Liquid chromatography-mass spectrometry (LC-MS) is a robust tool that combines chromatographic separation with mass spectrum detection. This technique involves high-resolution separation of study compounds followed by specific and sensitive detection through MS units. Mass spectrometers are robust detection units for determining the structural and elemental composition of a sample. Therefore, LC-MS has numerous applications, such as bioavailability studies. But what is bioavailability? Bioavailability is the amount of a drug compound available at the site of action.
LC-MS has a specific role in pharmaceutical analysis. Besides, advanced hyphenated techniques such as LC-MS/MS analysis have further skyrocketed their applications in pharmaceutical studies. Hence, the current article focuses on LC-MS method development and validation in pharmaceutical analysis while understanding different regulatory standards. But let’s first begin with understanding the advantages of LC-MS analysis.
Advantages of LC-MS analysis
LC-MS systems have several advantages over other HPLC methods.
- LC-MS systems are highly selective, and coeluted peaks can be isolated readily through mass spectrometers
- LC-MS analysis has a unique chemical fingerprint that ensures correct peak assignment for the compound of interest
- LC-MS assays can confirm and identify the molecular weight of known and unknown compounds
- Through controlled fragmentation in LC-MS analysis, scientists can gain structural information
- Notably, LC-MS assays can provide qualitative and quantitative data
Regulatory standards for LC-MS method development and validation
LC-MS method development and validation has a systematic approach in pharmaceutical analysis. An overview of the procedure for method development includes:
- Collecting chemical properties of the compound from the literature
- Confirming solubility
- Scanning and optimization of MS units
- Selecting the mobile phase
- Selecting and optimizing the extraction technique
- Choosing the activity technique based on compound solubility
Adequate data on the compound of interest is crucial while developing the LC-MS method. The molecular weight, sample solubility, compound variety, data stability, and concentration of compounds in the study sample are some preliminary data needed for efficient method development.
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When the LC-MS method is developed, scientists focus on optimizing the system. Method optimization comprises evolving and improving the initial strategy and conditions used in method development and maximizing its performance in terms of resolution and peak. Method optimization may include manual or laptop-driven strategies.
As most pharmaceutical compounds are polar, scientists often employ reverse activity during the initial stage of identifying the mode of separation. However, they must have adequate knowledge about column packing before selecting the columns of the stationary phase. The choice of mobile phase mainly depends on attaining optimal separation.
LC-MS systems are highly sophisticated techniques with several operation modes and multiple parameters. Hence, method validation is crucial for obtaining reliable results. Robust method validation ensures that the LC-MS systems are working as expected and delivering reproducible results.
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A clear plan consisting of the reason for validation, experimental requirements, and protocol should be in place before beginning with method validation. Regulatory guidance is crucial for ensuring robust LC-MS method validation. Method validation includes assessing different parameters such as sensitivity, selectivity, precision, accuracy, stability, and limits of quantification. Evaluating the validity of a method based on research and experiments is the necessary last step of method validation.