Name: potentiodynamic corrosion testing
Uploaded: 2016-09-04T14:00:00
Description: Watch this Scientific Journal Video about Potentiodynamic Corrosion Testing at JoVE.com

The authors had no funding provided for this study.

1. Construction of the Sample Holder
<ol>
	<li>Construct the sample holder from stainless steel spacers and a M3 stainless steel threaded screw, held in place with a M3 hexagonal nut.</li>
	<li>Remove the head of the threaded screw using pliers and polish the cut segment to maintain the thread pattern.</li>
	<li>When all individual components are ready, assemble the electrode holders. Each electrode holder contains three spacers joined together by the M3 screws resulting in an 11.5 cm handle. Place the hexagonal nuts a...

<ol>
	<li>Isaacs, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aspects+of+corrosion+from+the+ECS+Publications.">Aspects of corrosion from the ECS Publications.</a> J. Electrochem. Soc. 149 (12), 85-87 (2002).</li><li>Fontana, M. G., Greene, N. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Corrosion Engineering. , (1978).</li><li>Pourbaix, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrochemical+corrosion+of+metallic+biomaterials.">Electrochemical corrosion of metallic biomaterials.</a> Biomaterials. 5 (3), 122-134 (1984).</li><li>Rechnitz, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Controlled-Potential Analysis. , (1963).</li><li>Silverman, D. C., Revie, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+68.">Chapter 68.</a> Uhlig's Corrosion Handbook. , (2000).</li><li>Gurappa, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+different+materials+for+corrosion+resistance+under+simulated+body+fluid+conditions.">Characterization of different materials for corrosion resistance under simulated body fluid conditions.</a> Mater Charact. 49 (1), 73-79 (2002).</li><li>Antoniou, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metal+ion+levels+in+the+blood+of+patients+after+hip+resurfacing:+a+comparison+between+twenty-eight+and+thirty-six-millimeter-head+metal-on-metal+prostheses.">Metal ion levels in the blood of patients after hip resurfacing: a comparison between twenty-eight and thirty-six-millimeter-head metal-on-metal prostheses.</a> J Bone Joint Surg Am. 90, 142-148 (2008).</li><li>Billi, F., Campbell, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanotoxicology+of+metal+wear+particles+in+total+joint+arthroplasty:+a+review+of+current+concepts.">Nanotoxicology of metal wear particles in total joint arthroplasty: a review of current concepts.</a> J Appl Biomater Funct Mater. 8 (1), 1-6 (2010).</li><li>Bradberry, S. M., Wilkinson, J. M., Ferner, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systemic+toxicity+related+to+metal+hip+prostheses.">Systemic toxicity related to metal hip prostheses.</a> Clin Toxicol (Phila). 52 (8), 837-847 (2014).</li><li>Davda, K., Lali, F. V., Sampson, B., Skinner, J. A., Hart, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+analysis+of+metal+ion+levels+in+the+joint+fluid+of+symptomatic+patients+with+metal-on-metal+hip+replacements.">An analysis of metal ion levels in the joint fluid of symptomatic patients with metal-on-metal hip replacements.</a> J Bone Joint Surg Br. 93 (6), 738-745 (2011).</li><li>Clarke, M. T., Lee, P. T., Arora, A., Villar, R. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Levels+of+metal+ions+after+small+and+large+diameter+metal-on-metal+hip+arthroplasty.">Levels of metal ions after small and large diameter metal-on-metal hip arthroplasty.</a> J Bone Joint Surg Br. 85 (6), 913-917 (2003).</li><li>Brown, S. A., Hughes, P. J., Merritt, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+studies+of+fretting+corrosion+of+orthopaedic+materials.">In vitro studies of fretting corrosion of orthopaedic materials.</a> J Orthop Res. 6 (4), 572-579 (1988).</li><li>Bryant, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterisation+of+the+surface+topography,+tomography+and+chemistry+of+fretting+corrosion+product+found+on+retrieved+polished+femoral+stems.">Characterisation of the surface topography, tomography and chemistry of fretting corrosion product found on retrieved polished femoral stems.</a> J Mech Behav Biomed Mater. 32, 321-334 (2014).</li><li>Jantzen, C., J&#248;rgensen, H. L., Duus, B. R., Sporring, S. L., Lauritzen, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromium+and+cobalt+ion+concentrations+in+blood+and+serum+following+various+types+of+metal-on-metal+hip+arthroplasties.+A+literature+review.">Chromium and cobalt ion concentrations in blood and serum following various types of metal-on-metal hip arthroplasties. A literature review.</a> Acta Orthopaedica. 84 (3), 229-236 (2013).</li><li>Campbell, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histological+Features+of+Pseudotumor-like+Tissues+From+Metal-on-Metal+Hips.">Histological Features of Pseudotumor-like Tissues From Metal-on-Metal Hips.</a> Clin. Orthop. Relat. Res. 468 (9), 2321-2327 (2010).</li><li>Cook, S. