Boron is NOT our Friend
Since 1994, we had operated the cosmogenic nuclide lab without
boron issues. Sure, there was that one batch of samples from Boliva
that was loaded with boron (where the hell did that come from?) but all
the rest were fine. Then, in November 2006, we carried over 100 targets
to LLNL, all the lab production between July and the end of October.
Every sample processed before the end of August was perfect; every
sample processed after the end of August was unmeasurable. Boron was
the culprit. B-10 masquerades as Be-10 and overloads the AMS detector.
Bottom line, no data, for a little while. LLNL savvy came to the rescue
with the installation of a final stripper foil and all but 4 samples
were salvaged. The lab shut down immediately so we could figure out what
went wrong.
The real question was...where did all the boron come from? It took us
several weeks to figure out that two things had happened during the
summer of 2006. First, the synthetic, boron-free filters specified for our HVAC
system had been replaced with borosilicate glass filters and those
filters were not tightly seated on their racks. Second, during
re-roofing of our new building, boron-bearing insulation had been
stripped, pulverized, and injected into the air supply system as it was
ripped off the roof. With gaps between the filters, this material had
gone all the way to the cosmogenic lab where it plugged the ULPA final
filters on our hoods and...since boron has a tendency to become
volatile, degassed, and permeated every sample processed between August
and November 2006. You can see some pictures of this mess,
here.
We spent 6 months figuring out what went wrong, replacing all the
filters, cleaning the ducts, and cleaning the lab. Three 3 days after
bringing the lab back on line in May 2007, it was destroyed by an
electrical
fire on Memorial Day.
The fire vaporized a sheetrock wall (sheet rock contains boron both
naturally and as an added fire retardant) and the fiberglass insulation
behind the wall (yes, fiberglass is made from borosilicate glass). Test
samples run in an adjacent lab after the fire
showed extremely high boron
levels.
We did learn loads about boron in the process and share that information
in the links below. Those interested in boron, might enjoy the
information
(Powerpoint) (PDF file) that we put
together for the construction team rebuilding the laboratory.
Air Filters are Critical Air
handling...the reason for anomalously high boron background levels
Water Quality Matters Ultrapure water blank for boron
trace analysis Ultrapure Water for Boron
and Silica Sensitive Laboratory Applications
Boron Chemistry and Sources, Background Information Boron
Supresion of Boron
Volitilization... Boron as a tracer for material
transfer...
Measuring Boron Microwave Digestion and
Ultrasonic Nebulization for Determination of Boron...
Use of
Inductively Coupled Plasma-Mass Spectrometry in Boron Stable Isotopes