DETERMINATION OF ALKALINE-PHOSPHATASE ACTIVITY IN HUMAN SERA BY MID-FTIR SPECTROSCOPY

Fourier transform infrared spectroscopy is applied to the determinatio n of alkaline phosphatase (ALP) activity in human sera. 4-nitrophenylp hosphate was found to be an excellent ALP substrate for FT-IR spectros copic detection. The developed method is based on the acquisition of t wo FT-IR spectra: one recorded immediately after mixing the sample and assay solution and the other after an incubation time of 10 min. Spec tral changes in the mid IR range due to the enzymatic reaction could b e correlated to the ALP activity in the sample. Experimental condition s were established such that the clinically relevant range for determi nation of ALP activity in human sera (50 to 900 U/L) was covered. The method was applied to the analysis of ALP activities in standard solut ions as well as in human sera yielding results which agreed well with those obtained by a standard reference method.