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+in+vivo+performance+of+250+internal+fixation+devices:+a+follow-up+study.">The in vivo performance of 250 internal fixation devices: a follow-up study.</a> Biomaterials. 8 (3), 177-184 (1987).</li><li>Cooper, H. J., Urban, R. M., Wixson, R. L., Meneghini, R. M., Jacobs, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adverse+local+tissue+reaction+arising+from+corrosion+at+the+femoral+neck-body+junction+in+a+dual-taper+stem+with+a+cobalt-chromium+modular+neck.">Adverse local tissue reaction arising from corrosion at the femoral neck-body junction in a dual-taper stem with a cobalt-chromium modular neck.</a> J Bone Joint Surg Am. 95 (10), 865-872 (2013).</li><li>Langton, D. J., Sprowson, A. P., Joyce, T. J., Reed, M., Carluke, I., Partington, P., Nargol, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood+metal+ion+concentrations+after+hip+resurfacing+arthroplasty.">Blood metal ion concentrations after hip resurfacing arthroplasty.</a> J Bone Joint Surg Br. 91 (10), 1287-1295 (2009).</li><li>Langton, D. J., Jameson, S. S., Joyce, T. J., Webb, J., Nargol, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+component+size+and+orientation+on+the+concentrations+of+metal+ions+after+resurfacing+arthroplasty+of+the+hip.">The effect of component size and orientation on the concentrations of metal ions after resurfacing arthroplasty of the hip.</a> J Bone Joint Surg Br. 90 (9), 1143-1151 (2008).</li><li>Daniel, J., Ziaee, H., Pradhan, C., McMinn, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Six-year+results+of+a+prospective+study+of+metal+ion+levels+in+young+patients+with+metal-on-metal+hip+resurfacings.">Six-year results of a prospective study of metal ion levels in young patients with metal-on-metal hip resurfacings.</a> J Bone Joint Surg Br. 91 (2), 176-179 (2009).</li><li>De Haan, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correlation+between+inclination+of+the+acetabular+component+and+metal+ion+levels+in+metal-on-metal+hip+resurfacing+replacement.">Correlation between inclination of the acetabular component and metal ion levels in metal-on-metal hip resurfacing replacement.</a> J Bone Joint Surg Br. 90 (10), 1291-1297 (2008).</li><li>Dijkman, M. A., de Vries, I., Mulder-Spijkerboer, H., Meulenbelt, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cobalt+poisoning+due+to+metal-on-metal+hip+implants.">Cobalt poisoning due to metal-on-metal hip implants.</a> Ned Tijdschr Geneeskd. 156 (42), A4983 (2012).</li><li>Fisher, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioengineering+reasons+for+the+failure+of+metal-on-metal+hip+prostheses:+an+engineer's+perspective.">Bioengineering reasons for the failure of metal-on-metal hip prostheses: an engineer's perspective.</a> J Bone Joint Surg Br. 93 (8), 1001-1004 (2011).</li><li>Goldberg, J. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Multicenter+Retrieval+Study+of+the+Taper+Interfaces+of+Modular+Hip+Prostheses.">A Multicenter Retrieval Study of the Taper Interfaces of Modular Hip Prostheses.</a> Clin. Orthop. Relat. Res. (401), 149-161 (2002).</li><li>Ingham, E., Fisher, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biological+reactions+to+wear+debris+in+total+joint+replacement.">Biological reactions to wear debris in total joint replacement.</a> Proc Inst Mech Eng H. 214 (1), 21-37 (2000).</li><li>Gilbert, J. L., Buckley, C. A., Jacobs, J. J., Res, J. .. B. i. o. m. e. d. .. M. a. t. e. r. .. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+corrosion+of+modular+hip+prosthesis+components+in+mixed+and+similar+metal+combinations.+The+effect+of+crevice,+stress,+motion+and+allot+coupling.">In vivo corrosion of modular hip prosthesis components in mixed and similar metal combinations. The effect of crevice, stress, motion and allot coupling.</a> J. Biomed. Mater. Res. 76 (1), 1533-1544 (1993).</li><li>Browne, J. A., Bechtold, C. D., Berry, D. J., Hanssen, A. D., Lewallen, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Failed+metal-on-metal+hip+arthroplasties:+a+spectrum+of+clinical+presentations+and+operative+findings.">Failed metal-on-metal hip arthroplasties: a spectrum of clinical presentations and operative findings.</a> Clin. Orthop. Relat. Res. 468 (9), 2313-2320 (2010).</li><li>Jantzen, C., Jorgensen, H. L., Duus, B. R., Sporring, S. L., Lauritzen, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromium+and+cobalt+ion+concentrations+in+blood+and+serum+following+various+types+of+metal-on-metal+hip+arthroplasties:+a+literature+overview.">Chromium and cobalt ion concentrations in blood and serum following various types of metal-on-metal hip arthroplasties: a literature overview.</a> Acta Orthop. 84 (3), 229-236 (2013).</li><li>Frangini, S., De Cristofaro, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+galvanostatic+polarisation+method+for+determining+reliable+pitting+potentials+on+stainless+steels+in+crevice-free+conditions.">Analysis of galvanostatic polarisation method for determining reliable pitting potentials on stainless steels in crevice-free conditions.</a> Corros Sci. 45 (12), 2769-2786 (2002).</li></ol>

