分光光度法连续测定土壤中铁和钛的研究

Continuous Determination of Iron and Titanium in Soil by Spectrophotometry

[目的]研究分光光度法连续测定土壤中铁和钛的方法,探讨该方法的最佳条件。[方法]在铁、钛标准溶液中加入铁钛试剂,稀氨水滴定pH值,静置显色,在340～800 nm处进行光谱扫描,确定连续测定铁和钛含量的试验参数。并在试验确定参数条件下进行土壤样品分析。[结果]结果表明,以钛铁试剂为显色剂,可在同一份土壤样品中于560 nm处测定铁、于380 nm处测定钛,实现了在同一土壤消解体系中连续测定铁和钛含量的目的,铁含量在0～4 mg/L范围内服从比尔定律,线性回归方程为-y=0.070 9 x,相关系数r=0.999 3,表观摩尔吸光系数5κ60=4.24×104L/(mol.cm);钛含量在0～0.3mg/L范围内服从比尔定律,线性回归方程为-y=0.2905x,相关系数r=0.998 6,表观摩尔吸光系数3κ80=1.46×104 L/(mol.cm)。[结论]该方法简便,选择性好,灵敏度高。用于土壤中铁和钛的测定,结果与常规方法分析结果相符;样品标准加入回收率分别为91.4%～109.1%和91.0%～103.8%,相对标准偏差分别为0.58%～0.70%和1.10%～1.80%(n=6)。

[Objective] A new method for continuous determination of iron and titanium in soil by spectrophotometry was studied,and the optimal conditions of the method were investigated.[Method] Iron and titanium reagents were added into the standard solutions of iron and titanium.spectral scanning was carried out at 340-800 nm to determine test parameters of iron and titanium contents after titration by dilute ammonia solution to be colored.Soil sample was analyzed under the condition of test determined parameters.[Result] The results showed that using tiron as chromogenic reagent,the amount of Fe could be determined at 560 nm and the amount of Ti could be determined at 380 nm in a same soil sample.Continuous determination of iron and titanium in a system of soil digestion was realized.Beer＇s law was obeyed in the range of 0-4 mg/L for iron（Ⅲ）,the linear regression equation was y=0.070 9 x with correlation coefficient being 0.999 3,and the apparent molor absorption coefficient was 4.24×10^4 L/（mol·cm） Beer＇s law was obeyed in the range of 0-0.3 mg/L for titanium（Ⅳ）,the linear regression equation was y = 0.290 5 x with correlation coefficient being 0.998 6,and the apparent molor absorption coefficient was 1.46×10^4 L/（mol·cm）.[Conclusion] This method was simple,sensitive and had good selectivity.It could be used for the determination of iron and titanium in soil,and the results obtained accorded with those by routine methods.The recovery rate was 91.4%-109.1% and 91.0%-103.8%,the RSD was 0.58%-0.70% and 1.10%-1.80%（n=6）.