DIY Alkatronic reagent

[Jason_MrFrags]

Randy is been years since chemistry class can you please check my calculations?

Alkatronic uses sulfuric acid for their reagent and I would like to DIY instead of spending way too much for the concentrate.

The concentrate reagent is 1mg/m3 that is diluted 1:4 with RODI to .2mg/m3 for testing


Calculation of DIY 1mg/m3 H2S04 concentrate

1mg/1000l = .001g/1000l = .000001g/l

.000001g/98.08g = .00000001019475 mol H2SO4


[H2SO4] 00000001019475 mol/1l
= .00000001019475M

.00000001019475M/.05M =.000000203915

Using .05 M stock concentration H2SO4 from Amazon
Would add .000203915ml with RODI for 1L total volume for reagent concentrate.

That number seems low so I feel like my math is off someplace.

 

[Silver14SS]

@Randy Holmes-Farley

I'm interested as well, thanks for posting the topic!

 

[Dennis Cartier]

@Randy Holmes-Farley

I'm interested as well, thanks for posting the topic!

Ditto here. I am running low on concentrate and it is not sold here (in Canada).

Dennis

 

[JimWelsh]

The concentrate reagent is 1mg/m3 that is diluted 1:4 with RODI to .2mg/m3 for testing

What is your source for this? Whatever it is, please double-check it. I seriously doubt that the "1mg/m3" part is correct. I mean, is this chemistry or homeopathy?

Would add .000203915ml

I want to know what sort of equipment you have that can measure volumes down to the picoliter with six significant figures of precision.

 

[Jason_MrFrags]

What is your source for this? Whatever it is, please double-check it. I seriously doubt that the "1mg/m3" part is correct. I mean, is this chemistry or homeopathy?


I want to know what sort of equipment you have that can measure volumes down to the picoliter with six significant figures of precision.

I have a pipette that will measure 10-200ul

I ordered direct from foustronic and was one of the first to receive before coralvue took over as distributor. I had to fill out the fedex customs paperwork. Those were the concentrations provided to me on paperwork from manufacturer because FedEx would not take proprietary formula.

 

[ReeferBud]

Very interested in this as well. There’s a thread around here from someone who came up with a diy formula for the KH Guardian, but that was using HCl

Agree that 1 mg/1000 l seems funny.

Following...

 

[JimWelsh]

I have a pipette that will measure 10-200ul

I ordered direct from foustronic and was one of the first to receive before coralvue took over as distributor. I had to fill out the fedex customs paperwork. Those were the concentrations provided to me on paperwork from manufacturer because FedEx would not take proprietary formula.

Fair enough. But the volume you are describing is 0.2 uL. In a whole liter. To make the "concentrated" reagent. Which you will then dilute 4:1.

Aside from the sig fig abuse, your math looks fine. So, if you're going to dig in on the original formula being correct, then I really can't help you.

But, please indulge me while I think out loud about this: I don't know how much sample Alkatronic uses, but I can use a "what-if" value of, say, 10 mL, and you can then adjust my numbers up or down proportionally to fit them to the actual sample volume used. 10 mL of tank water at, say, 8.0 dKH contains 8.0 / 2.8 = 2.86 (please notice that I didn't say "2.857142857") * 10 / 1000 = 0.0286 meq of alkalinity. Now, your 0.0000000102M (sorry for rounding -- I just can't do that many sig figs with a straight face) "concentrate" will be diluted 4:1 for a final normality of 0.0000000102 / 4 * 2 = 0.0000000051 N. In order to neutralize 0.0286 meq with 0.0000000051 N reagent will require 0.0286/0.0000000051/1000 = 5600 liters of reagent. As I said, feel free to adjust that number up or down with regards to the actual Alkatronic sample volume, in proportion to my 10 mL assumption.

Now, I've seen the Alkatronic in person, and I'm quite certain that it's not big enough to hold that much reagent in the reaction chamber.

Again, your math is fine. But the underlying premise of the "1mg/m3" "concentrated" reagent is fundamentally flawed.

 

[Beonedge]

Just an thought how to measure how strong is diluted alkatronic reagent - measure the weight of reagent in container before /after measurement will give amount of reagent used , and need to be measured ph before/after + total volume of sample . With this data maybe can be calculated how stronger acid is reagent

 

[ReeferBud]

I think the way to do this would be to determine the concentration of the diluted alkatronic reagent by titrating against a standard base.

