Does the Hanna Iodine Test Read Iodide?

USING HANNA CHECKER Hullo-707 TO Test FOR IODINE
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In my quest to ameliorate my testing accuracy and precision I plant the standard colorimetric tests for Iodine hard to become any kind of accurate reading and the repeatability (precision) was not very good. Being that I dosed Iodine this made me uneasy almost the actual levels. So I decided to take the same approach I did with Nitrates. I institute a Hanna Checker that I could utilize with the Red Ocean Iodine Test Chemical science and proceed to set up a DIY exam protocol. What follows is a bit of groundwork on the test evolution, the data on accuracy and precision…The exam procedure in particular (video) and comparisons of results to outside testing services.
My quest started well over a year ago and has taken several twists and turns…Different examination chemistries…dissimilar measuring instruments…dissimilar procedural steps, and combinations thereof. I will not bore yous with all of the details (and at that place are lots) but will hit the highlights that support the results.
Here is what I will comprehend:

• Summary ---The Process (With Video)
• The principle of the exam
• The Chemistry
• The Instrument
• The generation of the regression
• The Standards
• The Measurements
• Goodness of Regression Fit
• The test Accuracy Results
• The test Precision Results
• The test results measured against outside testing
• Boosted Work

SUMMARY
This summary provides the general details of the procedure step by step. It is intended to get forth with the posted video and volition allow to perform the test without going into the technical details of the procedure development. For those of you who might be interest in the details of the exam evolution and all the "Technical Stuff" that starts with section
II THE PRINCIPLE.

I THE Process

EQUIPMENT NECESSARY

1) Hanna Howdy-707 Nitrite LR Checker ​

2) Red Sea Iodine Pro Reagents A & B​

3) Two Hanna Checker Vials ​

4) Timer​

v) Authentic Pipette(s) or Syringe cable of measuring .v mL and .8 mL ​

6) RODI Water for rinsing vials & pipettes ​

7) Accurate Thermometer​

8) Sample Water Container (I use a chalice or plastic bottle)​

Procedure…STEP BY Stride (See Included Video)

1) Fill vial with water to be tested. This volition be the Blank. Place it into the Checker​

ii) Set Timer to 1 Minute 45 seconds​

three) Rinse 2nd vial with water to be tested​

4) Fill second vial with h2o to be tested.​

5) Add .5 mL of reagent "A" to second vial containing the examination water.​

6) Add .viii mL of reagent "B' to the second test vial — IMMEDIATELY Offset TIMER!! ​

7) Put the cap on the second vial and invert the vial several times​

8) Press the button on the Hanna Checker…When "C1" appears press again…."C2" will now be on the brandish.​

9) Remove the blank vial from the checker and put the second vial into the checker.​

10) The Timer should be still counting down from ane:45…When the timer reaches "0" IMMEDIATELY Printing THE Push button ON THE CHECKER TO GET THE READING ​

11) Tape the value appearing on the meter…This is the value you put onto the formula below.​

12) Measure out AND Tape THE TEMPERATURE OF THE SAMPLE BEING TESTED​

NOTE ON TEMPERATURE: Temperature beneath 73⁰F at lower iodine (<.02ppm) concentration levels will cause the HI-707 to exceed its measurement limits of 600. It is recommended to keep the sample temperature to a higher place 73⁰F. Meet the section on the "Regression Equations" for details in computing the PPM iodine.

Multiply the meter reading by -.0003292492 and so add 0.1973653 This will = PPM Iodine

Case: (No Temperature Correction)

Meter Reading 422

1) 422 x -0.0003292492 = -0.138943162​

ii) -0.138943162 + 0.1973653 = 0.058 PPM Iodine​

NOTE ON TEMPERATURE: Temperature beneath 73⁰F at lower iodine (<.02ppm) concentration levels will cause the HI-707 to exceed its measurement limits of 600. It is recommended to keep the sample temperature to a higher place 73⁰F. See the section on the "Regression Equations" for details in computing the PPM iodine. NOTES ON THE PROCEDURE : The time is very critical to achieving accurate and precise results so paying attention to first and stop times is important. In add-on the authentic measurement of the reagents is of import to getting skillful results. I generally run ii tests dorsum to dorsum and take an average of the values. If the two results are greater than 5% from each other I run a third test and take the average of the 3 every bit my value…This does not happen very often. (Run into Table 3) Total testing fourth dimension is approximately vi-viii minutes….One note on the video. The video shows Pace 7 and 8 in different order than the process calls for…The procedure is the correct mode.