Polarization scans produced from the stainless steel samples showed clean continuous plots correlating with scans seen in literature indicative of a well functioning corrosion system which is both reliable and reproducible 29. Poor reproducibility of potentiodynamic pitting potentials is identified with a spread of a few hundred millivolts, with pitting potential being characterized by a stochastic process 29. This is commonly due to the variables of temperature, halide content and potential (V); th...

Electrochemical techniques provide a quick and relatively inexpensive method to obtain the electrochemical properties of a material. These techniques are based predominately on the ability to detect corrosion of a metal by observing the response of the charge-transfer process to a controlled electrochemical disturbance 1-5. Corrosion of metal implants within a body environment is critical due to the adverse implications on biocompatibility and material integrity 6. The main factor contributing to corrosion of implants within the body is the dissolution of the surface oxide leading to an increased release of metallic ions 7-11. This results in adverse biological reactions, which can be found locally, but with potentially systemic effects leading to the premature failure of the implant 10,12-28.
The corrosion characteristics of a test specimen are predicted from the polarization scan produced by a potentiostat. A polarization scan allows for the extrapolation of the kinetic and corrosion parameters of a metal substrate. During a scan, the oxidation or reduction of an electro-active species can be limited by charge transfer and the movement of reactants or products. These factors are all encapsulated by the polarization scan; therefore the importance of having a system that produces a reliable and repeatable polarization scan across multiple cycles is of great importance. The main focus of this manuscript is to provide a protocol identifying the rationale and steps taken to obtain a well-functioning potentiodynamic corrosion system.

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Potentiostat</td>
			<td style="width:71px;">Metrohm</td>
			<td style="width:119px;">PGSTAT101</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Ag/AgCl reference electrode, shielded</td>
			<td style="width:71px;">Metrohm</td>
			<td style="width:119px;">6.0729.100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Electrode shaft</td>
			<td style="width:71px;">Metrohm</td>
			<td style="width:119px;">6.1241.060</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Polisher Forcipol 1v</td>
			<td style="width:71px;">Metkon</td>
			<td align="right" style="width:119px;">3602</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Clindrical flask 700mL</td>
			<td style="width:71px;">SciLabware</td>
			<td style="width:119px;">FR700F</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Reaction lid</td>
			<td style="width:71px;">SciLabware</td>
			<td style="width:119px;">MAF2/41</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dichloromethane</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">MKBR7629V</td>
			<td>use under a fumehood. Wear protective clothing</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thermo / HAAKE D Series Immersion Circulators</td>
			<td style="width:71px;">Haake</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

potentiodynamic corrosion testing

Different metallic materials have different polarization characteristics as dictated by the open circuit potential, breakdown potential, and passivation potential of the material. The detection of these electrochemical parameters identifies the corrosion factors of a material. A reliable and well-functioning corrosion system is required to achieve this.
Corrosion of the samples was achieved via a potentiodynamic polarization technique employing a three-electrode configuration, consisting of reference, counter, and working electrodes. Prior to commencement a baseline potential is obtained. Following the stabilization of the corrosion potential (Ecorr), the applied potential is ramped at a slow rate in the positive direction relative to the reference electrode. The working electrode was a stainless steel screw. The reference electrode was a standard Ag/AgCl. The counter electrode used was a platinum mesh. Having a reliable and well-functioning in vitro corrosion system to test biomaterials provides an in-expensive technique that allows for the systematic characterization of the material by determining the breakdown potential, to further understand the material's response to corrosion. The goal of the protocol is to set up and run an in vitro potentiodynamic corrosion system to analyze pitting corrosion for small metallic medical devices.

