Figure 3.

Spectra acquired in 2.5% MeOH and water and NEt₄OH (2:1 NEt₄OH:LG). Fluorescence response of 5 μM LG to common biologically available cations. The bars represent the final fluorescence response (F_f) over the initial fluorescence response (F_i). White bars represent the addition of each ion (2 mM for Li⁺, Na⁺, K⁺, Ca²⁺, and Mg²⁺ and 75 μM for Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Mn²⁺, Hg²⁺, As³⁺, Sn²⁺, and Pb²⁺. Black bars represent the addition of 75 μM Pb²⁺ to the solution. Excitation was provided at 389 nm. a. Li⁺, b. Na⁺, c. K⁺, d. Ca²⁺, e. Mg²⁺, f. Fe²⁺, g. Co²⁺, h. Ni²⁺, i. Cu²⁺, j. Zn²⁺, k. Cd²⁺, l. Mn²⁺, m. Hg²⁺, n. As³⁺, o. Sn²⁺, p. Pb²⁺.