From: A round robin approach to the analysis of bisphenol a (BPA) in human blood samples
 | Laboratory #1 | Laboratory #2 | Laboratory #3 | Laboratory #4 |
---|---|---|---|---|
Detection method | UHPLC-MS/MS using a Shimadzu (Kyoto, Japan) Nexera UHPLC system and Shimadzu LCMS-8080 triple quadrupole tandem mass spectrometer | Agilent 1100 series HPLC (Agilent Technologies Inc.,) interfaced with an Applied Biosystems API 5500 electrospray triple-quadrupole mass spectrometer (ESI-MS/MS; Applied Biosystems). | LC-MS/MS (Agilent LC 1260- AB Sciex 5500 Triple Quadrupole) | LC-MS/MS using a Thermo Surveyor TSQ plus connected to an integrated Thermo-Accela LC system. |
Blanks | Charcoal/dextran stripped human serum | Milli-Q water. Trace levels of free BPA were found in procedural blanks in some batches (0.40-0.46 for Phase 2, 0.19-0.28 for Phase 3). | Double-charcoal stripped human serum | HPLC-grade water (Fisher Scientific; cat# W5-4). |
Blanks: parallel? | Yes | Yes | Yes | Yes |
Blank values subtracted from environmental samples? | Yes | Yes | Not required – no contamination found in blanks | Yes |
LLOQ | 0.10 ng/ml (uBPA) | 0.01 ng/ml (uBPA) | 0.1 ng/ml (uBPA and BPA-G) | 0.13 ng/ml (uBPA) |
0.01 ng/ml (BPA-G) | 0.05 ng/ml (BPA-G) | Â | 0.06 ng/ml (BPA-G) | |
ULOQ | 50 ng/mL | Â | 40 ng/ml (uBPA and BPA-G) | Â |
Calculations for determining LLOQ, ULOQ | FDA Guidance for industry biomedical method validation | The LOD and LOQ were calculated as 3 times (3S) and 10 times (10S) of the standard deviations (S) of five replicate analyses, using the lowest calibration standard (0.01 ng/mL) | a signal that has a S/N of at least 10 and is the lowest calibrant that allows a linear regression coefficient of at least 0.95 | The LOD and LOQ were calculated as 3 times (3S) and 10 times (10S) of the standard deviations (S) of three replicate analyses, using the lowest calibration standard. The means of three assays are given. |
Standard procedure. C1 pg. 6 of Guidance | ||||
LOD | 0.02 ng/ml (uBPA) 0.002 ng/ml (BPA-G) | 0.003 ng/ml (uBPA) 0.02 ng/ml (BPA-G) | 0.05 ng/ml (uBPA and BPA-G) | 0.04 ng/ml (uBPA) 0.02 ng/ml (BPA-G) |