Accurate mass and nuclear magnetic resonance identification of bisphenolic can coating migrants and their interference with liquid chromatography/tandem mass spectrometric analysis of bisphenol A

Two unknown compounds were previously determined to be potential interferences in liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of bisphenol A (BPA) in canned infant formula. Both yielded two identical MS/MS transitions to BPA. The identities of the unknowns were investigated using accurate mass LC/MS, LC/MS/MS, and elemental formula and structures proposed. Exact identities were confirmed through purification or synthesis followed by (1)H and (13)C nuclear magnetic resonance (NMR) experiments, as well as comparisons of one unknown with commercial standards. Comparisons of negative ion electrospray ionization (ESI) MS/MS and accurate mass spectra suggested both unknowns to be structurally identical (to BPA and each other). Positive ion ESI spectra confirmed both were larger molecules, suggesting that in the negative mode they likely fragmented to the deprotonated BPA ion in the source [corrected]. Elemental composition of positive ion accurate mass spectra and NMR analysis concluded the unknowns were oxidized forms of the known epoxy can coating monomer, bisphenol A diglycidyl ether (BADGE). One of the unknowns, 2,2-[bis-4-(2,3-dihydroxypropoxy)phenyl]propane, commonly known as BADGE*2H(2)O, is widely reported as an epoxy-phenolic can coating migrant, but has not been suggested to interfere with the MS/MS analysis of BPA. The other unknown, 2-[4-(2,3-dihydroxypropoxy)phenyl]-2-[4'-hydroxyphenyl]propane, or the oxidized form of bisphenol A monoglycidyl ether (BAMGE*H(2)O), has not been previously reported in food or packaging.     

Green chemiluminescence from a bis-cyclometalated iridium(III) complex with an ancillary bathophenanthroline disulfonate ligand

The reaction of a fluorinated iridium complex with cerium(IV) and organic reducing agents generates an intense emission with a significant hypsochromic shift compared to contemporary chemically-initiated luminescence from metal complexes.     

Membrane assisted passive sampler for triazine compounds in water bodies--characterization of environmental conditions and field performance

This article reports the integration of the fiber optic-particle plasmon resonance (FO-PPR) biosensor with a microfluidic chip to reduce response time and improve detection limit. The microfluidic chip made of poly(methyl methacrylate) had a flow-channel of dimensions 4.0 cm × 900 μm × 900 μm. A partially unclad optical fiber with gold or silver nanoparticles on the core surface was placed within the flow-channel, where the volume of the flow space was about 14 μL. Results using sucrose solutions of various refractive indexes show that the refractive index resolution improves by 2.4-fold in the microfluidic system. The microfluidic chip is capable of delivering a precise amount of biological samples to the detection area without sample dilution. Several receptor/analyte pairs were chosen to examine the biosensing capability of the integrated platform: biotin/streptavidin, biotin/anti-biotin, DNP/anti-DNP, OVA/anti-OVA, and anti-MMP-3/MMP-3. Results show that the response time to achieve equilibrium can be shortened from several thousand seconds in a conventional liquid cell to several hundred seconds in a microfluidic flow-cell. In addition, the detection limit also improves by about one order of magnitude. Furthermore, the normalization by using the relative change of transmission response as the sensor output alleviate the demand on precise optical alignment, resulting in reasonably good chip-to-chip measurement reproducibility.     

New methods for the acquisition of ultra-wideline solid-state NMR spectra of spin-1/2 nuclides

The Wideband Uniform Rate Smooth Truncation - Carr-Purcell Meiboom-Gill (WURST-CPMG) pulse sequence was recently introduced as a new method of acquiring ultra-wideline solid-state NMR (SSNMR) patterns of quadrupolar nuclei (Chem. Phys. Lett. 464 (2008) 97). Herein, we describe the application of the WURST-CPMG pulse sequence to stationary samples (i.e., non-spinning or "static" samples) of various spin-1/2 nuclides ((119)Sn, (207)Pb, (199)Hg and (195)Pt) in order to examine its effectiveness for acquiring ultra-wideline SSNMR patterns. WURST-CPMG is compared to the CPMG and Cross Polarization (CP)-CPMG pulse sequences in select cases ((119)Sn and (207)Pb, respectively), and its usefulness in obtaining ultra-wideline SSNMR spectra in a piecewise fashion is explored. In addition, a preliminary investigation of pulses generated using optimal control theory (OCT) for the purpose of wideline excitation is presented; spectra acquired using these pulses are compared with standard, rectangular pulses of similar pulse powers. Both methods show much promise for acquiring high quality wideline patterns dominated by chemical shift anisotropy, with minimal distortions and significantly reduced experimental times.     

Development of a Gas-Tight Syringe Headspace GC-FID Method for the Detection of Ethanol,and a Description of the Legal and Practical Framework for Its Analysis,in Samples of English and Welsh Motorists’ Blood and Urine

Ethanol is the most commonly used recreational drug worldwide. This study describes the development and validation of a headspace gas chromatography flame ionisation detection (HS-GC-FID) method using dual columns and detectors for simultaneous separation and quantitation. The use of a dual-column, dual-detector HS-GC-FID to quantitate ethanol is a common analytical technique in forensic toxicology; however, most analytical systems utilise pressure-balance injection rather than a simplified gas-tight syringe, as per this technique. This study is the first to develop and validate a technique that meets the specifications of the United Kingdom’s requirements for road traffic toxicology testing using a Shimadzu GC-2014 gas-tight syringe. The calibration ranged from 10 to 400 mg/100 mL, with a target minimum linearity of r2 > 0.999, using tertiary butanol as the internal standard marker. The method has an expanded uncertainty at 99.73% confidence of 3.64% at 80 mg/100 mL, which is the blood alcohol limit for drink driving in England and Wales. In addition, at 200 mg%—the limit at which a custodial sentence may be imposed on the defendant—the expanded uncertainty was 1.95%. For both the 80 mg% and 200 mg% concentrations, no bias was present in the analytical method. This method displays sufficient separation for other alcohols, such as methanol, isopropanol, acetaldehyde, and acetone. The validation of this technique complies with the recommended laboratory guidelines set out by United Kingdom and Ireland Association of Forensic Toxicologists (UKIAFT), the recently issued Laboratory 51 guidelines by the United Kingdom Accreditation Service (UKAS), and the criteria set out by the California Code of Regulations (CCR), 17 CCR § 1220.1.     

Designing High-Donicity Anions for Rechargeable Potassium Superoxide/Peroxide Batteries

A battery cathode based on the superoxide/peroxide redox not only inherits the advantage of oxygen (O₂) batteries in high capacities and low costs but also overcomes the disadvantages in O₂ storage, electrolyte evaporation, and anode deactivation due to O₂ crossover. Herein, we report an enhanced potassium superoxide (KO₂)/peroxide (K₂O₂) conversion by adopting a high-donicity anion additive in the ether-based electrolyte. Such an anion was synthesized via a “Solvent-in-Anion” strategy and validated to enhance the electron donicity of the electrolyte. The use of high-donicity anion could lead to enhanced KO₂ utilization (≈90.2 %) by retarding electrode passivation and allow the full charging back of K₂O₂ through the solution-mediated pathway without electrocatalysts. No apparent cell degradation is observed during the first 120 cycles by controlling the reversible depth-of-discharge capacity at 292 mAh g⁻¹ within an O₂-free region. The K−KO₂ cell delivers a high energy efficiency (>84.4 %) and a lifespan of over 1440 hours.