Hello group, I was wondering if any of you out there use a continous inline monitoring system to monitor your chlorine/chloramine levels in your water rooms. We currently use a Hach pocket colorimeter to do our checks x3 daily, but because the checks are done by different staff etc, we get some inconsistancies. This has caused our unit director to ask me to find some alternatives for monitoring our chlorine/chloramine levels. He is wanting something that is relatively hands off that continously monitors the chlorine/chloramine levels going into/between and after our carbon beds.
I appreciate any information I can get.
Thanks

We use Hach Stericheck Sensitive Total Chloramines and Residual Chlorine Test Strips
But, hold on, what does your technical policy and standard manual states? There should be an election of your governing body to what procedure your clinic should be using

My personal fedeling is that NO ONE should be using those test strips to check chlorine/chloramine levels post carbons. The reason being is two fold, one, the sensitivity only goes down to .1ppm which is the maximum allowable level, and two, the color variation on those strips is so slight and subject to each persons interpetation that reading errors could easily occur. Plus, factor in the fact that if the bottle of strips is left open for any length of time the strips will often give errant readings. Because of this we have adopted a policy against using these type of strips.

The maximum level of chlorine and chloramine in water used to prepare dialysis fluid will not exceed AAMI standards of: 0.5 ppm for chlorine and 0.1 ppm for chloramine. Total chlorine (max) will not exceed 0.1 ppm (free chlorine + chloramine). Any person doing the said job should be inserviced properly and two people should be interpreting the readings. Check for expirations. As long as the procedure being used by the clinic is goverment approved (State audit OK) there should be no worry.

We are making a Triple ORP monitor for monitoring dechlorination. ORP is a surrogate measurement of oxidant concentration. This monitor is used with three ORP probes and alarms on high mid or out ORP. You can see on our website: awewater.com.

I agree with svh-biomed to not use the test strips for the reasons given.

I have used inline chlorine analyzers in other industries, but I have never seen them in the dialysis industry. HACH makes a nice inline chlorine analyzer, but it is expensive.

The hand-held colorimeters say they can read to 0.01 ppm, but they are not accurate below 0.1 ppm, especially when using a powder DPD reagent. This is true for the HACH, LaMotte, or the Orbecco meter. The powder adds cloudiness to the sample and blocks some light, but typically not enough for it to read above 0.1 ppm. The result you get can depend on how long you wait for the powder to settle and how much you stir the sample. There are liquid DPD reagents available that do not create the cloudiness, and, therefore, give a more consistent result. The liquid reagents are a little more expensive than the powder reagents. I would suggest trying the liquid reagents before installing an inline chlorine meter.

The DPD method used for the chlorine analysis has some interferences; over 300 ppm alkalinity can interfere, bromine, iodine, ozone, manganese and chromium can also interfere. There are ways to neutralize the sample if you have these interferences.

I have never use ORP for chlorine. I have heard some clinics use ORP to measure ozone residual. The critical issue will be what ORP reading guarantees <0.1 ppm Total chlorine.

The other option is get rid of the colorimeter and just use the color chart. As long as the color of your sample is lighter than the 0.1 ppm window, you meet the requirement. The colorimeter leads to too much discussion. One sample is 0.04; another is 0.07. Technically, these results are the same. The colorimeter just makes people believe they are different.

One more thought on this.

I also don't recommend using the color wheel like the one used in the Hach kit. This is an excellent kit, but it allows you to interpret results below 0.1 ppm just like the colorimeter....especially when you put the mirror in to read 5x more accurate. I prefer the kits that have a single window showing the 0.1 ppm color. If your sample is lighter than this window, you meet the requirement. The kit does not allow you to interpret a result below 0.1 ppm. If you use the color wheel, I would suggest glueing the wheel at 0.1 ppm so your tech can not try to record a result below 0.1 ppm (but glueing the wheel at 0.1 ppm does not allow you to use the kit to measure raw water chlorine). It would be nice if the color wheel only went down to 0.1 ppm.

In regard to total chlorine test strips vs. DPD test kits:

The RPC K100-0106 EZ-Chek(R) Sensitive Total Chlorine Test Strips:

1) Compete favorably with the DPD colorimeter kits.
A. There are less variables for error with the strips (e.g. no powder to spill, no long time periods to overshoot, etc.).

