Salifert strontium test kit

[hawkinsrgk]

This is the first time I have ever tried to test strontium and I must have done something wrong

When I got to the calcium part it read 434 ppm. I then added the two scoops to get the strontium part and and let it sit for 15 min and the color was blue. According to the test that would mean that my strontium is greater than 40 ppm

I have been using the balling lite from BRS to add 10 ml of strontium to one gallon of calcium solution. I have been doing this for about a year and then stopped two part for around two months after I started dosing kalk. I started two part back up when kalk could no longer keep up

Would it be possible that strontium is this high? I really wouldn't think this would be possible. The corals do not seem to show any problems

Thanks
Randy

 

[hawkinsrgk]

Also I should add that I do 8 to 10 percent water changes with reef crystals

 

[hawkinsrgk]

Every week

 

[Randy Holmes-Farley]

FWIW, I have no idea how much strontium might be in that strontium dosing liquid, so I can't really say if it is reasonable or not.

I'd use the kit on some new reef crystals salt mix and see how that comes out. It should be close to NSW levels of about 8 ppm.

The owner of Salifert (Habib) has occasionally been popping in here recently, so he might have some kit use comments.

 

[JimWelsh]

This is the first time I have ever tried to test strontium and I must have done something wrong

When I got to the calcium part it read 434 ppm. I then added the two scoops to get the strontium part and and let it sit for 15 min and the color was blue. According to the test that would mean that my strontium is greater than 40 ppm

You don't say anything about adding the 0.5 mL of Sr-4 reagent after you took your calcium reading and before adding the two scoops. Is it possible you missed a step? I'm referring to Step 7 in the instructions listed below, which I found online (perhaps your kit has different instructions):

Instructions

1] Fill test vial with 5 ml of water (use the 5 ml syringe)

2] Add 12 drops of Sr-1 and swirl gently for approx. 10 seconds

3] Add 1 level spoon of Sr-2. Swirl gently for 5 seconds.The color should be red/pink.

4] Fit the 1 ml syringe without the red label with the small plastic tip. Ensure that the tip is mounted firmly.
Fill this syringe with 1 ml of Sr-3 (lower end of black rubber ring at 1.00 ml mark)
Dose this amount in the test vial end swirl gently for 20 seconds. If the color has changed to blue and remains so even after an additional 30 seconds then the calcium concentration is far too low (approx. 300 mg/L or less) and should be corrected first before doing strontium testing.

5] Again fill this syringe with 1 ml of Sr-3. Add this drop wise to the test vial. Swirl gently for a few seconds after each drop until the color changes to blue.
If the color has changed to blue then swirl gently for 15 seconds. It is very likely that the color will revert back and will not be pure blue. In that case add one more drop of Sr-3 and swirl again for 15 seconds. Repeat this until the color remains blue.

6] Hold the syringe with the plastic tip facing upward. Read the value at the upper part of the black rubber ring. Look for this value in the calcium table to get the calcium concentration.

7] Fill the 1 ml syringe with the red label (no plastic tip needed and is not supplied) with 0.5 ml Sr-4 (lower end of black rubber ring at 0.50 ml mark. Add this to the test vial and swirl gently for 10 seconds. The color will now be red/pink.

8] Add two level scoops of Sr-5 and swirl gently until this powder has dissolved.
Let it stand for 12 - 15 minutes (use a clock).

9] Fill the 1 ml syringe without the yellow label and fitted with the plastic tip with 1 ml of Sr-3. Add this drop wise to the test vial. Swirl gently for 20 seconds (should definitely not be less than 20 seconds!) after each drop until the color changes to blue.

10] Hold the syringe with the plastic tip facing upward. Read the value at the upper part of the black rubber ring. Look for this value in the strontium table to obtain the strontium concentration.

 

[hawkinsrgk]

I didn't skip step 7. Basically it was blue after step 8

 

[JimWelsh]

OK, just checking.

