LC-MS/MS PFAS Analysis Using an Alkaline Mobile Phase
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Solution Overview
Problem
Existing methods lack a rapid and simultaneous detection method for per- and polyfluoroalkyl substances, particularly perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, and polyfluoroalkyl phosphate esters, which are not effectively separated or detected in conventional liquid chromatography-tandem mass spectrometry systems.
Innovation Solution
The use of an alkaline mobile phase with a pH of 8 to 10 in liquid chromatography-tandem mass spectrometry (LC-MS/MS) systems allows for the separation and detection of up to 93 types of PFASs, including PFPAs, PFPiAs, and PAPs, by single injection, with the system equipped with a delay column to prevent fluorine interference and temperature adjustments to reduce in-source pyrolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional mobile phases are used in LC-MS/MS, then the system operates within standard pH ranges, but fewer types of PFASs (especially PFPAs, PFPiAs, and PAPs) can be effectively separated and detected
Solution Approach 1:
The patent changes the pH parameter of the mobile phase to alkaline conditions (pH 8-10), which fundamentally alters the separation and ionization behavior of PFAS compounds. This parameter change enables effective detection of PFPAs, PFPiAs, and PAPs that cannot be detected with conventional mobile phases, directly resolving the contradiction between detection capability and system complexity.
2Productivity
If alkaline mobile phase is used to expand detection range, then more PFASs can be detected by single injection, but pH range restrictions of chromatographic column are exceeded
Solution Approach 1:
The patent selects a chromatographic column with alkaline stability and adjusts the mobile phase pH to 8-10, changing the operational parameters to be compatible with the column's stability range. This allows the system to achieve rapid single-injection analysis of 93 PFAS targets while maintaining column reliability and preventing degradation.
Solution Approach 2:
The patent develops a universal detection method that can analyze 93 different PFAS targets including PFCAs, PFSAs, FASAs, PFPAs, PFPiAs, PAPs, and fluorotelomer compounds using a single alkaline mobile phase system. This multi-functional approach eliminates the need for multiple separate analysis methods, achieving high productivity while maintaining system reliability through standardized operating conditions.
3Loss of time
If single injection method is used for rapid analysis, then analysis time is reduced, but separation of PFASs with vastly different physical and chemical properties becomes difficult
Solution Approach 1:
The patent optimizes the alkaline mobile phase composition and gradient elution parameters to achieve baseline separation of 93 PFAS compounds with vastly different physical and chemical properties within a single injection. The gradient elution program adjusts flow conditions dynamically to resolve early-eluting and late-eluting compounds, maintaining high separation precision while completing the analysis in a single run, thus resolving the contradiction between analysis time and separation precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables rapid and sensitive analysis of a wide range of PFASs, achieving higher detection sensitivity and accuracy through improved ionization and separation, allowing for the detection of 93 PFAS targets with diverse physical and chemical properties.
Implementation Method 1
by using an alkaline mobile phase to elute a sample, 93 PFASs targets, including PFP As/PFPiAs and PAPs, can be eluted sequentially at different retention times in single injection
Implementation Method 2
more types of PFASs can be better ionized and have better response on a mass spectrometer detector
Implementation Method 3
the eluted PFASs can be obviously distinguished by measuring different ion pairs using the LC-MS/MS
Data Source
AI summary
The present disclosure provides a method for measuring a concentration of a per- and polyfluoroalkyl substance and a liquid chromatography-tandem mass spectrometry system. The method includes: measuring concentrations of a plurality of per-and polyfluoroalkyl substances in a sample by liquid chromatography-tandem mass spectrometry in a primary measurement process of eluting the sample with an alkaline mobile phase, in which the plurality of per- and polyfluoroalkyl substances at least include one or more perfluoroalkyl phosphonic acids/phosphinic acids or polyfluoroalkyl phosphate esters. According to the method, by using the alkaline mobile phase to elute the sample, the rapid analysis on 93 PFASs including perfluoroalkyl phosphonic acids/phosphinic acids and polyfluoroalkyl phosphate esters can be completed by single injection. Additionally, the present disclosure also provides a method to rapidly analyze 10 PFASs by GC-MS/MS.