The sample preparation laboratories of PCIGR are located on the top floor of the EOS Main building. The three labs are completely independent in terms of air supply. The labs are accessed by a vestibule. The entire air-handling system is filtered by 42 HEPA filters, with two levels of pre-filtration.
The labs were custom designed by Clean Rooms West Inc. to achieve Class 1000 — all the measurements are close to Class 100. Each lab is equipped with two or three Class 100 laminar flow hoods. In each lab, one hood is an exhaust hood; the tracer lab is also equipped with a perchloric hood.
The three clean labs are metal free and are divided according to specific analytical needs and the level of the required chemical processing:
– Tracer lab: devoted to “routine” Pb-Sr-Nd-Hf separation for isotopic studies, together with separation for heavy stable isotope studies;
– U-Pb lab: used only for U-Pb zircon (+baddeleyite/monazite/titanite) chemistry;
– Low-level lab (funded by CFI to D. Weis): devoted to low-level chemical analyses and preparations that have special requirements (sub-ppm to ppb level).
Access to the labs is strictly limited to authorized users and requires complete gowning. Sample preparation, cleaning, and high-pressure dissolution are carried out in the prep room before taking only the cleanest necessary items into the clean labs.
Two systems of high-capacity Elix/MilliQ water filtration provide ultra-clean water, and all of the acids are either quartz-distilled or sub-boiled (Savillex DST-1000, and DST-4000 systems) as needed. Our blank levels are excellent, in the 10–100 pg range for all the elements that we are dealing with.
In addition to including procedural blank samples for each set of analyses, we carry out analyses to monitor all reagent acids used in the clean lab regularly. We also monitor the air quality of the labs by analyzing blank ‘air samples’ collected in open-top containers in the clean labs.