铅溶液中钾检测方案(ICP-AES)

ICP ATOMIC EMISSION SPECTROSCOPYAPPLICATION NOTE 21 HORIBAExplore the futureAutomotive Test Systemss 1Process & Environmental IMedicalSemiconductorI1 Scientific Samples containing 10 g/L of Pb were presentedto this laboratory for trace determination.Concentrations of the analytes were expected tobe less than 100 ppm. This Application Notepresents a selection of the best wavelengths foreach analyte in this matrix as well as an estima-tion of the detection limits. 2 Principle 2.1 Technique used The elemental analysis of these samples wasundertaken by Inductively Coupled PlasmaAtomic Emission Spectrometry (ICP-AES)..Thesample is nebulized then transferred to anargon plasma. It is decomposed， atomized andionized whereby the atoms and ions are excited.We measure the intensity of the light emittedwhen the atoms or ions return to lower levels ofenergy. Each element emits light at characteris-tic wavelengths and these lines can be used forquantitative analysis after a calibration. 2.2 Wavelength choice The choice of the wavelength in a given matrixcan be made using the "profile" function， or byusing Win-IMAGE， which is rapid semi-quantita-tive analysis mode using multiple wavelengths.The principle is the same in either case： recordthe scans of analytes at low concentration， andof the matrix. By superimposing the spectra， wesee possible interferences. 2.3 Limits of detection estimation The limits of detection are calculated using thefollowing formula： With： LOD = limits of detection， k=3 for the normal 3-sigma values， BEC= Background equivalent concentration， RSDo= relative standard deviation of the blank. To calculate the LOD， a calibration curve is con-structed using two points，0 ppm and 5 ppm， orsome concentration where the calibration is lin-ear；this gives the BEC. The RSDo is evaluatedby running the blank ten times. 3 Sample preparation 10 g of pure Pb was dissolved with 40 mL of50% HNO3 and diluted to 1000 mL with 1 %HNO3. 4. Instrument specification The work was done on a ULTIMA.The specifica-tions of this instrument are listed Table 1 and 2. Table 2： Specification of spectrometer Parameters Specifications Mounting Czerny Turner Focal length 1m Nitrogen purge Yes Variable resolution Yes Grating number of grooves 2400 gr/mm Order 2nd order Table 3： Specification of RF Generator Parameters Specifications Type of generator Solid state Observation Radial Frequency 40.68 MHz Control of gas flowrate by computer Control of pump flow by computer Cooling air 5 Operating conditions The operating conditions are listed in Table 3below. Table 3： Operating conditions Parameter Condition RF Generator power 1050 W Plasma gas flowrate 12 L/min Auxiliary gas flowrate 0 L/min Sheath gas flowrate 0.15 L/min Nebulizer gas flowrate 0.8 L/min Nebulizer flowrate 3 bars (45 psi) Sample uptake 1 mL/min Type of nebulizer Concentric Type of spray chamber Cyclonic Argon humidifier Yes Injector tube diameter 3.0 mm For each element， the line with the highest sensi-tivity was used for analysis， because there were noproblems with interferences. For all the elementsthe conditions were the same except for alkalineelements. Table 4： Analytical conditions Element Slits Analysis Integration (um) mode time (sec) Minor elements 20 x 15 Direct peaking 8 Major elements 20x80 Gaussian 0.5 The use of the argon humidifier， the large internaldiameter (ID) of the injector tube enabled troublefree analysis， even with high dissolved salts. Thelarger ID injector tube also ensures a minimizationof interferences. Due to the high dissolved salts，an initial conditioning of the spray chamber isadvisable for maximum stability. It is imperative touse matched standards or standards additions dueto the viscosity of the solutions. 7 Limis of detection The limits of detection have been calculated usingthe formula in paragraph 2.3. Table 5： Limits of detection Element Wavelength (nm) BEC (mg/L) LOD (mg/kg) Ag 328.068 0.042 0.10 AI 167.020 0.04 0.35 Al 396.520 0.12 0.36 As 189.042 0.26 0.78 Au 267.795 0.029 0.087 Ba 455.403 0.0024 0.007 Bi 223.061 0.22 0.30 Cd 228.802 0.014 0.04 Co 228.616 0.02 0.03 Cu 324.754 0.032 0.11 Fe 259.940 0.048 0.14 Hg 184.890 0.053 0.16 Hg 194.227 0.26 0.78 K 766.490 0.039 0.12 Ni 221.647 0.066 0.20 Pt 214.423 0.08 0.24 Pt 224.552 0.32 0.96 Pt 265.945 0.10 0.30 Pt 306.471 0.17 0.51 Sb 206.833 0.24 0.72 Se 196.090 0.553 1.6 Te 214.275 0.198 0.6 Te 238.578 0.75 2.25 TI 190.864 2.45 7 TI 276.787 0.53 2 TI 351.924 1.2 4 Sr 407.771 0.0015 0.005 Zn 202.548 0.050 0.15 8 Summary To achieve the lowest detection limits， dilution isundesirable. The results show the HORIBA spec-trometers are able to perform an excellent analy-sis， even with high dissolved solids. This enablesthe analysis to be performed to the best detectionlimits possible. Other Countries： Tel： +33 (0)1 64 54 13 00-Email： info.sci@horiba.com To achieve the lowest detection limits, dilution is undesirable. The results show the HORIBA spectrometers are able to perform an excellent analysis, even with high dissolved solids. This enables the analysis to be performed to the best detection limits possible.