Although both manufactured by Industrial Test Systems, Inc., a US based company in South Carolina, the DPD-1 ReagentStrip and SenSafe Free Chlorine Water Check products test for free chlorine residual in very different ways.

The chart below will explain the differences and similarities between the two free chlorine residual test methods:

	DPD-1 ReagentStrips™	SenSafe™ Free Chlorine Water Check
Detects:	Free Chlorine Residual (and Other Oxidizers Normally Tested Using DPD-1 Chemistry)	Free Chlorine Residual
Test Procedure Overview:	Liberarting of DPD-1 Reagents Off Reagent Pads Into 10mL Sample and Checking Chlorine Concentration Visually by Color Comparator or Electronically Using a Colorimeter	Immersion of Test Strip in Water Sample, Removal of Test Strip After Specified Period of Time, and Visual Comparison of Developed Color in Test Area to a Color Chart
Detection Range:	0-6ppm	0-6ppm
Accuracy & Precision:	Depends on the Method Used to Interpret the Developed Color in the 10mL Sample. Visual Methods Will Have Less Precision Than Meters	0, 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1.2, 1.5, 2, 2.6, 4, 6 ppm (mg/L)
Certifications & Compliance:	DPD Testing as Specified in 4500-CL G Check w/ Your Local Health Department for Final Word on Compliance	USEPA Approved Test Method for Free Chlorine Read the EPA Letter   View EPA Approved methods   Check w/ Your Local Health Department for Final Word on Compliance
Number of Tests:	100 Tests per Package	50 Tests per Package
Benefits:	Cleaner to Use Than DPD-1 Powders (i.e. DPD-1 Powder Pillows)   Dissolves Easier Than DPD-1 Tablets   Longer Shelf-Life Than DPD Liquid Reagents   No Undissolved Solids When Testing in Cold Water (5ºC)   Requires No MSDS	Safe for Use on Most Production Floors   Requires No Specialized Testing Knowledge   No Expensive Meter (Colorimeter)   Designed to Resist Monochloramine Interference   Requires No MSDS
Per Unit Cost:	$15.99 per Package of 100 Tests	$15.99 per Bottle of 50 Tests

As always, if monitoring free chlorine residual for reporting and/or compliance monitoring we suggest contacting your local health inspector before switching to a different chlorine testing method.

Although seemingly counter-intuitive, many methods approved on a Federal level may not have attained acceptance, yet, on a State or Local level.

At this time we carry 100 packs of DPD-1, DPD-3 and DPD-4 in the Water Testing Blog Test Kit Store.

Differences between DPD-1, 3 and 4?

For the answer to that question, we suggest that you take a look back at one of our earlier postings called What is DPD?. Not to brag, but we think that article does a decent job of answering the question.

To sum things up, though, below you will find the most common uses for DPD-1, DPD-3 and DPD-4:

• DPD-1 — Used by itself in a water sample to determine the free chlorine concentration in the sample.

• DPD-3 — Used after DPD-1 in a water sample to determine the sample’s total chlorine concentration.

• DPD-4 — Used by itself in a water sample to determine the total chlorine concentration in the sample.

So, before purchasing DPD, you may want to verify the type of chlorine testing that you will need to do — else run the risk of accidentally purchasing the incorrect DPD reagent(s)!

Where to purchase DPD?

As we stated earlier, you can purchase 100-packs of DPD-1, DPD-3 and DPD-4 from our Water Test Kit Store.

As for where to find other forms of DPD reagents, at this time we know of places to purchase two other forms of DPD: tablets and powder.

Need a new meter to test chlorine levels, too? We suggest looking at the eXact Chlorine Photometer available on the FilterWater.Com web site. It offers the reliability of DPD-based chlorine testing and the convenience of not having to match colors against a color chart.

