A portable assessment kit for measuring metal content of an aqueous solution, the portable assessment kit comprising: - a sample container for containing a sample of the aqueous solution to be assessed, wherein the sample container comprises an opening at its first end for receiving the sample; - a disc holder (106, 302) having a first end (206, 306), and a second end (208, 308) opposite to the first end, wherein the first end of the disc holder is detachably attached to the opening of the sample container, wherein the disc holder comprises a first part having the first end, a second part and a third part; - a permeable pre-concentration disc for collecting metals, the pre-concentration disc having a first side, and a second side opposite to the first side, and being arrangeable in the disc holder, wherein the pre-concentration disc is arranged between the second part and the third part of the disc holder in a manner that the first side of the pre-concentration disc is facing the second part of the disc holder and the second side of the pre-concentration disc is facing the third part of the disc holder; - means for pumping the sample of the aqueous solution through the opening of the sample container to the first side of the pre-concentration disc and through the pre-concentration disc; and - measurement device for measuring amount of metals in the pre-concentration disc, the measurement device being arrangeable in connection with the disc holder in such a manner that the first side of the pre-concentration disc is facing the measurement device, wherein the second part of the disc holder is detached from the first part of the disc holder, and wherein the disc holder is detachably attached to a receiving portion of the measurement device using one of the second part of the disc holder or a combination of the second part and the third part of the disc holder. - a sample container for containing a sample of the aqueous solution to be assessed, wherein the sample container comprises an opening at its first end for receiving the sample; - a disc holder (106, 302) having a first end (206, 306), and a second end (208, 308) opposite to the first end, wherein the first end of the disc holder is detachably attached to the opening of the sample container, wherein the disc holder comprises a first part having the first end, a second part and a third part; - a permeable pre-concentration disc for collecting metals, the pre-concentration disc having a first side, and a second side opposite to the first side, and being arrangeable in the disc holder, wherein the pre-concentration disc is arranged between the second part and the third part of the disc holder in a manner that the first side of the pre-concentration disc is facing the second part of the disc holder and the second side of the pre-concentration disc is facing the third part of the disc holder; - means for pumping the sample of the aqueous solution through the opening of the sample container to the first side of the pre-concentration disc and through the pre-concentration disc; and - measurement device for measuring amount of metals in the pre-concentration disc, the measurement device being arrangeable in connection with the disc holder in such a manner that the first side of the pre-concentration disc is facing the measurement device, wherein the second part of the disc holder is detached from the first part of the disc holder, and wherein the disc holder is detachably attached to a receiving portion of the measurement device using one of the second part of the disc holder or a combination of the second part and the third part of the disc holder.