In these fora, he has actively pursued the advancement of human rights, humanitarian issues and the rule of law, disarmament, the fight against climate change, and the promotion of development, including through the strengthening and improvement of the relevant international mechanisms.

Among other tasks, he coordinated the participation of the Mexican Delegations in different international meetings, in particular the 2001 World Conference against Racism in Durban, South Africa, and the Special Session of the General Assembly on Children (2002).

He was a member of the Mexican Delegation to the United Nations Conference on the Illicit Trade in Small Arms (2001), where he promoted a multidimensional approach to include humanitarian and human rights concerns.

During his tenure, he undertook broad consultations leading to a comprehensive proposal for a new strategy to further improve the work and functioning of IOM and to develop a new paradigm on migration placing the rights of migrants at its core.

From 2011 to 2013 De Alba was Mexico's Permanent Representative to the United Nations (New York),[4] where he introduced a new resolution on Special Political Missions of the UN, seeking greater transparency and accountability.

He actively participated at the Rio+20 Conference on Sustainable Development (Rio, Brazil, 2012) and was elected Senior Vice-President of the United Nations Economic and Social Council (ECOSOC) in 2012.

In June 2013 De Alba was appointed Mexican Ambassador to Austria, concurrent with Slovakia and Slovenia and Permanent Representative to the International Organizations based in Vienna.

Since September 2017 De Alba has been serving as the Undersecretary for Latin America and the Caribbean, appointed by the Minister of Foreign Affairs of Mexico.