Contents of selected B vitamins in NIST SRM 3280 multivitamin/multielement tablets by liquid chromatography isotope dilution mass spectrometry

There is increased interest in accurately assessing the total dietary intake of vitamins from all sources, including foods and dietary supplements. Consequently, a Dietary Supplement Ingredient Database (DSID), based upon analytical values, is being established by USDA with support of the Office of Dietary Supplements (ODS), NIH. The DSID necessitated the development of a new SRM, 3280 — Multivitamin/Multimineral Tablets, by the National Institute of Standards and Technology (NIST), with support from the ODS. As a continuation of a long-term project to develop and validate new methods of determining water-soluble B vitamins in foods and dietary supplements, and as part of a collaborative effort with NIST to characterize SRM 3280, values for the vitamin contents of SRM 3280 have been generated by a liquid chromatographic isotope dilution mass spectrometric (LC/IDMS) method. Isotope-labeled (¹³C and/or ²H) B vitamins (B1-thiamine, B6-pyridoxine, B3-nicotinamide, and B5-pantothenic acid) were obtained from commercial sources, with the support of the ODS/NIH. Our LC/IDMS method uses a C18 reversed phase column, an Agilent 1100 HPLC system, and a Quattro Micro triple-quad mass spectrometer (MS). B vitamin determination was achieved using a gradient LC profile combined with MS/MS detection in multiple reaction monitoring mode. Stock solutions of the isotope-labeled vitamins were calibrated against USP standard solutions. The SRM tablets, with added amounts of the four isotope-labeled B vitamins, were extracted and the vitamins simultaneously determined in a single LC run, in contrast with the single-component determinations performed via IDMS. Unknown vitamin concentrations were calculated by comparing the ratios of the integrated LC peaks at the different masses of the unlabeled and labeled vitamins.     

Quantum Fisher Information of N Particles in the Superposition of W and GHZ States

We investigate the quantum Fisher information of a multipartite entangled state of N particles in a superposition of W and GHZ states. We find that the mean quantum Fisher information per particle (RMQFI) decreases with respect to the number of the particles and the peak is observed between 0.6 and 0.8 values of the superposition coefficient of W state. We present the behavior of RMQFI for N from 2 to 10 and discuss some interesting results.     

Quantum dot enabled detection of Escherichia coli using a cell-phone

We report a cell-phone based Escherichia coli (E. coli) detection platform for screening of liquid samples. In this compact and cost-effective design attached to a cell-phone, we utilize anti-E. coli O157:H7 antibody functionalized glass capillaries as solid substrates to perform a quantum dot based sandwich assay for specific detection of E. coli O157:H7 in liquid samples. Using battery-powered inexpensive light-emitting-diodes (LEDs) we excite/pump these labelled E. coli particles captured on the capillary surface, where the emission from the quantum dots is then imaged using the cell-phone camera unit through an additional lens that is inserted between the capillary and the cell-phone. By quantifying the fluorescent light emission from each capillary tube, the concentration of E. coli in the sample is determined. We experimentally confirmed the detection limit of this cell-phone based fluorescent imaging and sensing platform as ～5 to 10 cfu mL(-1) in buffer solution. We also tested the specificity of this E. coli detection platform by spiking samples with different species (e.g., Salmonella) to confirm that non-specific binding/detection is negligible. We further demonstrated the proof-of-concept of our approach in a complex food matrix, e.g., fat-free milk, where a similar detection limit of ～5 to 10 cfu mL(-1) was achieved despite challenges associated with the density of proteins that exist in milk. Our results reveal the promising potential of this cell-phone enabled field-portable and cost-effective E. coli detection platform for e.g., screening of water and food samples even in resource limited environments. The presented platform can also be applicable to other pathogens of interest through the use of different antibodies.     

Determination of tocopherol contents of some olive varieties harvested at different ripening periods

The tocopherol contents of oils obtained from Ayval?k, Domat and Gemlik olive varieties harvested at different ripening periods were evaluated by high-performance liquid chromatography. α-Tocopherol was the major tocol detected in all the studied olive oil samples. The oils extracted from olive fruits composed of 130.54-180.43?mg?kg?1 α-tocopherol, 0.73-1.61?mg?kg?1 β-tocopherol and 0.53-2.28?mg?kg?1 γ-tocopherol for Ayval?k oil. The α-, β- and γ-tocopherol contents of Domat oil are in the ranges 95.60-125.56, 0.71-2.70 and 0.49-1.25?mg?kg?1 at different harvesting periods. The α-, β- and γ-tocopherol contents of Gemlik olive oil are in the ranges 112.59-168.19, 0.94-1.21 and 0.85-2.40?mg?kg?1, respectively. There were significant differences between the oils from cultivars grown in different environments.     

