The glass structure in two ternary systems was investigated with respect to their applicability as electrode glasses. For Na 2 O–Al 2 O 3 –SiO 2 glasses, a good pNa electrode signal is observed if (i) AlO − 4 units exist, linked mainly to Q 4 m units (Q n m : silicate tetrahedra, n: number of Si–O–Si bridges, m: number of Si–O–Al bridges), (ii) some other AlO − 4 units are bonded to mainly Q 3 m units and (iii) the condition 2>Q 4 m /Q 3 m >1 holds. In Na 2 O–B 2 O 3 –SiO 2 glasses, a pNa signal is measured if the ratio of the BO − 4 units linked to BO 3 or to Q 4 is less than 1. Two-dimensional double quantum nuclear magnetic resonance (DQ NMR) spectroscopy has been applied to 29 Si enriched sodium silicate glasses for measuring the connectivities of the Q n units (m=0), enabling improved studies of the medium range order. We are able, for the first time, to distinguish between the various Q 3 and Q 4 units bonded to different numbers of Q 3 and/or Q 4 groups.