Study On The Sensitive Determination Of Low-molecule Aliphatic Aldehydes By Non-chip Miniature Electrophoresis With Amperometric Detection

1. PrefaceCapillary electrophoresis (CE), as one of the new analytical techniques after liquid chromatography, has been widely developed and used in many fields such as Pharmaceuticals, food analysis, biological analysis, etc. This chapter introduces the principles and instrumentation of capillary electrophoresis, the applications and principles of sample enrichment technologies in capillary electrophoresis, as well as the research progresses in the field of low molecule aldehydes determination In this paper, on the basis of their predecessors, we use 2-thiobarbituric acid as the derivative reagent, to react with originally non-electroactive aldehydes to make them become electrically active adducts, combined with sample preconcentration method and miniature capillary electrophoresis system to accelerate the separation speed while further improving the detection sensitivity, thus achieving the goal of sensitive electrochemical detection of low-molecule aliphatic aldehydes.2. Fast determination of aldehyde preservatives by transient moving chemical reaction boundary on-line enrichment/miniature capillary electrophoresis with amperometric detectionA novel miniature CE with amperometric detection (mini-CE-AD) method has been developed for fast determination of aliphatic aldehyde preservatives, namely formaldehyde and glyoxal, in commodities. After derivatization with an electroactive compound 2-thiobarbituric acid, these two non-electroactive aldehydes were converted to electroactive adducts, therefore detectable by mini-CE-AD approach. Under the optimum conditions, two aldehydes can be well separated with the coexisting interferents as well as their homologs (acetaldehyde and methyl-glyoxal), and the limits of detection (S/N=3) were achieved at nanogram-per-milliliter level (1.64-2.80 ng/mL) based on the online enrichment method of transient moving chemical reaction boundary. The proposed method has been applied to the analyses of above aldehyde preservatives in different real commodity samples including skin-care products, baby lotion and toothpaste, and the average recoveries were in the range of 94%-105%, which should find a wide range of analytical applications as an alternative to conventional and microchip CE approaches.3. Miniature capillary electrophoresis coupled with hollow-fiber liquid-phase microextraction for trace analysis of water disinfection by-productsAn environment-friendly method for the trace analysis of four disinfection by-products (DPBs) in water samples has been developed based on hollow-fiber liquid-phase microextraction followed by miniature capillary electrophoresis with amperometric detection (HF-LPME/mini-CE-AD). After derivatization with 2-thiobarbituric acid, four DPBs (formaldehyde, acetaldehyde, propylaldehyde and butyraldehyde) became detectable by mini-CE-AD. Under the optimum conditions, four DPBs can be well separated from the coexisting interferents as well as their homologs (pentanal, glyoxal and methyl- glyoxal), and the limits of detection were in the range of 0.24-1.12 ng/mL (S/N=3) which could reach sub-nanogram-per-milliliter level based on HF-LPME approach. The proposed method has been applied for the analyses of above four DPBs in different water samples such as drinking water, tap water, and river water, and the average recoveries were in the range of 90%-113%, providing an alternative to conventional and microchip CE approaches.