 

[hawkinsrgk]

Just to give an update on this. I tested with Reef Crystals at 1.0245 and this is what I got after step 8 and letting it stand for 15 minutes.
I am not able to start step 9 because its already blue.

 

[Randy Holmes-Farley]

Looks purple on my screen. Does it not get darker blue after adding enough of the titrant?

 

[hawkinsrgk]

I was not able to see a difference. Going to run another test and see if I can get a blue color.

 

[Habib(Salifert)]

It looks on my screen as pinkish, close to getting purple.
Typically the color one obtains after adding the o.5 ml of Sr-4 and depending on the Sr concentration, after adding the Sr-5.

It definitely isn't blue. Despite drawbacks of uncalibrated computer/phone screens I'll take some pictures at various points and steps of the test and post it.
Hopefully it will be tomorrow otherwise on Friday.

 

[hawkinsrgk]

It looks on my screen as pinkish, close to getting purple.
Typically the color one obtains after adding the o.5 ml of Sr-4 and depending on the Sr concentration, after adding the Sr-5.

It definitely isn't blue. Despite drawbacks of uncalibrated computer/phone screens I'll take some pictures at various points and steps of the test and post it.
Hopefully it will be tomorrow otherwise on Friday.

Thank you so much for your help. I think that will really help. It is the 2 scoops of Sr-5 that is throwing me off.

 

[Habib(Salifert)]

Sorry, I was not able to post the pictures yesterday. I'll try it now.

The pictures were taken using a simple iphone, the colors appear darker than actual but the hue appears to be correct. Each induvidual screen will show it differently, depending on the settings and ambient light.
That is a sort of disclaimer that the colors/hues might not be represented correctly on devices.

The Strontium kit is the most difficult one within our line of kits. Strontium is very difficult to measure correctly in seawater by chemical means.

The test has a calcium part and a strontium part which can be performed after the calcium part.

In the next post pictures of the strontium part. Here the calcium part.

Step 3 is after addition of Sr-1 and Sr-2. The titration has not been started yet.

After that several more pictures are shown. The color starts to change clearly about 10 - 15 ppm before the end point.

The color goes from pink (which is a kind of red) to blue.
Once the color starts to show a change, there will be a transition from pink to blue and halway of that it will be a mix of both colors. That mix is a purple color. Once all the pink/red tinge is gone the color will be blue.


It is important to know that the color change is sharp and takes place in a narrow range of approx 10 -15 ppm!!!

This means that one should not strive to a even brighter blue. Blue is blue and knowing the transition range one could not be away from the true end point by more than 5 ppm calcium. Recognising a distinct change taking place in combination with the transition range of 10-15 ppm calcium should suffice.

The end point is at 413 /416 ppm calcium in this case.

 

[Habib(Salifert)]

In the strontium part, after the calcium part 0.5 ml of Sr-4 is added.
The color changes to red/purper.

After adding two scoops of Sr-5 and waiting time:

Now a few additions of one drop at a time with the swirling time etc. as in the instructions:

As one can seee the change in color is for both the calcium and strontium part very similar.

 

[hawkinsrgk]

Thank you for the detailed explanation. I really appreciate it. This gives me something to work toward. This is the only test that I have had trouble with

 

[JimWelsh]

I have a couple of questions. Isn't it true that in the first "Calcium" titration, both calcium and strontium together are actually being titrated? Also, since the same titrant is used for both titrations, and since strontium is 87.62 / 40.078 = 2.2 times heavier than calcium, doesn't that imply that a 5 ppm error in the calcium titration would cause an 11 ppm error in the strontium result?

