两步洗脱法FIA-FAAS测定水样中的锌

Two Steps Elution Method FI On-Line Adsorption and Preconcentration Coupled with FAAS for the Determination of Trace Zinc

建立了流动注射(FI)在线预富集与火焰原子吸收光谱(FAAS)联用测定水样中痕量锌的两步洗脱新方法。将洗脱和检测分成2个步骤进行。洗脱过程中,洗脱剂不经过蠕动泵管而是依靠蠕动泵的吸力通过聚四氟乙烯管(PTFE tube)进入编结反应器(KR),然后送入FAAS进行检测,大大延长了蠕动泵管的使用寿命。同时,洗脱过程依靠蠕动泵的吸力而不是推力实现洗脱剂的输送,明显降低了被分析物在洗脱过程中的分散,提高了原子吸收信号峰值(A)和浓集系数(EF)。增加了样品溶液排空步骤,保证了每次实验的准确性和重复性。进样流速6.0mL.min-1;进样时间60s,测定20μg.L-1的锌,EF由传统方法的9提高到28;检出限为0.35μg.L-1;测样频率为37.h-1;相对标准偏差(RSD,n=11)为2.1%。以0.1‰φ的三乙醇胺为掩蔽剂,在水样中的回收率为98.7%～99.6%。

A flow injection two steps elution method on-line sorption and preconcentration system coupled to flame atomic ab-sorption spectrometry（FAAS）was developed for the determination of trace Zn in water samples.The conventional elution pro-cedure was divided into two steps：elution procedure and detection procedure.During the elution procedure,the eluent waspumped into KR by the suction of the peristaltic pump and through PTFE tube instead of peristaltic pump tube.By the newmethod,the dispersion of the analyte was decreased notably,and high absorbance peak value was achieved.Because the eluentwas not through the peristaltic pump tube,the peristaltic pump tube was protected from being eroded.Emptying procedure wasadded in order to insure the veracity and repeatability of the experiment of every time.With 60s（sample throughput of 37.h-1）of sampling at a flow rate of 6.0mL.min-1,an enhancement factor（EF）of 28（higher than 9achieved by conventional e-lution method）and a detection limit（3σ）of 0.35μg.L-1 were obtained.The precision（RSD,n=11）was 2.1%at the 20μg.L-1 level.When 0.1‰φtriethannolamine was used as masking reagent,the recovery rate was from 98.7%to 99.6%.