Combined reflection and transmission microscope for telemedicine applications in field settings

We demonstrate a field-portable upright and inverted microscope that can image specimens in both reflection and transmission modes. This compact and cost-effective dual-mode microscope weighs only ～135 grams (<4.8 ounces) and utilizes a simple light emitting diode (LED) to illuminate the sample of interest using a beam-splitter cube that is positioned above the object plane. This LED illumination is then partially reflected from the sample to be collected by two lenses, creating a reflection image of the specimen onto an opto-electronic sensor-array that is positioned above the beam-splitter cube. In addition to this, the illumination beam is also partially transmitted through the same specimen, which then casts lensfree in-line holograms of the same objects onto a second opto-electronic sensor-array that is positioned underneath the beam-splitter cube. By rapid digital reconstruction of the acquired lensfree holograms, transmission images (both phase and amplitude) of the same specimen are also created. We tested the performance of this field-portable microscope by imaging various micro-particles, blood smears as well as a histopathology slide corresponding to skin tissue. Being compact, light-weight and cost-effective, this combined reflection and transmission microscope might especially be useful for telemedicine applications in resource limited settings.     

Synthesis and oxoanions (dichromate/arsenate) sorption study of N-methylglucamine derivative of calix[4]arene immobilized onto poly[(phenyl glycidyl ether)-co-formaldehyde]

The article describes synthesis as well as the evaluation of sorption properties of new N-methylglucamine substituted calix[4]arene and its poly[(phenyl glycidyl ether)-co-formaldehyde] immobilized product. Firstly, 5,17-bis-[(N-methylglucamine)methyl]-25,26,27,28-tetrahydroxy-calix[4]arene (3) was synthesized by the treatment of calix[4]arene with a secondary amine N-methylglucamine and formaldehyde via Mannich reaction. The immobilization of 3 onto poly[(phenyl glycidyl ether)-co-formaldehyde] to form calixarene based polymer (4) was carried out under suitable reaction conditions via nucleophilic substitution reaction. All the new compounds were characterized by a combination of FT-IR, ¹H-NMR spectroscopic and elemental analysis techniques. The sorption studies of 4 reveal that it is an excellent material for the removal of toxic oxoanions especially arsenate from aqueous environment. To understand the selectivity of 4, we also examined the retention of dichromate anions in the presence of Cl^?, NO₃ ^? and SO₄ ^2? anions at pH 1.5.     

Synthesis of poly(methyl methacrylate)‐b‐polystyrene containing a crown ether unit at the junction point via combination of atom transfer radical polymerization and nitroxide mediated radical polymerization routes

Poly(methyl methacrylate)‐b‐polystyrene (PMMA‐b‐PS) containing a benzo‐15‐crown‐5 unit at the junction point was prepared by combining atom transfer radical polymerization and nitroxide‐mediated radical polymerization. For this purpose, 6,7,9,10,12,13,15,16‐octahydro‐5,8,11,14,17‐pentaoxa‐benzocyclopentadecene‐2‐carboxylic acid 3‐(2‐bromo‐2‐methyl‐propionyloxy)‐2‐methyl‐2‐[2‐phenyl‐2‐(2,2,6,6‐tetramethyl‐piperidin‐1‐yloxy)‐ethoxycarbonyl]‐propyl ester ( 3 ) was synthesized and used as an initiator in atom transfer radical polymerization of methyl methacrylate in the presence of CuCl and pentamethyldiethylenetriamine at 60°C. A linear behavior was observed in both plots of ln([M]₀/[M]) versus time and M_n,_GPC versus conversion indicating that the polymerization proceeded in a controlled/living manner. Thus obtained PMMA precursor was used as a macroinitiator in nitroxide‐mediated radical polymerization of styrene (St) at 125°C to give well‐defined PMMA‐b‐PS with crown ether per chain. Kinetic data were also obtained for copolymerization. Moreover, potassium picrate (K⁺ picrate) complexation of 3 and PMMA‐b‐PS copolymer was studied. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3242–3249, 2006     

