Health Minister Recep Akdag was quoted by the Anadolu news agency as saying traces of one of the decomposition products of Sarin had been detected in the blood and urine of several victims.
At least 89 people were killed in the incident in rebel-held Khan Sheikhoun.
Syria's government has repeatedly denied using any chemical weapons.
The US has rejected the assertion, however, and on Friday it carried out a missile strike on the Shayrat airbase, where it said a Syrian Air Force jet that attacked Khan Sheikhoun with chemical weapons took off.
President Bashar al-Assad's ally Russia, which says the Syrian jet had in fact hit a rebel depot full of chemical munitions, denounced the "illegal action" by the US.
A number of casualties were treated at hospitals in Turkey, which opposes Mr Assad, following last Tuesday's incident in neighbouring Idlib province.
The World Health Organization said their apparent lack of external injuries and similar symptoms, including acute respiratory distress, suggested they had been exposed to organophosphorus chemicals, a category that includes nerve agents.
On Tuesday, Mr Akdag announced that a chemical known as isopropyl methyphosphonic acid (IMPA) had been "identified in the blood and urine tests conducted on samples taken from the victims".
Once exposed to air and water, Sarin breaks down into IMPA and methylphosphonic acid (MPA).
The UN concluded that rockets filled with sarin were fired at several rebel-held suburbs of Damascus in August 2013 after finding traces of IMPA in samples taken from the scene of the attack, which the US blamed on Syria's government.
Earlier on Thursday, Russia's president urged the Organisation for the Prohibition of Chemical Weapons (OPCW) to open a full investigation into last week's incident.
Vladimir Putin also claimed rebels were planning "acts of provocation" using chemical weapons to encourage further US strikes on government forces.
A Russian military spokesman said that the Syrian government was prepared to allow OPCW experts to visit the Shayrat airbase to search for chemical weapons.

The incident happened on Wednesday at about 18:00 in Wardieburn Place West.
The men, aged 43 and 45, had travelled from Aberdeen. They were attacked in a stairwell by two men who are then thought to have left by the back of the block.
Both victims suffered serious injuries and the 43-year-old man is in a critical condition.
Police are appealing for witnesses.
The first attacker is white and aged 17-19.  He has a Central Scotland accent and light-coloured short hair, which is shaved at the sides.
He was wearing a light-coloured sky blue hooded sweatshirt and grey jogging bottoms.
The second attacker is a white man in his mid-20s. He has a stocky build and was wearing a striped top.
Det Ch Insp Stuart Houston, of Police Scotland, said: "This was an appalling attack on two men who came to the address in good faith.
"This attack happened in daylight and we believe there may be a number of witnesses who may have seen the suspects in the area.
"Anyone with information that can help with our inquiries is urged to contact police immediately."

Fly-half Sam Davies is released with Rhodri Jones, Rory Thornton, Olly Cracknell. Nicky Smith and James King.
They will return to the Wales camp on Sunday to prepare for the Six Nations game with Ireland on 10 March.
The other Welsh regions play on Saturday and will not receive players from Rob Howley's squad, with Wales playing just six days later.
Turkey says it has "concrete evidence" the nerve agent Sarin was used in a suspected attack by Syrian government forces a week ago, state media report.
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An investigation has been launched into the attempted murder of two men who had travelled to Edinburgh to buy a car.
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Ospreys will be boosted by six Wales squad members for their Pro12 match with Edinburgh on Friday, 3 March.