FEASIBILITY OF USING ELECTRONIC RAPID TESTING KITS (eRTK) FOR IMPROVED MONITORING OF SALT PROCESSORS Jha R1, Dey S1 and Mannar V2. 1 The Micronutrient Initiative, India 2 The Micronutrient Initiative, Ottawa, Canada ABSTRACT Background: Small and medium-scale salt producers do not have laboratories in the vicinity of the production line resulting in time-lag between sample collection, testing and incorporation of corrective guidance. This lag increases the risk of producing non-standard iodized salt. Objective: To assess accuracy during field-use of an electronic Rapid Testing Kit (eRTK) as a method for testing iodine content. Under the study, a total of 3,198 iodized salt samples (504 samples of crystals, 1,596 crushed and 1,098 samples of crushed and washed salt) were tested using 15 eRTKs in 15 different sites in six states of India. Results: In comparison with the gold standard (Iodometric titration), eRTK has a sensitivity of 76.3%, specificity of 81.9%, positive predictive value of 79.5% and negative predictive value of 79%. The cut off point in eRTK was ±3 parts per million (ppm) as compared to the titration method. eRTK test cost 25% of titration cost. Conclusions: The eRTK was found to be a reasonably accurate and portable testing kit suitable for use in different field settings. SALT PRODUCTION AND IODINE TESTING SCENARIO IN INDIA Total production of salt in the country (million metric ton): 24.5 Total edible salt (million metric ton): 6.2 Share of edible salt covered in study: 34% of India’s total iodised salt production Highest salt producing State: Gujarat Type of salts available: Crystal, Crushed, Crushed and washed, Refined salt Types of iodization processes: Salt Refinery, Salt Upgradation plant, Mobile salt Iodization plant and Knap Sac Gold Standard of testing: Iodometric Titration Test introduced here: Electronic Rapid Testing Kit (eRTK, Innovative Design). METHOD There are four major iodization processes for nonrefined salt. The instrument works best for the Salt Upgradation Plant . Currently, the salt Iodization plants and Knap Sacs (spray used for iodization) are getting upgraded to salt upgradation plants. The cut off point was ±3 parts per million (ppm) in eRTK as compared to the titration method. Samples A total of 3,198 salt samples from 6 states of India were tested. 3 types of salt: 1. Crystal (504 samples). 2. Crushed (1,596 samples). 3. Crushed and washed (1,098 samples). Testing 1. 15 eRTKs units located at 15 different centres 2. Tested by individual chemists. 3. 20 g of iodized salt taken for iodine estimation using iodometric titration method. 4. The remaining salt was used for estimation through eRTK. Diagnostic screening Indicators computed in Excel 1.Sensitivity=TP/(TP+FN)*100 2. Specificity= TN/(TN+FP)*100 3. Positive Predictive Value= TP/(TP+FP)*100 and 4. Negative Predictive Value= TN/(TN+FN)*100 Where, TP: True Positives, FP: False Positives, TN: True Negatives and FN: False Negatives CONCLUSION The result of the study suggest that eRTK produces reasonably accurate results in field settings. It is not, however, a replacement of Iodometric titration, which is the “Gold Standard”. eRTK’s light weight and battery-powered option makes it highly useful in diverse field sites. RESULT FIGURE 1: DIAGNOSTIC SCREENING INDICATORS OF eRTK COMPARED TO TITRATION METHOD BY TYPES OF SALT Access to immediate iodine results in the field allows instant feedback and rapid corrections to processing methods. Cost of testing iodized salt samples using eRTK is 25% to that of Iodometric titration. ACKNOWLEDGEMENT We would like to acknowledge the support from Government of Canada through the Department of Foreign Affairs, Trade and Development and Innovative Design, Chennai, India (developer of eRTK) for their efforts to achieve desired results. OBJECTIVE To assess accuracy during field-use of an Electronic Rapid Testing Kit (eRTK) for assessing iodine content of salt in the production line, to monitor and maintain iodine levels during its production, particularly in small and medium scale production units. Note: Point estimates presented alongwith 95% confidence intervals. BACKGROUND • Quality control is a process to detect and correct production default from specified standards during actual processing. In salt iodization units, iodized salt samples are collected and tested through iodometric titration in a laboratory attached to the production unit. • Small and medium-scale producers do not have these adjacent laboratories. The time-lag between sample collection, testing, and incorporation of corrective guidance increases the risk of producing non-standard iodized salt. • MI has been working with ~300 small and medium scale salt producers to improve production method and quality control. They collectively produce ~ 2.1 million metric ton comprising 34% of India’s iodized salt production. • eRTK was developed as an instrument designed specifically as a more rapid method of measuring iodine levels in salt, particularly in small-scale production sites. It uses the absorbing characteristics of iodine-starch blue compound and applying the BeerLambert Law. FIGURE 2: DIAGNOSTIC SCREENING INDICATORS OF eRTK COMPARED TO TITRATION METHOD BY IODIZATION PROCESSES Note: The range of sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) vary from 70-90 per cent among the three types of salts, which shows that it works reasonably well for the three types of salts. Correspondence: Ranjan Kumar Jha; [email protected]
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