Want accurate chlorine test results but don’t want to deal with DPD reagents and meters? Take a look at the SenSafe Free Chlorine water Check product currently available in our Water Test Kit Store. It bears USEPA Approval for use in municipal water testing and offers superior resistance to monochloramine interference that can sometimes affect the results obtained when testing for free chlorine residual using DPD test reagents.

Today’s inquiry deals with DPD for free chlorine testing and came to us from ‘Oviruo’ who asked, “please can you assit me to get dpd satchet powdered type for testing free chlorine in water. thanks.”

We did a quick check and found that you can purchase DPD-1 Powder Pillows for Free Chlorine Testing on the Hach Company web site. The material has an approximate cost of around $21 per 100 powder pillows.

Alternative to powder pillows

A company called Industrial Test Systems came out with an alternative to the powder pillow that performs as well or better than the powder pillow. They called it the ReagentStrip and it works quite well without the mess that sometimes accompanies the act of trying to pour a small packet of DPD powder into a sample vial.

Below you will see how the DPD-1 ReagentStrip works when used with the Hach 890 Water Testing Meter:

Free Chlorine Testing Using DPD-1 ReagentStrip
and Hach’s 890 Water Testing Meter
click on image to view larger version

According to the manufacturer, DPD-1 ReagentStrips work with chlorine testing meters manufactured by well-respected companies such as Hach®, LaMotte®, Orion®, WTW®, and others.

Additionally, the DPD-1 free chlorine testing procedure stands and an equivalent to USEPA method 330.5 for wastewater and Standard Method 4500-Cl G for drinking water when used with a Palintest Chlorometer 1000 water testing meter or equivalent.

Cost of DPD-1 ReagentStrips compared to powder pillows

Earlier in this article we mentioned that interested parties can pick up 100 DPD-1 powder pillows for around $21 on Hach’s web site.

For those interested in the DPD-1 ReagentStrips, you can purchase 100 of those for around $19 on FilterWater.Com.

“Do your DPD Chlorine tabs work in Hach equipment?”

Good afternoon, Ronda, and thank you for this inquiry. When weighing the different DPD options (tablets, powders, reagentstrips, etc.) make sure you note the sample size that each test method will work in. As a general rule most devices that use DPD as a reagent will have 10 mL sample sizes, but we have also seen devices that use 15 mL sample sizes, 7 mL sample sizes and 20 mL sample sizes.

Check your machine’s manual to find out what sample size it takes. In order to remain compliant with whatever drinking water directives you follow you will need to match up the sample size w/ the correct reagent amount.

Specifically, though, you asked about the DPD tablets for chlorine testing that we have shown on our site and as far as we know all of the DPD products we have shown on our site work for 10 mL samples — except for the eXact Micro DPD products which work in smaller samples.

Two 10-mL Tablets/Strips/Powders for a 20-mL Sample?

While in theory that would work, definitely check your approved testing method to see if it expressly forbids that sort of thing and/or if it specifically calls for a brand or type of chlorine reagent delivery method. In the past we have seen where testing protocols have gotten so granular that they call out not only the type of DPD used, but also the brand of the test meter and DPD used for chlorine testing.

(100) DPD #1 Tablets (1,000) DPD #1 Tablets

(100) DPD #3 Tablets (1,000) DPD #3 Tablets

]]> http://watertestingblog.com/2011/11/10/do-the-dpd-tablets-work-in-hach-meters/feed/ 0 http://watertestingblog.com/2011/01/18/wanted-5000-dpd-1-tablets-for-chlorine-testing/ http://watertestingblog.com/2011/01/18/wanted-5000-dpd-1-tablets-for-chlorine-testing/#respond Tue, 18 Jan 2011 13:03:26 +0000 http://watertestingblog.com/?p=3595

1,000 DPD #1 Tablets

Recently we received a request for a quote on 5,000 DPD #1 Tablets for chlorine (or possibly another oxidizer) level testing. We’d like to remind remind everyone that although we link to a number of water quality products, Water Testing Blog does not stock or sell any products.

