Abstract: Methods and systems are disclosed for rapid detection of cerebrospinal fluid (CSF) in a sample. In some embodiments, the methods comprise depleting a biological sample of beta-1 transferrin by contacting the sample with a sialic acid-specific lectin bound to a solid support, followed by subjecting the beta-1 transferrin-depleted sample to a lateral flow immunoassay. The methods can be used to detect CSF comprised by a sample in under one hour. Furthermore, the methods can detect CSF in a biological sample such as a plasma sample of a volume as small as about 10 ?l.