You can't have both a qualitative and quantitative characteristic for a test. It's either one, or the other. Your test is really a quantitative test and should be set up as such.
SAP deals with this by allowing you to enter in <1 or <5 or whatever you determine the lower detection limit is, (or LOQ if you want to use that). If the spec is < 5 ppm and your lowest detection limit is 1 ppm you can enter < 1 ppm. You can't claim the value is zero because the test can't actually prove zero.
This is pretty standard in the analytical world. <1 would be the same as your <LOD probably.
SAP does not have a means to account for LOQ.
If you report this out on a COA, you would probably than use a text element in the COA profile to change the < 1 to a < LOD. But internally you would always see <1 ppm. Which would be accurate and true unless of course you actually feel zero is a real possibility.
I can't say I've ever had a client that needed, for a given test, to be able to distinguish between both LOD and LOQ when it came to reporting out results. And I've worked for several high-end chemical firms and pharmaceutical firms.
It would be great if you could share the industry this is required for and even better if you could point to a standard test method, (like ASTM), where it would be required to distinguish and be able to report out both LOQ and LOD levels. I.e. the end user or customer demands it.
I know that lab folks can get real picky on these nuances in testing and I totally get that. I've fought these battles many times. But when it comes down to most manufacturing, even at the most demanding levels for chemicals and pharmas, most of your customers don't give a hoot about the difference between LOQ or LOD on day to day products. There is usually a lower spec required that is over both the LOQ and LOD and as long as the product meets that, they don't care if the value is zero, LOQ or LOD. As long as it isn't >1 ppm or whatever their spec is. I know that is sacrilegious to many analytical folks.
Where I find the LOQ and LOD come into play is in the method development work and the "showing your work" process for why a particular specification or test method has been chosen. Being able to say to a customer our spec is < 2 ppm because....and our chosen test method is xyz because.... for instance < 1 is still above both the LOQ and LOD for this method and we can be totally confident of any reported result above 1 ppm and for the application the material is being used for, up to 2 ppm is an acceptable.
The customer isn't caring later on if you report <LOD or <LOQ. As long as it isn't over 2 ppm because, when they buy the material, that's all your test method can guarantee to them down to 1 ppm.
This is a system in support of business manufacturing. Don't spend a fortune on trying to do something that in the end is very little added value. Unless a specific customer is actually demanding this, and accounts for a large percentage of your profits, (not sales), it's usually not worth the effort to do. Send them to your competitor.
If you are trying to use SAP as a LIMS for method development work or other pilot or R&D type work, you probably need to rethink that. SAP was never really designed for that type of work.
Now.. if the business is still insistent on providing this functionality, AND the business can really justify paying for it and there is a reasonable ROI, the only way I can think of accommodating this would be to use the 1st and 2nd warning levels that are available for a MIC, usually used for SPC characteristics. Enter the LOQ in the 1st lower warning limit and the LOD in the second. Results recording wouldn't change, the actual recorded test value is recorded in the inspection lot.
Now you might have to develop your own valuation FM and use that for valuating the characteristic in the inspection lot. Have it compare against the warning values and valuate it accordingly. My guess is you might not even need this since LOQ and LOD would normally always fall within a given spec. (i.e. 0 - 5 or < 5) So as long as the actual value or <nnn is recorded, normal valuation would probably work.
You will need to develop your COA form to print either <LOD or <LOQ based on a comparison to the warning limits. Not simple, but it should be able to be done. Possibly in a custom FM for the results origin that gets the results and some custom text elements. I.e. have the custom FM get the test value and do the comparison. If <LOD (i.e. lower than 2nd warning limit), return the value -2, if <LOQ return -1 else return the actual value. In the text element you do substitution, if -2 report <LOD, if -1 report <LOQ, otherwise report the actual value.
You'll also need to re-write or write your custom reports to make the same comparison and report <LOD or <LOQ if that is required.
Craig
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