General FAQs—Laboratory Services
WQCF’s state-of-the-art laboratory provides chemical characterization of aqueous samples. Currently, WQCF can analyze for the following parameters:
- Total dissolved metals by ICPOES (inductively-coupled plasma optical emission spectrometry)
- Total dissolved ions (anions and cations) by IC (ion chromatography)
- Dissolved carbon (total, inorganic, or organic) by TDCA (thermal decomposition carbon analysis)
- Total dissolved nitrogen by PCNA (photo-catalytic decomposition nitrogen analysis)
- Total suspended solids (TSS) and Total dissolved solids (TDS)
- Wet chemistry: Alkalinity (ALK) or Acid-Neutralization Capacity (ANC), pH, conductivity
- Hot Acidity (HA) for mine drainage characterization
The WQCF also provides the following support functions:
- Hot plate digestion (liquids)
- Instrument operation training
- Mentoring/consulting: data quality objectives (DQO); experiment/research design; good laboratory practice and safety
We recommend contacting WQCF Lab Manager Adrian Gonzalez very early in your program’s timeline, even during project development/planning. Coordination and discussion of analytical needs early in the process could uncover limitations or beneficial analytical capabilities to your overall objectives. Information learned from these discussions could impact the feasibility, objectives, direction, or progress of your project.
Topics to discuss with the WQCF lab manager include (but not limited to) the following:
- Understand available WQCF services, capabilities, methods
- Project Data Quality Objectives (DQO) requirement: detection limit requirements, speciation vs. total, digestion matrix composition requirements, concentration units, PARCC parameters, etc.
- Analytical quality assurance (QA) / quality control (QC) requirements
- Schedule logistics (when to submit samples, turnaround time requirements)
- Account to be charged, price/cost estimates
- Results reporting format and delivery method
Submit your samples in water-tight containers (e.g., vials) that are clearly labeled. Physically bring your secured samples to the Science and Engineering Research Facility (SERF) Room 317, on the campus of University of Tennessee, Knoxville. With your secured samples, bring a completed Request for Services (RFS) form. List your samples’ alpha-numeric identification codes (IDs) in the order to be analyzed. Please also remember to record the appropriate charge account number or payment source(s) on the RFS. At the WQCF lab, you will sign-over custody of your samples to the lab manager (unless analyzed by your qualified trained representative).
QA/QC is a critical part of all chemical analyses. The appropriate QA/QC level is 100% dependent on your job’s data quality objectives (DQO) and data end-use (e.g., application; purpose) of the results. Thus, there is a wide range of QA/QC levels to apply to any given job. It can range from a minimum of calibration standards and at least one instrument blanks to full accreditation-level QA/QC programs that include numerous calibration standards, calibration verification standards, instrument blanks, method blanks, field duplicates, laboratory duplicates, matrix spikes, QA reference standard solutions, etc. Discuss this with the lab manager before submitting a job.
The following true story should illustrate what QC samples provide with respect to data quality and data robustness.
“Several years ago, a grad-student was trained to run his own samples on a particular instrument in the WQCF lab. Months later, he contacted the lab manager for advice. His research manuscript had been reviewed and returned for revision. The grad student said his reviewers requested data demonstrating precision and accuracy of his analyses. He asked the WQCF lab manager what needed to done to meet the reviewers’ request. The lab manager reminded him of their original conversation in which the lab manager strongly urged him to include some QC samples with the analysis of his samples. Doing so would provide him with “known” results for comparison and a basis to judge the success of his analyses. He ignored the manager’s admonition at the time of his analyses. Months later, with manuscript review comments in hand, he asked if he could run the QC samples then. Of course that was meaningless since his research samples were analyzed months prior.”
The level of QC required for any particular set of samples is directly related to the end-use of the resulting data.
For example, results used in a regulatory role require the highest and most robust level of QC because public health or the course of legal action depends on those results.
Unfortunately, for academic research, the level of required QC is not established and thus most P.I.s take a “just the absolute minimum to get by” approach.
We always recommend something in the middle. But even that often is seen as “overkill” or “can’t afford that.”
