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As businesses feel increasing pressure to compete globally, their finance departments are continually searching for cost control efforts to improve the bottom line. The annual budget for testing may bring such cost-cutting campaigns to a standstill, especially if your customers require certification or if testing is a necessary step in your research or quality control processes.
However, several simple strategies can help companies get the most out of their testing dollars. Although it doesn’t hurt to compare prices, the right lab can deliver a greater value by acting as a partner in your business process, providing expertise on test selection, helping you cost-effectively prepare samples, and producing reports with meaningful information.
Select the Right LabChoosing a lab is probably the most important part of the equation. Get to know the lab’s strengths and get a feel for your ability to build a rapport and work in partnership. The inorganic analysis field typically works with three types of labs. A general chem lab performs most mainstream inorganic testing and may also offer organic testing. These labs generally feature a range of standard equipment used for the most commonly required tests.
A specialty lab focuses its services on one or two types of materials and should feature material-specific equipment. These labs can typically conduct in-depth analysis on a few matrices, but might lack the ability to perform basic testing on samples outside of their normal scope.
Environmental labs test samples in compliance with discharging or landfill regulations, such as those related to the Resource Conservation and Recovery Act (RCRA) and Toxicity Characteristic Leaching Procedure (TCLP). Environmental labs typically do not perform tests for industry; they specialize in providing test results that are relevant to the environmental protection field. A “total aluminum” analysis, for example, means something very different in the environmental area as opposed to an aluminosilicate producer.
Any lab should be able to present customers with its qualifications in the form of relevant accreditation, such as ISO 17025 General Requirements for Competence of Calibration and Testing Laboratories, American Association for Laboratory Accreditation (A2LA), National Aerospace and Defense Contractors Accreditation Program (NADCAP), or state Department of Environmental Protection (DEP) and Environmental Protection Agency (EPA) certifications.
Understand Lab ResourcesSome customers are comfortable with specifying the exact test they might need for their material. However, it can be useful-and possibly economical-to begin a discussion with a lab by focusing first on the type of results that are required. With today’s range of equipment, it might be possible to obtain the needed data through an alternate form of testing. Regardless of the lab type, several pieces of equipment will be found at many of the labs being considered. Understanding the capabilities of this equipment can guide the lab selection process.
X-ray fluorescence (XRF) is a solid state analyzer, meaning that it requires a solid sample (approximately 1 in. diameter) to produce results. XRF bombards a sample with high-powered X-rays and measures the fluorescence using specific angles, crystals and detectors. Using advanced software, it produces quantitative results in the form of calibration curves that compare the sample to certified standards. XRF’s primary benefits are accuracy, precision, speed and little interference. XRF does have some drawbacks. It generally cannot be used to determine concentrations in liquids, very small samples, or elements lighter than sodium or fluorine. Also, matrix-similar standards must be available to calibrate the XRF.
Inductively coupled plasma emission (ICP) or direct current plasma emission (DCP) might be used to analyze samples that are smaller in size or lacking matching standards. In either technique, the solid sample is dissolved in acid, and inorganic liquid samples can be analyzed as received. Because the matrix is mostly water, the lab can produce standards using commercially available solutions. Typically, the calibration is produced with only one or two standards and a blank.
Samples are pumped via an aerosol directly into the plasma. As the sample passes through the plasma, excess energy is absorbed by the individual ions and then released moments later as light. Each element emits its own characteristic wavelengths, and this light is measured with a spectrometer. The amount of light is directly proportional to the amount of the element present in the sample. Again, a software system easily determines the concentration of each analyte.
The main advantage of ICP/DCP is the flexibility to analyze almost any type of inorganic material that can be dissolved. Although not typically as fast or as precise as XRF, ICP is a good alternative depending on sample size, type and elements of interest.
Atomic absorption (AA) is the cousin of plasma testing. Unlike ICP, AA analyzes a single element at a time and uses a lower temperature than ICP or DCP, though it often uses the same solution as ICP. Graphite furnace atomic absorption (GFAA) is an even slower AA method that uses high-temperature, electrically heated tubes to burn a sample and measure trace elements that might not be run by other methods.
LECO combustion equipment has almost become synonymous with the analyses it performs. LECO makes specific analyzers for carbon, sulfur, nitrogen, oxygen and hydrogen using combustion methods. Solid samples of 0.1-1.0 grams are weighed into a vessel and placed in a stream of inert gas. The sample is heated, and the gases of interest are evolved into the gas stream and carried to a detector like an IR cell.
Like ICP, calibration typically uses a blank and one standard, and the amount of each analyte is proportional to the counts present. Carbon and sulfur can be detected in most solid, inorganic materials, while nitrogen, oxygen and hydrogen are usually performed only on metal samples. The high levels of oxygen present in ceramics and refractories can damage the detectors in the N/O and H units.
