Emergency Radiobioassay Method for Determination of ⁹⁰Sr and ²²⁶Ra in a Spot Urine Sample

Abstract

A new radiobioassay method has been developed for simultaneous determination of (90)Sr and (226)Ra in a spot urine sample. The method is based on a matrix removal procedure to purify the target radionuclides from a urine sample followed by an automated high performance ion chromatographic (HPIC) separation of (90)Sr and (226)Ra and offline radiometric detection by liquid scintillation counting (LSC). A Sr-resin extraction chromatographic cartridge was used for matrix removal and purification of (90)Sr and (226)Ra from a urine sample prior to its introduction to the HPIC system. The HPIC separation was carried out through cation exchange chromatography using methanesulfonic acid (75 mM) as the mobile phase at 0.25 mL/min flow rate. The performance criteria of the method was evaluated against the American National Standard Institute ANSI/HPS N13.30-2011 standard for the root mean squared error (RMSE) of relative bias (Br) and relative precision (SB) at two different spiked activity levels. The RMSE of Br and SB for (90)Sr and (226)Ra were found to be satisfactory (≤0.25). The minimum detectable activity (MDA) of the method for (90)Sr and (226)Ra are 2 Bq/L and 0.2 Bq/L, respectively. The MDA values are at least 1/10th of the concentrations of (90)Sr (190 Bq/L) and (226)Ra (2 Bq/L) excreted in urine on the third day following an acute exposure (inhalation) that would lead to an effective dose of 0.1 Sv in the first year. The sample turnaround time is less than 8 h for simultaneous determination of (90)Sr and (226)Ra.

Recent Development on Determination of Low-Level 90Sr in Environmental and Biological Samples: A Review

“…Milk contains large amount of fat and protein as well as antiseptic additives, e.g., formaldehyde or sodium azide [48,80]. Urine contains a large amount of organic compounds and inorganic salts [54,55,81,82]. Blood has a high concentration of iron and even more complex matrix composition.…”

“…For example, Hawkins et al [55] developed a rapid method for detecting 90 Sr in human urine, wherein the organic matrix was removed by activated carbon. Sadi et al [54] applied Sr resin in an HPLC system to remove the urine matrix, while some other researchers used cation exchange resin [54,55]. It is noteworthy that direct pretreatment with adsorption and chromatographic methods are mostly applicable to small-size samples (e.g., up to 250 mL).…”