FAQs

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Frequently Asked Questions

Instrumentation

1. 1. Which elements can be measured by ICP-AES and ICP-MS?
      • ICP-AES and ICP-MS can analyze most elements in the periodic table except C, H, O, N, and the halogens.
   2. What is the difference between ICP-AES and ICP-MS?
      • ICP-MS and ICP-AES are two techniques that quantify elemental concentrations in aqueous solutions. ICP-AES is suitable for higher concentrations (ppm level) while ICP-MS quantifies concentrations at the ppb level. ICP-AES measures light photons emitted by elements that are electronically excited in an Ar plasma, while ICP-MS analyzes ions generated in an ion source (in this case, an Ar plasma).
      • Interferences are less of an issue in ICP-AES but can be problematic in ICP-MS. Isobaric interferences are ions that have the same mass to charge ratio as – and are not distinguished from – the analyte of interest during analysis (e.g., ⁴⁴Ca⁺ and ⁸⁸Sr⁺⁺). Non-spectral interferences are matrix-specific effects that are not distinct isobars but may change the ionization characteristics and/or transmission behavior of analytes of interest in the source relative to calibration standards. Such effects are best dealt with by analyzing matrix-matched standards.
   3. What are the detection limits of ICP instruments?
      • Detection limits depend on the counts at which one can distinguish a true signal from noise. Therefore, they can vary element by element. Generally, the detection limits of the ICP-AES and ICP-MS are on the order of 0.1 ppm and 0.1 ppb, respectively.
   4. Can I measure the isotopic composition of an element that you don’t have listed on your website?
      • Additional isotopic systems require method development, which takes time and effort. It is certainly possible, and we are always interested in expanding what we do, but it requires careful consideration and is typically more of a collaborative effort than a ‘for-fee’ service. Please contact the instrument specialist and/or the co-directors to initiate a discussion.

Sample requirements

1. 1. What are LIME’s requirements for aqueous samples?
      • Samples must be aqueous in nature, free of organic components, solvents, and particulates/precipitates; we prefer all samples to be acidified to 2 to 5 vol. % nitric acid using trace metal grade/high-purity acid. If the client is unsure what kind of acid to use, please contact us. Please refer to the sample requirements on the LIME website (https://lime.psu.edu/).
      • Sample volumes should be greater than 3 to 5 mL, depending on the instrument. Samples with organics generally need to be digested, though dilution may be acceptable for analysis by ICP-AES; please discuss with the instrument contact)
      • Samples with high analyte and/or matrix concentrations are diluted prior analysis.
      • If you dilute your samples, please do the dilution by mass (gravimetric) rather than by volume (volumetric). The former is more precise and ensures that the precision that you get from the analytical technique is not impacted by the dilution.
   2. What are LIME’s requirements for solid samples?
      • Samples should be dry and finely-powdered for most processing methods; larger particles/pieces may work for acid digestions but this must be confirmed with the analyst.
      • For samples that are difficult to powder, please discuss with the instrument contact (listed on the LIME website: https://lime.psu.edu).
      • Solid samples are generally digested with various acids prior to analysis. Direct questions regarding LIME’s SOPs for acid digestion to instrument contacts. 
      • Sample preparation for laser ablation ICP-MS — which does not require digestion but may have other requirements — should be discussed with the ICP-MS instrument contact (https://lime.psu.edu/icp-ms/).

