水泥中之總鉻與可抽出性六價鉻之定量分析

Determination of Total Chromium Content and Extractable Hexavalent Chromium Content in Cement

本項研究利用石墨爐原子吸收光譜法於357.9nm偵測總鉻與紫外光－可見光譜法於540nm偵測六價鉻，總鉻與六價鉻之偵測極限分別為0.28/μg/L與3.44/μg/L，相對標準偏差分別為2.01％與0.59％。在針對台灣六種廠牌水泥進行pH值、總鉻含量與可抽出性六價鉻含量測定，其pH值範圍為pH12.4～pH12.6，總鉻含量範圍為23.7～56.6μg/g，水可抽出性六價鉻含量範圍為2.7μg/g～32.9μg/g，但以水作為水泥可抽出性六價鉻之萃取劑，會受到基質效應之干擾而影響測定結果，以水萃取水泥之六價鉻添加回收率範圍為18.8％～65.4％，硫酸鈉可抽出性六價鉻含量範圍為5.8/μg/g～47.7μg/g，硫酸鈉溶液（1.42 M，pH 9.0）為一良好的水泥可抽出性六價鉻之萃取劑，以硫酸鈉溶液萃取水泥之六價鉻添加回收率範圍為87.4％～96.1％，總鉻含量與水可抽出性六價鉻含量或硫酸鈉可抽出性六價鉻無直接相關性存在。

The total chromium and hexavalent chromium were determined by graphite furnace atomic spectroscopy at 357.9 nm and UV-VIS spectroscopy at 540 nm. The detection limits were 0.28 μg/L for total chromium and 3.44μg/L for hexavalent chromium. The relative standard deviations for total chromium and hexavalent chromium were 2.01% and 0.59%, respectively. The pH values, total chromium, water extractable hexavalent chromium and sodium sulphate extractable hexavalent chromium of 6 different Taiwan cements were studied. The pH value ranged from pH12.4 to pH12.6. Total chromium content of the 6 brands of cements ranged from 23.7μg/g to 56.6μg/g. The water extractable hexavalent chromium ranged from 2.7μg/g to 32.9μg/g while the sodium sulphate extractable hexavalent chromium ranged from 5.8μg/g to 47.7μg/g. The recovery of hexavalent chromium with water as the extraction reagent ranged from 18.8% to 65.4%. Sodium sulphate is a good alternative to the use of water as an extraction reagent. The recovery of hexavalent chromium with sodium sulphate as the extraction reagent ranged from 87.4% to 96.1%. There is no direct correlation between total chromium and water soluble hexavalent chromium or between total chromium and sodium sulphate extractable hexavalent chromium found in cement.