Red Sea Alkalinity Test - Save Unused Titrate?

[undermind]

I've been squirting my unused Alkalinity titrate back into the bottle.

I thought when I first read the instructions, that it said to do that. But I am mistaken. It says to do that with the Calcium test but specifically says to dispose of unused Alkalinity titrate.

Is there truly a good reason for this? What do you do? I do notice that the liquid is more "oily" than the other titrates, and doesn't leave as much of an air gap when filling 1ml into the vial. Not sure what that has to do with anything but the difference in perceived volume always bugs me when testing.

Thanks!

 

[lostcause]

I'm not certain but now that I look at the directions you're right. I've been doing it wrong too.

 

[JimWelsh]

First, the word is "titrant" (sorry - I can't help myself). IMHO, you can return unused titrant from the syringe back into the bottle for the Alkalinity test without worry or concern. Same goes for Ca and Mg. Same goes for Salifert as well as Red Sea.

 

[Dan_P]

I've been squirting my unused Alkalinity titrate back into the bottle.

I thought when I first read the instructions, that it said to do that. But I am mistaken. It says to do that with the Calcium test but specifically says to dispose of unused Alkalinity titrate.

Is there truly a good reason for this? What do you do? I do notice that the liquid is more "oily" than the other titrates, and doesn't leave as much of an air gap when filling 1ml into the vial. Not sure what that has to do with anything but the difference in perceived volume always bugs me when testing.

Thanks!

If you follow standard laboratory practices, you would never return a reagent to the bottle because of contamination risk and a ruined reagent that you just don’t know how ruined it is without extensive work. It is a bad practice.

Your choice: save a few pennies by saving leftover titrant and possibly ruin a kit worth dollars AND waste your time doing tests with a bad test kit, or waste the used reagent.

I would guess the majority of forum members return unused titrant to the bottle. I do.

Interlude. Funny how the human brain works, playing the odds wrong and then being mystified why things go wrong. Maybe that is why maintaining a complicated system like a saltwater aquarium often goes wrong.

 

[JimWelsh]

If you follow standard laboratory practices, you would never return a reagent to the bottle because of contamination risk and a ruined reagent that you just don’t know how ruined it is without extensive work.

If you follow standard laboratory practices, you would never re-use a disposable syringe either. So, by that argument we should be discarding the still partially full syringe, and using a clean, new syringe for each test! Taken a step further, we should also be "conditioning" each new syringe by initially filling it with the reagent, discarding that reagent, and then filling it a second time to do the titration.

Sure, absolute best practice would be to discard the reagent. But, as a practical matter, I must wonder aloud where this mysterious magical "contamination" is going to come from when using the same syringe for the same reagent for the same test each time? If someone is able to get, say, 70 tests out of a kit designed to give 50, then where's the harm?

 

[Randy Holmes-Farley]

If you follow standard laboratory practices, you would never re-use a disposable syringe either.

One time use alk kits. Go for it, Jim!

 

[Dan_P]

If you follow standard laboratory practices, you would never re-use a disposable syringe either. So, by that argument we should be discarding the still partially full syringe, and using a clean, new syringe for each test! Taken a step further, we should also be "conditioning" each new syringe by initially filling it with the reagent, discarding that reagent, and then filling it a second time to do the titration.

Sure, absolute best practice would be to discard the reagent. But, as a practical matter, I must wonder aloud where this mysterious magical "contamination" is going to come from when using the same syringe for the same reagent for the same test each time? If someone is able to get, say, 70 tests out of a kit designed to give 50, then where's the harm?

With regards to a clean syringe every time you run a test: YES. You are absolutely correct.

As far as “conditioning” the syringe, that depends on the size of the variability introduced by not doing it and whether the reagent actually affects the surface. A glass surface with all its hydroxyl groups might need “conditioning”. Plastic has a rather inert hydrocarbon surface and unlikely to require conditioning, but good to check on the compatibility of the material of construction.

Disposable equipment is disposable because it is cheaper than non-disposable equipment that requires manual labor to clean. Disposable equipment does not necessarily get used up or degrade with use, unless it is the markings on a syringe or flask, the stiffness of the rubber tip on the syringe plunger, or the sterility of plastic equipment.

So, a clean, re-used one-use syringe can be OK for the frugal analytical chemist.

Not cleaning the syringe introduces the possibility of reagent decomposition, for example, air oxidation, CO2 absorption, and bits of concentrated reagent on the surfaces. It does not guarantee a disaster, just increases risk of variability. Not cleaning the outside of the syringe pretty much guarantees contaminating the reagent with the test solution. Not a guaranteed disaster though, more like Russian roulette with a BB gun

Getting seventy tests instead of fifty tests? We’ll need some real numbers before we kick this idea around.

By the way, is the cost of test kits really that big a percent of the annual cost of owning a reef tank? What about electricity? Salt? Food? Additives?

If you are really, really, really interested in lowering the cost of testing, reduce the size of the test sample by half or one third where possible.

 

[infinite0180]

I just know where my alk should be and instead of drawing up a full syringe i only take a little more than i need. Works out fine if you know your alk...