Requesting analyses

1. 1. How do I submit a sample request? How do I get LIME my samples? How should I label my samples?
      1. Fill out a ‘Request Analysis’ form on the LIME website (https://lime.psu.edu/submit-samples/).
      2. Labeling samples in a unique manner is important and LIME analysts request that all users create short IDs for all samples submitted. The analysts prefer that you use three initials (abc)-sample #. For example: abc-1, abc-2, etc.
         1. If your sample is a procedural or reagent blank, please include BLK in the short ID: e.g, abc-BLK-1.
         2. Users should make a sample ID key that allows you to translate the short ID into your long-format sample ID. LIME does not need the long format sample ID or the key.
      3. Ship or drop off your samples:
         • Ship for ICP-AES and IC: Laura Liermann, 312 Hosler Building, University Park, Penn State University 16801
           • Drop off for ICP-AES: 312 Hosler Bldg.
         • Ship for ICP-MS: Maggie Wang, 317 Hosler Building, University Park, Penn State University 16801
           • Drop off for ICP-MS: 301 Hosler Bldg.
         • Ship & drop off for MC-ICP-MS and TIMS: contact instrument specialist.
         • Ship & drop off for EA-IRMS and gas bench IRMS: contact instrument specialist.
   2. I am a PSU user. On the ‘Request Analysis’ form, you ask for a LEO project number? What is LEO? What is a LEO project? How do I obtain this number?
      • LEO is Penn State’s billing system for core analytical facilities. Clients must have an active project in LEO, which is associated with an active budget, for LIME to analyze a client’s samples. LEO is used by Penn State users, not external users.
      • To get started, go to the LEO website: https://leo.psu.edu/
      • Log in. On the home page, click on the LEO Registration icon. Complete the requested information regarding the LEO project you are setting up. For most users (students, postdocs), the LEO Requestor Role is LEO System User; PIs or unit billing contacts make the appropriate selection. Users should have the appropriate internal order, cost center, etc. on hand before initiating the registration process. If the user is not the project PI, obtain the PIs approval to add the desired budget, and alert the PI that they receive an email to approve. This ensures that there is limited delay in setting up the project.
      • Note that LIME staff are unable to set up LEO accounts for users.
   3. What is the process for submitting samples from external institutions?
      • Samples cannot be accepted for analysis from external institutions until an ARSO contract is in place (see ARSO section below). Once the contract is in place, samples can be shipped to LIME for analysis. The sample requirements are as stated above and on the LIME website: https://lime.psu.edu/

Sample preparation services

1. 1. What kind of sample preparation services does LIME offer?
      • Sample digestion (ICP-AES; ICP-MS; MC-ICP-MS; TIMS): for users that are not familiar with digestion techniques or cannot digest samples at their home institution, we offer solid digestion by various means.
        • For bulk silicate rocks and sediments where Si is a required analyte, we offer lithium metaborate (LiMB) fusions. These are typically only analyzed by ICP-AES and have higher procedural blanks.
        • For bulk silicate rocks and sediments where Si is not a required analyte, we offer acid digestion, which have markedly lower procedural blanks than LiMB fusions. We typically utilize HF, HClO4, HCl, and/or HNO3 to dissolve silicate rocks; aqueous fluoride complexes with Si and forms a volatile compound, which is lost when the sample is heated uncovered. However, fluoride will also form insoluble precipitates with elements such as Ca, Mg, and Na. If your sample has high concentrations of these elements, inform us when you submit your sample request.
        • For carbonates and other soluble salts, we are able to leach sediments and/or soils in acetic, nitric, and/or hydrochloric acids. If the user has a procedure they are interested in utilizing, please contact us.
        • Note that some samples types may require dry ashing prior to digestion to break down organic matter, for instance. Ashing may release volatile elements. If this is a problem for you, you must let us know prior to sample analysis.
        • We do not use sulfuric acid to digest samples in LIME.
      • Ion exchange chromatography: all samples must be digested and chromatographically purified prior to isotopic analysis by MC-ICP-MS and TIMS.  This is a manual, time-consuming process and adds significant cost to isotopic analyses, compared to ICP-AES and ICP-MS. This is not optional, though the user may choose to perform this work themselves at their home institution. In such cases, we ask that users run internationally-accepted standards through the columns and send them as unknowns to ascertain the soundness of their chromatographic procedures.
      • NB: we currently do not offer microwave digestion.

