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Venous air-embolism (VAE) potentially catastrophic complication surgery. Based on previous data using changes in end-tidal nitrogen as an indicator of VAE, we surmised that changes in end-tidal argon (EtAr) may be an indicator of VAE. We sought to determine if a commercial mass-spectrometer (PCT Proline Analyzer 61700-8 Class 85, Ametek, Pittsburgh, PA 15238) could be used to detect changes in EtAr in an invitro model. A Drager Apollo™ (Drager, Lubeck, Germany) anesthesia machine was used to ventilate a dummy lung (2 L bag) with a minute ventilation of 6 L/min in 100% oxygen. The quadrupole mass-spectrometer (sampling at 0.0004 atm-cc/sec) was attached to the end-tidal inlet of the machine. Room air (1–60 mL) was injected into the dummy lung to simulate VAE. A strong baseline ion-current (1.2 × 10−12 amps) of argon was noted. Due to this contamination we were unable to detect “VAE” events of injected air. Argon represents approximately 0.93% of room air, or about 9300 parts per million (ppm). We detected about 2000 ppm argon in medical-grade oxygen (or 0.2%), limiting our ability to detect changes in EtAr. This is a USP-accepted contaminant, rendering this technology is insensitive for early, rapid detection of VAE. We assumed medical grade oxygen was pure and were surprised to learn otherwise. We want to share this likely largely unknown finding with the medical community.

Ninhydrin (the fingerprint developing agent) spontaneously dehydrates in liquid ammonia and in hexamethylphosphoramide (HMPA) to form indantrione, which has a sufficiently large solution electron affinity to extract an electron from the solvent (HMPA) to produce the indantrione anion radical. In liquid NH(3), the presence of trace amounts of amide ion causes the spontaneous formation of an anion radical condensation product, wherein the no. 2 carbon (originally a carbonyl carbon) becomes substituted with -NH(2) and -OH groups. In HMPA, the indantrione anion radical spontaneously forms condensation products with the HMPA to produce a variety of zwitterionic radicals, wherein the no. 2 carbon becomes directly attached to a nitrogen of the HMPA. The mechanisms for the formation of the zwitterionic paramagnetic condensation products are analogous to that observed in the reaction of ninhydrin with amino acids to yield Ruhemann's Purple, the contrast product in fingerprint development. The formation of anion and zwitterionic radical condensation products from ninhydrin and nitrogen-containing solvents may represent an example of a host of analogous polyketone-solvent reactions.

N-Methoxycarbonyl-1H-azepine-2,7-dicarboxaldehyde (I) was synthesized via the SeO(2)-mediated oxidation of N-methoxycarbonyl-2,7-dimethyl-1H-azepine. The reductions of I in tetrahydrofuran with (6)Li or (7)Li resulted in anion radicals, which are tightly associated with the lithium cations. EPR and ab initio calculations both show a nonequivalency in all of the protons in I(-*),Li(+) due to the closer approach of the Li(+) to one of the carbonyls and a twist of the ester carbonyl group (slow rotation of the carbamate group) toward the Li(+). Further, as predicted by the MO calculations, I(-*),Li(+) appears to exist with the nitrogen puckered above the twisted ring system, and the lithium cation is asymmetrically complexed between the two electronegative aldehydic oxygen atoms and the carbamate carbonyl oxygen. It is also Coulombically attracted to the puckered and twisted ring system.