Li Yan, Jiang Yan, Yan Xiu-Ping
State Key Laboratory of Functional Polymer Materials for Adsorption and Separation, and Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin 300071, China.
Talanta. 2004 Oct 20;64(3):758-65. doi: 10.1016/j.talanta.2004.03.045.
A further study on a newly developed flow injection (FI) on-line multiplexed sorption preconcentration (MSP) using a knotted reactor coupled with flame atomic absorption spectrometry (FAAS) was carried out to demonstrate its applicability and limitation for trace element determination. For this purpose, Cr(VI), Cu(II), Ni(II) and Co(II) were selected as the analytes, and detailed comparison was made between the MSP-FAAS and conventional FI on-line sorption preconcentration FAAS in respect to retention efficiency and linear ranges of absorbance versus sample loading flow rate and total preconcentration time. Introduction of an air-flow for removal of the residual solution in the KR after each sub-injection in the MSP procedure played a decisive role in the improvement of retention efficiency. The linearity of absorbance versus sample loading flow rate or total preconcentration time was extended to a more degree for the metal ions with less stability of their PDC (pyrrolidine dithiocarbamate) complexes than those with more stable PDC complexes. It seems that the MSP procedure behaves advantages beyond the inflection points in the diagrams of absorbance versus total preconcentration time and sample loading flow rate obtained by conventional (a single continuous) preconcentration procedure. With a sample loading flow rate of 6.0mlmin(-1) and a total preconcentration time of 180s, the retention efficiencies were increased from 25, 46, 41 and 63% with a single continuous sorption preconcentration to 44, 78, 65 and 75% with a six sub-injection preconcentration procedure for Cr(VI), Co(II), Ni(II), and Cu(II), respectively. The detection limits were 0.40, 0.33, 0.31 and 0.26mugl(-1) for Cr(VI), Co(II), Ni(II), and Cu(II), respectively. The precision (R.S.D.) for eleven replicate determination of 2mugl(-1) Cr(VI), Co(II) and Ni(II), and 1mugl(-1) Cu(II), was 2.1, 4.1, 2.6 and 1.7%, respectively.
开展了一项进一步的研究，该研究使用打结反应器与火焰原子吸收光谱法（FAAS）联用，对新开发的流动注射（FI）在线多重吸附预富集（MSP）进行研究，以证明其在痕量元素测定中的适用性和局限性。为此，选择Cr(VI)、Cu(II)、Ni(II)和Co(II)作为分析物，并就保留效率以及吸光度相对于进样流速和总预富集时间的线性范围，对MSP-FAAS和传统的FI在线吸附预富集FAAS进行了详细比较。在MSP程序中每次子进样后引入气流以去除打结反应器中的残留溶液，这对保留效率的提高起到了决定性作用。对于吡咯烷二硫代氨基甲酸盐（PDC）配合物稳定性较低的金属离子，吸光度相对于进样流速或总预富集时间的线性范围比PDC配合物稳定性较高的金属离子有更大程度的扩展。在通过传统（单一连续）预富集程序获得的吸光度相对于总预富集时间和进样流速的图表中，MSP程序似乎在拐点之外表现出优势。进样流速为6.0mlmin(-1)且总预富集时间为180s时，对于Cr(VI)、Co(II)、Ni(II)和Cu(II)，通过单次连续吸附预富集的保留效率分别为25%、46%、41%和63%，而通过六次子进样预富集程序的保留效率分别提高到44%、78%、65%和75%。Cr(VI)、Co(II)、Ni(II)和Cu(II)的检测限分别为0.40、0.33、0.31和0.26mugl(-1)。对2mugl(-1)的Cr(VI)、Co(II)和Ni(II)以及1mugl(-1)的Cu(II)进行十一次重复测定的精密度（相对标准偏差）分别为2.1%、4.1%、2.6%和1.7%。