At the conclusion of the procedure an in vitro corrosion system is setup to conduct corrosion studies. Specific procedures such as the cleaning of the corrosion vessel and the Faraday cage were introduced into the protocol to improve noise performance. The fundamental concept of a good polarization scan is to identify the electro-physical conditions of the material providing valuable information in order to understand the corrosion susceptibility of a metallic material. The proce...

Watch this Scientific Journal Video about Potentiodynamic Corrosion Testing at JoVE.com

Potentiodynamic Corrosion Testing

Here, we present a protocol to set up and run an in vitro potentiodynamic corrosion system to analyze pitting corrosion for small metallic medical devices.

Different metallic materials have different polarization characteristics as dictated by the open circuit potential, breakdown potential, and passivation ...

The overall goal of this procedure is to provide a reliable setup used to carry out potentiodynamic corrosion on small metallic samples. This method can answer key questions in the biomedical field, such as being able to deduce the corrosion susceptibility of implant or materials. The main advantage of this technique is that it is a relatively inexpensive method of corroding small metallic samples.Construct the sample holder from stainless steel spacers and an M3 stainless-steel threaded screw held in place with an M3 hexagonal nut. Remove the head of the threaded screw using pliers, and polish the cut segment to maintain the thread pattern. When all individual components are ready, assemble the electrode holders.Each electrode holder contains three spacers joined together by the M3 screws, resulting in an 11.5 centimeter handle. Place the hexagonal nuts at the junction of the screw and spacers to lock the connection. Once the electrode holders are assembled, apply multiple coats of stop-off lacquer to prevent the stainless steel rods from corroding while immersed in the corrosion chamber.To do this, quickly coat half of each electrode holder and allow it to dry before coating the other half. This will help obtain a complete well-sealed coat without damaging the areas to be coated. Place the electrodes in an elevated position in the fume hood to dry.Ensure the freshly coated regions do not touch other surfaces, as this will ruin the applied coat. Clean the corrosion vessel before every corrosion run. Scrub the vessel with household detergent and rinse thoroughly with tap water.Repeat this step three times. Then, rinse the corrosion vessel three times with deionized water to remove potential contaminants found in tap water. Once rinsing with deionized water is completed, pour 300 milliliters of 95%ethanol into the corrosion vessel and swirl around to contact all internal surfaces.Pour out the ethanol and repeat this step three times. Leave the corrosion vessel under a fume hood for 30 minutes to allow all of the ethanol to completely evaporate before rinsing with the electrolyte to be used for the corrosion run, as described in the text protocol. The working electrode is the stainless steel screw, the specimen under analysis.Before inserting the electrode into the corrosion vessel, wipe it with an 80%ethanol soaked wipe, and place it in a glass beaker filled with 100 milliliters of phosphate buffered saline. Use a connection pin to attach the electrode holders onto the electrode suspenders, Fit the electric suspenders into the entry points of the corrosion vessel's lid. Seal the corrosion vessel with a glass reaction lid and clamp to ensure a waterproof seal.The lid of the chamber provides five entry points for the experimental and measurement apparatus. Use a three-electrode configuration, consisting of a reference, counter, and working electrode. For the reference electrode, use a standard silver-silver chloride electrode.For the counter electrode, use a platinum mesh that is loosely bent to wrap around the specimen under test. Once the chamber is sealed with all electrodes placed inside the corrosion vessel, set the temperature to 37 degrees celsius, and open the nitrogen valve with a flow rate of 150 cubic centimeters per minute. Leave the temperature and nitrogen running for 60 minutes before conducting a run.Keep the nitrogen running for the duration of the experiment. Make electrical connections between the potentia stat and the three electrodes, and then turn the potentia stat on. Leave the sample to equilibrate and stabilize within the corrosion vessel environment.The time duration for this varies and is dependent on material. Monitor the potential using measurement view to determine if stabilized conditions are reached. The potentia will be constant with no fluctuations when stable conditions are achieved.Select the cyclic voltammetry potentia stat procedure within the setup view from the procedure tab. Select the option to automate the current range. Set the highest current in the range to be 10 milliamps and the lowest current in the range to be 10 nanoamps for the working electrode.Ensure the final cut off selection is controlled through the potential, by setting the cycle back parameter to 800 millivolts to allow the hysteresis loop to complete. Record the open circuit potential, or OCP, from the measurement view into the OCP parameter text box. Set the start potential 100 millivolts below the recorded OCP value.Set the upper vertex potential to 800 millivolts, the lower vertex to 100 millivolts below the start potential, and the stop potential to 100 millivolts below the lower vertex potential. Then, set the scan rate to 0.001 volts per second, and the step potential to 0.0024 volts per second. Now, press start.To remove the sample from the electrode holder, prepare three small jars of 50 milliliters of dichloromethane under the fume hood. Remove the tested samples from the electrode holders by immersing the lower end of the holder in dichloromethane for 30 minutes inside the fume hood. Once detached, place the specimen into the next jar of dichloromethane and leave for 15 minutes.Repeat this process with the third and final rinse to get rid of any excess coating on the attachment sections of the sample. Shown here, is the representative results of a potentiodynamic polarization scan from a corrosion run for stainless steel 316, which can be further used to extract important corrosion parameters that provide corrosion characterization of the test specimen. This polarization scan shows the direction of the forward and reverse scans.and specifies the point at which the protection potential and pitting potential are observed. The hysteresis loop is reversed at the set potential and returns to intercept the anodic curve, identifying the protection potential. It is critical to have a system that provides high-quality scans, which are reproducible and reliable, since potentiodynamic polarization plots are used to calculate the corrosion current and corrosion potential using tafel extrapolation.Once mastered, this technique can be done in approximately two hours if performed properly. This does not include the time for the sample to corrode, as this time is material dependent. While attempting this procedure, it is important to remember not to contaminate any electrodes and any glassware prior to the corrosion run.Limiting any impurities is critical. Following this procedure, other methods like scanning electron microscopies, surface analysis, or other imaging techniques, or quantification of corrosion techniques, can be performed in order to answer additional questions. After watching this video, you should have a good understanding of how to conduct a reliable electro-dynamic corrosion system.Don't forget that working with microstop laquer can be extremely hazardous, and precautions such as double gloves and working under a film hood, should always be taken while performing this procedure.

