Analysis of turbid solutions by laser-induced photoacoustic spectroscopy

Photoacoustic immunoassay using sensitivity size dependency for determination of turbid solutions

“…The selection of analytical wavelengths becomes more and more important in the case of overdetermined systems. One criterion for wavelength selection is the selectivity (4,5).…”

“…Junker and Bergmann use distension and sensitivity as criteria for wavelength selection (9). Other authors describe the use of selectivity and related criteria for evaluating analytical procedures (5,7,8).…”

“…This method is quite sensitive for optical absorption and has been applied to trace analysis in parts-per-trillion (pg/mL) to sub-part-per-trillion levels (3,4). Trace analysis with PAS can be applied not only to true solutions but to turbid and colloidal solutions which are light scattering materials (5,6). Oda et al (5) have shown the sensitivity of PAS, that is the slope of the calibration curve, is independent of particle size, because the PA signal magnitude is proportional to the optical energy absorbed by the solution and is not affected by light scattering.…”

“…Trace analysis with PAS can be applied not only to true solutions but to turbid and colloidal solutions which are light scattering materials (5,6). Oda et al (5) have shown the sensitivity of PAS, that is the slope of the calibration curve, is independent of particle size, because the PA signal magnitude is proportional to the optical energy absorbed by the solution and is not affected by light scattering. They showed that two calibration curves for a precipitated BaS04 mixture of 6-20 and 0.5-6 jim particles overlapped each other when the 514.5-nm lasing line of an Ar laser was used for the excitation beam.…”

Laser Induced Photoacoustic Spectroscopy Applied to a Study on Colloid Formation Processes

“…Sawada et al [6,7] reported the detection of ppb order of Te and BaS0 4 colloids. Kim et al [5] observed the occurrence of plutonium hydroxides colloids from a change of intensity in photoacoustic signals in aqueous solution.…”