B. Research studies prove the accuracy of the strips relative to the DPD kits and more importantly, relative to the benchmark chlorine test: amperometric titration. To get a true picture of accuracy, both the strips and the DPD kits must be compared to an amperometric titration test for the same water sample. Contact me if you want me to email you copies of the properly designed controlled, scientific comparison studies, etc.

C. Some of our customers have pointed out that they have experienced manganese interference with the DPD test. Manganese in
their water caused the DPD test to read false positive for total chlorine. In these clinics, our K100-0106 test strip correctly showed no discernable chlorine. Because the DPD test was their original test method, their first inclination was to believe it over the test strip...when in fact the test strip was reading properly and the DPD test was not. Typing "DPD manganese interference" into Google results in articles and studies that prove /discuss this interference.

2) Have been used for years by a majority of dialysis clinics for total chlorine testing between carbon tanks (RPC records)
A. Given the huge number of centers that test their water with the strips, the test strips are now the clinical norm for testing between carbons. The use of the DPD colorimeter methods have become the exception.

3) Use only the quantitative instructions when using the test strips for testing water between the carbon tanks.
For best strip performance, be sure to swish (move back and forth) the strips within the water sample.

The other K100-0106 strip instructions (qualitative procedure) have been used to test the rinse water of dialysis machines when a
0.1 ppm sensitive test is not needed, nor desired. Because of potential confusion with two procedures, we recommend that the
K100-0106 only be used for sensitive testing (water between the carbons). Use our K100-0101B (0.5 ppm) to check for the removal of bleach from dialysis machines. See RPC application note: appl0101.doc

4) Occasionally we find that a technician, who is used to using the DPD kit, will try to compare strip results to the DPD kit results. In most cases the comparison is not carried out in a controlled, scientific manner and therefore the comparison results are not valid. In fact, as pointed out in #1B above, the results from both methods should be compared to the results from an amperometric titration test of the same water sample. This is necessary because the test strip may be providing the more accurate result...yet, the technician may believe the DPD kit results because that is what they are used to using.

Nick Grimley
RPC
cc Vern Taaffe

Nick/Verne,
Hello, its good to see you guys are still out there. I appreciate your reply and information, however it has been my experience(as well as others)that the test strips you are refering too DO NOT indicate any levels below .1 ppm and the color difference/change between 0 and .1 is so slight that it is often misinterpeted. Personally the risk to our patients is not worth this risk and I have a very hard time believing that these strips are "the clinical norm" and "have been used for years by a majority of dialysis clinics".

The strip idea is great in theory for speed and may very well be accurate at higher levels but at the levels seen in the dialysis industry they simply are not the answer. The trade off for ease of use and speed isn't and never should be accepted over patient safety. I have seen too many times someone misinterpeted the difference between 0 and .1ppm. Until the industry can come up with a strip that is more color definative and reads at lower levels, strips should never be used to measure total chlorine/chloramines post carbon.
As always, these are my views and are not indicative of my employer's views.

Svh-biomed,

Thank you very much for your comments.

If you send me your email address, we will send you the controlled studies, etc. that address your concerns about being able to discern the test strip 0.1 ppm color value and color below 0.1 ppm. In addition, we will include a table comparison of variables to consider when the test strips or DPD kits are used.

There are more variables to control with the DPD kit and that can lead to a less accurate DPD test result. We hope you agree that to focus on the test strip "readability" without comparing and considering the very real DPD kit issues, would not be a fair or reasonable approach. Both the strips and DPD kits will provide for patient safety when the variables associated with each test are properly controlled.

Regarding the widespread use of the test strips:
In a year, RPC ships literally millions of the strips to a wide base of dialysis customers that includes large chains, mid-size chains, small chains, and independents. We are a technician / technical oriented dialysis company and take pride in having earned a good reputation for honesty, product knowledge, customer service, etc.

We do listen to our customers and very much appreciate all input (negative and positive). At the same time, we feel it is very important to stand behind our products and provide customers with the necessary technical information that supports the product use for its intended application.

Svh-biomed,thanks again for your input and best regards,

Vern Taaffe
RPC
763-546-6602 (my direct phone at RPC MN location)
763-546-6063 (my direct fax at RPC MN location)
800-647-3873 (toll-free phone to RPC AZ location)
877-352-5557 (toll-free fax to RPC AZ location)
vtaaffe@rpc-rabrenco.com
www.rpc-rabrenco.com

The overall goal of a lower range test is not only to insure patient safety, but also to plan maintanence and track trends. These superceed the convience of swiping a strip under a flow stream. And lets not kid ourselves, thats exactly what happens at 04:30 by many PCT's.