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Environment

Preparation and Testing of Plant Seed Meal-based Wood Adhesives

Recently, the interest in plant seed meal-based products as wood adhesives has steadily increased, as these plant raw materials are considered renewable and environment-friendly. These natural products may serve as alternatives to petroleum-based adhesives to ease environmental and sustainability concerns. This work demonstrates the preparation and testing of the plant seed-based wood adhesives using cottonseed and soy meal as raw materials. In addition to untreated meals, water washed meals and protein isolates are prepared and tested. Adhesive slurries are prepared by mixing a freeze-dried meal product with deionized water (3:25 w/w) for 2 hr. Each adhesive preparation is applied to one end of 2 wood veneer strips using a brush. The tacky adhesive coated areas of the wood veneer strips are lapped and glued by hot-pressing. Adhesive strength is reported as the shear strength of the bonded wood specimen at break. Water resistance of the adhesives is measured by the change in shear strength of the bonded wood specimens at break after water soaking. This protocol allows one to assess plant seed-based agricultural products as suitable candidates for substitution of synthetic-based wood adhesives. Adjustments to the adhesive formulation with or without additives and bonding conditions could optimize their adhesive properties for various practical applications.

To facilitate the effort in seeking more economic and environment-friendly formulations of natural product-based wood adhesives, this work demonstrates the preparation and testing of plant seed-based wood adhesives. This protocol allows one to assess plant seed-based agricultural products as suitable candidates for the substitution of synthetic-based wood adhesives.

Recently, the interest in plant seed meal-based products as wood adhesives has steadily increased, as these plant raw materials are considered renewable ...

Protocols for Robust Herbicide Resistance Testing in Different Weed Species

Robust protocols to test putative herbicide resistant weed populations at whole plant level are essential to confirm the resistance status. The presented protocols, based on whole-plant bioassays performed in a greenhouse, can be readily adapted to a wide range of weed species and herbicides through appropriate variants. Seed samples from plants that survived a field herbicide treatment are collected and stored dry at low temperature until used. Germination methods differ according to weed species and seed dormancy type. Seedlings at similar growth stage are transplanted and maintained in the greenhouse under appropriate conditions until plants have reached the right growth stage for herbicide treatment. Accuracy is required to prepare the herbicide solution to avoid unverifiable mistakes. Other critical steps such as the application volume and spray speed are also evaluated. The advantages of this protocol, compared to others based on whole plant bioassays using one herbicide dose, are related to the higher reliability and the possibility of inferring the resistance level. Quicker and less expensive in vivo or in vitro diagnostic screening tests have been proposed (Petri dish bioassays, spectrophotometric tests), but they provide only qualitative information and their widespread use is hindered by the laborious set-up that some species may require. For routine resistance testing, the proposed whole plant bioassay can be applied at only one herbicide dose, so reducing the costs.

