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A method for the determination of non-lactose oligosaccharides (NLO) in milk using liquid chromatography has been developed. Oligosaccharides were labelled with a fluorescent tag, 2-aminobenzamide (2AB), and were identified by comparison of their retention times to those of oligosaccharide standards, their mass (as measured by mass spectrometry) and their fragmentation patterns in the mass spectrometer. The concentrations of the NLO in milk have been determined using 2 different approaches: (1) by preparing a calibration curve using genuine standards of each oligosaccharide. (2) by preparing a calibration curve using maltotriose as a universal standard for all NLO, and assuming all 2AB labelled oligosaccharides give an equimolar response in the detector. The accuracy of the method was assessed by spike-recovery experiments. Using genuine NLO standards for calibration, recoveries were in the range 96–114%. Using maltotriose as a universal calibrant, recoveries were in the range 86–120%. Method precision was assessed by determining the relative standard deviation of the results under repeatability (RSD(r)) and intermediate reproducibility (RSD(iR)) conditions. In most cases RSD(r) and RSD(iR) were below 5% irrespective of calibration method, but increased when NLO levels were close to LoQ. [ABSTRACT FROM AUTHOR]

Abstract: A new kind of ultrabright fluorescent and chemiluminescent difunctional mesoporous silica nanoparticle (FCMSN) is reported. A luminescent dye, Rhodamine 6G or tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate (Rubpy), is doped inside nanochannels of a silica matrix. The hydrophobic groups in the silica matrix avoid the leakage of dye from open channels. The amines groups on the surface of the FCMSN improve the modification performance of the nanoparticle. Because the nanochannels are isolated by a network skeleton of silica, fluorescence quenching based on the inner filter effect of the fluorescent dyes immobilized in nanochannels is weakened effectively. The Quantum Yield of obtained 90nm silica particles was about 61%. Compared with the fluorescent core–shell nanoparticle, the chemiluminescence reagents can freely enter the nanoparticles to react with fluorescent dyes to create chemiluminescence. The results show that the FCMSN are both fluorescent labels and chemiluminescent labels. In biological applications, the NaIO4 oxidation method was proven to be superior to the glutaraldehyde method. The amount of amino could affect the specificity of the FCMSN. The fluorescence microscopy imaging demonstrated that the FCMSN is viable for biological applications. [Copyright &y& Elsevier]