Low-endotoxin recovery (LER) is a time-dependent masking of endotoxin activity in certain biopharmaceutical formulations that can lead to underestimation of endotoxin levels by standard assays. Understanding its mechanisms, detection, and regulatory implications is essential to ensure patient safety and product quality.

Endotoxin control is critical in pharmaceutical workflows from early-stage research through commercial manufacturing. However, the industry frequently uses broad labels such as “low endotoxin”, “endotoxin-tested”, or even “endotoxin-free” across consumables and reagents without a standardised numerical definition. Unlike Water for Injection (WFI), where specific endotoxin limits are clearly defined in Pharmacopoeias, many other reagents and consumables carry claims that remain loosely interpreted or inconsistently validated. This lack of clarity can affect data quality, comparability, and regulatory confidence.