They contain nitrogen and usually occur as salts of asids such as citric, malic, and succinic acids such as citric, malic, and succinic acids.
They contain nitrogen and usually occur as salts of asids such as citric, malic, and succinic acids such as citric, malic, and succinic acids.
它们是一类含氮的，一般由酸性盐如柠檬酸，苹果酸，琥珀酸所形成。