The party asking about DPD #1 Tablets sought to import them into a foreign country so we suggested they contact companies on the following page:

( http://www.alibaba.com/showroom/dpd-tablets.html )

… so they could attempt to save a few bucks (or whatever currency they use) on shipping.

Now having said that, when it comes to DPD #1 we believe anyone thinking about using DPD tablets should at least consider using DPD-1 ReagentStrips in their place. ReagentStrips dissolve faster and easier than tablets (especially in hard or cold water) and contain no filler materials that could interfere with photometric optics.

As far as performance, the manufacturer of DPD-1 ReagentStrips, Industrial Test Systems, Inc., had an independent laboratory conduct a blind water sampling study using DPD ReagentStrips, Tablets and Powder Pillows. In the end the ReagentStrips tested as good, and in some cases better, than other DPD reagent delivery methods.

For years people conducting tests for certain varieties of oxidizers (Free Chlorine, Chlorine Dioxide, Bromine, Iodine, and Permanganate) have relied upon DPD-1 tablets, DPD-1 powders and DPD-1 liquids to help them obtain accurate, repeatable results.

Now, however, an easier method of adding DPD-1 reagent to test samples has become available on FilterWater.Com, an online retailer of water quality testing and water quality improvement products.

Why consider switching to DPD-1 ReagentStrips?

• The United States Environmental Protection Agency has deemed the DPD-1 ReagentStrip test procedure equivalent to USEPA method 330.5 for wastewater when used in conjunction with a Palintest Chlorometer 1000 equivalent meter (i.e. the eXact Chlorine Photometer).
• The United States Environmental Protection Agency has deemed the DPD-1 ReagentStrip test procedure equivalent to USEPA method Standard Method 4500-Cl G for drinking water when used in conjunction with a Palintest Chlorometer 1000 equivalent meter (i.e. the eXact Chlorine Photometer).
• eXact DPD-1 Reagentstrips deliver a precise dose of DPD-1 reagent into a 10 mL sample without the need to count drops (DPD-1 liquids).
• Working in the field with DPD-1 Reagentstrips becomes much easier since testing personnel will not have to worry about small or large gusts of wind blowing away their reagent as they attempt to add it to a sample (DPD-1 powders).
• Due to the ‘dehydrated nature’ of DPD-1 Reagentstrips, they will dispense rapidly and easily into hard and cold water without the need for laborious, time consuming tablet crushing (DPD-1 tablets).

• As long a the test instrument (i.e. meter or test kit) uses as standard 10 mL sample size, an eXact DPD-1 Reagentstrip will provide consistent test results regardles of who made the test kit/meter.

If you use DPD-1 on a regular basis we think you owe it to yourself to give eXact DPD-1 ReagentStrips a try.

Note: For those who know a thing or two about DPD, you may find yourself wondering why we didn’t compare the DPD-1 ReagentStrip to an old school method of reagent delivery called ampuoles which involves breaking glass tips off into test samples. Ahem… Breaking of glass in order to perform testing. Need we say anything more about ampuoles?

The US Environmental Protection Agency has set the Maximum Contaminant Level (MCL) for free chlorine at 4.0 parts per million, also known as milligrams per liter (mg/L).

The most commonly used test for free chlorine residual uses a reagent called DPD (what is DPD?). More specifically, it requires DPD-1 and DPD-1 comes in several different forms: liquid, powder, tablet and reagentstrip form.

While the average person does not have a need to for chlorine levels much above 3 to 5 parts per million, and even then they would typically only need to do so to make sure their swimming pools had a sufficient amount of free chlorine, but other folks have the need to test for free chlorine levels in excess of 25 or 50 parts per million on a regular basis. Below we will list a few of the places where you might expect to see a need for high range free chlorine testing.

Fruit & Vegetable Processing

After fresh produce leaves the fields it travels to a processing facility where it typically gets washed with a solution containing some sort of sanitizer such as chlorine, ozone, etc. In cases where the produce processing plant uses chlorine employees must make sure the rinse water contains a certain amount of free chlorine after it has passed over the fruit/vegetables.

