Two apparent platypus sighting in the Adelaide foothills sparked a flurry of excitement during May, with locals hoping they had returned to the wild after more than 100 years being extinct in the region.

But four stop-motion cameras set up on location at Sturt Gorge by SA Government ecologist Jason van Weenen failed to capture any platypus sighting, despite recording a "good number" of native water rats and other fauna.

Sorry, this video has expired A native water rat filmed by a stop-motion camera at Sturt Gorge

Enter scientists from the Australian Water Quality Centre (AWQC) at SA Water — the first team in Australia to use cutting-edge DNA equipment to determine what organisms have been in contact with a water source.

SA Water staff collected 22 water samples from Sturt Gorge and took them back to the laboratory to be analysed for traces of platypus — its traces most likely to be cells expelled in faeces.

In a technique reminiscent of the Hollywood film, Gattaca — where a registry of peoples' DNA is used to match their identity in seconds — the DNA data was extracted and analysed, albeit over a period of weeks rather than seconds.

SA Water Laboratory Services senior manager Karen Simpson said the technology had vast capabilities and could be used for such areas as identifying source water contamination, learning more about fish species in certain water bodies, and tracking the abundance of endangered animals in particular areas.

"We aren't actively pursuing this, but it would also be possible to take samples from water bodies in Tasmania, to see if there's any chance of detection of a Thylacine [Tasmanian Tiger]."

Ecologist Jason van Weenen considers the platypus sighting at Sturt Gorge to be credible. ( ABC News: Malcolm Sutton )

How does it work?

AWQC molecular scientist Lisa Teakle said sampling sites were chosen based on peoples' possible sightings, "and also locations where the samplers felt it was likely to be a potential habitat".

A chip is loaded with barcoded DNA in the Ion Chef. ( ABC News: Malcolm Sutton )

She said cells are drawn from the water using a very fine filter and the DNA extracted.

"We basically have to burst open the cells, take the DNA out, get rid of all the cellular debris, then purify the DNA that's present," Ms Teakle said.

Primers from a database of DNA are used to isolate mitochondria cells — a special type of DNA for vertebrates (animals with a spine) — and each of the relevant DNA samples is given a barcode.

Barcoded DNA are applied to Ion Sphere Particles (ISPs), microscopic beads, which are then distributed in their millions onto a computer chip in a piece of equipment called the ION Chef.

Ms Teakle said a second piece of equipment, the ION S5, floods each chip with the four bases that make up DNA — A (Adenosine) pairs with T (Thymine), and G (Guanine) pairs with C (Cytosine) — the letters from which the film Gattaca draws its title.

Each time a pair is matched, a signal is sent to the machine — effectively making copies of the DNA for sequencing.

More complex than The Matrix

Method Development coordinator Gary Hallas said everything and everyone had their own unique sequence, including the platypus.

The DNA technology could be used to confirm or help debunk the existence of the Thylacine. ( Wikimedia Commons: David Fleay )

"We get to about 300-400 base pairs long of each environmental animal's barcoded sequence, and if that sequence is perfect, it matches perfectly in our database and we know the platypus is there," he said.

"This is Gattaca. This is real."

He said the millions of pairs detected by the ION S5 are is simply too much data "for humans to handle".

Mr Hallas likened it to special effects scenes in another Hollywood film, The Matrix, where streams of binary code are shown to represent the virtual reality world its characters occupy.

"Instead of a binary code of ones and zeros, you've got four bases, so it's like two binary codes."

Mr Hallas said the best way to collate the data was to use software and the emerging field of informatics to visualise it into a pie chart that showed the percentage of detected vertebrate DNA.

"If it says there's pond turtle at 0.5 per cent, rat kangaroo at 0.1 per cent — that would be one sample — and it breaks down all of those DNA signals into a percentage of how much we found of it," Mr Hallas said.

AWQC molecular scientist Lisa Teakle with the laboratory's Ion Chef and Ion S5. ( ABC News: Malcolm Sutton )

Further sites to be tested

Despite the advanced science, the team were unable to detect traces of platypus, which are believed to have escaped from Warrawong Sanctuary in the Adelaide Hills, in the Sturt Gorge samples.

Ms Simpson said the lack of results did not mean platypus were not in the area, "but just may not have been in contact with the waterways within our sampling range".

A platypus may also have been sighted upstream in a park at Coromandel Valley. ( ABC News: Malcolm Sutton )

SA Water may now follow the advice of Warrawong founder John Wamsley, who said while it was plausible platypus had made it to the Sturt River, they were more likely to be in the upper reaches of the Onkaparinga and Mount Bold Reservoir because it is closer.

He said two breeding pairs at Warrawong gave birth to new platypus each year, which were forced to leave Warrawong due to the territorial nature of the mammals.

The theory is this summer was very wet and retained a lot of water in tributaries, potentially giving the platypus a better chance of remaining out of reach from predators like feral foxes.

Mr van Weenen and his team at the Adelaide and Mount Lofty Ranges Natural Resources Management Board (NRM) believed the reported platypus sighting was "qualified" and remained hopeful of confirming the mammal.

If a platypus was confirmed, he said the NRM board could think about what it meant to have platypus in the region "and plan ahead".

"For example, the genetics of the population might be fairly limited, and is it important to consider the broader implications of having a low genetic base," he said.

"Similarly, we might be able to look at educating people against using things like opera house nets for catching yabbies.

"They're quite a problem for platypus and the native water rat."

In the meantime, the imagination of locals has been captured by one of one of the world's strangest mammals making a potential appearance in their backyard.