2025-07-11 CRM Accuracy Checks for Titrator
CBLS CRM ACCURACY TROUBLESHOOTING AND CALIBRATION
Protocol Link from Personal Notebook and from Putnam Lab
Titrations of total 6 samples consisting of 3 JUNKS and 3 CRMs were ran to look for CRM accuracy.
- Since 2025-06-04 until 2025-07-03 Putnam and Puritz lab ran couple of titrations and after careful consideration of the CRM Accuracy data file, the CRMs were off from 1.7 to 2%.
- *Note: The inefficiency came into attention after recognizing that the CRM accuracy should have been tested after the CRM Totration is completed and not at the end of the sample titrations.For further titrations remember that NEVER PROCEED BEYOND THIS STEP UNTIL THE CALCULATED CRM IS ONLY OFF BY <1% OF THE REPORTED CRM CERTIFICATE *
- In order to test and troubleshoot this inefficiency, along with Hollie Putnam (HP), we tried to adjust and recalibrate the pH probe and run the CRMs with the Batch #180.
1. pH probe cleaning, maintenance and calibration
- Firstly, using the user manual present in the titrator supplies drawer (located on organismal side, BD11) go through the checks for the pH probe.
- Make sure the pH probe is submerged in the KCl solution and not dried out.
- After checking the health of the probe, go through the steps present in the manual to clean the probe with 0.5mol KCl solution present on the BS10 shelf. While cleaning, take out the glass debris from previous pipettes (if present). Rinse the KCl probe one or twice till you feel its cleaned out. Incase of any bubbles, shake the probe for clear solution. (add picture of the manual here)
- After this is done, proceed to the adjustment and calibration step on the manual by running the pH calibration and observing the results.
Observations during this run: All the tests for pH calibrarion were passed by the probe. However, when checking the efficiency, HP noticed that even though the values fall within the expected range, there is not a steady incline instead the graph in between shows unusual loss and gains but still increases over the period of the analysis.The graphs from all the pH calibration trails were also accurate and depicted an expected, steady decline straightline
- Following are the pH calibration values from today and the previous titration trails of Putnam Lab:
| Date | ZeroPoint | Slope | pH4 | pH7 | pH10 | Temp | Status | Notes |
|---|---|---|---|---|---|---|---|---|
| 20250604 | 7.013 | -57 | 172 | -0.9 | -172.1 | 22 | OK | 20250604_TJW |
| 20250618 | 7.037 | -56.68 | 172.8 | -0.4 | -170.9 | 19.7 | OK | 20250618_JH |
| 20250703 | 7.038 | -56.62 | 172.5 | 0 | -171 | 19.5 | OK | 20250703_PP |
| 20250711 | 7.035 | -56.48 | 171.9 | -0.1 | -170.7 | 19.5 | OK | 20250711_HP |
-
The plot for this pH calibration is below:
-
Below are the resulted CRM values from titrations which are off by >1% depicting the inaccuracy of CRMs!
| Date | CRM value | Batch value | % off | Batch # | Status | Notes |
|---|---|---|---|---|---|---|
| 20250604 | 2172.75 | 2224.47 | -2.324 | 180 | OK | CRM180_opened20250502_SS |
| 20250618 | 2185.80 | 2224.47 | -1.738 | 180 | OK | CRM180_opened20250502_SS |
| 20250703 | 2183.678 | 2224.47 | -1.833 | 180 | OK | CRM180_opened20250502_SS |
| 20250711 | 2176.875 | 2224.47 | -2.139 | 180 | OK | CRM180_opened20250502_SS |
| 20250711 | 2180.854 | 2224.47 | -1.960 | 180 | OK | CRM180_opened20250502_SS |
| 20250711 | 2170.418 | 2224.47 | -2.429 s | 180 | OK | CRM180_opened20250502_SS |
Observations from the previous titration trails: Even though the CRMs showed inaccuracy after running the analysis, the CRMs for all times of Batch #180 came out to be OK. With the Puritz lab, the CRMs titration results on LabX showed out to be NOT OKAY in addition with >2% off during analysis.