Nexera HPLC Troubleshooting Flat Peaks

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<div class="container"><h1 class="title">Troubleshooting Flat Peaks</h1> <div class="center"><img src="https://www.ssi.shimadzu.com/sites/ssi.shimadzu.com/files/support/virtual-advisors/nexera/troubleshooting-flat-peaks/full-scale-display-flat.jpg" alt="Troubleshooting Baseline Problems"></div> <h3><strong>Determine if the peaks are displayed as a flat-topped peak because of the Y-axis setting.</strong></h3> Absorbance units or volts are displayed on the Y-axis. Changing the Y-axis full scale display will change the size of the displayed peaks. If the displayed peaks are flat-topped, it may be due to an inappropriate full scale Y-axis setting. <div class="ts-question">Are the display parameters set properly?</div><div class="buttons"> <span class="btn-yes">[[Yes->Detector Output Scale]]</span> <span class="btn-no">[[No->Full Scale Display]]</span> </div> </div>

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<div class="container"><h1 class="title">Detector Output Scale</h1> <div class="center"><img src="https://www.ssi.shimadzu.com/sites/ssi.shimadzu.com/files/support/virtual-advisors/nexera/troubleshooting-flat-peaks/detector-output-scale.jpg" alt="Detector Output Scale"></div> The AUX RANGE setting affects both the analog and digital output signal from the SPD-20A and SPD-20AV UV detectors. The table at the left displays the AUX RANGE settings that area possible with the SPD-20A and SPD-20AV detectors. Set the AUX RANGE to 4 (4.0 AU/V) to determine whether the flat-topped peaks are related to saturated optics. If the peaks continue to be flat-topped at this setting, the sample is too concentrated for the limitations of the optics of the detector. The sample concentration or injection volume must be decreased. <div class="ts-question">Is the UV detector output scale set properly?</div><div class="buttons"> <span class="btn-yes">[[Yes->Detector Saturation]]</span> <span class="btn-no">[[No->Setting the AUX RANGE Parameter]]</span><span class="btn-back"><<back "Back">></span> </div> </div>

<div class="container"><h1 class="title">Full Scale Display</h1> <div class="center"><img src="https://www.ssi.shimadzu.com/sites/ssi.shimadzu.com/files/support/virtual-advisors/nexera/troubleshooting-flat-peaks/full-scale-display-flat.jpg" alt="Full Scale Display"></div> Examine the full scale display parameters for the data system that you are using. Because there are many different types of data systems are available, it is not possible to describe the procedures for all of these data systems fully. Therefore, please refer to your data system instruction manual to learn how to examine and change the display parameters <div class="buttons"> <span class="btn-back"><<back "Back">></span> </div> </div>

<div class="container"><h1 class="title">Detector Saturation</h1> <div class="center"><img src="https://www.ssi.shimadzu.com/sites/ssi.shimadzu.com/files/support/virtual-advisors/nexera/troubleshooting-flat-peaks/detector-flow-cell.jpg" alt="Detector Saturation"></div> <h3>Click your lamp and detector type to review how to monitor the sample energy.</h3> If peaks are flat-topped while using a SPD-M30A detector (PDA), the sample is too concentrated and must be diluted. As energy passes through the detector flow cell it is recorded as the baseline. When something inside the flow cell absorbs the energy, it is recorded as a peak in the chromatogram. <ol> <li>Run another injection of the sample that is causing flat-topped peaks.</li> <li>Monitor the sample energy display throughout the injection.</li> </ol> If the sample energy is normal at the beginning of the injection and falls to nearly 0 (during the flat-top peak), it is an indication that all of the energy is being absorbed by the flow cell and is not passing through the flow cell. <span class="btn-link">[[Lamp Intensity Check - LCsolution->Lamp Intensity Check - LCsolution]]</span> <div class="ts-question">Is the sample solution too concentrated for the detector optics?</div><div class="buttons"> <span class="btn-yes">[[Yes->Detector Saturation - Correcting]]</span> <span class="btn-no"><a href="https://www.ssi.shimadzu.com/forms/tech-support/index.html?product_category=VirtualAdvisor&product_name=Nexera&page=webform_start">Contact Shimadzu</a></span><span class="btn-back"><<back "Back">></span> </div> </div>

<div class="container"><h1 class="title">Setting the AUX RANGE Parameter</h1> <div class="center"><iframe width="900" height="506" src="https://www.youtube.com/embed/kPgR6UMtDqg?rel=0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe></div> <ol> <li>From the Initial screen, press the FUNC key. The PARAMETER screen is displayed.</li> <li>Press the ENTER key and then press the FUNC key four times. The AUX RANGE parameter screen is displayed.</li> <li>Enter the numeric value (1-6) for the parameter and press the ENTER key.</li> <li>Press the CE key twice to return to the Initial screen.</li> </ol> <div class="buttons"> <span class="btn-back"><<back "Back">></span> </div> </div>

<div class="container"><h1 class="title">Lamp Intensity Check - LCsolution</h1> <div class="center"><iframe width="900" height="506" src="https://www.youtube.com/embed/rv4XK8kIcF8?rel=0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe></div> D2 - maximum intensity at or around 235 nm ≥ 7V Record the lamp intensities for future reference. <ol> <li>Use the supplied syringe and needle to fill the flow cell with degassed DI (deionized) water.</li> <li>Select START - PROGRAMS - LABSOLUTIONS - LCSOLUTION - LC MAINTENANCE TOOLS.</li> <li>The LC Tool Launcher is displayed. Select 'PDA Utility' and 'Instrument 1' and then press the Run button.</li> <li>The Login screen is displayed. Enter the User ID and Password and then press the OK button.</li> <li>The default UserID/password are as follows: UserID: admin Password: (none)</li> <li>The PDA Utility screen is displayed. Press the Wavelength Calibration button.</li> <li>The PDA Wavelength Calibration screen is displayed. Select Function - Check Light F7.</li> <li>The Adjust Light screen is displayed. Select either the D2 or the W lamp.</li> <li>Enter the wavelength used for the Intensity check.</li> <li>Enter the threshold to be used for the acceptance criterion. Press the OK button.</li> <li>The PDA Wavelength Calibration screen is displayed.</li> <li>Confirm that the voltage at the selected wavelength is larger than the set threshold.</li> </ol> <div class="buttons"> <span class="btn-back"><<back "Back">></span> </div> </div>

<div class="container"><h1 class="title">Detector Saturation - Correcting</h1> <div class="center"><img src="https://www.ssi.shimadzu.com/sites/ssi.shimadzu.com/files/support/virtual-advisors/nexera/troubleshooting-flat-peaks/vial-choice.jpg" alt="Detector Saturation - Correcting"></div> If the sample is absorbing nearly all of the energy as it passes through the detector flow cell, flat-topped peaks are generated. In order to reduce the energy being absorbed to a measurable amount, the amount of sample in the flow cell at any one time needs to be reduced. This can be achieved in a number of ways: <ul> <li>Reduce the injection size</li> <li>Dilute the sample concentration in the sample solution</li> <li>Change the detector sensitivity settings</li> </ul> <div class="buttons"> <span class="btn-back"><<back "Back">></span> </div> </div>