Making It Easy

A chemistry system and a new spectrophotometer are designed to bring greater simplicity to sample analysis in water plant labs
Making It Easy
The TNTplus chemistry system uses special barcoded vials.

Water plant laboratories seek to balance speed and accuracy in sampletesting — accuracy of course being paramount. The optimum testing protocols are fast and accurate as well as simple to follow, even for staff members who are not necessarily chemists.

The marriage of those characteristics is the goal behind a newly introduced set of vial chemistries and a new spectrophotometer from Hach Company. The TNTplus chemistry system uses barcoded vials in packaging that is color-coded for ease in recognizing parameters and ranges.

The DR 3900 spectrophotometer is designed to provide consistently accurate results using simple, step-by-step, on-screen instructions for each test. It also allows simple and easy updates to program calibration factors, connectivity to laboratory information management systems, and sample tracking with radio frequency identification (RFID) smart tags.

Hach product managers Katy Guthrie and Dave MacDonald discussed these innovations in an interview with Water System Operator.

wso: What is it about this chemistry and the new instrument that makes testing easier for lab personnel?

MacDonald: The aim was to make the chemistry so easy that anyone could use it. Traditionally, the idea was that if you could read, you could do the chemistry. Now it’s being taken a step further: If you can look at a picture on the box, you have a good chance of being able to figure out everything you need to know.

All the products have step-by-step instructions in picture format on the packaging, telling exactly how to do the test. The reagents are integrated into the packaging. The vials are barcoded, so that to pull up the correct test method, you simply put the vial into the DR 3900 spectrophotometer. The first scan of that barcode identifies the method, so that the instrument pulls up the correct wavelengths and automatically performs the reading without the need to use a blank.

wso: Does the DR 3900 itself help guide users through the procedure for each test?

Guthrie: Yes. The device is simple to use, with a color display and intuitive touch-screen user interface and a built-in help guide. In the past, users had to keep a thick book on the bench with instructions for all the chemical methods. Now the instrument provides that in electronic form.

MacDonald: Rather than describe the tests in a way that sounds like something written by and for a Ph.D. chemist, it provides simple instructions with a picture, making it crystal clear what steps to perform for each test. Most of the methods take just a handful of steps, and all the chemistry is pre-packaged, making it very easy to perform the analysis.

wso: Just for example, how exactly would the instrument guide the user through a specific test?

Guthrie: The user touches an on-screen information icon — the letter “i” with a circle around it. That brings up a pictogram and instructions for the first step, such as ‘Fill the sample cell to the line with the sample.’ Touching an arrow brings up the next step. Every individual step of the procedure is shown and described in this way.

wso: How does this system help assure accuracy?

MacDonald: The instrument performs a tenfold measurement by rotating the vial, and the average of those readings is displayed on the screen. The result is that the user gets a consistent average value, despite any flaws in the glassware, or any smudges or fingerprints. The instrument contains an algorithm that rejects any readings that are outliers and still gives an accurate average reading. In addition, the packaging is color-coded so there is a low probability of the user making a mistake.

wso: Are there other advantages to this approach to chemistry?

MacDonald: The TNTplus chemistry is in our green or environmentally friendly portfolio. It reduces exposure to the chemicals. The vials use DosiCaps that are easier to use than powder pillows or liquid reagents. There’s no spill risk, no safety risk, and no risk of contamination because the reagents are completely contained within the vial cap.

The system uses very small-scale wet chemistry – at most about a milliliter of sample, and microliters of reagents in most cases. That reduces the waste generated by doing the tests. The packaging is also more eco-friendly, using recyclable cardboard instead of foam.

wso: How would you describe the range of chemistries available for testing in water treatment plant labs?

MacDonald: The spectrophotometer is made specifically for water analysis, and with TNTplus chemistry there are about 200 methods that can be used. The tests cover parameters for every step from source water to finished water.

Last June we received approval from the U.S. EPA for the TNTplus method for nitrate, a development that has real value. Until now, there wasn’t a particularly easy way of doing this test. Nitrate testing has been done using ion chromatography or the cadmium reduction method. Most plants were sending this test to an outside lab and paying $25 to $35 a test. Now they have a way to do it in-house on their own time in a matter of minutes, and at substantial savings.

wso: How does the RFID technology work within this system?

Guthrie: The spectrophotometer includes an RFID module, and there is an RFID tag on each box of chemistry that includes two key pieces of information. First is a certificate of analysis. The user simply holds the box of chemistry up to the instrument, and the certificate comes up on screen and can be printed out.

The second item on the RFID tag is the calibration factors. Traditionally, if there was a change in the chemistry raw material that would cause the calibration curve in the instrument to change, the user would have to update the software, which meant going to a website, downloading the software to a USB stick, and uploading it to the instrument.

Now, when they insert the barcoded vial, the instrument tells them if they need to update the calibration factors. If so, they simply put the box from the chemistry next to the RFID module, and the instrument automatically uploads the new calibration factors.

wso: How does this system improve the tracking of samples and test results?

Guthrie: The TNTplus chemistry uses a 2-D matrix barcode that can contain more information than a traditional barcode such as we see at the grocery store. For each reagent, it includes the lot number and the expiration date. So when using the chemistry, with the spectrophotometer, the instrument tells if you are using expired chemistry.

All the chemistry information is logged along with the measurement, so that it is completely traceable. In case questions about the result arise later, you can always trace that measurement back to the lot number and expiration date of the chemistry.

There is also an optional accessory called the LOC 100 locator that lets users track samples from collection to measurement. This system uses RFID operator key tags, RFID sample location tags, and sticky RFID tags on the sample bottles.

The sample collector goes to a sample point, scans his or her operator tag by holding it up to the locator device, scans the sample location tag, and transmits the information to the bottle tag. Now the bottle tag contains the operator ID and the sample location, date and time. Back at the lab, the bottles are held in front of the RFID module on the spectrophotometer, and all the information from the bottle tag is transferred to the instrument.

So in the end, that data is all tracked with the measurement. It provides a high level of trust in the results. There is essentially an electronic trail from beginning to end.


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