COMPARATIVE-STUDY OF SEVERAL NEBULIZERS IN INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY - LOW-PRESSURE VERSUS HIGH-PRESSURE NEBULIZATION

Five nebulizers for use in ICP-AES were compared, Two of them work at low pressure, a Meinhard and a V-groove nebulizer (VGN), and three at high pressure, a single-bore high-pressure pneumatic nebulizer (SBHPPN ), a hydraulic high-pressure nebulizer and a thermospray (TN), The com parison was made using three solvents, water, ethanol and butan-1-ol, using the sample uptake rate (Q(1)) as a variable and studying its inf luence on drop size distribution, analyte transport rate and analytica l behaviour, i.e., emission intensity and limits of detection (LODs), The sample introduction system includes a desolvation unit, The Sauter mean diameters of the primary aerosols generated by the high-pressure nebulizers (HPNs) are between 1.5 and 5.8 times lower than those gene rated by the low-pressure nebulizers (LPNs), this reduction being more noticeable at high liquid how rates, In addition, at high liquid flow rates, HPNs achieve higher analyte transport rates (between 2.4 and 1 9 times higher), higher emission signals (up to 1.8 times for methanol and up to 4.5 times for water, using the Mn II 257.610 nm line) and l ower LODs for nine elements than the LPNs, Among HPNs, the SBHPPN give s rise to the best results at low Q(1) (i.e., 0.6 mi min(-1)), whereas at high Q(1) (i.e., 1.2 mi min(-1)) the results are similar for all t hree HPNs when using methanol and butan-1-ol. With water, at high Q(1) , the TN gives the best results, For all the nebulizers tested, organi c solvents (methanol and butan-1-ol) provide better results than water , the relative improvement being more important for LPNs (e.g., with V GN at 1.2 mi min(-1), the improvement with methanol over water for Mn II is around sixfold) than for HPNs (e.g., when SBHPPN is used at 1.2 mi min(-1) for Mn II this improvement is 4.5-fold).