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. Author manuscript; available in PMC: 2019 Jul 23.
Published in final edited form as: Clin Chem. 2019 Jan 15;65(3):406–418. doi: 10.1373/clinchem.2018.288092

Table 3.

Interassay imprecision and recovery of analyte values at the LLOQ.

Analyte LLOQ QC
Actual
concentration,
μg/mL		 Validation (n = 90) Multiinstrument
validationa (n = 75)
Mean measured
concentration,
μg/mL		 CV,
%		 Recoveryb, % Mean measured
concentration,
μg/mL		 CV,
%		 CV, Recoveryb,
%
Acetylthreonine    0.0200    0.0203 6.5 102    0.0199 6.7   99.5
Phenylacetylglutamine 0.100    0.0955 8.6   95.5    0.0954 6.7   95.4
Pseudouridine 0.400 0.393 7.0   98.3 0.394 8.8   98.5
Tryptophan   1.00     1.02 9.3 102     1.04 7.9 104
a

Data reported are from all 3 LC-MS/MS systems tested.

b

Recovery of the LLOQ QC measurement is the comparison of the quantification of the independently prepared LLOQ QC sample against the nominal concentration.