By Rich Ross and Dr. Chris Maupin
At MACNA 25 in Denver, the potential for the new ICP-OES aquarium water testing by Triton Lab in Germany made many saltwater hobbyists swoon. The possibility of getting a real good look at what is going on chemically with the water in our glass boxes for an affordable price is incredibly appealing, since traditional ICP-OES testing is expensive and time consuming. In this installment of Skeptical Reefkeeping, we explain how ICP-OES testing works, explore the challenges of testing saltwater with ICP-OES, develop an understanding of the methods used to address those challenges, and discuss the results from the testing of a certified artificial saltwater standard that was sent to Triton Lab.
A Brief Reminder to Set the Scene Skepticism is a method, not a position. It can be defined as a method of intellectual caution and suspended judgment. As a Skeptical Reefkeeper, you decide what is best for you, your animals, and your wallet, based upon critical thinking, not just because you heard someone else say it. The goal of this series of articles is not to provide you with reef recipes or to tell you which ideas are flat out wrong or which products really do what they say they do or which claims or which expert to believe. The goal is to help you make those kinds of determinations for yourself, while developing your saltwater expertise in the face of sometimes overwhelming or conflicting advice. Introduction: Why We Don’t all use ICP Testing Already When reefkeepers daydream about water testing, they tend to imagine testing their aquarium water with a university or research institution’s complicated and expensive inductively coupled plasma (ICP) mass spectrometer or optical emission spectrometer, because, when properly calibrated and used, these instruments can produce incredibly accurate and precise results. However, a request to test tank water often is met with the response “Get that the hell out of my lab” from the lab technician, or by a seemingly outrageous price from a commercial lab. Saltwater presents ICP testing with special problems. Most notably, it can be detrimental to the instrument’s components, and the saltwater itself can help produce unreliable results. Compensating for these issues makes the testing expensive and time consuming. Sometimes months are required to get results, and at considerable financial cost: sometimes hundreds if not thousands of dollars per analysis of each individual element. However, Triton Lab is now offering ICP OES testing of 321 elements in a saltwater sample for a reasonable cost and a fast turnaround2 – a service that no other ICP-OES lab seems willing to provide. In the Skeptical Reefkeeping series, we often quote They Might Be Giants – “Are you sure that that thing is true, or did someone just tell it to you”3, and in that spirit we looked at some of the Triton Lab claims and are sharing our results. It is important to note that that being skeptical is not the same as being cynical, and that nothing would please us more than an inexpensive, accurate and precise water test providing values for 32 elements in a single report at a relatively inexpensive cost; however, understanding traditional ICP-OES and the numbers from our experiment tell a more complicated story. How ICP-OES Works In chemistry class, many of us became familiar with a flame test, where you put some stuff in a Bunsen burner and watch what color the flame burns, indicating what elements are in the stuff you burned. Table salt, for example, turns the flame yellow/orange (fun fact – both authors suffer from poor color perception) due to the presence of sodium in the salt. This test is the beginning of many a mad scientist – Muhahaha! Colored flame! An ICP-OES, when distilled to its most bare fundamentals, is a sensitive, quantitative means of performing a flame test. Instead of a natural gas flame in a Bunsen burner, it uses an argon plasma torch to burn the ions and record the colors they produce, and how brightly, which tells us what elements in what amounts, are in the sample. Muhahaha plasma! The ICP in ICP-OES is the inductively coupled plasma, while the OES stands for optical emission spectrometer. More »