The application of solar ultraviolet radiation as sample pretreatment or preparation step in stripping voltammetric analysis of trace metals in presence of low levels of dissolved organic carbon (DOC) natural water samples (river water) was studied. River water samples were collected from downstream of Warnow river (Germany) and acidified to pH of (by addition of 1？mL of ultrapure 65% HNO3 per liter sample). Furthermore, 100？μL/L of hydrogen peroxide solution (ultrapure, 30% H2O2) was added to the samples as photochemical reaction initiator. The samples were transferred to polyethylene terephthalate (PET) bottles and irradiated with solar radiation of UV-A intensity of 3.6？mW/m2 for six hours, and the concentrations of Zn, Cd, Pb, and Cu were determined by differential pulse anodic stripping voltammetry (DPASV). The comparison of the values with the results obtained for the original untreated sample and artificial UV-treated one proved that solar UV radiation can be applied to the digestion of dissolved organic carbon in trace metal analysis in natural waters like river water, lake waters, well waters, and so forth. 1. Introduction The determination of the concentration of trace elements requires homogeneous samples which are free of organic matter that might interact with the electrode materials by adsorbing to the electrode and reducing the active surface area of the electrode. It also complexes with the metals ions, can increase background current or shift the peak potential disturbing the signal and making the determination impossible [1]. The determination of the metal ions by adsorptive stripping voltammetric (AdSV) method is applied for metal ions that do not form amalgams with mercury and in the absence of dissolved organic matter (DOM) that interacts with the electrodes or the metal ions. Methods like wet digestion and dry ashing have been introduced long ago in the mineralization of organic matter for both liquid and solid samples. Application of these methods is associated with high risk of contamination of the sample due to the addition of different acidic agents like mineral acid, bisulfate ions, and others. To avoid the problem of contamination of the samples, an alternative clean and efficient method of sample treatment by UV irradiation has been developed long ago [2, 3]. The method is considered environmentally friendly, effective and minimizes the risks of contamination or loss of sample through evaporation [3]. Commercially, there are several UV sources designed for general and specific purposes to be used in science laboratories,
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