New Method Significantly Improves Detection of Large Peptides in Biological Samples

Peptides larger than 2 kDa are increasingly relevant as biomarkers and therapeutic agents, yet their detection in complex biological matrices like blood or urine remains a significant analytical challenge. Traditional methods often struggle with the sensitivity and specificity required to accurately identify and quantify these larger molecules amidst a vast array of endogenous compounds. This study addresses the critical need for a more robust and sensitive analytical platform capable of reliably detecting and characterizing peptides exceeding 2 kDa.

The developed IAP-LC-HRMS/MS method demonstrated significantly enhanced analytical performance for peptides >2 kDa. It achieved detection limits (LODs) that were 5 to 10-fold lower than conventional LC-MS/MS methods, with some target peptides reaching LODs as low as 0.1 ng/mL. The method exhibited excellent linearity over a concentration range spanning two orders of magnitude (R² > 0.995), indicating high quantitative accuracy. The most significant finding was an average recovery rate of 85% ± 5% for the target peptides from complex urine matrices, representing a 30% improvement compared to previous methods lacking immunoaffinity enrichment. Specificity was also remarkably high, with no significant matrix interference observed in 98% of the tested samples, leading to a false positive rate below 1%. This robust performance allows for reliable identification and quantification of large peptides even at very low concentrations.