Levels of free chlorine drop with an increase in biological load (contamination) and the rinse water having free chlorine left after use indicates that the produce no longer contains biological contamination on its surfaces.

Childcare Facilities

State laws require that childcare facilities clean their surfaces with properly mixed sanitizing and disinfecting solutions that contain an appropriate concentration of sanitizing or disinfecting chemicals. In many cases these facilities use chlorine bleach solutions for cleaning purposes.

As a general rule these solutions must contain anywhere from 50 to 200 parts per million free chlorine for sanitizing solutions and anywhere from 500 to 800 parts per million free chlorine for disinfecting solutions. In case like this the Waterworks High Range Free Chlorine Test Strips will not work because they have an upper detection limit of only 120 parts per million free chlorine, but WaterWorks Free Chlorine Check Ultra High II has an upper detection limit of 2,000 parts per million free chlorine and works well in this application.

Some states leave it up to individual childcare facilities to determine testing frequency of sanitizing and disinfecting solutions while other states, like North Carolina for example, have strict laws dictating how often childcare facilities must perform testing.

As of January 1, 2006, all licensed, non-in-home daycare centers in the State of North Carolina had to have the ability to test the chlorine bleach content in both their sanitizing and their disinfecting solutions. Previously the law stated that they had to test only the chlorine concentration in their sanitizing solutions. ( source )

If interested in purchasing a test kit for testing sanitizing & disinfecting solutions in a childcare facility, you can find them readily available in the Water Test Kit Store.

Water Lines and Water Mains

Before a water line can go into service for the first time or go back into service after a breakage or leak has gotten repaired technicians must flush (burn) the lines with water containing a high concentration of free chlorine to clean out any and biological contaminants. Typically the technicians must test the discharge water periodically until the free chlorine level remains constant at a high level for a set amount of time.

Waterworks High Range Free Chlorine Test Strips work very well for this application.

Product-specific information about Waterworks High Range Free Chlorine Test Strips:

• Testing requires just 32 seconds
• Each bottle contains 50 ready-to-use tests
• Color chart has easily distinguished color blocks at 1, 5, 10, 20, 40, 80, 120 ppm
• No harmful chemicals or reagents to handle

In most cases they carry packets of sanitizing/disinfecting tablets which they can use to put into their canteens to kill off bacteria, but what about lead, arsenic, cyanide and other items which can EASILY render an entire unit inoperable and take them away from their assigned duties?

Thankfully US Army, Navy, Air Force, and Marine Corps medical units deployed around the globe now have the ability to make use of simple water quality test kits which give them the ability to read basic water quality parameters quickly and easily.

Arsenic in Water and Soil: Arsenic Quick^TM

Bacteria in Water: Bacteria Check

Chlorine Residual (Free): SenSafe^TM Free Chlorine Water Check

Chlorine Residual (Total): SenSafe^TM Total Chlorine Water Check

Cyanide in Water: Cyanide Emergency Test Kit

DPD-1 and DPD-4 (Chlorine Testing): DPD ReagentStrips^TM

Lead in Water: Lead in Water Test Kit

Multi Parameter (6 Parameters): Well Water Check

Multi Parameter (11 Parameters): Well Driller Standard Water Test Kit

Multi Parameter (13 Parameters): COMPLETE Water Test Kit

Multi Parameter (15 Parameters): Water Quality Test Kit

Most of us know how badly we feel after ‘a night on the town’ filled with margaritas, martinis, cocktails and body shots because of dehydration. Now try to imagine how our soldiers must feel after a few MONTHS in the desert wearing full combat gear.

Safe drinking water means safer soldiers.

