Inter-laboratory comparison trials for turbidity analysis of petroleum in soil samples to confirm its performance for universal practical application

To confirm the performance of turbidity analysis (TA) of petroleum in soil samples, comparison tests were organized between two countries. For this purpose, two TA procedures were checked; one is in batch-wise operation and the other by a method using a commercially available test kit. To evaluate the performance, the petroleum spiked in the soil samples was determined also by GC-FID, which were provided for the TA detection in the two procedures. The results support that TA quickly detects the petroleum extracted with lower alcohols in easy operation and with good recoveries equal to those given by GC-FID.