A widely applicable plasma renin activity assay by LC-MS/MS with offline solid phase extraction

Area of Science:

• Clinical Chemistry
• Analytical Chemistry
• Mass Spectrometry

Background:

• Plasma renin activity (PRA) measurement is crucial for diagnosing and managing various conditions.
• Radioimmunoassay (RIA) is a traditional method for PRA, but LC-MS/MS offers an attractive alternative.
• Existing LC-MS/MS methods for PRA often require specialized equipment, limiting accessibility.

Purpose of the Study:

• To develop and validate an offline modification for PRA measurement using LC-MS/MS.
• To provide a method that does not require specialized equipment, enhancing accessibility for LC-MS/MS users.
• To compare the performance of the offline method with a previously published online method.

Main Methods:

• Samples were prepared and incubated for 6.5 h and 24 h.
• Offline solid-phase extraction was performed using a commercially available 96-well plate.
• Method comparison was conducted against a previously established online solid-phase extraction assay.

Main Results:

• The offline method yielded results comparable to the online method across the measured concentration range.
• Analytical performance of the offline method was found to be similar to the online assay.
• A 24-hour incubation period was determined to be unnecessary for low-concentration samples.

Conclusions:

• The described offline method is a viable alternative to existing PRA assays.
• This method does not necessitate highly specialized equipment, broadening its applicability.
• The approach is suitable for the majority of laboratories equipped with LC-MS/MS systems.