Abstract: A 2 g portion of 3-guanidinopropionic acid [3-GPA; N-(aminoiminomethyl)β-alanine] was dissolved in 5 mL 2N-H3PO4 and HCN was stripped from the solution with a He stream (40 ml/min). The stripping was carried out for 15 min at 75°C. The HCN was trapped in 1 mL 0.05 M NaOH. The resulting alkaline solution was analyzed for cyanide using a FIA system consisting of an autosampler with 50 µL injection loop and an electrochemical detector equipped with a Ag working electrode held at 0 mV vs. Ag/AgCl. The carrier stream (0.6 ml/min) was 0.05 M NaOH. The average recovery of 5-100 ppb cyanide from spiked 3-GPA was 81.7% and the detection limit was 5 ppb. The RSD (n = 8) for the determination of 25 ppb cyanide was 7.5%. The four samples of 3-GPA analyzed by the proposed method were found to contain 5 ppb cyanide.