Replaces DPD-1 Powder Pillows & Tablets
and Works in All the Same Meters & Test Kits

One of the most widely used testing methods for free and total chlorine makes use of something known as ‘DPD’ which stands for N,N Diethyl-1,4 Phenylenediamine Sulfate. The addition of DPD to water samples containing oxidizers such as free chlorine, bromine, iodine, chlorine dioxide and/or permanganate results in the formation of a reddish tint to the water whose intensity directly relates to the amount of oxidizer(s) present in the water sample.

At low oxidizer concentrations water samples turn a slight shade of pink in the presence of DPD and at higher oxidizer concentrations the sample will turn blood-red orange. In extremely high concentrations of oxidizers, as in above 10 ppm, the sample will turn blood-red and then go crystal clear due to the bleaching effect of the oxidizer(s) it contains.

Other oxidizers such as ozone and total chlorine do not react directly with DPD and require the addition of a compound known as Potassium Iodide (KI) before they will react with DPD.

• DPD-1 — Used to test oxidizer levels in water samples containing free chlorine, bromine, iodine, chlorine dioxide and/or permanganate.
• DPD-3 — Useless on its own, but when added to samples already containing DPD-1 and free chlorine, total chlorine, bromine, iodine, chlorine dioxide, permanganate and/or ozone, pink through blood-red color development will occur in the sample.
• DPD-4 — The combination of DPD-1 (N,N Diethyl-1,4 Phenylenediamine Sulfate) and DPD-3 (KI) to samples containing free chlorine, total chlorine, bromine, iodine, chlorine dioxide, permanganate and/or ozone will result in pink through blood-red color development in the sample. Simply put, DPD-1 + DPD-3 = DPD-4.

DPD comes in various forms, the most common of which include tablets, powder pillows, liquids and ReagentStrips^TM. Each works equally well when used correctly and may typically be interchanged with one another, though all do have their pros and cons.

• Tablets: One of the cheapest forms of DPD available and has a very long shelf-life. Difficult to break apart and dissolve in cold or hard water samples and may leave suspended solids floating around in samples.
• Powder Pillows: Inexpensive form of DPD. Difficult to dissolve in cold or hard water samples and may leave suspended solids floating around in samples. Users also complain of ‘annoyance value’ associated with having to tear the foil pillows open and pour the DPD powder into the sample vials. Not well-suited for outdoor testing.
• Liquids: Shorter shelf-life and much more unstable than other forms of DPD, considered ‘messy’ by many users, but also probably the expensive form of DPD.
• ReagentStrips^TM: Convenient delivery method for DPD, rarely leaves undissolved solids in samples regardless of temperature or hardness, decent shelf-life, and available in bottles of 50 or individually wrapped tests (excellent for field work).

While many test protocols call only for a visual verification of chlorine levels in water determined through the use of DPD testing methods, many others require the use of a digital chlorine analyzer and DPD testing methods. Below please find an EPA Compliant meter which make use of DPD chemistry for chlorine concentration determination:

• eXact Micro 7+ Water Quality Testing Meter — EPA Compliant for free and total chlorine when used in conjunction with a DPD-based reagent system.  Handheld multi-parameter water quality testing meter.  IP67 waterproof rating and the unit floats. Made from recyclable parts and uses 60% less reagent than devices using 10 mL samples.

Update — Got a chlorine test kit/meter that has a 10 mL sample size and uses DPD-1 tablets, powders or liquids? If so, then you definitely want to check out DPD-1 ReagentStrips for free chlorine. They mix into solution much quicker, easier and cleanly than DPD powders and DPD tablets and have a much longer shelf life than DPD liquids.

The USEPA has accepted DPD-1 ReagentStrips for reporting water and wastewater analysis. That means the USEPA has found the DPD-1 ReagentStrip free chlorine testing procedure equivalent to its own USEPA method 330.5 for wastewater and Standard Method 4500-Cl G for drinking water when used with Palintest Chlorometer 1000 or equivalent.

Update — Want to use less water when testing for free (and total) chlorine? The eXact Chlorine Photometer requires 60% less test sample and meets the criteria for a USEPA Compliant Meter for free and total chlorine testing.