Table 5: Accuracy of TPH determination by reflectance spectroscopy and three commercial laboratories.

LabSpectroscopyABC
TPH level (calculated)AVG
delta
AVG deviationMax
delta
Max deviationAVG
delta
AVG deviationMax
delta
Max deviationAVG
delta
AVG deviationMax
delta
Max deviationAVG
delta
AVG deviationMax deltaMax deviation

Low (400–600)32568%747143%34968%50093%19242%35684%28357%50897%
Medium (2500–6000)205547%436074%195651%279592%101030%253278%259060%478197%
High
(9000–12000)
618761%1149483%439249%615081%182726%421073%441350%585995%