B--RFI - MICADAS analyses plant macrofossil samples

This is a Request For Information - This synopsis is for information and planning purposes only and is not to be construed as a commitment by the Government. No contract will be awarded as a result of this Sources Sought announcement. The United States Geological Survey, Office of Acquisition and Grants is soliciting information from qualified sources; the results of this announcement will be evaluated to determine if there are businesses capable of performing the proposed work. The US Geological Survey, Office of Acquisition and Grants seeks responses from vendors that possess the capability to perform high-precision, MIni CArbon DAting System (MICADAS) analyses of small (<1 mg) plant macrofossil samples. The samples must be prepared using highly specialized methods to remove all contaminants. Analyses must be completed within three months of submitting the samples and costs for analyses should be kept to a minimum to maximize the number of samples that can be analyzed. The contractor shall perform radiocarbon analyses using the latest MICADAS technology, which features a versatile accelerator mass spectrometer that can measure 14C in samples either as graphite (after sample preparation) or more rapidly as CO2 gas (after purification). Gas analysis allows for a smaller sample size and faster throughput, but at lower precision than traditional graphite analysis. Recent studies (Zander et al., 2020) show evidence that dating more samples at lower precision can lead to more accurate age models for similar cost as models developed with fewer, higher-precision ages. Samples from lakes along the West Coast of the United States and Alaska will be processed and analyzed according to the technical procedures specified below: (a) The contractor shall pretreat organic samples for removal of exogenous carbon (Olsson, 1986). The sample is treated with 1N HCl for 30 minutes at 60'C, then 1N NaOH for 30 minutes at 60'C, and again for 30 minutes at 60'C, with an 18.2 M water rinse between each step. The sample is then dried in a freeze-drier or an oven at 60'C. For very small samples, a less-rigorous treatment will be followed to avoid destroying the material. Very small samples will be treated at 40'C with with 0.5'mol'L1 HCl, 0.1'mol'L1'NaOH, and 0.5'mol'L1'HCl for 3, 2, and 3'h, respectively (Zander, et al., 2020). (b) Contractor shall combust larger (1 1 mg) solid samples for graphite analysis (Boutton et al., 1986). Graphitization involves a reaction in a gas reactor heated to 400'C. Over 3 hours of reaction time, the sample is converted to graphite coated on an iron catalyst (Vogel et al., 1984). Each sample shall be converted to graphite and analyzed in the accelerator mass spectrometer. (c) Contractor shall combust smaller (1 mg) solid samples for direct gas analysis. Sample is combusted with an elemental analyzer; the CO2 is transferred to a syringe (Fahrni, et al., 2013) and pumped directly into the MICADAS for analysis (Synal et al., 2007). Generally,100 ug of carbon are analyzed with this method, but samples weighing as little as 10 ug may be analyzed at lower precision than large samples. (d) Contractor shall perform radiocarbon analysis of graphite using MICADAS technology (Synal et al., 2007). Graphite analysis produces higher precision than direct gas analysis by analyzing more carbon and counting more 14C atoms. Ideally, 1 mg of carbon is analyzed. Analysis of smaller samples will achieve lower precision than large samples. References: Boutton et al., Comparison of quartz and pyrex tubes for combustion of organic samples for stable carbon isotope analysis, Analytical Chemistry 1983, 1832-1833 Fahrni, et al., Nucl. Instrum. Meth. B 2013, 320'327 Synal et al., MICADAS: A new compact radiocarbon AMS system, Nucl. Instrum. Meth. B 2007, 7-13 Vogel et al., Performance of catalytically condensed carbon for use in accelerator mass spectrometry, Nucl. Instrum. Meth. B 1984, 289-293 Zander, et al., 2020, Miniature radiocarbon measurements (< 150 - g C) from sediments of Lake Zabi'nskie, Poland: effect of precision and dating density on age-depth models Geochronology, 2, 63-79, https://doi.org/10.5194/gchron-2-63-2020 Interested parties should submit a Capability Statement to the Contracting Officer, Charlan Fejarang at contact@example.gov by the due date, Monday, April 21, 2025 at 12pm PST.