METHOD DEVELOPMENT AND VALIDATION OF TOTAL VIABLE COUNT USING SPECIFIED TECHNIQUES AND PERFORMANCE CHARACTERISTICS OF ISO/IEC 17025:2017 IN MICROBIOLOGICAL SAMPLES

Abstract

Biofertilizers are microbial based products, and their quality control is very much tricky job due to their biological nature and susceptibility to environmental factors. There are certain parameters that needs to be satisfied for the fitness of product. The principal parameter that showed the presence of microbes in the desired number is Total Viable Count besides other parameters etc. The series of lab studies were carried out at Biofertilizer Testing Laboratory (BTL-FSD), Soil Bacteriology Section, Faisalabad to evaluate the method development and validation characters mentioned in ISO/IEC 17025: 2017 standard for testing laboratories. The method developed keeping in view of (PSQCA standard) PS: 5330/2014 and amended according to the lab conditions and validated. Different techniques mentioned in clauses 7.2.2 and 7.2.2.3 were carried out in the lab environment. The bias expressed as LOG 10 were within the range of -0.024 to 0.034 and relative standard deviation (RSD) was <2%. The RSD of repeatability was 0.607% and reproducibility was 0.656 and 0.744%. The significance determined as t-stat was 0.280 well below the t-critical one and two tail i.e., 1.86 and 2.31, respectively and accuracy of method using robust mean was 99.8%. The measurement of uncertainty (MoU) was ±0.05 at 95% confidence interval and expanded uncertainty of the method was 0.1145. The LOD and LOQ of the method was evaluated as 0.090897 and 0.275445 expressed as LOG 10.  On the basis of techniques and characters under assessment, it was concluded that method of total viable count satisfied the requirements of ISO/IEC 17025:2017 standard and validated