scholarly journals Quantification of N 6 ‐formylated lysine in bacterial protein digests by liquid chromatography‐tandem mass spectrometry despite spontaneous formation and matrix effects

2020 ◽  
Author(s):  
J.S. Folz ◽  
J.A. Patterson ◽  
A.D. Hanson ◽  
O. Fiehn
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Matrix Effects ◽  
Tandem Mass ◽  
Bacterial Protein ◽  
Spontaneous Formation ◽  
Chromatography Tandem Mass Spectrometry ◽  
Protein Digests ◽  
Liquid Chromatography Tandem Mass

scholarly journals Isotope-Dilution Liquid Chromatography–Tandem Mass Spectrometry Candidate Reference Method for Total Testosterone in Human Serum

2013 ◽  
Vol 59 (2) ◽  
pp. 372-380 ◽  
Author(s):  
Julianne Cook Botelho ◽  
Christopher Shacklady ◽  
Hans C Cooper ◽  
Susan S-C Tai ◽  
Katleen Van Uytfanghe ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Isotope Dilution ◽  
Matrix Effects ◽  
Reference Method ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Deming Regression ◽  
Liquid Chromatography Tandem Mass

BACKGROUND We developed and evaluated a candidate reference measurement procedure (RMP) to standardize testosterone measurements, provide highly accurate and precise value assignments for the CDC Hormone Standardization Program, and ensure accurate and comparable results across testing systems and laboratories. METHODS After 2 liquid/liquid extractions of serum with a combination of ethyl acetate and hexane, we quantified testosterone by isotope-dilution liquid chromatography–tandem mass spectrometry with electrospray ionization in the positive ion mode monitoring 289→97 m/z (testosterone) and 292→112 m/z (3C13 testosterone). We used calibrator bracketing and gravimetric measurements to give higher specificity and accuracy to serum value assignments. The candidate RMP was evaluated for accuracy by use of NIST-certified reference material SRM971 and validated by split-sample comparison to established RMPs. We evaluated intraassay and interassay imprecision, measurement uncertainty, potential interferences, and matrix effects. RESULTS A weighted Deming regression comparison of the candidate RMP to established RMPs showed agreement with no statistical difference (slope 0.99, 95% CI 0.98–1.00, intercept 0.54, 95% CI −1.24 to 2.32) and a bias of ≤0.3% for NIST SRM971. The candidate RMP gave maximum intraassay, interassay, and total percent CVs of 1.5%, 1.4%, and 1.7% across the concentrations of testosterone typically found in healthy men and women. We tested structural analogs of testosterone and 125 serum samples and found no interferences with the measurement. CONCLUSIONS This RMP for testosterone can serve as a higher-order standard for measurement traceability and can be used to provide an accuracy base to which routine methods can be compared in the CDC Hormone Standardization Program.

Simultaneous Determination of Isopyrazam and Azoxystrobin in Cucumbers by Liquid Chromatography–Tandem Mass Spectrometry

2017 ◽  
Vol 80 (12) ◽  
pp. 2112-2118 ◽  
Author(s):  
Dan Hu ◽  
Xu Xu ◽  
Tian Cai ◽  
Wei-Ying Wang ◽  
Chun-Jie Wu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Matrix Effects ◽  
Fast Method ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Relative Standard ◽  
Liquid Chromatography Tandem Mass

ABSTRACTA rapid and sensitive analytical method based on high-performance liquid chromatography–tandem mass spectrometry was developed and validated for the determination of isopyrazam (IZM) and azoxystrobin (AZT) in cucumbers. A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was used as the pretreatment procedure. The samples were extracted with acetonitrile and cleaned up with octadecylsilyl silica (C18) and graphite carbon black. The proposed method resulted in satisfactory recovery of IZM and AZT (91.48 to 114.62%), and relative standard deviations were less than 13.1% at fortification concentrations of 1, 20, and 500 μg kg−1 (n = 3). The limits of quantification for IZM and AZT were 0.498 and 0.499 μg kg−1, respectively, which are far below the maximum residue level (0.5 mg kg−1) established for this type of sample. Matrix effects were also evaluated. This study established a sensitive and fast method for the detection of IZM and AZT in cucumber samples.

scholarly journals Pitfalls Associated with the Use of Liquid Chromatography–Tandem Mass Spectrometry in the Clinical Laboratory

2010 ◽  
Vol 56 (8) ◽  
pp. 1234-1244 ◽  
Author(s):  
Michael Vogeser ◽  
Christoph Seger
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Matrix Effects ◽  
Clinical Chemistry ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Target Analytes ◽  
Potential Sources ◽  
Liquid Chromatography Tandem Mass

BACKGROUND Novel mass spectrometric techniques such as atmospheric pressure ionization and tandem mass spectrometry have substantially extended the spectrum of clinical chemistry methods during the past decade. In particular, liquid chromatography tandem–mass spectrometry (LC-MS/MS) has become a standard tool in research laboratories as well as in many clinical laboratories. Although LC-MS/MS has features that suggest it has a very high analytical accuracy, potential sources of inaccuracy have recently been identified. CONTENT The sources of inaccuracy in LC-MS/MS methods used in the routine quantification of small molecules are described and discussed. Inaccuracy of LC-MS/MS methods can be related to the process of ionization through the insource transformation of conjugate metabolites or target analytes and may also be attributable to ionization matrix effects that have a differential impact on target analytes and internal-standard compounds. Inaccuracy can also be associated with the process of ion selection, which mainly occurs when compounds from the sample matrix share mass transitions with a target analyte. In individual assays, most potential sources of inaccuracy can be controlled by sufficient LC separation–based sample workup before MS analysis. SUMMARY LC-MS/MS methods should undergo rigorous and systematic validation before introduction into patient care.

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