At an absolute minimum, a batch of samples should be run with a number of calibration standards, at least one matrix blank that you provide, at least one instrument blank that the lab provides, and at least one known-concentration reference sample.
- Calibration standards are used to correlate instrument signal to analyte concentration. There is no “correct” number of calibration standards to run. It depends on the instrument, the method, the analyte(s) being measured, etc. At an absolute minimum, we recommend 3 calibration standards: a “zero” calibration blank, a low-concentration standard, and a high-concentration standard. The concentration range of the calibration standards must bracket the expected concentrations in your unknown samples. Sample results that fall outside of the calibration standard range have a lower level of certainty with respect to accuracy.
- The matrix blank (also called a method blank) is project-dependent. For traditional experiment samples, the matrix/method blank can be obtained (for example) from the experiment run with all reagents except the material or ingredient being investigated. For field samples, the matrix or method blank is more difficult to define. Sometimes a method blank in the field is a DI water samples that is processed in the same way as investigation samples collected in the field (e.g., filtered, preserved, stored, shipped, transferred, etc.).
- The instrument blank is prepared in the lab. It consists of DI water amended with whatever method-specific preservatives and/or reagents, at the same final concentrations, as required for all samples.
- The known-concentration reference sample can be one prepared in the lab, or (preferably) an experiment or field sample with a precisely-known concentration of the analyte(s) of interest. Whatever sample is used must be relatively fresh (i.e., not old and prone to have changed concentration during storage) and relevant to the unknown samples being analyzed.
As a first “mid-range” QC recommendation, the same blanks and reference samples may be measured multiple times at regular intervals throughout the batch. This is especially valuable when large sample batches (i.e., > 10 samples) are analyzed. Doing so provides two benefits:
- a test on the consistency of the instrument operation from beginning to end (i.e., no instrument drift or mid-run failure of some sort); and
- ability to calculate the precision of the QC results (e.g., running 3 or 4 reference samples provide you data to calculate/report a mean and standard deviation of the QC result that can then be compared to the “known” or “expected” value.).
We hope this information helps you in making your QA/QC decision.
There are several types of detection limits (DLs), including instrument DL (IDL), method DL (MDL), and limits of quantitation (LOQ). By accreditation requirements, WQCF performs annual method MDL studies for all instruments. This means MDLs can change slightly year-to-year. However, the LOQ is an assigned value (greater than the MDL) that the lab is highly confident in measuring accurately consistently. WQCF generally has defined its LOQ at 0.1 mg/L for most analytes. Discuss current LOQs with the Lab Manager.
Your samples are stored in the WQCF lab in a secured refrigerator until analysis. The lab manager keeps strict control of access to the lab (samples and standards; instruments and equipment). If a technical issue is identified with your samples prior to analysis, the lab manager can suspend work on your job and contact you. What happens next will depend on the outcome of those discussions.
You and the lab manager should agree on how you want results reported back to you. Typically, each instrument exports final results to an electronic file. The lab manager consolidates results from all instruments into one electronic spreadsheet file for your job. At a minimum, you can ask to receive this basic summary spreadsheet as your job report. More detailed report formats might involve labor charges for time spent preparing custom reports. In all cases, you will receive your job report after the job has been processed by our department’s business manager.
Yes. WQCF provides training on operating the ICPOES, IC, and carbon/nitrogen analyzer (CNA) located in the lab. WQCF charges an hourly rate for training. View WQCF website for current rates. Training per instrument usually consists of two sessions (different days) of approximately 3-4 hours per session. The first day consists of introduction to the WQCF’s lab facilities and instrument function, available methods and configurations of the instrument, and analytical theory. The lab manager demonstrates operation while the trainee takes notes and asks questions. The second day consists of the trainee operating the instrument as the lab manager observes and guides as needed. The trainee is documented as proficient on an instrument when one or more known-concentration reference standards are analyzed, and the trainee’s results match the expected values. A qualified, trained analyst is given access to the lab only after coordinating instrument schedule/availability with the lab manager. Samples analyzed by a qualified, trained analyst will be charged the “self-serve” price, available on the WQCF website.
ICPOES FAQs—Dissolved Metals Analysis
The following elements can be analyzed by the WQCF instrument. Asterisks indicate the most common elements analyzed by WQCF.