Dendrimer‐like miktoarm star terpolymers: A3‐(B‐C)3 via click reaction strategy

Two samples of dendrimer‐like miktoarm star terpolymers: (poly(tert‐butyl acrylate))₃‐(polystyrene‐poly(ε‐caprolactone))₃ (PtBA)₃‐(PS‐PCL)₃, and (PS)₃‐(PtBA‐poly(ethylene glycol)₃ were prepared using efficient Cu catalyzed Huisgen cycloaddition (click reaction). As a first step, azido‐terminated 3‐arm star polymers PtBA and PS as core (A) were synthesized by atom transfer radical polymerization (ATRP) of tBA and St, respectively, followed by the conversion of bromide end group to azide. Secondly, PS‐PCL and PtBA‐PEG block copolymers with alkyne group at the junction as peripheral arms (B‐C) were obtained via multiple living polymerization mechanisms such as nitroxide mediated radical polymerization (NMP) of St, ring opening polymerization (ROP) of ε‐CL, ATRP of tBA. Thus obtained core and peripheral arms were linked via click reaction to give target (A)₃‐(B‐C)₃ dendrimer‐like miktoarm star terpolymers. (PtBA)₃‐(PS‐PCL)₃ and (PS)₃‐(PEG‐PtBA)₃ have been characterized by GPC, DSC, AFM, and SAXS measurements. (PtBA)₃‐(PS‐PCL)₃ did not show any self‐organization with annealing due to the miscibility of the peripheral arm segments. In contrast, the micro‐phase separation of the peripheral arm segments in (PS)₃‐(PtBA‐PEG)₃ resulted in self‐organized phase‐separated morphology with a long period of ～ 13 nm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5916–5928, 2008     

One‐pot preparation of 3‐miktoarm star terpolymers via click [3 + 2] reaction

The preparation of 3‐miktoarm star terpolymers using nitroxide mediated radical polymerization (NMP), ring opening polymerization (ROP), and click reaction [3 + 2] are carried out by applying two types of one‐pot technique. In the first one‐pot technique, NMP of styrene (St), ROP of ε‐caprolactone (ε‐CL), and [3 + 2] click reaction (between azide end‐functionalized poly(ethylene glycol) (PEG‐N₃)/or azide end‐functionalized poly(methyl methacrylate) (PMMA‐N₃) and alkyne) are carried out in the presence of 2‐(hydroxymethyl)‐2‐methyl‐3‐oxo‐3‐(2‐phenyl‐2‐(2,2,6,6‐tetramethylpiperidin‐1‐yloxy)ethoxy) propyl pent‐4‐ynoate, 2 , as an initiator for 48 h at 125 °C (one‐pot/one‐step). As a second technique, NMP of St and ROP of ε‐CL were conducted using 2 as an initiator for 20 h at 125 °C, and subsequently PEG‐N₃ or azide end‐functionalized poly(tert‐butyl acrylate (PtBA‐N₃) was added to the polymerization mixture, followed by a click reaction [3 + 2] for 24 h at room temperature (one‐pot/two‐step). The 3‐miktoarm star terpolymers, PEG‐poly(ε‐caprolactone)(PCL)‐PS, PtBA‐PCL‐PS and PMMA‐PCL‐PS, were recovered by a simple precipitation in methanol without further purification. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3588–3598, 2007     

ABCD 4‐miktoarm star quarterpolymers using click [3 + 2] reaction strategy

Two samples of ABCD 4‐miktoarm star quarterpolymer with A = polystyrene (PS), B = poly(ε‐caprolactone) (PCL), C = poly(methyl methacrylate) (PMMA) or poly(tert‐butyl acrylate) (PtBA), and D = poly(ethylene glycol) (PEG) were prepared using click reaction strategy (Cu(I)‐catalyzed Huisgen [3 + 2] reaction). Thus, first, predefined block copolymers of different polymerization routes, PS‐b‐PCL with azide and PMMA‐b‐PEG and PtBA‐b‐PEG copolymers with alkyne functionality, were synthesized and then these blocks were combined together in the presence of Cu(I)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as a catalyst in DMF at room temperature to give the target 4‐miktoarm star quarterpolymers. The obtained miktoarm star quarter polymers were characterized by GPC, NMR, and DSC measurements. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1218–1228, 2008