VIDEO of PROCEDURE

2 THE PRINCIPLE

The principle is much the same equally other colorimetric tests. A sample is mixed with a serial of reagents that react with the ion beingness tested for in such a manner as to produce a distinct colour. The saturation of the color is proportional to the concentration of the ion in the test water. Is some tests the higher the concentration the more saturated the color (straight proportional to concentration). In other tests (similar the Blood-red Sea Iodine Test) the higher the concentration the lower the saturation (Inversely proportional). Once the reaction is complete the color can be compared to a standard color carte du jour or measured spectrophotometrically by using an musical instrument like a Hanna Checker to determine the value.

THE Chemical science
The chemical science I chose for my work is the Red Sea Iodine Pro Test. I tried others but this one ended up the best for my application. I am not going to go into the chemical science itself but am going to note two important factors that bear on the effect of the test results.
First the reaction is fourth dimension sensitive….This is best illustrated by Effigy 1.

Fig 1 ​

As y'all can see every bit the level of Iodine concentration increases the steeper the time dependency becomes. I ran two tests at each level to confirm the results. The cherry line represents the time interval I chose every bit my standard fourth dimension, 1 min 45 seconds. I chose this because this was the time interval that the Red Body of water Standard matched the .06 level on the standard color card but given the results in Fig 1 other time intervals could work. The implications of this fourth dimension dependency on the test procedure is the test must be accurately timed.

The 2d gene is the reaction is temperature dependent. Encounter Fig two

Fig ii

Once again I ran 2 sample sets to ostend the results. The outcome is for every 1⁰ F it changes the meter value by ±v units. The implications for this temperature dependency are that the sample temperature needs to be folded into the regression formula.

Annotation: Temperatures below 73⁰F at the lower levels of Iodine (<.02) will exceed the range of the HI-707 Meter (600). And then it is recommended if the sample temperature is below 73⁰F that the sample be warmed upwardly.

THE INSTRUMENT

The Hanna Checker I finally chose after testing several others is the Howdy-707 Depression Range Nitrite Colorimeter. Its light source is a 470nm LED. It measures in parts per billion from 0- to 600 ppb. Stated accuracy is ± 20 ppb ± v% of meter reading. The detector is a Silicon Photocell. Subsequently running multiple Iodine samples at v different levels (.01, .03, .06, .07, and .ane ppm) the relative precision was very good < ± 5 % of the mean at every level except the .01ppm level which was college because it is well-nigh the limits of detection.

III. THE REGRESSION

THE STANDARDS
All of the standards were prepared using reagent grade potassium iodide (KI). The standard levels prepared were .01, .03, .06, .one ppm using a volumetric flask and an analytical scale. The water used to set up the standards was salt water made from reagent class Sodium Chloride at 35 ppt. There is a slight salinity effect (Run into Fig 3) so standards should be prepared in water close to your tanks standard salinity. Information technology does not work with RODI water! Two sets of standards were prepared and compared against each other to cheek for errors. In improver some time later a three set was prepared every bit a last validation. I besides prepared 2 sets of standards using the Blood-red Sea Potassium Standard (KI) and measured them as well. There is a great bargain of information associated with this project. I will not diameter you with all of it just the concluding confirmation data volition exist included in this write up. If you lot are interested PM me and I would exist happy to share it with you.

THE MEASUREMENT
Each standard was measured a minimum of 5 times and in some cases 8 times according to the above procedure. The information was recorded and used to generate the regression bend for the PPM Iodine calculation (See Table 1). I used the Excel Information Assay too every bit a program chosen MyCurveFit (

https://www.mycurvefit.com/ ) to generate the regression curve. (Meet Fig 4 & 5)

Table 1

Fig three

Fig four

Fig 5

GOODNESS OF FIT

The goodness of fit of a statistical model describes how well it fits a ready of observations. Measures of goodness of fit typically summarize the discrepancy between observed values and the values expected under the model in question. In the to a higher place figure the columns labeled "Measure out" and "Value provide the data for the Goodness of fit for the selected regression. The depression P value and loftier F value are indicators that the regression is good. Besides the Standard Fault of the Estimate (SE) is low which indicates the regression is relatively accurate.

