Certification of NIST standard reference material 2389a, amino acids in 0.1 mol/L HCl--quantification by ID LC-MS/MS.
An isotope-dilution liquid chromatography-tandem mass spectrometry (ID LC-MS/MS) measurement procedure was developed to accurately quantify amino acid concentrations in National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 2389a-amino acids in 0.1 mol/L hydrochloric acid. Seventeen amino acids were quantified using selected reaction monitoring on a triple quadrupole mass spectrometer. LC-MS/MS results were compared to gravimetric measurements from the preparation of SRM 2389a-a reference material developed at NIST and intended for use in intra-laboratory calibrations and quality control. Quantitative mass spectrometry results and gravimetric values were statistically combined into NIST-certified mass fraction values with associated uncertainty estimates. Coefficients of variation (CV) for the repeatability of the LC-MS/MS measurements among amino acids ranged from 0.33% to 2.7% with an average CV of 1.2%. Average relative expanded uncertainty of the certified values including Types A and B uncertainties was 3.5%. Mean accuracy of the LC-MS/MS measurements with gravimetric preparation values agreed to within |1.1|% for all amino acids. NIST SRM 2389a will be available for characterization of routine methods for amino acid analysis and serves as a standard for higher-order measurement traceability. This is the first time an ID LC-MS/MS methodology has been applied for quantifying amino acids in a NIST SRM material.
Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8392, USA. mark.lowenthal@nist.gov
Mark S
MS
Lowenthal
James
J
Yen
David M
DM
Bunk
Karen W
KW
Phinney
D000596:Amino Acids / Q000032:analysis* / Q000592:standards*; D002853:Chromatography, Liquid / Q000379:methods*; D006851:Hydrochloric Acid / Q000737:chemistry; D007201:Indicator Dilution Techniques; D007554:Isotopes / Q000032:analysis; D012015:Reference Standards; D012680:Sensitivity and Specificity; D012996:Solutions / Q000737:chemistry; D053719:Tandem Mass Spectrometry / Q000379:methods*
D000596:Amino Acids; D007554:Isotopes; D012996:Solutions; D006851:Hydrochloric Acid