David Burslem

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45 appearances 1 recordings 1 series first heard Jul 2026 last heard 22 Jul

David Burslem’s voice in public audio — every appearance, attributed to the second.

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Science Weekly · Revisited: A Scottish tea mystery, episode two – the list · 22 Jul 2026 podcast

So taking, for example, this package of tea that's got on the label Dalry Scottish White Tea, which was produced, I think, in 2016 and part of the original set of samples that the tea growers of Scotland acquired.

So it is one of the products that highlighted their concern because it's a very large packet, 250 grams.

That was the marketing of it, yes.

So we have to prepare that for analysis.

So the first step is to grind it into a fine powder.

And I have some examples of that here too.

And you can see it has to be very, very finely ground in order to be prepared for the next stage.

Indeed, they all look very similar, except they have slightly different colours once they're powdered.

Oh look, lab coats, excellent.

So this is what a digest looks like and you would be forgiven for thinking that was just a vial of water.

So they then go into this container in batches as you can see and then there's a robotic system that sucks up a very small sample from each one

It feeds it into the ICP-MS that actually does the analysis, which is this machine here.

Yes, it contains the mass separation and the detection.

And then we get outputs in the form of spreadsheets.

They supplied me with samples from the same set of Scottish estates and a few others as well, where their geographical origin was known and was recorded by them.

And they supplied me with a set of samples which they didn't tell me a great deal about, for very good reasons.

It wasn't explicit where those unknown samples came from.

I was asked to analyse those samples, to make a judgement on whether they were distinct chemically from the Scottish-grown samples and whether there was any evidence that they were more similar to the overseas library of reference samples that I had already.

In most cases, the unknown samples that were supplied by Food Standard Scotland clustered within the group of overseas teas and not among the Scottish grown, authentically Scottish grown teas.

First of all, I was concerned.

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