Highly sensitive detection of melamine and its derivatives by capillary electrophoresis coupled with online preconcentration techniques

Abstract

Two kinds of online preconcentration techniques including large-volume sample stacking-sweeping and selective-exhaustive injection-sweeping (SEI-S) were employed in CE to develop a rapid, simple and sensitive method for determination of melamine (MM) and its derivatives such as ammeline (AMN), ammelide (AMD) and cyanuric acid (CA) in liquid milk products. Though the sensitivity of large-volume sample stacking-sweeping is not particularly high, it can be used to detect all the four compounds simultaneously. However, it is very difficult to improve the sensitivity of these four compounds by using single SEI-S method directly, owing to their completely different extents of protonation or deprotonation. Grouping can solve this problem perfectly. After the four compounds are divided into two groups (MM/AMN and AMD/CA), cation-SEI-S or anion-SEI-S can be applied for their online stacking. In cation-SEI-S, the detection limits for MM and AMN were both 0.01 ng/mL based on the signal-to-noise ratio of 3. In anion-SEI-S, the detection limits were 0.05 and 0.02 ng/mL for CA and AMD, respectively. Results of this study show a great potential for the SEI-S method to be a useful tool for the rapid and sensitive determination of MM and its derivatives in liquid milk products.

Rapid determination of melamine in milk using water-soluble CdTe quantum dots as fluorescence probes

“…In addition, no melamine could be found in some kinds of brand milk available locally such as Mengniu, Yili, Guangming and Guangze, indicating that the proposed fluorescence sensing has promising feasibility for rapid detection of melamine in milk. Compared with the existing methods, seen from Table 2, the detection limit of the proposed method was a little higher than that of conventional methods such as GC-MS/MS (Miao et al 2010) or capillary electrophoresis (Jin et al 2010;Wen et al 2010), but it is lower than some sensors, for instance, the colorimetric analysis based on Au NPs and Ag NPs Li et al 2010;Balabin and Smirnov 2011). The detection limit for melamine analysis in raw milk is 0.04 mg L À1 , which is well below the safety limit (2.5 ppm in China, United States and EU for adult foods; 1.0 ppm for infant formula in United States and China) of melamine ingestion.…”

“…Common methodologies used for melamine detection are mainly based on highperformance liquid chromatography (HPLC) , LC-mass spectrometry (MS) (Braekevelt et al 2011;Goscinny et al 2011), gas chromatography (GC)-MS (Miao et al 2010), enzyme-linked immunosorbent assay (ELISA) ) and capillary electrophoresis (Jin et al 2010;Wen et al 2010). Although the above methods are generally very sensitive and accurate, they are not suitable for routine analysis because of such drawbacks as expensive equipment, complicated and time-consuming procedures for sample pre-treatment, specific skills for operation.…”

Single-Run Separation of Closely Related Cationic and Anionic Compounds by CE-ESI-MS: Application to the Simultaneous Analysis of Melamine and its Analogs in Milk

“…[21][22][23][24] CE methods were also developed to analyze MEL with UV or MS detection. [25][26][27][28][29][30][31][32][33][34] Capillary electrophoresis (CE) is a powerful separation technique for polar compounds with several advantages including high separation efficiency, low sample and solvent consumption, short analysis time, and simple instrumentation. UV-vis spectrophotometry is probably the most widely used detection technique due to the simplicity of the on-line configuration.…”

Efficient sample clean‐up and online preconcentration for sensitive determination of melamine in milk samples by capillary electrophoresis with contactless conductivity detection

“…Up to now, some analytical methods have been developed for the determination of MEL, including HPLC with optical detectors or coupled with MS and MS/MS , GC–MS , low‐temperature plasma combined with MS/MS , flow injection analysis with chemiluminescence , and screening methods (NMR spectroscopy, IR spectroscopy, and ELISA) are also considered as potential solutions for fast analysis with the drawback of being only qualitative . Several CE methods had been also described for assaying MEL in milk samples . However, the big problem that existed in the milk assay was the very complex matrix, because milk samples are constituted of complicated matrices and MEL exists in low concentration.…”