Analysis of water samples can consume substantial time and expense. Water utilities are on the lookout for ways to simplify tests while maintaining or improving accuracy.

Now Hach Company has developed a hand-held analyzer that can perform tests for several parameters at once, in less time than by conventional testing methods. While designed mainly for use in the field, it has seen applications in water treatment plants and in the lab.

The SL1000 Portable Parallel Analyzer (PPA) can perform two probe-based and four colorimetric measurements simultaneously. The colorimetric tests use the new Chemkey reagent delivery device, which uses the same chemistry Hach users are familiar with. Tom Siller, global product manager for hand-held instruments, talked about the device in an interview with Treatment Plant Operator.

TPO: What market demand drove the development of this product?

Siller: In extensive research with water professionals, we found they had three main concerns. First and foremost, they wanted to complete more tests in less time. Second, they wanted more accurate measurements that would eliminate opportunity for variability and errors. Third, they wanted something easier to use with less equipment to juggle.

TPO: How does this offering help satisfy those desires?

Siller: The SL1000, combined with our Chemkey technology, enables users to test six parameters simultaneously with one instrument and one sample. To put that in perspective, consider the nitrification suite of six parameters. That would take at least two pieces of equipment and more than a half hour by conventional methods. Our instrument lets users do those six tests in eight minutes.

TPO: In what settings would water utility personnel use this device?

Siller: It’s primarily designed for use in the field for drinking water distribution monitoring, but we have seen customers taking advantage of it in a variety of other settings. We see them using it in the plant to validate their online equipment. We see them using it in their labs because a test for a parameter like nitrite takes 20 to 25 minutes to run with traditional methods, and with our instrument they can do it in seven minutes.

TPO: How is the instrument structured to perform all the different tests?

Siller: At the base of the instrument there are four slots for inserting the Chemkeys. You can insert one, two, three or four, then just dip the unit in the sample and the entire testing process is fully automated. All the Chemkey tests are colorimetric and use the same Hach chemistry customers use today in powder or vial form. At the top of the instrument are two ports for connecting a variety of probes.

TPO: What tests can be performed with this unit?

Siller: Currently, we have seven Chemkey parameters: free chlorine, total chlorine, monochloramine, free ammonia, total ammonia, nitrite and copper. We will be constantly developing new parameters: Our goal is to roll out at least four or five on a yearly basis. On the probe side, we have pH, conductivity, dissolved oxygen, nitrate, fluoride and chloride. ORP will be available shortly. The device uses the same IntelliCAL probes we offer today. So if, for example, you own one of our HQd meters with an IntelliCAL pH probe, you can use that same probe with the SL1000.

TPO: How would you assess the accuracy of all these tests?

Siller: It is as good as or better than any powder form of testing we have. There are various reasons for that. The easiest to pinpoint is reduction in variability. A typical powder pillow test has a host of opportunities for error.

Take for instance the monochloramine free ammonia vial test. In powder pillow form it requires a dropper. It’s very time- and temperature-sensitive, and it requires the operator to follow the method precisely. They have to precisely measure the amount of reagent and the amount of sample. They need to mix the sample properly and make sure the sample cell is clean and free of scratches or smudges. That’s all very cumbersome.

With the SL1000, they simply insert the Chemkeys into the bottom of the instrument and dip it in the sample. The testing time and the temperature are controlled automatically. The amount of reagent is predetermined. Any opportunity for user error is eliminated.

TPO: Can you describe the process of performing a test with the Chemkey reagents?

Siller: When you insert a Chemkey, the device reads the barcode and the screen tells you what parameter you’ll be testing. We provide a sample cup that fits perfectly on the bottom of the instrument. You fill that sample cup and dip the instrument in it for two or three seconds. The instrument draws the sample into the Chemkeys. Then you can take the instrument out of the sample cup, set it down and go do something else. On the screen, there’s a progress bar with a timer that tells how long until the test is completed.

TPO: How well does the device stand up to life in the field?

Siller: The instrument is drop-proof up to 1 meter. It is also rated IP64, which means it can take a driving rain and if you drop it in water, it will float. You can pick it up and not worry about water getting in.

TPO: What happens to the data once the testing is completed?

Siller: The device eliminates transcription errors inherent in manual, paper-based recording of data. The instrument can store up to 1,000 discrete measurements. You connect the USB cable that comes with the unit, plug it into a computer and the data seamlessly transfers to an XML format. Then you can manipulate that data and export it into a laboratory information management system.