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Table 3 Detection and analytical methods utilized in the four participating laboratories

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)   0.06 ng/ml (BPA-G)
ULOQ 50 ng/mL   40 ng/ml (uBPA and BPA-G)  
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)