Journal of the Brazilian Chemical Society
Print version ISSN 0103-5053
DIAS, Tuanne R. and REIS, Boaventura F.. A LED based photometer for solid phase photometry: zinc determination in pharmaceutical preparation employing a multicommuted flow analysis approach. J. Braz. Chem. Soc. [online]. 2012, vol.23, n.8, pp. 1515-1522. Epub Aug 09, 2012. ISSN 0103-5053. http://dx.doi.org/10.1590/S0103-50532012005000014.
In this work, a LED (light emitting diode) based photometer for solid phase photometry is described. The photometer was designed to permit direct coupling of a light source (LED) and a photodiode to a flow cell with an optical pathlength of 4 mm. The flow cell was filled with adsorbing solid phase material (C18), which was used to immobilize the chromogenic reagent 1-(2-thiazolylazo)-2-naphthol (TAN). Aiming to allow accuracy assessment, samples were also analyzed employing ICP OES (inductively coupled plasma optical emission spectrometry) methodology. Applying the paired t-test at the 95% confidence level, no significant difference was observed. Other useful features were also achieved: linear response ranging from 0.05 to 0.85 mg L-1 Zn, limit of detection of 9 µg L-1 Zn (3σ criterion), standard deviation of 1.4% (n = 10), sampling throughput of 36 determinations per h, and a waste generation and reagent consumption of 1.7 mL and of 0.03 µg per determination, respectively.
Keywords : flow injection analysis; multicommuted flow analysis; solid phase spectrophotometry; LED based photometer; pharmaceutical formulation; green chemistry.