AWWA WQTC69227

Standard Method 6040D is a sensitive method for analyses of geosmin and 2-methylisoborneol (MIB) that are two commonly cited compounds for earthy/musty taste and odor problems of drinking water. The odor threshold concentrations of geosmin and MIB are 4 ng/L and 9 ng/L, respectively. This method uses solid-phase microextraction (SPME) GC/MS with selected ion monitoring (SIM) and with isobutyl methoxy pyrazine (IBMP) used as an internal standard and isopropyl methoxy pyrazine (IPMP) used as a surrogate standard. Four main challenges are often associated with the routine performance of Method 6040D. First, it is very difficult to meet a minimal reporting level (MRL) of 1 ng/L, which is often required by clients. Second, real water sample matrices often cause recovery failure of the surrogate and internal standards, which will sigificantly affect the accuracy of results. Third, SPME fiber damage or deterioration is a very common phenomenon. Finally, sample re-analysis is often required due to various reasons described above, which definitely affects the turn-around time. This paper describes an improved Standard Method 6040D to overcome these challenges. Includes tables, figure.