Detection of ricin in beverages using the Bio-Threat Alert test strips

Ricin, which is a proteinous toxin contained in castor beans, is one of the chemical warfare agents and strictly regulated by law. Regardless of the high toxicity, they have been used in some cases such as attempted murder cases due to the easy accessibility of castor beans. For these cases, detection of ricin is important for case control and proper remediation or decontamination. In this work, we have investigated the applicability of Bio-Threat Alert (BTA) test strips for the detection of ricin in beverages. By using BTA test strips, standard ricin protein in various beverages as low as 0.1 mg/mL could be detected by visual detection or by Guardian BTA Test Strip Reader. The calibration curves for ricin in tomato juice and cafe au lait were constructed using sample values obtained from Guardian BTA Test Strip Reader, which is the intensity of the color developed by the reaction of ricin and antibody. At high concentrations, the response seemed to be saturated. From the beverages added with mashed castor beans, ricin could also be detected by BTA test strips. Some beverages such as milk showed interfering behavior, but the reason seemed to not only come from the total protein amount but other factors.