A robust and flexible approach to confirm herbicide resistance in weed populations is presented. This protocol allows the herbicide resistance levels to be inferred and applied to a wide range of weed species and herbicides with minor adaptations.

Robust protocols to test putative herbicide resistant weed populations at whole plant level are essential to confirm the resistance status. The presented ...

A CO2 Concentration Gradient Facility for Testing CO2 Enrichment and Soil Effects on Grassland Ecosystem Function

Continuing increases in atmospheric carbon dioxide concentrations (CA) mandate techniques for examining impacts on terrestrial ecosystems. Most experiments examine only two or a few levels of CA concentration and a single soil type, but if CA can be varied as a gradient from subambient to superambient concentrations on multiple soils, we can discern whether past ecosystem responses may continue linearly in the future and whether responses may vary across the landscape. The Lysimeter Carbon Dioxide Gradient Facility applies a 250 to 500 &#181;l L-1 CA gradient to Blackland prairie plant communities established on lysimeters containing clay, silty clay, and sandy soils. The gradient is created as photosynthesis by vegetation enclosed in in temperature-controlled chambers progressively depletes carbon dioxide from air flowing directionally through the chambers. Maintaining proper air flow rate, adequate photosynthetic capacity, and temperature control are critical to overcome the main limitations of the system, which are declining photosynthetic rates and increased water stress during summer. The facility is an economical alternative to other techniques of CA enrichment, successfully discerns the shape of ecosystem responses to subambient to superambient CA enrichment, and can be adapted to test for interactions of carbon dioxide with other greenhouse gases such as methane or ozone.

A CO2 Concentration Gradient Facility for Testing CO2 Enrichment and Soil Effects on Grassland Ecosystem Function

The Lysimeter Carbon Dioxide Gradient Facility creates a 250 to 500 &#181;l L-1 linear carbon dioxide gradient in temperature-controlled chambers housing grassland plant communities on clay, silty clay, and sandy soil monoliths. The facility is used to determine how past and future carbon dioxide levels affect grassland carbon cycling.

Continuing increases in atmospheric carbon dioxide concentrations (CA) mandate techniques for examining impacts on terrestrial ecosystems. Most ...

Preparation and Testing of Impedance-based Fluidic Biochips with RTgill-W1 Cells for Rapid Evaluation of Drinking Water Samples for Toxicity

This manuscript describes how to prepare fluidic biochips with Rainbow trout gill epithelial (RTgill-W1) cells for use in a field portable water toxicity sensor. A monolayer of RTgill-W1 cells forms on the sensing electrodes enclosed within the biochips. The biochips are then used for testing in a field portable electric cell-substrate impedance sensing (ECIS) device designed for rapid toxicity testing of drinking water. The manuscript further describes how to run a toxicity test using the prepared biochips. A control water sample and the test water sample are mixed with pre-measured powdered media and injected into separate channels of the biochip. Impedance readings from the sensing electrodes in each of the biochip channels are measured and compared by an automated statistical software program. The screen on the ECIS instrument will indicate either "Contamination Detected" or "No Contamination Detected" within an hour of sample injection. Advantages are ease of use and rapid response to a broad spectrum of inorganic and organic chemicals at concentrations that are relevant to human health concerns, as well as the long-term stability of stored biochips in a ready state for testing. Limitations are the requirement for cold storage of the biochips and limited sensitivity to cholinesterase-inhibiting pesticides. Applications for this toxicity detector are for rapid field-portable testing of drinking water supplies by Army Preventative Medicine personnel or for use at municipal water treatment facilities.

This manuscript describes how to prepare fluidic biochips with Rainbow trout gill epithelial cells for use in a field portable electric cell-substrate impedance sensor. The protocol for running a rapid drinking water toxicity test with the sensor is also described.

This manuscript describes how to prepare fluidic biochips with Rainbow trout gill epithelial (RTgill-W1) cells for use in a field portable water toxicity ...

Dispersion of Nanomaterials in Aqueous Media: Towards Protocol Optimization

The sonication process is commonly used for de-agglomerating and dispersing nanomaterials in aqueous based media, necessary to improve homogeneity and stability of the suspension. In this study, a systematic step-wise approach is carried out to identify optimal sonication conditions in order to achieve a stable dispersion. This approach has been adopted and shown to be suitable for several nanomaterials (cerium oxide, zinc oxide, and carbon nanotubes) dispersed in deionized (DI) water. However, with any change in either the nanomaterial type or dispersing medium, there needs to be optimization of the basic protocol by adjusting various factors such as sonication time, power, and sonicator type as well as temperature rise during the process. The approach records the dispersion process in detail. This is necessary to identify the time points as well as other above-mentioned conditions during the sonication process in which there may be undesirable changes, such as damage to the particle surface thus affecting surface properties. Our goal is to offer a harmonized approach that can control the quality of the final, produced dispersion. Such a guideline is instrumental in ensuring dispersion quality repeatability in the nanoscience community, particularly in the field of nanotoxicology.

