DETERMINATION OF ARSENIC AND SELENIUM BY HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROMETRY (FLOW-INJECTION OR CONTINUOUS-FLOW) METHOD COMBINED WITH A HYDRIDE COLLECTING TRAP

A hydride collecting cold trap hydride generation AAS method has been developed using a flow injection (FI) or a continuous flow (CF) system , applicable to the high sensitivity determination of arsenic and sele nium, characterized by a detection limit of 10-20 pg/mL. The best rela tive detection limits and sensitivity for this system could be achieve d using the CF operation mode. Accuracy and reproducibility of the met hod were investigated by the analysis of dilute solutions produced by decomposition of international CRM samples of various types. The resul ts of the determinations agree well with the certified values. Reprodu cibility of the measurements is good considering especially the extrem e low initial concentrations. The remarkable feature of the method is the relatively low blank value which is partly due to the use of high purity acids and reagents, and partly to the very low risk of contamin ation when the work is done in a closed system. Further on, several wa ter samples were investigated by this method, the arsenic and selenium content of which could not be determined previously. Also numerous fo od samples having low content of As and Se were analyzed.