Application of an integrated prepstation-GC-NPD system to automated continuous measurement of formaldehyde and acetaldehyde in the atmosphere.

An integrated PrepStation-gas chromatography-nitrogen phosphorus detection (GC-NPD) system was used for the fully automated, continuous, low parts per billion analysis of lower aldehydes in the atmosphere. Analysis involved a solid phase extraction procedure based on the collection of aldehydes from air pumped through a silica gel cartridge impregnated with acidified 2,4-dinitrophenylhydrazine (DNPH). Automated continuous measurements were performed with a typical temporal resolution of 3 h, including 146 min for sampling of air at a constant air flow rate of 0.15 L min(-1) and 34 min for the preparation and extraction of several cartridges. Analysis of samples could be performed in parallel by using previously defined scheduler settings from separate, independent software to operate the PrepStation module. GC-NPD measurements were highly repeatable, and relative standard deviations were < 3.0%. Recoveries for all compounds were 88-101%. DNPH decomposition products did not adversely affect the quantitative determination of aldehyde DNPHs; therefore, it was not necessary to remove excess DNPH reagent. The limits of quantification (10sigma of the blank hydrazones) of formaldehyde and acetaldehyde were 2.2 and 1.2 ppb, respectively, for 21.9 L (0.15 L min(-1) for 146 min) of air sample volume. The integrated PrepStation GC-NPD system gave results comparable to those of the Sep-Pak DNPH silica cartridge method.

New synthetic routes to biscarbonylbipyridinerhenium(I) complexes cis,trans-[Re(X2bpy)(CO)2(PR3)(Y)n+ (X2bpy = 4,4'-X2-2,2'-bipyridine) via photochemical ligand substitution reactions, and their photophysical and electrochemical properties.

Photochemical ligand substitution of fac-[Re(X2bpy)(CO)3(PR3)]+ (X2bpy = 4,4'-X2-2,2'-bipyridine; X = Me, H, CF3; R = OEt, Ph) with acetonitrile quantitatively gave a new class of biscarbonyl complexes, cis,trans[Re(X2bpy)(CO)2(PR3)(MeCN)]+, coordinated with four different kinds of ligands. Similarly, other biscarbonylrhenium complexes, cis,trans-[Re(X2bpy)(CO)2(PR3)(Y)]n+ (n = 0, Y = Cl-; n = 1, Y = pyridine, PR'3), were synthesized in good yields via photochemical ligand substitution reactions. The structure of cis,trans-[Re(Me2bpy)(CO)2[P(OEt)3](PPh3)](PF6) was determined by X-ray analysis. Crystal data: C38H42N2O5F6P3Re, monoclinic, P2(1/a), a = 11.592(1) A, b = 30.953(4) A, c = 11.799(2) A, V = 4221.6(1) A3, Z = 4, 7813 reflections, R = 0.066. The biscarbonyl complexes with two phosphorus ligands were strongly emissive from their 3MLCT state with lifetimes of 20-640 ns in fluid solutions at room temperature. Only weak or no emission was observed in the cases Y = Cl-, MeCN, and pyridine. Electrochemical reduction of the biscarbonyl complexes with Y = Cl- and pyridine in MeCN resulted in efficient ligand substitution to give the solvento complexes cis,trans-[Re(X2bpy)(CO)2(PR3)(MeCN)]+.