Here, we present a step-wise protocol for the dispersion of nanomaterials in aqueous media with real-time characterization to identify the optimal sonication conditions, intensity, and duration for improved stability and uniformity of nanoparticle dispersions without impacting the sample integrity.

The sonication process is commonly used for de-agglomerating and dispersing nanomaterials in aqueous based media, necessary to improve homogeneity and ...

On the Preparation and Testing of Fuel Cell Catalysts Using the Thin Film Rotating Disk Electrode Method

We present a step-by-step tutorial to prepare proton exchange membrane fuel cell (PEMFC) catalysts, consisting of Pt nanoparticles (NPs) supported on a high surface area carbon, and to test their performance in thin film rotating disk electrode (TF-RDE) measurements. The TF-RDE methodology is widely used for catalyst screening; nevertheless, the measured performance sometimes considerably differs among research groups. These uncertainties impede the advancement of new catalyst materials and, consequently, several authors discussed possible best practice methods and the importance of benchmarking.
The visual tutorial highlights possible pitfalls in the TF-RDE testing of Pt/C catalysts. A synthesis and testing protocol to assess standard Pt/C catalysts is introduced that can be used together with polycrystalline Pt disks as benchmark catalysts. In particular, this study highlights how the properties of the catalyst film on the glassy carbon (GC) electrode influence the measured performance in TF-RDE testing. To obtain thin, homogeneous catalyst films, not only the catalyst preparation, but also the ink deposition and drying procedures are essential. It is demonstrated that an adjustment of the ink&#39;s pH might be necessary, and how simple control measurements can be used to check film quality. Once reproducible TF-RDE measurements are obtained, determining the Pt loading on the catalyst support (expressed as Pt wt%) and the electrochemical surface area is necessary to normalize the determined reaction rates to either surface area or Pt mass. For the surface area determination, so-called CO stripping, or the determination of the hydrogen underpotential deposition (Hupd) charge, are standard. For the determination of the Pt loading, a straightforward and cheap procedure using digestion in aqua regia with subsequent conversion of Pt(IV) to Pt(II) and UV-vis measurements is introduced.

Preparing and testing Pt/C fuel cell catalysts is subject to continuous discussion in the scientific community with respect to reproducibility and best practice. With the presented work, we intend to present a step-by-step tutorial to make and test Pt/C catalysts, which can serve as benchmark for novel catalyst systems.

We present a step-by-step tutorial to prepare proton exchange membrane fuel cell (PEMFC) catalysts, consisting of Pt nanoparticles (NPs) supported on a ...

Protocol for Acute and Chronic Ecotoxicity Testing of the Turquoise Killifish Nothobranchius furzeri

The killifish Nothobranchius furzeri is an emerging model organism in the field of ecotoxicology and its applicability in acute and chronic ecotoxicity testing has been demonstrated. Overall, the sensitivity of the species to toxic compounds is in the range with, or higher than, that of other model species.
This work describes protocols for acute, chronic, and multigenerational bioassays of single and combined stressor effects on N. furzeri. Due to its short maturation time and life-cycle, this vertebrate model allows the study of endpoints such as maturation time and fecundity within four months. Transgenerational full life-cycle exposure trials can be performed in as little as 8 months. Since this species produces eggs that are drought-resistant and remain viable for years, the on-site culture of the species is not needed but individuals can be recruited when required. The protocols are designed to measure life-history traits (mortality, growth, fecundity, weight) and critical thermal maximum.

Protocol for Acute and Chronic Ecotoxicity Testing of the Turquoise Killifish Nothobranchius furzeri

In this work, we describe an acute, chronic and multigenerational bioassay to study the effects of single and combined stressors on the Turquoise killifish Nothobranchius furzeri. This protocol is designed to study life-history traits (mortality, growth, fecundity, weight) and critical thermal maximum.

The killifish Nothobranchius furzeri is an emerging model organism in the field of ecotoxicology and its applicability in acute and chronic ecotoxicity ...

Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

Knowledge of habitat suitability for freshwater mussels is an important step in the conservation of this endangered species group. We describe a protocol for performing in situ juvenile exposure tests within oligotrophic river catchments over one-month and three-month periods. Two methods (in both modifications) are presented to evaluate the juvenile growth and survival rate. The methods and modifications differ in value for the locality bioindication and each has its benefits as well as limitations. The sandy cage method works with a large set of individuals, but only some of the individuals are measured and the results are evaluated in bulk. In the mesh cage method, the individuals are kept and measured separately, but a low individual number is evaluated. The open water exposure modification is relatively easy to apply; it shows the juvenile growth potential of sites and can also be effective for water toxicity testing. The within-bed exposure modification needs a high workload but is closer to the conditions of a natural juvenile environment and it is better for reporting the real suitability of localities. On the other hand, more replications are needed in this modification due to its high-hyporheic environment variability.

Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

In situ bioindications enable determination of the suitability of an environment for endangered mussel species. We describe two methods based on the juvenile exposure of freshwater pearl mussels in cages to oligotrophic river habitats. Both methods are implemented in variants for open water and hyporheic water environments.

Knowledge of habitat suitability for freshwater mussels is an important step in the conservation of this endangered species group. We describe a protocol ...

Metal Corrosion and the Efficiency of Corrosion Inhibitors in Less Conductive Media

Material corrosion can be a limiting factor for different materials in many applications. Thus, it is necessary to better understand corrosion processes, prevent them and minimize the damages associated with them. One of the most important characteristics of corrosion processes is the corrosion rate. The measurement of corrosion rates is often very difficult or even impossible especially in less conductive, non-aqueous environments such as biofuels. Here, we present five different methods for the determination of corrosion rates and the efficiency of anti-corrosion protection in biofuels: (i) a static test, (ii) a dynamic test, (iii) a static test with a reflux cooler and electrochemical measurements (iv) in a two-electrode arrangement and (v) in a three-electrode arrangement. The static test is advantageous due to its low demands on material and instrumental equipment. The dynamic test allows for the testing of corrosion rates of metallic materials at more severe conditions. The static test with a reflux cooler allows for the testing in environments with higher viscosity (e.g., engine oils) at higher temperatures in the presence of oxidation or an inert atmosphere. The electrochemical measurements provide a more comprehensive view on corrosion processes. The presented cell geometries and arrangements (the two-electrode and three-electrode systems) make it possible to perform measurements in biofuel environments without base electrolytes that could have a negative impact on the results and load them with measurement errors. The presented methods make it possible to study the corrosion aggressiveness of an environment, the corrosion resistance of metallic materials, and the efficiency of corrosion inhibitors with representative and reproducible results. The results obtained using these methods can help to understand corrosion processes in more detail to minimize the damages caused by corrosion.

The testing of processes associated with material corrosion can often be difficult especially in non-aqueous environments. Here, we present different methods for short-term and long-term testing of corrosion behavior of non-aqueous environments such as biofuels, especially those containing bioethanol.

Material corrosion can be a limiting factor for different materials in many applications. Thus, it is necessary to better understand corrosion processes, ...

A Small-Scale Setup for Algal Toxicity Testing of Nanomaterials and Other Difficult Substances

Ecotoxicity data is a requirement for pre- and post-market registration of chemicals by European and international regulations (e.g., REACH). The algal toxicity test is frequently used in regulatory risk assessment of chemicals. In order to achieve high reliability and reproducibility the development of standardized guidelines is vital. For algal toxicity testing, the guidelines require stable and uniform conditions of parameters such as pH, temperature, carbon dioxide levels and light intensity. Nanomaterials and other so-called difficult substances can interfere with light causing a large variation in results obtained hampering their regulatory acceptance. To address these challenges, we have developed LEVITATT (LED Vertical Illumination Table for Algal Toxicity Tests). The setup utilizes LED illumination from below allowing for a homogenous light distribution and temperature control while also minimizing intra-sample shading. The setup optimizes the sample volume for biomass quantification and does at the same time ensure a sufficient influx of CO2 to support exponential growth of the algae. Additionally, the material of the test containers can be tailored to minimize adsorption and volatilization. When testing colored substances or particle suspensions, the use of LED lights also allows for increasing the light intensity without additional heat generation. The compact design and minimal equipment requirements increase the possibilities for implementation of the LEVITATT in a wide range of laboratories. While compliant with standardized ISO and OECD guidelines for algal toxicity testing, LEVITATT also showed a lower inter-sample variability for two reference substances (3,5-Dicholorophenol and K2Cr2O7) and three nanomaterials (ZnO, CeO2, and BaSO4) compared to Erlenmeyer flasks and microtiter plates.

We demonstrate algal toxicity testing for difficult substances (e.g., colored substances or nanomaterials) using a setup illuminated vertically with an LED.

Ecotoxicity data is a requirement for pre- and post-market registration of chemicals by European and international regulations (e.g., REACH). The algal ...