 

[Ponraj A]

May be its foolish but i am getting confused on it, can anybody help me out,
when measuring the calcium part in strontium testing with Salifert if the reading in syringe is standing for example if we read from top of the syringe it stands at 38 and the same reading lines we can read from bottom as 42. Reading the measuring line marks in the syringe body from top or bottom is always making me confused.
I hope what I have written is clear, can some body clarify me please

 

[Randy Holmes-Farley]

I describe in detail exactly how to measure with a syring here:

https://www.reef2reef.com/threads/reef-chemistry-question-of-the-day-161-using-a-syringe.226267/

The thread has pictures and more discussion, but here's the answer to the question posed there:

Here's how to think about how a syringe works:

When the plunger is pushed all the way in, the leading edge of the plunger aligns with the zero mL marking. That is true of nearly every syringe I've seen. When you begin to use it, the tip and barrel are empty, with the tip containing air and the barrel occupied by the plunger.

As you draw back the plunger with the tip in a liquid, the plunger creates a vacuum between it and the liquid, drawing in the liquid. The movement of the plunger draws in exactly the amount of liquid equal in volume to the travel of the plunger backwards (or upwards). So you can track how much fluid is taken up exactly by the travel of the plunger against the volume markings, regardless of what you see with the fluid (assuming it is functioning properly).

Some of the drawn in liquid will be in the tip, and some (or perhaps none, if it is all in the tip) will be in the barrel of the syringe. If the volume of the tip is larger than the volume indicated by the movement of the plunger, none will show in the barrel. Many modern pipettes work this way to avoid contaminating the barrel of the device. The device stays clean and the tip is discarded after each use.

Now, when you go to dispense the liquid, the plunger is pushed in, and all of the liquid is dispensed and the air is pushed back into the tip.

If you mistakenly tipped the syringe upward during dispensing, and blew out the air before the liquid, then when you push the plunger all the way in, there will still be liquid in the tip, and you probably won't know how much so you end up with a mismeasurement.

In the medical world, it can be super important to not inject air into a patient's bloodstream. In that case, the syringe must first be overfilled. It is then tipped up and all of the air blown out and some liquid may be blown out until the end of the plunger is exactly aligned with the volume marking you want to dispense. The syringe in total now contains the amount you want to inject, plus the volume of the the needle. Then you inject and when done, the needle is still full of liquid in the exact amount as before injection, and like before, the amount dispensed is exactly determined by the movement of the plunger. So this situation is no different except that you start and end with a full tip/needle. In a non-injection setting, you start and end with an air-filled tip.

So it doesn't matter how much liquid you see in the barrel. Only the movement of the plunger is important, whatever the use.

 

[Ponraj A]

Dear Mr.Randy,
Many thanks for your time and reply, So as you mean, after filling the syringe with 1ml of liquid till the top of black tip and after the insertion of liquid by pushing the syringe from top to bottom and when the tip of syringe stands between 0.3 to 0.4ml. Then as per the calcium chart of strontium test as below whether I have to take the reading as 0.35 or 0.45 or 0.65, this is my biggest confusion Mr.Randy,

"6] Hold the syringe with the plastic tip facing upward. Read the value at the upper part of the black rubber ring. Look for this value in the calcium table to get the calcium concentration."

 

[Ponraj A]

@Randy Holmes-Farley
I hope you understood my confusion as per the #6 of Salifert instruction it has mentioned to read the upper part of the black rubber ring and my confusion is when the upper part is standing in the middle of 0.3 to 0.4 if we count the numbers from top it will 0.35 and if we count the numbers from bottom it will be 0.45 which makes difference in the reading as per the below chart of salifert strontium test.

If i read 0.35 then the calcium as per below chart is 491 mg/L
If i read 0.45 then the calcium as per below chart is 467 mg/L

Calcium Table

Reading from step #5 Calcium mg/L

0.96 308

0.92 320

0.88 332

0.84 344

0.80 356

0.76 368

0.72 380

0.68 392

0.64 404

0.60 416

0.56 428

0.52 440

0.48 452

0.44 464

0.40 476

0.36 488

0.32 500

0.28 512

0.24 524

0.20 536

0.16 548

0.12 560

0.08 572

0.04 584

0.0 596