Centrifugal partition chromatography: A preparative tool for isolation and purification of xylindein from Chlorociboria aeruginosa.

A centrifugal partition chromatography (CPC) method was developed for the preparative-scale isolation and purification of xylindein from the wood-staining fungi, Chlorociboria aeruginosa. Xylindein, a blue-green pigment naturally secreted from the hyphae and fruiting bodies of the fungus, has great value in the decorative wood industry and textile coloration. Xylindein has great potential for use as a fluorescent labeling agent as well as in organic semiconductor applications. However, a primary limitation of xylindein is its poor solubility in most common HPLC solvents. Consequently, it is arduous to purify using preparative liquid chromatography or solid-phase extraction (SPE). Support-free, liquid-liquid chromatographic methods, including CPC, where solutes are separated based on their different distribution coefficients (KD) between two immiscible solvent systems, are promising alternatives for the purification of the compound on a preparative scale. In this work, a new biphasic solvent system suitable for CPC separation of xylindein was developed. Various groups of solvents were assessed for their suitability as xylindein extractants. A new solvent system suitable for CPC separation of xylindein, composed of heptane/THF/MEK/acetonitrile/acetic acid/water, was developed. This solvent system yielded a KD value for xylindein of 1.54±0.04, as determined by HPLC (n=3). The compositions of the upper phase and lower phase of the solvent system were determined by Heteronuclear Single Quantum Correlation (HSQC) NMR and proton NMR. A CPC system, equipped with a fraction collector, was used for the isolation of xylindein from crude extracts. The xylindein fractions isolated by the CPC were then analyzed using HPLC and presented as a fractogram. Based on the CPC fractogram, the purified xylindein fractions were achieved after 30min CPC separation time, yielding 71% extraction efficiency. The developed CPC method allowed for isolation of this naturally sourced xylindein in amounts suitable for further study.

Clinical chemistry measurements with commercially available test slides on a smartphone platform: Colorimetric determination of glucose and urea.

BACKGKROUND: Rapidly increasing healthcare costs in economically advantaged countries are currently unsustainable, while in many developing nations, even 50-year-old technologies are too expensive to implement. New and unconventional technologies are being explored as solutions to this problem. In this study, we examined the use of a smartphone as the detection platform for 2 well-developed, relatively inexpensive, commercially available clinical chemistry assays as a model for rapid and inexpensive clinical diagnostic testing. METHODS: An Apple iPhone 4 camera phone equipped with a color analysis application (ColorAssist) was combined with Vitros® glucose and urea colorimetric assays. Color images of assay slides at various concentrations of glucose or urea were collected with the iPhone 4 and quantitated in three different spectral ranges (red/green/blue or RGB) using the ColorAssist app. When the diffuse reflectance data was converted into absorbance, it was possible to quantitate glucose or blood urea nitrogen (BUN) over their clinically important concentration ranges (30-515mg/dl for glucose or 2-190mg/dl for BUN), with good linearity (R(2)=0.9994 or 0.9996, respectively [n=5]). RESULTS: Data collected using the iPhone 4 and canine serum samples were in agreement with results from the instrumental "gold standard" (Beckman Coulter AU480 Chemistry System) (R(2)=0.9966 and slope=1.0001 for glucose; R(2)=0.9958 and slope=0.9454 for BUN). Glucose determinations of serum samples made using this smartphone method were as accurate as or more accurate than a commercial colorimetric dry slide analyzer (Heska® Element DC Chemistry Analyzer, Loveland, CO) and 2 glucometers: ReliOn® Ultima (Abbott Diabetes Care Inc) and Presto® (AgaMatrix Inc.H). BUN determinations made using the smartphone approach were comparable in accuracy to the Heska instrument. CONCLUSION: This demonstration shows that smartphones have the potential to be used as simple, effective colorimetric detectors for quantitative diagnostic tests, and may be applicable for both point-of-care applications in the developed world and field deployment in developing nations.

Low-cost, high-speed identification of counterfeit antimalarial drugs on paper.

With the emergence of artesunate antimalarial counterfeiting in Southeast Asia and sub-Saharan Africa, we present the production of a rapid, inexpensive and simple colorimetric-based testing kit for the detection of counterfeit artesunate in order to preserve life and prevent the development of multi-drug resistant malaria. The kit works based on paper microfluidics which offer several advantages over conventional microfluidics, and has great potential to generate inexpensive, easy-to-use, rapid and disposable diagnostic devices. Here, we have developed a colorimetric assay that is specific to artesunate and turns yellow upon addition of the sample. The test can be done within minutes, and allows for a semi-quantitative analysis of the artesunate tablets by comparing the developed yellow color on the paper test to a color-coded key chart that comes with the kit. A more accurate and precise analysis is done by utilizing a color analyzer on an iPhone camera that measures the color intensity of the developed color on the paper chip. A digital image of the chip was taken and analyzed by measuring the average gray intensity of the color developed on the paper circle. A plot of the artesunate concentration versus the average gray scale intensity was generated. Results show that the intensity of the yellow color developed on the paper test was consistent and proportional to the amount of artesunate present in the sample. With artesunate concentrations ranging from 0.0 to 20mg/mL, a linear calibration plot was obtained with a detection limit of 0.98 mg/mL.