Table 1.

Number of compounds and number of compounds with identification information detected in both the positive and negative ion modes.

Mode	Number of compounds	Number of compounds with identification information
Positive ion mode (pos)	1606	543
Negative ion mode (neg)	532	204

Positive ion mode (pos): when the substances are ionized in an ion source, the adduct ions are positive ions, such as H⁺, ${\text{NH}}_4^{+}$ , Na⁺, K⁺.

Negative ion mode (neg): when the substances are ionized in an ion source, the adduct ions are negative ions, such as -H, +Cl.