# Calculating Relative Resolution of a peak

Good Morning,

We are currently facing an issue for impurity runs that require the resolution between specific peaks. For some runs, with the peaks separated fairly far apart, there is a chance of impurities eluting between the peaks we have resolution requirements for.

Since we care about those impurities in the sample, we cannot disable integration (though we could use integration events such as height/area rejects, we would like to avoid if possible).

In Empower, there is a way to specify the relative resolution of a peak compared to a specific peak - is there any way to do that in OpenLab CDS? If not, is that something that could be added to future revisions of OpenLab?

We are currently using OpenLab CDS 2.5.

• Hello,

Do you want the resolution between all identified peaks in the signal or just specific peaks? If you want named peak resolution where the system will ignore the unknowns for resolution calculation and example is below.  This is for USP resolution. If(Len(Compound_Name) > 0 AND Compound_Type = 1, CurrentInjection.AllIdentifiedPeaks.Where(function (x) x.Signal.Signal_Name = CurrentSignal.Signal_Name).Where(function (x) x.Compound_Type = 1).OrderBy(function(x) x.Peak_RetentionTime).Select(function(x) x.Peak_RetentionTime).Distinct.ToList.FindIndex(function(x) x=Peak_RetentionTime)+1,"Test")

(CurrentInjection.AllIdentifiedPeaks.Where(function (x) x.GetIntegerCC("PeakIndex") = CurrentPeakOrGroup.GetIntegerCC("PeakIndex")+1).Where(function (x) x.Signal.Signal_Name = CurrentSignal.Signal_Name).Select(function(x) x.GetDoubleCC("ModRT")).Max - CurrentPeakOrGroup.GetCustomField("PeakModelRT")) / (CurrentInjection.AllIdentifiedPeaks.Where(function (x) x.GetIntegerCC("PeakIndex") = CurrentPeakOrGroup.GetIntegerCC("PeakIndex")+1).Where(function (x) x.Signal.Signal_Name = CurrentSignal.Signal_Name).Select(function(x) x.Peak_WidthTangent).Max + Peak_WidthTangent) * 2

(CurrentPeakOrGroup.GetCustomField("PeakModelRT") - CurrentInjection.AllIdentifiedPeaks.Where(function (x) x.GetIntegerCC("PeakIndex") = CurrentPeakOrGroup.GetIntegerCC("PeakIndex")-1).Where(function (x) x.Signal.Signal_Name = CurrentSignal.Signal_Name).Select(function(x) x.GetDoubleCC("ModRT")).Max) / (Peak_WidthTangent + (CurrentInjection.AllIdentifiedPeaks.Where(function (x) x.GetIntegerCC("PeakIndex") = CurrentPeakOrGroup.GetIntegerCC("PeakIndex")-1).Where(function (x) x.Signal.Signal_Name = CurrentSignal.Signal_Name).Select(function(x) x.Peak_WidthTangent).Max)) * 2

CurrentPeakOrGroup.GetCustomField("PeakModelRT")

• Between specific peaks - we will still typically integrate and label unknown peaks, so we need a way to specify the resolution between two specific peaks.

• Hello,

This is a simple example below, the CC would allow calculation of 2 peaks named in the CCF file. This could be changed to pull the names from custom fields if needed. It would also be possible to key multiple compound pairs through the use of custom fields if needed.

ModRT

CurrentPeakOrGroup.GetCustomField("PeakModelRT")

Peak1

Peak Name in upper case

Peak2

Peak Name in upper case

SpecificResolution

(CurrentSignal.AllIdentifiedPeaks.Where(function (x) x.Compound_Name.Toupper = CurrentInjection.GetStringCC("Peak2")).Select(function(x) x.GetDoubleCC("ModRT")).Max - CurrentSignal.AllIdentifiedPeaks.Where(function (x) x.Compound_Name.Toupper = CurrentInjection.GetStringCC("Peak1")).Select(function(x) x.GetDoubleCC("ModRT")).Max) / (CurrentSignal.AllIdentifiedPeaks.Where(function (x) x.Compound_Name.Toupper = CurrentInjection.GetStringCC("Peak2")).Select(function(x) x.Peak_WidthTangent).Max + CurrentSignal.AllIdentifiedPeaks.Where(function (x) x.Compound_Name.Toupper = CurrentInjection.GetStringCC("Peak1")).Select(function(x) x.Peak_WidthTangent).Max) * 2 • Hi Marty,

On following the calculation, i am not getting any values generated into the report or elsewhere. It is giving me an error when entering the 'formula' for Peak1 and Peak2. Any help is really appreciated. Thanks!

• Hello,

The peak names need to be in double quotes, as any time you enter static text it needs to be in double quotes. If you have errors in the formulas you will not see any calculations. If you have no errors in the CC file the results will be under the summary section in DA. • Hey Marty, it worked.

Thank you.

Last question, How do I put it on the report to show on only one line?

It is showing up for every compound?

Thanks,
-Ben

EX  