The move by the bloc's foreign ministers brings to 255 people now facing a travel ban and an assets freeze over President Bashar al-Assad's violent crackdown on civilians during a five-year civil war.
"The EU added these 16 persons for their role in the development and use of chemical weapons against the civilian population," an EU statement said.
The EU will release the names of those hit by the sanctions on Tuesday, it said.
The UN's chemical watchdog, the OPCW, last month concluded that sarin was used as a chemical weapon in the April 4 attack in the Syrian town of Khan Sheikhun that killed at least 87 people including children.
The sanctions decision "shows the resolve of the UK and the rest of our friends in Europe in dealing with those who are responsible for chemical weapons attacks," British Foreign Secretary Boris Johnson told reporters just before the decision was announced.
Syria is already subject to an oil embargo, restrictions on certain investments, a freeze of the assets of the Syrian central bank held in the EU, as well as export restrictions.
It also is under sanctoins on equipment and technology that might be used for internal repression as well as on equipment and technology for the monitoring or interception of internet or telephone communications.
Jordanian soldier gets life for killing 3 US trainersJordan-US-trial Amman, July 17, 2017 (AFP) - A Jordanian court on Monday sentenced a soldier to life imprisonment over the killing of three American military trainers outside an army base last year.
The military court in Amman found 39-year-old Maarik Al-Tawaiha guilty of shooting the trainers as they waited to enter the King Faisal base at Al-Jafr in southern Jordan on November 4.
The charge sheet did not indicate that he had any ties to militant groups.
The court sentenced him to "hard labour for life", a term that usually lasts 20 years but could stretch to a full lifetime, a judicial official told an AFP correspondent at the courthouse.
It also demoted him from sergeant to second private and threw him out of military service.
Tawaiha, who wore a suit throughout the hearing, had been in custody since November but denied the charge.
The court had heard evidence from guards at the base and forensic experts.
The prosecution in June accused him of "voluntary manslaughter" as well as "insulting the dignity and reputation of the armed forces and violating military orders".
Tawaiha said he had opened fire on the cars carrying the American trainers after hearing gunshots. Suspecting an attack on the base, he shot at them, killing the three Americans and wounding a Jordanian soldier.
The King Faisal air base hosts trainers of various nationalities including Americans, an official said.
The incident came a year after a police officer wounded two American instructors, four Jordanians and a Lebanese in a shooting at a Jordanian police training centre before being shot dead.
Jordan, which hosts some 2,200 American military personnel, is a key American ally and a member of the United States-led coalition fighting the Islamic State group.
Tens of thousands of Iraqi, Yemeni and Libyan forces have also received training in Jordan.