Nuclear reaction analysis (NRA) has been developed to achieve a sufficient sensitivity for the determination of low Z elements in narrow regions (around 1 millimeter²) of a matrix rich in high Z elements (gold, silver, copper). Traces of sulfur and silicon are especially useful for the understanding of the antique brazing procedures of archaeological silver artifacts. Proton spectra from (d, p) reactions on thick targets for the analysis of silicon and sulfur, and incidentally magnesium, aluminum, phosphorus, chlorine, and potassium, have been investigated to determine the most useful deuteron energy for sensitive and interference free determinations. Applications to brazing alloys obtained by dissolution of cadmium ores in melted gold (as done in antiquity), and to artifacts of Byzantine times (9 century A.D.) are presented. -- AATA