In our chem lab we are checking sulfuric acid concentration for anodazing process and using titration method to obtain density. After the density is obtained the acid concentration is calculated. Do you have any experience with conducting MSA study for titration?
This is a throwback question for me. (Chemical engineer-- took my fair share of Chem classes). For MSA, can you do a simple error analysis in a root mean square fashion? What measurements go into the calculation? Accumulate the impact using an RMS approach?
Alternatively, can you buy a standard off the shelf with a known concentration and density and then see how your in house lab results stand up? (Statistical test of differences. You will need some replication. You could do routine GRR here with multiple analysts / techs).
This is my first pass and I am sure those more in the know will refine this or completely blow it up. Have fun. Enjoy the ride.
Thanks for answer. Can you describe more detailed RMS approach? For the second approach you have mentioed (standard with a known concentration and density... how to measure this standard? At least 25 times and calculate bias? We have 3 operators in our lab. For GRR I need to have ca 10 parts taken in whole tolerance. Sorry, but I'm not familiar with chem methods like titration and don't know what is the best way to start up.
Error analysis was done by estimating uncertainty in a given measurement. Running those uncertainties through the calculation and seeing the impact. It was an estimate not a true measure.
MSA principles, IMHO, would be applicable to titration. Buy a standard (an off the shelf solution of known assay-- you will probably have to pay extra for this to get the supplier to provide a cert of analysis that the sulphuric acid is X.XX % / molarity / molality / whatever. Have your analysts test that standard and see how close they get. Google is your friend. Read about titration Wet chem labs have many opportunities for error. Your MSA participants will have their own error rates / tendencies that will show up in the final results. You should be able to get a GRR as well as an accuracy to standard element. Which analyst had the most accurate results? Which had the least variation? Titration is adding one solution to another, at the end, in a drop by drop fashion, to get a color change when an indicator is triggered at a certain concentration. Some will overshoot; some may undershoot. Plan your statistics BEFORE sending your team to the lab. Have a pre determined analysis plan and, if possible, acceptance criteria for accuracy to the standard. Will you introduce equipment variation? Different pipettes? Scales? Glassware? Etc. Or, will you keep the equpment the same and focus on the operator / tester differences.
Hope this helps