Benedict's weirdness

I have two batches of Benedict's reagent currently, Batch A I made, is about five months old, used right after being made, worked perfectly. We tried using it again this week, and there was some white precipitate in the bottle and when I drew some up into a teat pipette, it turned quite purple.

Now, my school is janky and reuses plastic teat pipettes until they split, and I've read about Benedict's reacting weakly with protein like biuret, so I wondered if the pipette was contaminated with something. I mixed the Benedict's with the hydrolysed sucrose solutions to see if it would still react, and all concentrations (1.0M, 0.5M, 0.25M, 0.125M) instantly turned reddish purple with no heat applied :confused::confused:

On to Batch B, found in the back of the cabinet, I don't know who made it or how long ago (>9 months for sure), no precipitate. We repeated the lab with Batch B today after school. No purple, the color changes didn't happen until after heat was applied, but only the 1.0M changed color (brick red), the 0.5M stayed clear blue with a very small amount of red precipitate, and 0.25M and 0.125M absolutely no change?

So, I'm confused. I'm a math teacher, I'm teaching CIE AS Biology because there was a staffing hole and I did my undergrad in bio, but troubleshooting in the lab is not my specialty at all. I'm leaning toward this having something to do with age and poor storage. Our lab is beyond under-resourced (I'm in Eastern Europe), and both batches were stored in clear, thin plastic bottles inside of dark cabinets. We have all the ingredients for more Benedict's, and it's hard to source chemicals here, so I'd prefer to make another batch over ordering, but obviously only if I can figure out how to ensure it works properly as it often pops up on the practical examination. Any thoughts?
 
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Sounds like a storage issue to me, although my life has been plagued the last year with non-functional Benedict's reagent. Whereabouts in Eastern Europe?
 
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Well thats a hefty mystery

Lets start at the beginning I suppose, what are your recipe's used for making both batch A and B?
 
Sorry for the late reply. @mike wilson I'm in Slovakia. I can order pre-made reagent from Germany, which I'm leaning toward despite the bureaucratic hoops involved, but am still worried about proper storage.

@CovTech Batch B recipe is totally unknown. Batch A was:

"dissolve 173 grams of sodium citrate and 100 g of anhydrous sodium carbonate in 800 mL of water. Filter, if necessary, and dilute to 850 mL. Dissolve 17.3 G of copper (II) sulfate pentahydrate in 100 mL of water. Pour the latter solution, with constant stirring, into the carbonate-citrate solution, and dilute to 1 L." There is a chem

How to improve storage, then? Amber glass? Also climate control in the lab is very poor, so temps could prob range from 0C to >35C depending on the season.
 
Not been to Slovakiia much, except for trekking over the Tatras and Pieniny. It's probably excess heat that's doing it in. You need to find some way of keeping it cool, even if it's an evaporative refrigerator.

A big aluminium box, insulated lid, set in a huge block of plaster of paris and standing in a large puddle of water would do it. Or leave a cold tap running over it. There are probably other chemicals that would benefit from it.
 
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