Figure 1.

Single stage mass spectrum of trehalose, a disaccharide found e.g., in insects. Due to the lack of basic residues in the molecule, [M + H]⁺ ions could not be detected if the sample was dissolved in acetonitrile-water 1:1 (v/v) solvent mixture, containing 0.1% acetic acid (spectrum not shown). However, using 5 mM of ammonium acetate in water resulted in the above spectrum. Although absolute intensity is still low, the ammonium adduct of trehalose and its cationized dimer could also be detected. Also, a possible in-source fragmentation product can be seen at m/z 325 displaying a neutral loss of water (°) and ammonia (*). Note the peaks corresponding to m/z 296.1 and m/z 338.4 are very likely the [M + NH₄]⁺ ion of dibutyl phtalate and [M + H]⁺ ion of erucamide, respectively, which are common plasticizers leaked from plastic sample tubes.