A question for the chemists amongst us.

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Masbustelo
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A question for the chemists amongst us.

Post by Masbustelo » July 1st, 2021, 8:29 am

https://academic.oup.com/jee/article/113/5/2293/5859736 In this study they mention making a 20% solution of Erythritol. I can't see in the study how they obtained the solution. As I thought about it, one could add either 20% Erythritol by volume or weight. One gallon of water weighs 3750 grams. I removed 750 grams of water (20%) and replaced it with 750 grams of Erythritol. My question is: Did I replicate the solution used in the afore mentioned scientific study?

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Re: A question for the chemists amongst us.

Post by andy10917 » July 1st, 2021, 10:26 am

My impression is that this is still primarily at the lab stage, with lots and lots of additional work to be done before it's ready for prime-time field use.

I'm familiar with Erythitol - as a diabetic, I use it regularly as a sugar substitute. Amongst the group of sugar alcohols, it has the least side-effect of digestive upsets. It's generally considered safe. Obviously, the target nymphs don't share the same safety profile after dealing with it. Sidebar item: I've moved away from Erythitol somewhat as ice cream made with Erythitol freezes far too hard, and I've moved to Allulose as the primary sweetener ($$$ goes up).

While there is a lot of promising stuff here for pear trees, it looks to me like they haven't really worked out the use of surfactants, or even settled on how often it would need to be applied in field situations. And then there are issues to figure out on whether there are any effects on beneficial insects, birds, etc. It seemed to me that they are even unsure about whether it works by topical contact or whether it gets into the leaves and is ingested. And Yes, I didn't see whether amounts are volume-based or weight-based (I only did one reading).

I think it's far earlier in the pipeline to consider using this, individually or commercially. I think the purpose of the article is to recruit others to help move the ball forward. I'd track it occasionally, but not expect real-world use or direction in the near/intermediate term.

Of course, you could contact the author if your really dying to use this...

Masbustelo
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Re: A question for the chemists amongst us.

Post by Masbustelo » July 1st, 2021, 2:02 pm

My pear tree was severely attacked by psylla this year and last. Six weeks ago it lost all of its foliage. The available chemical treatments are very expensive and need to be rotated, like fungicides. The psylla attack from spring until leaf fall. So I did mix up and apply a eryritol based concoction. I guess I'll be one of the persons doing some of the additional work to see if it makes it to prime time use. It would be pretty expensive to apply by the acre. If I ever get any pears maybe they will taste sweeter.

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Re: A question for the chemists amongst us.

Post by MorpheusPA » July 1st, 2021, 4:35 pm

I'm going to presume they're using a weight percent solution. I have no familiarity with Erythitol, so listen to Andy about it. If I'm reading this right--I really only scanned it--this was done in the test tube, effectively (petri dish, but same thing). That doesn't mean it's a real-world solution. Plenty of stuff kills cancer cells in the test tube but just doesn't work in the human body (or kills cancer cells just fine, but also kills all other cells as well, which is not a good answer to the cancer problem).

"How to Make Weight Percent (Wt%) Solutions

In weight percent solutions, the weight of the solute is divided by the weight of the solution (solute + water) and multiplied by 100. Since the density of water is 1 g/ml, the formula to calculate the amount of solute that must be mixed for a weight percent solution is:

grams of solute = (wt% solution) x (ml of water) ÷ (100 – wt% solution)
As an example, to make 100 ml of 10% NaCl (table salt) solution, use the previous formula to find out how much NaCl you need:

grams of NaCl = (10) x (100) ÷ (100 – 10) = 11.1 g
Now you can make your solution: dissolve 11.1 g NaCl in 100 ml of water."

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Re: A question for the chemists amongst us.

Post by Masbustelo » July 1st, 2021, 5:43 pm

I'm beginning to remember why I dropped chemistry.


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Re: A question for the chemists amongst us.

Post by MorpheusPA » July 1st, 2021, 6:45 pm

(Laughs) Tru dat, but it's really very easy.

For a 20% solution:

20x100/(100-20) = 2000/80 = 25g added to 100g water, for 125g mass total. (25g/125g = 0.2)

Or, for a gallon:

20*3750/(100-20) = 75000/80 = 937.5g added to 1 gallon water (you don't subtract any water in this example; the Erythritol will dissolve in it). So you'll need just about a kilogram of the stuff, or just about 2.067 pounds. 2 pounds to make a gallon is close enough.

Will it overflow the gallon container? As long as the Erythritol fully dissolves...no. Volumes do not change. Densities do, though.

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Re: A question for the chemists amongst us.

Post by Masbustelo » July 1st, 2021, 7:40 pm

Thanks for working that out for me.

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Re: A question for the chemists amongst us.

Post by Masbustelo » July 1st, 2021, 7:50 pm

Thats interesting that the volme doesn't change.

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Re: A question for the chemists amongst us.

Post by MorpheusPA » July 1st, 2021, 8:25 pm

It's a weird truth with solutions. Dissolved masses take up the (approximate) same volume as the liquid did. It does actually increase slightly, but by far less than the volume of the original solid. Masses, however, add exactly the way you'd expect them to*, and densities scale accordingly as per the mass and volume.

There's a boat ton of "space" between molecules, if you go down to that realm. The dissolving molecules "fit" in those "spaces." (I'm oversimplifying as there's a reason things dissolve in water or other liquids and it's not really due to "space" for them).

So you'll note some increase in volume (I'm not sure of the exact amount for that particular substance), but it's sure not going to be 20%. A few percent, sure.

* On the gross physical scale, at least. Exothermic or endothermic reactions technically result in a very slight mass change as temperatures adjust (mass and energy are the same thing), but when measuring in grams, and working with the kinds of things we do here, you're never going to notice that or care about it.

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