and poets say El Cid kept the Tizona by his side after taking it from a defeated enemy. Today, the sword resides in the Museo del Ejercito (Army Museum) in Madrid, Spain. In 1999, researchers tested the sword's origin by taking a tiny sample from its blade and performing a full quantitative analysis using inductively coupled plasma mass spectrometry (ICP-MS).

Finding clues in metal

The key to revealing a metal object's origins is in the pattern of impurities locked into its metallurgy. The combination of elements and their relative quantities are unique to the geographic region of manufacture. By comparing the composition of an artifact with samples taken from objects of known origin, scientists can pinpoint the site of creation.

In this case, researchers used a predecessor of the Agilent 7500 series ICP-MS to identify the origin of the museum's sword. Agilent ICP-MS instruments can simultaneously measure most elements in the periodic table and determine their concentrations down to the parts-per-trillion (ppt) level. With such high sensitivity, only a very small sample is required to obtain a complete trace-metal comparison. This is especially beneficial when testing artifacts that may truly be rare and priceless.

Using a 10-mg sample, the analysis confirmed the steel as an alloy that also contained nickel, copper and antimony along with trace amounts of tungsten and platinum. These clues helped researchers conclude the blade was probably manufactured in the early 11th Century in Andalucia, now called Sierra de Córdoba.

With analytical methods such as ICP-MS at their disposal, historians and archaeologists will be able to test the origin of various artifacts—and perhaps enhance other heroic legends.