摘  要:本實驗通過將水泥與氯化銨混勻，用濃鹽酸及濃硝酸溶樣，制取水泥試液。以六次甲基四胺-銅試劑-過硫酸銨作為分離劑，加入分離劑前，滴加適量的NH3H2O和HCl。用甲基橙顏色變化來確定沉淀pH，同時把Fe、Al、Mn、Ti、Cr、Cu等離子分離除去。分別以GBHA（乙二醛縮雙鄰氨基酚）、鉻黑T為鈣鎂的指示劑，在pH=12.6的氫氧化鈉-硼砂和pH=10的氨水-氯化銨緩沖條件下，EDTA容量法連續滴定，由于Fe3+、Al3+、Cu2+、Ni2+等離子封閉鉻黑T，故在滴定鎂時殘留的痕量金屬離子用三乙醇胺掩蔽，另外該方法移取待測溶液后加入抗壞血酸穩定pH，經本方法脫鐵鋁鈦除錳的滴定終點易觀察，得到了滿意的滴定效果，適合多種金屬離子存在的試液中鈣鎂的測定。

　　　該法氧化鈣的質量分數為59.30%，RSD為0.04%，氧化鎂的質量分數為2.75%，RSD為1.08%，將分離劑改為尿素、氨水沉淀分離后，在相同條件下，同樣用EDTA滴定，三種方法的測定結果為：氧化鈣的質量分數分別為57.07%、58.78%，RSD分別為0.13%、0.06%；氧化鎂的質量分數分別為3.09%、2.97%，RSD分別為1.29%、1.37%。將滴定結果分析對比發現：三種方法中本法的滴定突變明顯，六次甲基四胺、銅試劑聯合沉淀法分離操作，可以讓測定的干擾元素少，所測得的結果更接近標準值。

關鍵詞:六次甲基四胺；銅試劑；過硫酸銨；沉淀；對比

ABSTRACT:This experiment passed to mixing cement and ammonium chloride,dissolved samples with strong hydrochloric acid and strong nitric acid,maked cement test solution.Hexamethylene Tetramine and DDTC and (NH4)2S2O8 was as separating agent,before joined separating agent,afterwards dropwise added an appropriate amount of NH3H2O and HCl.Determine the precipitation pH with methyl red color changes,at the same time,Al,Fe,Mn,Ti,Cu ecs was separated and removed.To GBHA or Chromium Black T as the indicator of calcium and magnesium.In pH=12.60 NaOH–borax and pH=10 NH3H2O-NH4Cl buffer conditions,EDTA capacity method continuously titrated the liquor.Because Fe3+,Al3+,Cu2+,Ni2+ esc closed Chromium Black T,so when titrated the magnesium,the residual trace metal ions sheltered by triethanolamine .In addition,after removed liquor in this method,joined ascorbic acid to steadying pH.Iron and aluminum and titanium and manganese took off by this method,titration end was easily observed,the titration effect satisfied.It suitabled for the determination of calcium magnesium when various metal ions exists in the test solution.

　　　By using the methods,quality score of the CaO was 59.30%.RSD was 0.04%.Quality score of the MgO was 2.75%,RSD was 1.08%.Taked the precipitator instead Carbamide or NH3H2O,after precipitation and separated.Under the same conditions,also with EDTA titration,determination result.Quality score of CaO was respectively 57.07%,58.78%.RSD was respectively 0.13%,0.06%.Quality score of MgO was respectively 3.09%,2.97%.RSD was respectively 1.29%,1.37%.Analysed and contrasting the titration results,in three methods,titration mutations of the method was more obvious,separated operation by Hexamethylene Tetramine and DDTC joint precipitation,couled let the determination of the interference element less.The measured results more close to standard values.

Key words:Hexamethylene Tetramine;DDTC;(NH4)2S2O8;precipitate;comparison