External users and ARSOs

1. 1. I am not a PSU user. What is an ARSO?
      • ARSO stands for Academic Research Services Order; the ARSO process is initiated when LIME drafts a Statement of Work and related cost estimate, which outlines the proposed analyses and the estimated cost of those analyses. The cost estimate is a good faith estimate and not a formal quote, as various factors may change the final cost (e.g., change in sample numbers, unforeseen processing, cost increases over the time period of the ARSO, etc). Accordingly, we recommend an upper cost limit that is greater than the estimated cost, as any work done cannot go over this limit without creating a new ARSO. If the client accepts the Statement of Work, it is sent to Penn State’s Office of Sponsored Programs with the ARSO contract (contains terms and conditions, upper cost limit, period of performance, PI and billing contact information) for processing and approval. At some point during this process, the customer’s institution should receive electronic copies of the documents that they must sign.
      • We do not process ARSO’s for <$1000 of work. This is a function of the cost of preparing and shepherding ARSO’s through the process, a process that is onerous for us (as it is for you).
   2. What if I don’t spend all the money in my ARSO? Does LIME keep the extra money?
      • LIME does not receive any money up front and only charges for the services performed. Once services are rendered, the customer is billed and pays the invoice. It is similar to a credit card in this respect – the customer has an upper limit that cannot be exceeded, but if that limit is not reached, no money is lost.

Data analysis and data reports

1. 1. Why is it taking so long to get my samples analyzed? Where are my data?
      • The turnaround time for sample analysis and data reporting depends on several factors, including sample type (solutions, solids), processing required (dilutions, digestions, etc.), number of samples, and samples in the queue.
      • We recognize that all clients want data as soon as possible and we do our best to make that happen. Turnaround times can be anywhere from 1 to 3 weeks in most cases but can be longer, such as in cases in which samples require multiple processing steps or are numerous and therefore require multiple analytical sessions. Isotopic analysis via TIMS or MC-ICP-MS will require additional processing time to account for ion chromatography prior to analysis. Clients can reach out to the instrument contact to discuss the timeframe for analysis and any concerns.
   2. What kind of data report will I receive?
      • All instrument specialists utilize a data report template that they populate with your data. The reports typically include notes on the analysis, instrumentation details, and a data summary. Some instrument specialists include information on data corrections, analytical accuracy and precision, etc. Please contact the instrument specialist to confirm what your data report contains so that the expectations are clear to both parties.
      • If you wish to have information that is not typically communicated in data reports, such as calibration curves and raw data, please contact the instrument specialist. Note that time spent including such information, which varies by instrument, can be charged as staff time at the hourly staff rate.

CURRENT LIME FEE SCHEDULE

CORE FACILITIES AT PENN STATE

1. 1. What is a core facility or a shared user facility?
      • A core or shared facility at Penn State is an entity that provides analytical services to users at rates determined necessary to recover costs. These facilities do not make profits and do not compete with commercial operations. They typically serve both internal and external users, and are research-oriented. Fees are established annually based on previous years’ costs.
      • Core facilities, such as LIME, serve multiple purposes. Foremost is our desire to train future scientists on instrumentation and in sound and robust data collection techniques. We seek to create a new generation of researchers that understand the details of producing data and will be able, once they leave PSU, to design, build, and operation analytical facilities and produce high quality data that answer important scientific questions.
        • We also serve internal and external users seeking to use geochemical data to answer important scientific questions, explore the Earth and its operation, and characterize materials chemically. We are amenable to collaboration at any level, from conducting analyses to assisting with data interpretation.
        • Finally, LIME seeks to bring isotopic tools into the mainstream. Isotopic tools are prevalent in the geosciences, but are less common other disciplines. Generally speaking, isotopes are useful for identifying sources (i.e., provenance) and, in some cases, chemical processes. Please contact us and inquire about how isotopes can be useful to you.
   2. Are there other core facilities at PSU? How do I find them?
      • IEE has created a list of at least some of the core facilities at Penn State: https://iee.psu.edu/labs/penn-state-core-facilities
      • Note that this list might not be complete.