Autonomous in situ measurements of seawater alkalinity.

Total alkalinity (AT) is an important parameter for describing the marine inorganic carbon system and understanding the effects of atmospheric CO2 on the oceans. Measurements of AT are limited, however, because of the laborious process of collecting and analyzing samples. In this work we evaluate the performance of an autonomous instrument for high temporal resolution measurements of seawater AT.

Analysis and sequencing of the active-site peptide from native and organophosphate-inactivated acetylcholinesterase by electrospray ionization, quadrupole/time-of-flight (QTOF) mass spectrometry.

A method to identify and sequence recombinant mouse acetylcholinesterase (rMoAChE) including the native and organophosphate-modified active-site peptides was developed using capillary liquid chromatography with electrospray ionization, quadrupole/time-of-flight mass spectrometry. Addition of 2-propanol to the reversed-phase gradient system and a decreased gradient slope improved the peptide resolution and the signal of the active-site peptide. The highest protein coverage and active-site peptide signal were achieved when the rMoAChE:chymotrypsin ratio of 5:1 was used with digestion at 37 degrees C.

Albumin, a new biomarker of organophosphorus toxicant exposure, identified by mass spectrometry.

The classical laboratory tests for exposure to organophosphorus toxicants (OP) are inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity in blood. In a search for new biomarkers of OP exposure, we treated mice with a biotinylated organophosphorus agent, FP-biotin. The biotinylated proteins in muscle were purified by binding to avidin-Sepharose, separated by gel electrophoresis, digested with trypsin, and identified from their fragmentation patterns on a quadrupole time-of-flight mass spectrometer.

The synaptic vesicle proteome: a comparative study in membrane protein identification.

A proteomic analysis of the synaptic vesicle was undertaken to obtain a better understanding of vesicle regulation. Synaptic vesicles primarily consist of integral membrane proteins that are not well resolved on traditional isoelectric focusing/two-dimensional gel electrophoresis (IEF/2-DE) gels and are resistant to in-gel digestion with trypsin thereby reducing the number of peptides available for mass spectrometric analysis. To address these limitations, two complementary 2-DE methods were investigated in the proteome analysis: (a) IEF/sodium dodecyl sulfate-polyacrylamide gel electrophoresis (IEF/SDS-PAGE) for resolution of soluble proteins and, (b) Benzyl hexadecyl ammonium chloride/SDS-PAGE (16-BAC/SDS-PAGE) for resolution of integral membrane proteins.

Ambient air measurement of acrolein and other carbonyls at the Oakland-San Francisco Bay Bridge toll plaza.

Interest in ambient concentrations of acrolein and other alpha,beta-unsaturated aldehydes and dicarbonyls (e.g., crotonaldehyde, methyl glyoxal, glyoxal, malonaldehyde (malondialdehyde)) is growing because either they exist at high levels in motor vehicle emissions or they arise from photooxidation of other hydrocarbons emitted from mobile sources.

Ion trap mass spectrometry affords advances in the analytical and atmospheric chemistry of 2-hydroxy-2-methylpropanal, a proposed photooxidation product of 2-methyl-3-buten-2-Ol.

In the western United States, in areas where emissions of the biogenic hydrocarbon, 2-methyl-3-buten-2-ol (MBO) are high, MBO contributes significantly to the oxidative capacity of the atmosphere. Hydroxyl radical oxidation of MBO can play an important role in forming tropospheric ozone, and MBO reaction products may contribute to the formation of secondary organic aerosols [1-3]. Although 2-hdyroxy-2-methylpropanal was tentatively identified as a product from the reaction of MBO with .

Optimization of a mist chamber (Cofer scrubber) for sampling water-soluble organics in air.

While the atmospheric fate and transport of biogenic and anthropogenic hydrocarbons has been extensively studied, little is known about the behavior of first-, second-, and third generation photo-oxidation products that arise from OH radical oxidation of the parent species. The results of chamber experiments establish that *OH oxidation of biogenic and anthropogenic hydrocarbons yields carbonyls, dicarbonyls, hydroxycarbonyls, and keto-acids. However, little is known about the generation and fate of these products in the ambient atmospheric environment.