Group 1 and 2: Lithium, sodium*, potassium*, rubidium, cesium; beryllium, magnesium*, calcium*, strontium, barium
Transition metals: scandium, titanium, vanadium*, chromium*, manganese*, iron*, cobalt*, nickel*, copper*, zinc*; yttrium*, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, cadmium*; hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum
Group 13: boron*, aluminum*, gallium, indium, thallium*
Groups 14–17: silicon*, germanium, tin, lead*; phosphorus, arsenic*, antimony*, bismuth; sulfur, selenium*, tellurium, iodine
Samples absolutely must not contain hydroFLUORIC acid (HF).
All samples must be filtered through 0.45 um filter pore size.
All samples should be acidified to pH < 2 (preferably with trace-metal grade nitric acid). That pH is attained with at least 1% (by volume) acid in the sample.
You must provide at least 10 mL of each aqueous sample. A convenient vial for submitting ICPOES samples is the Falcon(R) 15-mL centrifuge vials. Label each sample vial clearly and submit in a vial rack.
Concentrations measured are restricted to the calibration standards’ concentration range. For some elements, ICPOES offers excellent linearity over a wide concentration range. For others, the internal physics of thermal ionization and photon emission limits the linearity response and results in non-linear response by the instrument detector. Calibration standard concentrations ranging from 0.1 mg/L to 20 mg/L are typical. Custom calibration ranges can be prepared as needed. For best accuracy, samples with concentrations that exceed the calibration standard range should be diluted with a metal-free diluent and reanalyzed.
Ion Chromatography (IC) FAQs—Dissolved Ions Analysis
Currently, the WQCF lab’s IC is configured to analyze the following:
- anions (fluoride, chloride, bromide, nitrate, nitrite, sulfate, and phosphate)
- cations (ammonium, sodium, potassium, magnesium, calcium).
All samples must be filtered through 0.45 um filter pore size
Samples to be analyzed for mineral ions (e.g., chloride, fluoride, bromide, sulfate) do not need to be preserved. EPA recommends specific preservation procedures for samples to be analyzed for ortho-phosphate or nitrate/nitrite. Discuss this with the lab manager before submitting a job.
Provide at least 2 mL of each aqueous sample in a plastic chromatography vial. Label each sample vial clearly and submit in a vial rack.
Concentrations measured are restricted to the calibration standards’ concentration range. For some ions, IC offers excellent linearity over a wide concentration range. For others, interactions between eluent chemistry (e.g., pH) and ion structure causes substantial non-linear response by the instrument detector. Calibration standard concentrations ranging from 0.1 mg/L to 20 mg/L are typical. Custom calibration ranges can be prepared as needed. For best accuracy, samples with concentrations that exceed the calibration standard range should be diluted with ion-free water and reanalyzed.
C/N Elemental Analysis (C/NEA) FAQs—Dissolved Carbon or Dissolved Nitrogen
Currently, the WQCF lab’s CNEA is configured to analyze the following:
- Dissolved carbon (total carbon, inorganic carbon, [by difference] organic carbon)
- Dissolved nitrogen (total nitrogen, organic and inorganic forms combined)
All samples must be filtered through 0.45 um filter pore size.
Samples to be analyzed for inorganic carbon (e.g., carbonates) should not be acidified. For samples to be analyzed for organic carbon only, EPA recommends specific preservation procedures to minimize bacterial growth and alteration of the sample’s integrity. Discuss this with the Lab Manager before submitting a job.
Provide at least 50 mL of each aqueous sample in a glass vial. Label each sample vial clearly and submit in a vial rack. Plastic vials should be avoided for carbon analysis because it’s possible they could contribute or remove dissolved carbon species to samples, altering the sample’s integrity.
Concentrations measured are restricted to the calibration standards’ concentration range. C/N Elemental Analysis offers excellent linearity over a wide concentration range. Calibration standard concentrations ranging from 0.1 mg/L to 50 mg/L are typical. Custom calibration ranges can be prepared as needed. For best accuracy, samples with concentrations that exceed the calibration standard range should be diluted with ion-free water and reanalyzed.