I have to ask myself, If it were me or a loved one on the machine, and I had to choose a test method, I would choose the low range meter every time.

I have used wheel's, with and without the mirrors, strips, meter's, and even inline methods. So far in my 19 years, the method with the least drawback is the colormeter. It may not be super super accurate at the low range, but its pretty darn close. It's close enough to see seasonal trends, city water maintanence issues, or other uncommon occurances that one may not be alerted to when reading "< 0.1".
If they were to develop a strip that could read the low range with definate color differences, or an inline method that didnt have to be validated daily for accuracy, I would consider it. Until then, the best thing for the patients is the colormeter and well trained staff that care about WHY they do what they do.

jdbnomad@hotmail.com

You can quote all of the validation studies you want. In the end, I need to trust several technicians to read a color and you can't calibrate a technicians eye. You can calibrate a colorimeter but the calibration uses colored water, not chlorine standards. They don't use chlorine standards since chlorine standards don't exist. And, let's face it, there is not much of a color change when using the test strips. You can clearly see the pink color at 0.1 ppm using the DPD test. I think jdbnomad and svh-biomed have the right attitude. Also, the next color for the test strips after 0.1 is 0.5. There is a lot more color change between 0.1 and 0.5 when using the DPD than when using the test strips and the DPD has a few more color windows between 0.1 and 0.5. For those of you who want to see the color charts for the test strips, here are some links.

Hach Sterichek (these are FDA 510k approved) http://www.rpc-rabrenco.com/PI/TCStrips.pdf

IBT http://www.ibtbiomed.com/product/germicide/watercheck_detail.html

RPC http://www.rpc-rabrenco.com/PI/tstrips.pdf

These remind me of the old Wendy's "Where's the beef?" commercials, but in this case, its "Where's the color?"

Manganese is an interference with the DPD test, but I could argue that it is a good interference. The interference is from oxidized manganese. This oxidant will distroy an RO membrane and red blood cells just like chlorine. So, an arguement could be made that if the test strips can not see this oxidant, this would be a bad thing.

I certainly appreciate someone standing behind their product. The test strips have a place in this world. But in this case, I believe the DPD is a better product. Does the chlorine analysis protect the patients or does the carbon (two beds with 10 minute EBCT)? If a bacteria filter had 0 cfu/ml going into it and 0 cfu/ml coming out of it, can you say the bacteria filter is protecting the patient? No! The carbon is protecting the patient, and it has a backup (Secondary Carbon Tank). But, there are a few cases of the Primary Carbon breaking on chlorine and soon after the Seconary Carbon also breaks. This can happen if the carbon in the secondary tank has been fouled with organics over its life and when called upon to remove chlorine, it has no sites left. Don't let the chlorine analysis tell you when to change your carbon. Change the carbon before it exhausts.

I did a little experiment. I made a 0.1 ppm chlorine solution (or at least a solution that should be very close to 0.1 ppm). You can do the same by mixing a 1:100 dilution of bleach (6% sodium hypochlorite), and then add 1 ml of this solution to 1.5 gallons of RO water (non-chlorinated). I tested the solution using the Hach color wheel, LaMotte Octa-slide, WET chlorine kit, and Orbecco colorimeter. The Hach color wheel (using the mirror) showed about 0.08 ppm, Lamotte - color very near 0.1 window and much lighter than 0.2 window, WET - near 0.1 ppm color. For the Orbecco colorimeter, I made solutions up using the Hach powder pillows, Lamotte pills (DPD1 and DPD3), and the WET powder pillows. I then measured them 3 times. The Hach result was 0.08, 0.08, 0.07, Lamotte was 0.07, 0.06, 0.06. WET was 0.11, 0.10, 0.10. I then measured the water that I used to dilute the chlorine. Hach said 0.00, 0.00, 0.00. Lamotte said 0.02, 0.02, 0.02. WET said 0.02, 0.02, 0.02.

The bottom line, I could clearly see a pink color of this solution and I could not see a pink color from the non-chlorinated sample.

