13 Replies Latest reply on May 7, 2018 12:49 PM by ryoboyle

    LOD & LOQ value required

    choushik

      Dear all,

       

      I am using Openlab CDS 2.2 software. I need LOD & LOQ valu for a compound. Please suggest how I can get this value from software and what is the total procedure for this operation.

        • Re: LOD & LOQ value required
          ryoboyle

          Hello,

           

          Calculating MDL/IDL/LOD/LOQ is very dependent on your instrumentation and the method parameters that you are running with. Below are links to some resources for calculating these values for gas phase instrumentation:

           

          https://www.agilent.com/cs/library/technicaloverviews/Public/59658901.pdf

           

          https://www.agilent.com/cs/library/technicaloverviews/public/5990-7651EN.pdf

           

          https://www.agilent.com/cs/library/technicaloverviews/Public/5989-3423EN.pdf

            • Re: LOD & LOQ value required
              choushik

              Thanks Ryoboyle for your response. But but I need LOD/LOQ valu for HPLC 1260 infinity II and detector is VWD. Please help how to calculate LOD/LOQ valu from Openlab CDS 2.2  software.

                • Re: LOD & LOQ value required
                  ryoboyle

                  So I checked with one of my colleagues who supports LC instruments. It looks like this is base off of the signal-to-noise ratio. GMP regulations require a signal-to-noise requirement greater than 3, but this can vary base on the lab.

                   

                  I can attempt to assist you with calculating LOC/LOQ values for your instrument in OpenLAB CDS 2.2, but you will need to determine how you want to define these values and provide me with the equations.

                    • Re: LOD & LOQ value required
                      choushik

                      I don't know how to calculate LOD/LOQ value......That's why I need your help how to calculate by software ....and what is the procedure to calculte those value by CDS 2.2

                        • Re: LOD & LOQ value required
                          ryoboyle

                          There is no set equation for LOD/LOQ when using HPLC instruments since these values will be widely variable based on the column and mobile phase that you are using. As stated in my previous reply, most labs instead use a signal-to-noise ratio threshold.

                           

                          Once you determine how you wish to approach calculating LOD/LOQ, let us know and we can pick up from there.

                            • Re: LOD & LOQ value required
                              choushik

                              Okay I want to use signal to noise ratio threshold .....Please tell me procedure for this......

                              Thanks

                                • Re: LOD & LOQ value required
                                  ryoboyle

                                  The first step is to set up your processing method to calculate noise. Below is the relevant section of the Help documentation, as well as a screenshot of the relevant window:

                                   

                                  Once your data has been processed with an appropriate method, the next step is to set up your report to display the signal-to-noise ratio for each peak. A good default report template to start from is the Performance+Noise.rdl report. If you have an existing report you want to add this value to, below is a screenshot of some appropriate column properties:

                                   

                                   

                                  If you want to go even further with this, you can set up conditional formatting for this column to have the color of the font or the cell background to change if the Signal-to-Noise Ratio falls below a certain value. Below is an example where the font color will turn red if the signal-to-noise ratio is less than 3:

                                   

                                   

                                  Hopefully this helps.

                                    • Re: LOD & LOQ value required
                                      choushik

                                      Thanks ryoboyle, ,But I have another queries,,,,,,,If I use 10ppm/ other concentration of standard in my analysis,,,,,in that case is it possible to automatic calculate lowest concentration that detect by system with respect to 10ppm/ other concentration? ?,,,,and I have found limit of detection in compound report item section. but no value is coming in that report item. How can I get value in this report item....plz suggest

                                        • Re: LOD & LOQ value required
                                          ryoboyle

                                          The compound report items for Limit of Detection and Limit of Quantitation are legacy report items from the EZChrom software product. These are currently not valid report items in OpenLAB CDS v2.x software and will not be calculated/populated if you add them to a report template.

                                           

                                          Below is information on how these values would be calculated in OpenLAB EZChrom:

                                           

                                           

                                          These equations are essentially the same as setting up a signal-to-noise ratio threshold as we discussed in previous replies. If you would like have OpenLAB 2.2 perform this calculation you would need to set up a sample or compound custom parameter for your project where you can enter in the signal-to-noise threshold value (SN in the above equations) so it can be called on the report.

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                                            • Re: LOD & LOQ value required
                                              choushik

                                              In your previous reply,  you mentioned that most of lab follow  S/N value for LOD greater than 3. But I would like to know what is the S/N value for LOQ.

                                                • Re: LOD & LOQ value required
                                                  ryoboyle

                                                  You and your lab must determine what S/N ratio value to use when calculating LOD/LOQ as you will need to be the ones to defend the value you select. This is not a value that Agilent can supply for you.

                                                    • Re: LOD & LOQ value required
                                                      choushik

                                                      I would like to share just what is the best practice of S/N value for LOD/LOQ. I have another queries if i perform multilevel calibration, for example......I use increasing concentrations of standard..50 ug/ml, 100, 200, 300, 500 ug/ml and analysed these standard using hplc and for each standard concentration, i get corresponding peak area; say mAU, 1.5 mAU, 3 mAU, 5 mAU, 10 mAU, respecyively. Now i want to know how to calculate LOD and LOQ from such data. Please suggest.

                                                        • Re: LOD & LOQ value required
                                                          ryoboyle

                                                          There is no one correct way to calculate the LOD or LOQ. The equations from EZChrom that I posted in my reply earlier today outline one possible approach, but there are definitely a number of other approaches. This is something that you will need to research by reviewing relevant literature for your application in order to determine how you want to calculate these values.

                                                           

                                                          Once you identify the method by which you want to calculate LOD and LOQ, then we can start to discuss how to set up that calculation in your OpenLAB 2.2 software.