Estimation of the homogeneity of reference materials by SS-ETAAS and use of the "tape-sandwich" sample-introduction technique.
The so called "tape sandwich", a novel sample-introduction technique developed for SS-ETAAS, has been employed in a study of the microheterogeneity of some biological CRM. Pb, Cd, and Cr were measured by use of a laboratory-assembled instrument with graphite-cup atomizer. Aqueous standards were found satisfactory for calibration. The average mass of sub-samples atomised was in the range 0.250-0.660 mg+/-30%. The relative sampling error found for the CRM investigated varied from 15-34%. Calculated relative homogeneity constants of the order of 4-21 mg(1/2) were obtained, and were reduced considerably by reduction of the particle size. The minimum sample sizes representative of the CRM were, with one exception, much lower (11-75 mg) than those recommended in the documentation accompanying the standards (100-200 mg). In a Chinese hair reference sample Cr data were normally distributed but the presence of nuggets was observed for Cd and Pb; this was associated with severe radial and longitudinal gradients of these elements in hair.
Stupar
J
J
Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
Dolinsek
F
F
Koren
U
U
D002104:Cadmium; D002857:Chromium; D006197:Hair / Q000737:chemistry; D006801:Humans; D007854:Lead; D019216:Metals, Heavy / Q000032:analysis / Q000592:standards*; D008722:Methods; D009330:Nebulizers and Vaporizers; D018514:Plant Structures / Q000737:chemistry; D012015:Reference Standards
D019216:Metals, Heavy; D002104:Cadmium; D002857:Chromium; D007854:Lead