UMAQL Class 100 Clean Room Laboratory
Lab History
The University of Michigan Air Quality Laboratory was established in the
Autumn 1990,within the University of Michigan's School of Public Health. At
that time, the facilities consisted of a single, two-room laboratory with
one room devoted to office space and one room devoted to inorganic chemical
analysis. The analysis laboratory contained an ion-chromatographer, pH meter
and a temporary "clean bag" for trace-level mercury analysis.
In the Spring of 1993, finishing touches were completed on a new, state-of-the-art
clean-room facility. The new 750 square foot, Class 100 (less than 100 particles per
cubic meter), all-plastic construction clean-room facility is uniquely suited for
ultra-clean trace element analysis, with an emphasis on environmental mercury determinations.
The laboratory equipment includes Class 100 laminar flow workstations, Class 100 laminar
flow exhausting hoods, individually HEPA-filtered drying cabinets, Millipore ultra-pure
water purification systems, quartz stills for acid distillation and purification, cold vapor
atomic fluorescence spectrometers (CVAFS), an Atomic Absorption Spectrophotometer (AAS),
a computer controlled Dionex 4500i HPLC with gradient pump and both UV-VIS and conductivity
detectors, as well as other standard laboratory equipment. In addition, the laboratory
contains a Perkin-Elmer ELAN 5000 ICP-MS for ultra-trace element and stable isotope
analysis. A second, 440 square foot Class 100 laboratory has recently been built and is
now in use.
Class 100 Clean Room
The UMAQL Class 100 clean room facility maintains a positive-pressure environment.
This "positive-pressure" environment insures that upon entrance into the laboratory,
air flows out of the clean room facility, limiting the possibility of contiminants
entering the clean room. Also, the all-wooden/plastic design insures that no metal
contamination can occur that would hamper the trace-level analyses performed in the
facility.
Class 100 laminar flow workstations are utilized during all steps of sample
preparation and analysis to insure sample integrity. Here an analyst is shown
preparing a mercury sample for analysis (above left). Clean gloves are worn by the
analyst at all times when the sample is being handled. The sample is then purged
(above right) with nitrogen gas, causing the elemental mercury vapor to be driven
from the solution and onto a gold-covered bead "trap". The "trap" gets its name
from the fact that the elemental mercury vapor becomes "trapped" onto the gold-covered
beads held within the glass tube making up the trap. In reality, the element mercury
vapor is adsorbed onto the gold.
Here, an analyst is seen at a cold vapor atomic fluorescence spectrometer
(CVAFS) workstation (above left). The gold-covered bead "trap" from the preceding
photo is placed within a flow stream of mercury-free helium gas. The traps are heated
(above right) to 600 degrees centigrade, which "desorbs" the mercury off of the
gold-covered beads. The stream of helium gas then carries the elemental vapor-phase
mercury into the analyzer, where the amount of mercury on the trap is determined.