Wet chemistry, another form of analysis, usually involves lots of hands-on analysis with typically one analyte per test. Wet chemical testing has several drawbacks, including the amount of time involved, waste generated and cost of reagents. For those reasons, wet chemistry is usually a last resort. In general, it is only used when no definitive instrumental method is available, such as testing for lead oxide in glass. One analysis can take several hours, but it is a very effective way of measuring 50% lead oxide.
The aforementioned equipment will handle 95% of the typical laboratory needs, but what about the other 5%? Specialty equipment like ICP/mass spectrometry, ICP with solid sampling ability, X-ray diffraction, LECO forms of carbon analyzers, thermogravimetric analyzers, ion chromatography, and even older direct reader spectrographs have their place in the modern inorganic testing lab. Depending on specific needs, they may be a critical piece of the puzzle.
Prepare a Useful SampleOnce you’ve determined that testing is required, create a list of samples and parameters. Describe the samples, the tests requested and the specifications, and include a product sheet or some general info about the samples in a letter and/or purchase order. Include a Material Safety Data Sheet (MSDS) when necessary.
The process sounds simple enough, but overlooking even one of these details can create problems. First, samples containing silicon carbide or ferro-alloys can destroy the costly platinum crucibles used in fusing the XRF beads. If lab equipment is damaged because of your failure to report such materials, the lab may pass the costs on to you.
Second, samples that contain either atypical elements or critical elements that are not included on the standard list of parameters (such as boron and lithium) can slow the analysis by driving the lab to focus on discovering the missing element. Lastly, most labs are not equipped to handle samples that are known to be hazardous or radioactive, so this information should always be disclosed in the initial discussion.
The best analysis in the world is worthless if the sampling is poor. Try to obtain a representative sample of the material to be tested and package it securely to maintain its integrity. If your plant has the ability to prepare your own lab-sized sample to less than 100 mesh, this step will usually save you time, cost and eliminate a potential source of contamination. Unless the sample will be hand-delivered to the lab, use a traceable shipping service to confirm the sample’s arrival.
Analysis and ResultsAfter they are logged in at the lab, samples are riffled and crushed into a small lab sample of a couple ounces. The lab then prepares samples for instrumental analysis. Samples are calcined to generate moisture and loss on ignition (LOI) data, and then fused for XRF analysis. ICP digestions are done either with fusions or acid dissolution, and the powdered samples may be run directly by LECO for carbon and sulfur.
After analysis, results are calculated and reported to the customer. Although reports might come in many different formats, they should contain some basic similarities. The lab’s name, address, a signature block and accreditations should appear on each report. The data should include both the lab’s and the customer’s sample ID, and a list of parameters with results and units. Unless noted otherwise, results will typically be reported on an as-received basis.
Often, and for ceramics in particular, results will appear on a calcined basis, meaning that the data is produced from the calcined sample. The moisture and LOI should not be included in any totaling of this data. Results may also appear on a dry basis, where the moisture has been removed prior to analysis. The report should also include the method of testing, the date of receipt and the report date. The date of analysis, the analyst’s initials and specifications may also be present.
The lab’s ability to produce thorough and accurate reports can support long-term cost control efforts. With proper planning, you may eliminate the need to re-test a sample because the report didn’t generate the level of detail you need for your development process. When talking to a lab about your test, ask about the format and detail of results that they will produce so you can be sure that the fee is covering the information you need.
Other ConsiderationsWhen possible, advanced planning can also help you control your testing costs. Find out the lab’s typical turnaround time for your project. Turnarounds might vary from a few days to several weeks. Knowing what to expect from the lab can help you avoid rush charges. In addition, some labs may be willing to offer volume discounts for large-scale or regular testing needs.
With the equipment available in today’s laboratories, getting valuable, cost-effective analyses is easier than ever. By adopting a few simple strategies, both you and your accounting team can be assured that you’re getting the best value for your testing dollars.
For more information about testing processes, contact West Penn Testing Group, 1010 Industrial Blvd., New Kensington, PA 15068; (724) 334-1900; fax (724) 334-9785; e-mail email@example.com; or visit www.westpenntesting.com.
Editor’s note: This article is based on a paper presented at the Ceramic Manufacturers Association (CerMA) conference held May 2007 in Pittsburgh, Pa.
SIDEBAR: A Secure Send-OffFollow these sample preparation and packaging tips to improve the cost-efficiency and accuracy of your testing process:
- Ask for the required form of the sample so you can get it right on the first delivery.
- Make certain your samples are secure and won’t leak. Double-bag or tape bags and bottles shut.
- Include sample and test specifications, instructions for the lab to e-mail or fax results, and a phone number for questions.
- Be descriptive. Samples with missing instructions or confusing paperwork are much more likely to be put on hold while other samples are processed.