THE REGRESSION EQUATIONS

Y= The Calculated PPM of Iodine 10= The Meter Reading on the Hanna Checker
T= The Temperature of the sample being tested

NO TEMP CORRECTION Y= -0.0003292492 ten X + .01973653
To get the PPM Iodine—

i) Multiply the Meter reading Value Past -0.0003292492​

2) And so add to the value in step 1 + .01973653​

TEMP CORRECTION Y= -.0003417494 x (((T-79)x 5) + 10)) +0.2008589

To become the PPM Iodine---

1) Subtract 79 from the measured sample temperature. Note if T is less than 79 the number will be negative.​

two) Multiply the value from step 1 by 5. ​

3) Take the value from step 2 and add it to the meter reading…Annotation the number may be negative so you will need to decrease it​

iv) Multiply the value from footstep 3 by ​

5) Then add to the value in step 4 ----THIS IS THE PPM Iodine in Your sample​

EXAMPLES

​

Meter Reading 422​

Temperature of Sample 77⁰ F​

NO TEMPERATURE CORRECTION

1) 422 x -0.0003292492= -0.138943162​

ii) -0.138943162 + 0.1973653 = 0.058 PPM Iodine ​

TEMPERATURE CORRECTION

1) 77-79 = -2 ​

two) v 10 -2= -10 ​

3) 422-x= 412 This is the meter reading corrected for temperature ​

4) 412 10 -0.0003417494 = -0.140800753 ​

5) -0.140800753 + 0.2008589 = .06 PPM Iodine ​

As you lot tin can see the divergence betwixt the temperature corrected value and the uncorrected value are not significant so the simpler method would be the ameliorate choice. However when the sample temperature is 75 or less or higher up 83 it starts to go significant… Remember this is not the tank temperature it is the sample temperature. The sample may have set around for a menses of time and gotten cooler or warmer depending on the surroundings.

4. Test Accurateness & PRECISION

KNOWN STANDARDS RESULTS:

Tabular array 2

For Accuracy I use

Relative Accuracy (RA).
This value is expressed every bit a %. Any value less than or greater than 100% indicates a level of fault. The relative Error can and then exist plant by subtracting the Relative Accuracy from 100. The math looks like this:
(Bodily value) - (Actual value – Measured Value) divide this past the Actual value

For Precision nosotros volition use Relative Standard Deviation (RSD).

This value expressed in % tells us if the calculated standard departure is small or big compared to the average value for our data set up. A pocket-size number ways there is pocket-size variability in our information clustered around the average. This would indicate practiced repeatability. A large number would signal a lot of variability in our measurement. The math looks like this
(Standard Deviation of the Data Set x 100) Divide by (The Average Value of the Data Set up)

The accurateness and Precision are quite skilful for this regression (Come across Table two). The .01PPM has a lower level of Accuracy and Precision due to the fact the test is approaching the limits of detection for the test but none the less it is withal within an adequate range for my use. I am currently working to refine the examination to get meliorate results at the lower levels.

RELATIVE PRECISION OF METER READING & CALCULATED PPM

As I mentioned higher up I have been measuring the sample 2-3 times to get an thought of the precision of the test. Table 3 shows the meter readings and calculated PPM over several exam dates testing my tank water. As you can meet the relative precision is very good. The lower the percentage the more repeatable the test is. Because the relative precision is this good I would feel confident in taking a single measurement.

Table 3

Outside TESTING LABS RESULTS:

Over the terminal yr I have been sending my water samples to 3 outside testing labs and the comparing my results to theirs. (Run into Tabular array 4)

TABLE 4

As the data in Table 4 shows my results using this exam for the most function agree with the outside testing service results. The 9/16/19 results were an error on my office. A retest of the sample gave a result of .057ppm. I am not sure why the outside testing results from vendor # 3 are so much lower, just as you can see they are consistently lower.

5. CONCLUSIONS

Well that nigh sums information technology up. The exam is relatively simple to do, but does take some practice. By paying close attention to time and temperature proficient accurate and repeatable results can be obtained. I am standing the piece of work to improve the lower level accuracy and precision and go along to employ the test to monitor the Iodine level in my tanks.
If you lot have whatsoever feedback or question don't hesitate to PM me…Hope you observe this useful.

ACKNOWLEDGMENTS
I would similar to personally give thanks @Dan_P and @taricha for their aid and support. Their input and management provided insights to working on developing this examination. Information technology is great to be in community similar Reef ii Reef where quality people like these two are willing to come along side to encourage and support….Thanks for your help!

An culling test method was developed by @taricha. It uses a different Hanna Checker and a different test kit. Information technology is a good repeatable test. The details can be found in the link below.

https://world wide web.reef2reef.com/threads/iodide-test-seachem-kit-and-hanna-silica-meter.391003/

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