If anyone has access to lab equipment and a standard base, this could be done pretty easily.

 

[Dennis Cartier]

I tend to agree with Jim here. The concentration numbers the OP is focusing on look very suspect. Perhaps the value that Focustronic provided to the shipper was not based in reality and was only intended to meet a requirement for approval.

I purchased a collection of small pycnometers awhile back but never got around to trying to establish the concentration of the reagent. The volumes that are involved gave me reason for pause as small errors will get magnified when scaled.

I am wondering if one cannot simply use the method that Focustronic suggests for testing your baseline calibration to do successive approximations on the concentration of the reagent until you zero in on the amount a standardized acid needs to be diluted. See http://www.focustronic.net/media/wysiwyg/Tip_how_to_use_the_baseline_cal.pdf

This method would be similar to what @ReeferBud suggested, except uses an off the shelf alk test instead of doing a manual titration. Doing a titration like @Randy Holmes-Farley lays out in one of his articles (http://www.reefedition.com/a-diy-alkalinity-test-by-randy-holmes-farley/) using a standard base should give pretty good results.

Dennis

 

[Randy Holmes-Farley]

As folks have noted, there’s no chance anyone is doing an alk titration using 1 mg/m3 as the sulfuric acid concentration. It won’t work. The solution would become massively diluted before the endpoint is reached, and the pH of the acid itself is higher than the endpoint, so no alk value can ever be determined.

 

[Jason_MrFrags]

As folks have noted, there’s no chance anyone is doing an alk titration using 1 mg/m3 as the sulfuric acid concentration. It won’t work. The solution would become massively diluted before the endpoint is reached, and the pH of the acid itself is higher than the endpoint, so no alk value can ever be determined.

I have 20 pages of the msds that foustronics provided.

 

[JimWelsh]

The "Exposure Limit" is not the concentration of the substance in the reagent. It's important to understand what the numbers you are reading actually mean, and what the context is.

 

[ReeferBud]

Ok, everything is cool

The original intent of the OPs post is still valid about trying to find a DIY reagent solution. Where do we go from here?

 

[Dkeller_nc]

Yep. MSDS sheets (more properly called "SDS sheets" now) generally don't give the actual concentrations of compounds in the formulated product. Instead, they simply note the identity of potentially hazardous reagents and the overall hazard of the product in its final formulation.

The correct way to determine the acid concentration in the Alkatronic reagent is, as ReeferBud noted, an acid-base titration with a pH meter using a base solution with a standardized concentration. The equipment to do this properly is fairly modest - you need a properly calibrated pH meter, a magnetic stir plate, stir bar, a graduated buret and buret stand, and a standardized base solution (typically, sodium hydroxide). You can buy all of this off of amazon for about $150, depending on your choice of pH meter.

If you choose to do this, I'd suggest purchasing a 0.1N standardized sodium hydroxide solution. If that turns out to be too concentrated, you'll also need a way to precisely dilute it with RODI. The standard laboratory method is to use a 100 mL graduated cylinder and a 1 liter volumetric flask (100 mL of 0.1N NaOH diluted to 1L in a volumetric flask will yield a 0.01N NaOH solution). Again, this glassware can be purchased off of Amazon very inexpensively.

If you cannot purchase a standardized sodium hydroxide solution in Canada because of shipping or other regulations, you can make a fairly accurate NaOH solution from pure lye using an accurate laboratory scale and a volumetric flask, stir bar and stir plate.

 

[ReeferBud]

Yep. MSDS sheets (more properly called "SDS sheets" now) generally don't give the actual concentrations of compounds in the formulated product. Instead, they simply note the identity of potentially hazardous reagents and the overall hazard of the product in its final formulation.

The correct way to determine the acid concentration in the Alkatronic reagent is, as ReeferBud noted, an acid-base titration with a pH meter using a base solution with a standardized concentration. The equipment to do this properly is fairly modest - you need a properly calibrated pH meter, a magnetic stir plate, stir bar, a graduated buret and buret stand, and a standardized base solution (typically, sodium hydroxide). You can buy all of this off of amazon for about $150, depending on your choice of pH meter.

