US EPA

7445256 

Journal Article 

UCMR4, Microcystins Analysis, and High-Resolution Mass Spectrometry for Confidence in Identity Confirmation 

Hyland, KC; Butt, C; Quinn-Paquet, A 

2018 

Yes 

American Laboratory
ISSN: 0044-7749 

International Scientific Communications Inc. 

50 

3 

24-27 

English 

WOS:000429505900007 

The Unregulated Contaminant Monitoring Rules (UCMR) is the result of the 1996 SDWA amendment requirement that the US EPA continually seek to identify and monitor potentially harmful or relevant contaminants that may be currently unregulated. Quantitation of a suite of microcystins and nodularin was demonstrated using LC-MS/MS on the SCIEX X500R QTOF system. Utilizing the TOF-MS spectral data and extracting a narrow XIC for analyte precursor ions provided quantitation results with sensitive detection and high reproducibility at low concentrations. If used with EPA method 544 suggested concentration factor of 500 fold, these detection limits are extended upto 0.0002 Å¡g/L, attaining the MRLs defined in the UCMR4 list. Linearity was reported over 5-6 concentration levels and pproximately three orders of magnitude with r-values from 0.95 to 0.99. Using the HRAM approach on the X500R system, confirmation of target identification can be attaines using accurate precursor mass matching, isotope pattern matching, accurate fragment mass matching, ion ratio matching, and retention time matching. Verifying across these five points reinforces the ability to confirm the presence of the analyte and helps safeguard against reporting false positives. 

Impurities; Mass spectrometry; Pattern matching; Concentration factors; Concentration levels; High reproducibility; High resolution mass spectrometry; Sensitive detection; Target identification; Three orders of magnitude; Unregulated contaminant monitoring rules; Magnetic prospecting