Determination of Potassium Ferrocyanide in Foods by Resonance Rayleigh Scattering Method with Double-Charged Triaminotriphenylmethane Dyes

In pH 1.0 acidic medium, double-charged triaminotriphenylmethane dyes such as methyl green （MEG） and iodine green （IG） react with potassium ferrocyanide to form 2 ： 1 ion-association complexes by virtue of electrostatic forces and hydrophobic interaction. It results in the change of absorption and the great enhancement of resonance Rayleigh scattering （RRS） and the appearance of new RRS spectra. Two systems have similar spectral characteristics and their maximum RRS wavelengths are all located at 276 nm and smaller peaks are located at 332 and 457 nm, respectively. The intensity of RRS is directly proportional to the concentration of [Fe（CN）6]^4- in the range of 0.03-5.7 μg·mL^-1 （MeG system） or 0.04-5.9 μg·mL^-1 （IG system）. The RRS method has high sensitivity and the detection limit （3σ） for potassium ferrocyanide is 9.3 ng·mL^-1 （MeG system） or 11.2 ng·mL^-1 （IG system）. The optimum conditions, influencing factors and effects of foreign substances are investigated. The method also has a good selectivity. A sensitive, rapid and simple RRS method for the determination of potassium ferrocyanide in salinized food and table salt has been developed.

Gold-leaching performance and mechanism of sodium dicyanamide

In this work,sodium dicyanamide(SD)was used as a leaching reagent for gold recovery,and the effects of the SD dosage and solution pH on the gold-leaching performance were investigated.A gold recovery of 34.8%was obtained when SD was used as the sole leaching reagent at a dosage of 15 kg/t.In the presence of a certain amount of potassium ferrocyanide(PF)in the SD solution,the gold recovery was found to increase from 34.8%to 57.08%.Using the quartz crystal microbalance with dissipation(QCM-D)technique,the leaching kinetics of SD with and without PF were studied.The QCM-D results indicate that the gold-leaching rate increased from 4.03 to 39.99 ng·cm^(–2)·min^(–1) when the SD concentration was increased from 0 to 0.17 mol/L,and increased from 39.99 to 272.62 ng·cm^(–2)·min^(–1) when 0.1 mol/L of PF was used in combination with SD.The pregnant solution in the leaching tests was characterized by X-ray photoelectron spectroscopy and electrospray mass spectrometry,which indicated that Au and(N(CN)2)–in the SD solution formed a series of metal complex ions,[AuNax(N(CN)2)x+2]–(x=1,2,3,or 4).

Unlocking the ultrastructure of colorectal cancer cells in vitro using selective staining

AIM: To characterise differences between three widely used colorectal cancer cell lines using ultrastructural selective staining for glycogen to determine variation in metastatic properties. METHODS: Transmission electron microscopy was used in this investigation to help identify intracellular structures and morphological features which are precursors of tumor invasion. In addition to morphological markers, we used selective staining of glycogen as a marker for neoplastic cellular proliferation and determined whether levels of glycogen change between the three different cell lines. RESULTS: Ultrastructural analysis revealed morphological differences between the cell lines, as well as differentiation into two sub-populations within each cell line. Caco-2 cells contained large glycogen deposits as well as showing the most obvious morphological changes between the two sub-populations. SW480 cells also contained large glycogen stores as well as deep cellular protrusions when grown on porous filter membranes. HT-29 cells had trace amounts of glycogen stores with few cellular projections into the filter pores and no tight junction formation.CONCLUSION: Morphology indicative of metastatic properties coincided with larger glycogen deposits, providing strong evidence for the use of selective staining to determine the neoplastic properties of cells.

A Reflectance Thin-layer Spectro-electrochemical Method

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