Rapid microwave digestion and microplate reading format method for urinary iodine determination

Abstract

High temperature and long heating time can be considered the main drawbacks of the conventional digestion methods of urinary iodine determination. The aim of this study was to assess the usefulness of a microwave for digestion and decomposition of urine interfering substances. It may help for shortening the time and increasing the safety of the method. In this study, two digestion methods were tested on urine samples. Random urine samples were processed by conventional electrical heat as well as new microwave digestion methods. The urine samples were digested using the two methods mentioned, and then urinary iodine was determined using a colorimetric reaction according to the Sandell-Kolthoff reaction. In order to increase speed and precision of the test, a microplate ELISA reader was used. Sensitivity, precision, and comparison of the results were assessed in both of the methods. In the case of microwave digestion, only a 10-min period was needed for complete digestion of urine samples. The precision and recovery of the new digestion step was acceptable. Furthermore, comparison of final results of iodine content obtained using the microwave and conventional method showed good correlation. These results show that a microwave method for urine digestion is advantageous due to its safety and ease of use, and quick preparation of urine samples to eliminate interfering substances and release iodine. Thus, it can replace the conventional electrical heat digestion method.