The Applications Of Dispersive Liquid-Liquid Microextraction On The High Performance Liquid Chromatographic Method

With the progress of society, higher requirements put forward to modern analytical techniques. It not only needs analytical techniques and analytical instruments have high sensitivity, low detection limit and good accuracy and so on, but also put forward the new demands to sample pre-treatment. Development of High-performence, fast, low cost and environmental friendly sample preparation techniques has become one of the most popular topics of modern analytical chemistry.Dispersed liquid-liquid micro-extraction (DLLME) is a new sample pre-treatment technique base on distributed, first reported in 2006 by Assadi and co-workers. Only a small amount of solvent, just about little microlitre, is needed in concentrating analytes from aqueous samples. The mixture of extraction solvent and disperser solvent were injected into the sample solution by syringe, rapidly. Then the solution was centrifuged and the organic phase was aspirated into a microsyringe and injected into the HPLC system for analysis. The method is sensitive, simple, rapid, and has been used widely.In this paper, the sample pre-treatment technology dispersed liquid-liquid micro-extraction (DLLME) is coupled with high-performance liquid chromatography-fluorescence detection and was used for the extraction and determination of biogenic amines in real samples. The main content is listed as follows:1. Ultrasound-assisted dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography-fluorescence detection was developed for the extraction and determination of three biogenic amines including octopamine, tyramine and phenethylamine in rice wine samples. Fluorescence probe 2,6-dimethyl-4-quinolinecarboxylic acid N-hydroxysuccinimide ester (DMQC-OSu) was applied for derivatization of biogenic amines. The LODs of biogenic amines were in the range of 5-0.02 ng mL-1. The intra-day precisions ranged from 2.4 to 3.2% and the inter-day precisions ranged from 3.2 to 5.5%. The proposed method was applied for the determination of biogenic amines in rice wine samples. The recoveries of the three amines ranged from 95.42 to 104.56% showed that the method was sufficiently applicable to determine biogenic amines in real samples. Therefore, it had the potential of practical applications and could be either a complementary or a parallel method for the biogenic amines determination.2. Room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (C4MIMPF6) was used as extraction solvent, coupled with ultrasound-assisted dispersive liquid-liquid microextraction (UDLLME) for the extraction of three biogenic amines (octopamine, tyramine and phenethylamine). Fluorescence probe 2,6-dimethyl-4-quinolinecarboxylic acid N-hydroxysuccinimide ester (DMQC-OSu) was applied for derivatization of biogenic amines. The limits of detection ranged from 0.0025 to 5 ng mL"1 (S/N= 3). The recoveries ranged from 90.2 to 116%. The method was applied for the determination of biogenic amines in beer samples with satisfactory results. The use of ionic liquid involved some advantages such as the reduction of exposure to toxic solvent. Because of the negligible vapor pressure and good solubility for organic and inorganic compounds of the ionic liquids, the proposed method was environmentally friendly.