A calibration curve was established for the determination of thiocyanate ions in urine. Twenty-five replicate determinations of the blank yielded a standard deviation of 1.85 response units. The slope of the calibration curve was 18.67 response unit per uM thocyanate. What is the minimum detectable concentration of thiocyanate for this method? And what is the limit of quanititation for thiocyanate by this method?