Integration of Flow Injection Capillary Liquid Electrode Discharge Optical Emission Spectrometry and Microplasma-Induced Vapor Generation: A System for Detection of Ultratrace Hg and Cd in a Single Drop of Human Whole Blood

A simple and miniature analytical system was developed to determine Hg and Cd in small amounts of samples by integrating flow injection capillary liquid electrode discharge (CLED) optical emission spectrometry (OES) and microplasma-induced vapor generation (PIVG) atomic fluorescence spectrometry (AFS). With the assistance of the inherent capillary driving force and the force arising from the solution vaporization in the microplasma, the sample solution was automatically transported into the discharge chamber wherein analytes were simultaneously excited to generate their atomic emission lines and converted to their volatile species. Subsequently, the volatile species were further swept into AFS for their further determination. Therefore, the same sample could be successively analyzed by OES and AFS. Owing to the unique independent linear-range and sensitivity of CLED-OES and PIVG-AFS, the developed system not only significantly extended its linear range to 6 orders of magnitude but also remarkably reduced the sample consumption to several microliters. Thus, wide linear-range and ultrasensitive determination of Hg and Cd in limited amounts of samples were accomplished simply by sharing one single capillary liquid electrode discharge source. Under the optimized conditions, limits of detection (LODs) of 10 mu g L-1 were obtained for both Hg and Cd when CLED-OES was used as a detector, whereas the LODs for Hg and Cd were improved to 0.03 mu g L-1 and 0.04 mu g L-1 with AFS detector, respectively. In addition, the extremely wide linear-range of 0.001-100 mg L-1 and 0.001-40 mg L-1 were obtained for Hg and Cd, respectively. The potential application of this method was validated by successfully analyzing three Certified Reference Materials (ZK021-1, GBW(E)090033, and GBW(E)090034) and six human blood samples.