[en] Direct sampling laser ablation plasma mass spectrometry (DS-LAMS) was applied to silica glasses doped with ²³⁷Np, ²⁴²Pu or ²⁴¹Am using a unique instrument recently installed into a transuranic glovebox. The primary goal was to assess the utility of mass spectrometry of directly ablated ions for facile evaluation of actinide (An) constituents of silicate glass immobilization matrices used for encapsulation of radionuclides. The instrument and general procedures have been described elsewhere. Three high-purity silicate glasses prepared by a sol-gel process (SG) and one conventional high-temperature (HT; melting point ∼ 1,450 C) borosilicate glass were studied. These glasses comprised the following constituents, with compositions expressed in mass percentages: Np-HT ∼ 30% SiO₂ + 6% B₂O₃ + 3% BaO + 13% Al₂O₃ + 10% PbO + 30% La₂O₃ + 8% ²³⁷NpO₂; Np-SG ∼ 70% SiO₂ + 30% ²³⁷NpO₂; Pu-SG ∼ 70% SiO₂ + 30% ²⁴²PuO₂; Am-SG ∼ 85% SiO₂ + 15% ²⁴¹AmO₂