Disclosed is a method of selectively predicting hydrocarbon concentration in a sample of unknown hydrocarbon concentration (the unknown sample). The method comprises the steps of: (i) separately subjecting two or more samples of known hydrocarbon concentration to infrared (IR) radiation; (ii) 5 separately detecting an IR signal from the samples of known hydrocarbon concentration; (iii) analysing the IR signals using a multivariate chemometric technique to produce a training data set; (iv) generating a predictive model for hydrocarbon concentration based on the training data set; (v) subjecting the unknown sample to infrared (IR) radiation; (vi) detecting an IR signal from the unknown sample; (vii) applying the predictive model to the IR signal from the unknown sample; and thereafter (viii) selectively 10 predicting hydrocarbon concentration in the unknown sample. Also disclosed is a method for generating a model to selectively predict hydrocarbon concentration in a sample of unknown hydrocarbon concentration and a software program for selectively predicting hydrocarbon concentration from inputted IR signal data of an unknown sample. TPH(c1O-c14) (mg/kg) T PH(c15-c28) (mg/kg) 10 ~ ---- H(c10-C14I, OTPH(c15-c2B) 8 (k(mg/kg) 0 z 10 50 100 200 500 1000 1500 TPH (ppm) TPH (ppm) TPH(c29-c36) (mg/kg) Total THC - 0 TPH(c29-36) oTotal THC 12 __(mg/kg) 12 z 8 2 f 0 UL 0 0 0 0 0 00 U y- 0 0 0 NP H\(pNmN (' Nt LTJ-D TPH (ppm) TPH (ppm) Figure 1(a)
Method of contaminant prediction