One last thing, NEVER use the DPD test to check for residual bleach after a disinfection. If the bleach concentration is too high, it will "bleach out" the color since there is not enough reagent to react with the bleach. At high concentrations, you will get a clear color (no pink). Use the proper range test strips for a disinfection...at least until the result is below 7 ppm chlorine.

Boy, this is some good mateial. I need to put it in my water treatment training class. Thanks for starting the discussion.

For those who are interested, let's continue this discussion while consuming large masses of fluids at the NANT symposium March 9-11 in Atlanta. See y'all there.

This message has been edited. Last edited by: Florian,

Very interesting thread here people! I love it!

What would you consider a level of manganese that would interfere with the DPD testing? We may have this issue here. We have iron filters with greensand(?) that have not been backwashed with potmag for a while because maintenance forgot to add it. I understand that these filters also remove manganese as well as the iron.

Isolated

The views concerning test strips are generally correct, but I feel test strips do have a place in detecting the total chlorine concentration in water used for dialysis.

Compared to the alternative methods such as titration, test strips are relatively accurate, quick & simple to use. Unfortunately “simple-to-use” often gets translated as “don't have to follow the instructions”. Improper storage or handling, interfering substances, lighting and color perception can affect the sensitivity/accuracy of any test; liquid or strips, read visually or with an instrument. Being properly trained and following the manufacturer’s instructions is the most effective way to minimize inconsistencies.

As Vern said “it’s very important we stand behind our products and provide customers with the necessary technical information that supports the product use for its intended application.” And to make customers aware of all the various types of tests available for a particular application. That being said let me bring up a total chlorine test strip that has not been mentioned thus far…Serim HiSENSE.

HiSENSE is a qualitative, low-level total chlorine test strip that can detect 0.05 ppm monochloramine and consistently yield Positive results in water samples of widely varying properties containing total chlorine concentrations >0.1 ppm.

HiSENSE Advantages:
*Simple to perform: Place strip in holder, add water sample, add 1 drop reagent solution, allow sample to drain, remove strip from holder

*Easy to interpret: POSITIVE - If blue color develops on the strip, the water contains a total chlorine concentration of 0.1 ppm or greater.
NEGATIVE - If there is no color change on the strip the water contains less than the maximum allowable concentration of 0.1 ppm chloramine.
*HiSENSE received FDA 510k clearance in 1995

The trade-off:
*HiSENSE is not a quick, dip & read test; it takes ~6 - 8 minutes for the result
*HiSENSE result is qualitative (POSITIVE or NEGATIVE)

It is clear from this discussion that we all have our biases as to which total chlorine test is best (except for Vern who sells both the test strips and the liquid DPD tests for total chlorine. ;-) !!! But how do you define “best”, accurate, easy, simple, quick, etc?
A test could be very accurate but if it is difficult to use, the accuracy could be lost by careless technique.
A test could be very quick, but if it’s not easy to interpret, you’ll waste time repeating the test or getting second opinions.
A test could be simple to perform, but if it is not consistently accurate, you might as well not test.

One type test will not suit everyone. We also have to consider the skill & focus of all the people who will be using the test. But most importantly we have to use a total chlorine test with sensitivity (the statistically valid lowest detectable amount) below 0.1 ppm in order to consistently, 100% of the time, detect 0.1 ppm.
Like jdbnomad said– we need to remember patient safety.

svh-biomed & jdbnomad, I’d be glad to send you a sample of HiSENSE to try.

PS: Unfortunately there is a fundamental truth in product development known as the “You can’t have it all Triangle”. The product options are good, fast and inexpensive…pick two, ‘cause you can’t have ‘em all!


Accurate + Quick = Expensive
If you want a test to be Quick and Accurate, it won’t be Inexpensive.

Accurate + Inexpensive = Slow
If you want a test to be Accurate and Inexpensive, it won’t be very Quick.

Quick + Inexpensive = Inferior
If you want a test to be Quick and Inexpensive, it won’t be Accurate.


Layne Montgomery
Serim Research

It's nice to see that the strip manufacturers are ferociously defending their respective product and taking a swipe at each other.

Question: Why can't these guys develop a strip that is consistantly accurate well below the 0.1 mg/L AAMI limit? It would be nice to know we aren't going to breach the limit before the treatment ends. If they can do that, the debate would definitely tip in their (and our) favor.