For contract labs considering adding or expanding their application offering to include the determination of HAAs in drinking water, the question of which instrument technology best serves the application and regulatory needs arises. Many factors are involved in the decision, such as: is it easy to learn, is it easy to operate, is it within my price range, and will it handle my current and future sample preparation throughput needs.
Knowing what you know and don’t know about HAAs
Sorting through the assortment of product/technology information to reach an informed decision can be time-consuming and daunting. For the determination of HAAs in drinking water, there are two methods to choose from: EPA Method 552.3 using GC-ECD (gas chromatography with electron capture detection) and EPA method 557 using IC-MS/MS (ion chromatography using triple quadrupole mass spectrometry). The integrated IC-MS/MS system with direct sample injection provides higher sample throughput. The GC-ECD comes at a lower price but requires a 4+ hour sample prep extraction and derivatization. Analysis time for the two methods is effectively the same at 35 minutes.
Why the HAAs cost of ownership calculator matters
Thermo Scientific developed a tool to help in the product/application decision process to suit your lab’s analysis objectives.
The Haloacetic Acid (HAA) cost of ownership calculator program provides the means for deciding on an instrument system based on your laboratory’s throughput needs using EPA Method 552.3 GC-ECD or EPA Method 557 IC-MS/MS. A linear graph mapping the cost savings and sample throughput provides a rapid and visual means of deciding on an instrument system based on the slope and the intersection of the two lines with respect to cost (y-axis) and batch volume (x-axis). An accompanying table provides a more exact numerical comparison.
How the HAAs Cost of Ownership Calculator Works
As mentioned above, the operation of the cost of ownership calculator is based on the following:
Estimated instrument price (GC-ECD and IC-MS/MS)
Cost per batch
For the GC-ECD, EPA Method 552.3 this includes the cost of chemicals and labor for sample prep (i.e., extraction and derivatization)
For the IC-MS/MS EPA Method 557, this includes the annual amortized cost of the two consumables, i.e., a suppressor (a Dionex ADRS 600 Anion Dynamically Regenerated Suppressor – 2mm) and EGC (an eluent generator cartridge for anion analysis). There is no sample prep cost as the sample is directly injected into the mass spectrometer.
One batch is defined as 20 samples, however, these do not include reagent blanks, calibration checks, fortified blanks or internal standards.
The data for each (GC-ECD and IC-MS/MS) are shown to two straight-line equations (y=mx+b). Cost appears on the y-axis and the number of batches appears on the x-axis.
The inflection point of the two lines is where the two provide the same cost of ownership.
At the left of the inflection, GC-ECD has a lower cost – with the advantage of a lower instrument price.
At the right of the inflection, IC-MS/MS has a lower cost of ownership – with the advantage of no sample prep that enables higher throughput capability. The take-home message is the cost of ownership advantages really depends on your sample throughput.