Quantitative Analysis of Total Petroleum Hydrocarbons in Soils: Comparison between Reflectance Spectroscopy and Solvent Extraction by 3 Certified Laboratories

Table 3

Intralab repetition statistics for low, medium, and high TPH levels.

Lab	A				B				C
TPH level (calculated)	AVG delta	AVG deviation	Max delta	Max deviation	AVG delta	AVG deviation	Max delta	Max deviation	AVG delta	AVG deviation	Max delta	Max deviation
Low; (400–600)	24	12%	80	32%	15	7%	37	24%	38	17%	78	40%
Medium (2500–6000)	473	20%	1169	68%	54	2%	183	6%	229	16%	750	35%
High (9000–12000)	712	13%	2840	39%	361	10%	861	55%	390	9%	706	18%