If you choose to do this, I'd suggest purchasing a 0.1N standardized sodium hydroxide solution. If that turns out to be too concentrated, you'll also need a way to precisely dilute it with RODI. The standard laboratory method is to use a 100 mL graduated cylinder and a 1 liter volumetric flask (100 mL of 0.1N NaOH diluted to 1L in a volumetric flask will yield a 0.01N NaOH solution). Again, this glassware can be purchased off of Amazon very inexpensively.

If you cannot purchase a standardized sodium hydroxide solution in Canada because of shipping or other regulations, you can make a fairly accurate NaOH solution from pure lye using an accurate laboratory scale and a volumetric flask, stir bar and stir plate.

Awesome, thanks.

Would one be able to use the same ph probe as is used in the aquarium? Or could it get damaged? Or is using phenolphthalein good enough?

I found this pretty good walkthrough to determine the concentration of sulphuric acid with NaOH. Had to dust off my chemistry cobwebs...

https://www.webassign.net/userimages/fgdennis@waynecc/Lab_Titration_H2SO4_Intro.pdf

 

[Dkeller_nc]

An aquarium pH meter would be suitable, and the electrode won't get damaged as long as you perform the titration then remove the probe and rinse it. Dilute sulfuric acid won't hurt the probe, but you don't want to leave it in a sodium hydroxide solution. Electrodes with a polymer membrane junction would probably be OK in sodium hydroxide, but one with a crushed-glass junction won't, at least if it's left in the sodium hydroxide solution for lengthy periods. Note that if the titration end point is correct (pH 7-8 or so), then you're not actually exposing it to sodium hydroxide. My cautionary statement is for instances when the endpoint is overshot (pretty common the first time you do one of these) and the pH goes to >12. No big deal if you remove the electrode and rinse it thoroughly within a few minutes, but problematic if you get interrupted and a glass-junction electrode stays in the solution for >10 minutes.

Phenolphthalein would be OK as an indicator, but most don't have that laying around.

 

[ReeferBud]

An aquarium pH meter would be suitable, and the electrode won't get damaged as long as you perform the titration then remove the probe and rinse it. Dilute sulfuric acid won't hurt the probe, but you don't want to leave it in a sodium hydroxide solution. Electrodes with a polymer membrane junction would probably be OK in sodium hydroxide, but one with a crushed-glass junction won't, at least if it's left in the sodium hydroxide solution for lengthy periods. Note that if the titration end point is correct (pH 7-8 or so), then you're not actually exposing it to sodium hydroxide. My cautionary statement is for instances when the endpoint is overshot (pretty common the first time you do one of these) and the pH goes to >12. No big deal if you remove the electrode and rinse it thoroughly within a few minutes, but problematic if you get interrupted and a glass-junction electrode stays in the solution for >10 minutes.

Phenolphthalein would be OK as an indicator, but most don't have that laying around.

Thanks! I found phenolphthalein for about $10 and was thinking that could be a better option if there was a good chance the probe could be damaged but it doesn’t seem like that’s the case.

I was also able to find most of the materials on Amazon for about $100 like you mentioned. Wish I had access to my old university chemistry lab though

Thinking ahead, one could buy 1L of 1M sulphuric acid for $40. Will be interested to do the econs to figure out how much would really be saved vs purchasing the concentrated reagent.

Found this on Amazon but did not see a purity listed. Assuming it should be good since it’s lab grade.

Sulfuric Acid Solution, 1M, 1L - The Curated Chemical Collection Amazon product

 

[Dkeller_nc]

I don't personally think the purity matters all that much (within reason) because you're not dosing it into the tank. One other aspect of buying something like this online is that a lot of the cost is hazardous materials shipping. So you might find that 4 liters is about the same cost as 1 liter.

 

[Randy Holmes-Farley]

Thanks! I found phenolphthalein for about $10 and was thinking that could be a better option if there was a good chance the probe could be damaged but it doesn’t seem like that’s the case.

I was also able to find most of the materials on Amazon for about $100 like you mentioned. Wish I had access to my old university chemistry lab though

Thinking ahead, one could buy 1L of 1M sulphuric acid for $40. Will be interested to do the econs to figure out how much would really be saved vs purchasing the concentrated reagent.

Found this on Amazon but did not see a purity listed. Assuming it should be good since it’s lab grade.

Sulfuric Acid Solution, 1M, 1L - The Curated Chemical Collection Amazon product

There is zero chance the probe would get damaged by properly doing a pH titration. I agree I would not sore it at high pH. Glass slowly dissolves at very high pH.