Environmental Engineering Reference
In-Depth Information
analytes, although currently the company focuses on the needs of its early customers, includ-
ing key analytes such as perchlorate.
10
It is not yet clear whether similar approaches will play
as online instruments, but as specialized ield instruments they are already available.
Companies like Intellitect have miniaturized and combined multiple common analytes
onto microchips, creating robust online instruments that can withstand dificult settings
like large fast-lowing pipes.
11
Using similar technology, start-up Fluid Measurement
12
takes common parameters such as pH, dissolved oxygen, free and/or combined chlorine,
turbidity and color, and miniaturizes and combines them for use in pipes and other appli-
cations. It sells the chips through integrators such as Censar Technologies.
Inorganic measurement by other next-generation techniques such as voltammetric “elec-
tronic tongues” are still in their infancy.
13
A wide variety of highly speciic but somewhat
unstable biologically derived (sometimes using exotic substrates such as carbon nanotubes)
quantum dots or electrically conductive diamond, has begun to emerge in the space.
9-13
10.6 Organic Species: A Moving and Expanding Target
If metal analysis is well deined with reasonable detection limits, organics analysis is the
opposite. Untold billions of organic species exist. Most have unknown toxicity. Worried
regulators tend to lurch from one set of contaminants to the next as research uncovers
dozens of new species and then slowly begins to sort through them for those that cause
the most harm.
• Organic targets are essentially ininite, favoring laboratory instruments. Only a
sophisticated laboratory instrument can sort through the hundreds or thousands
of organic molecules present in natural waters, which may derive from farm run-
off, industrial processes, as by-products of wastewater treatment, or simply be
naturally present. Even species that are naturally present can sometimes pose seri-
ous health risks. The wide variety of organics makes single-species recognition by
simpler instruments less relevant.
14
• Regulators are beginning to look for “reference” molecules. Ironically, the sheer
number of organics is likely to force regulators to pick a few indicator molecules,
opening the door to online instruments again. For speciic applications such as
food safety, i.e., measuring wash water from a speciic type of vegetable, a range of
sensors speciic to a few known pesticides or herbicides may sufice.
15
• Not all organics require high sensitivity. For those that do, extremely low con-
centrations offer both an opportunity and a challenge to next-generation instru-
ments. Few current technologies outside the laboratory can contemplate ppt
measurement. Repeated attempts to automate laboratory systems such as high-
performance liquid chromatography have resulted in cumbersome, leaky white
elephants. Developing such instruments for key parameters would be game
changing. It would also, by its very nature, almost certainly require the precision
of nanomaterials.
For organic species, even more than metals, even minute quantities of a highly bioac-
tive species can wreak havoc on an animal or human body. For cancer-causing species,
