Kenneth L. Froese

Rapid and sensitive differentiation of anomers, linkage, and position isomers of disaccharides using High-Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS)

A challenging aspect of structural elucidation of carbohydrates is gaining unambiguous information for anomers, linkage, and position isomers. Such isomers with identical mass can’t be easily distinguished in mass spectrometry and a separation step is required prior to mass spectrometry identification. In our laboratory, gas-phase separation and differentiation of anomers, linkage, and position isomers of disaccharides was achieved using High-Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS). The FAIMS method responds to changes in ion mobility at high field rather than absolute values of ion mobility, and was shown to provide efficient separation and identification of disaccharide isomers at high sensitivity. Separation of analyzed disaccharide isomers can be accomplished at low nM level in a matter of seconds without sample purification or fractionation. Capability for examining a large population of ionic species of disaccharides by this method allowed for correlating structural details of disaccharide isomers with their separation properties in FAIMS. Results for disaccharide isomers indicate that this method could be applied to a larger group of carbohydrates.

Detection of microcystins using electrospray ionization high-field asymmetric waveform ion mobility mass spectrometry/mass spectrometry

A combination of electrospray ionization, high-field asymmetric waveform ion mobility spectrometry, and mass spectrometry (ESI-FAIMS/MS) was used to analyze standard solutions of microcystins-LR, -RR, and -YR. The ability of FAIMS to separate ions in the gas phase reduced the amount of background in the mass spectrum without compromising the absolute signal for these microcystins. This reduction in background resulted in a ten-fold improvement in the signal-to-background ratio over conventional ESI-MS. Detection limits, using direct infusion, were determined to be 4, 2, and 1 nM for microcystins-LR, -RR, and -YR, respectively.

Improved gas chromatography methods for micro-volume analysis of haloacetic acids in water and biological matrices

A fast headspace solid-phase microextraction gas chromatography method for micro-volume (0.1 mL) samples was optimized for the analysis of haloacetic acids (HAAs) in aqueous and biological samples. It includes liquid-liquid microextraction (LLME), derivatization of the acids to their methyl esters using sulfuric acid and methanol after evaporation, followed by headspace solid-phase microextraction with gas chromatography and electron capture detection (SPME-GC-ECD). The derivatization procedure was optimized to achieve maximum sensitivity using the following conditions: esterification for 20 min at 80 degrees C in 10 microL methanol, 10 microL sulfuric acid and 0.1 g anhydrous sodium sulfate. Multi-point standard addition method was used to determine the effect of the sample matrix by comparing with internal standard method. It was shown that the effect of the matrix for urine and blood samples in this method is insignificant. The method detection limits are in the range of 1 microg L(-1) for most of the HAAs, except for monobromoacetic acid (MBAA) (3 microg L(-1)) and for monochloroacetic acid (MCAA) (16 microg L(-1)). The optimized procedure was applied to the analysis of HAAs in water, urine and blood samples. All nine HAAs can be separated in < 13 min for biological samples and < 7 min for drinking water samples, with total sample preparation and analysis time < 50 min. Analytical uncertainty can increase dramatically as the sample volume decreases; however, similar precision was observed with our method using 0.1 mL samples as with a standard method using 40 mL samples.

DISINFECTION BY-PRODUCTS IN SMALL ALBERTA COMMUNITY DRINKING-WATER SUPPLIES

Complacent attitudes toward drinking-water quality can lead to compromised disinfection practices, as noted in such episodes as Walkerton and North Battleford. The first priority for drinking-water providers must be to ensure microbial safety. However, it is recognized that effective disinfection may not be risk free. Consequently, drinking-water guidelines seek to balance the certain danger posed by microbial pathogens with the potential adverse health hazards that may arise from disinfection by-products (DBPs). Providers of drinking water in small communities often do not have the means to reduce concentrations of DBPs, compared to utilities in larger municipalities. A significant portion of Albertas population receives drinking water from smaller scale treatment plants or from private wells. A survey of selected DBPs was conducted in 11 rural Alberta communities, with populations ranging from 60 to 2300. The objectives were to evaluate source water quality, as measured by total organic carbon, and to measure representative concentrations of trihalomethanes (THMs) and haloacetic acids (HAAs) at a point within each distribution system as well as within each water treatment plant. During the 5-wk study, our data show: (1) averages of THM3 (chloroform, bromodichloromethane, chloro dibromomethane) concentrations often exceed 100 µg/L (Health Canadas running annual average guideline for total THMs); (2) source waters with the highest TOC concentrations (15 mg/L) had the highest average THM3 concentrations (200 µg/L); and (3) poor source water quality may necessitate using alternative disinfection options to ensure compliance with microbial and chemical drinking-water guidelines.

Automated Highway Sign Extraction Using Lidar Data

Traffic signs are integral elements of any transportation network; however, keeping records of those signs and their condition is a tedious, time-consuming, and labor-intensive process. As a result, many agencies worldwide have been working toward automating the process. One form of automation uses remote sensing techniques to extract traffic sign information. An algorithm is proposed that can automatically extract traffic signs from mobile light detection and ranging data. After the number of signs on a road segment has been determined, the coordinates of those signs are mapped onto the road segment. The sign extraction procedure involves applying multiple filters to the point cloud data and clustering the data into traffic signs. The proposed algorithm was tested on three highways located in different regions of the province of Alberta, Canada. The segments on which the algorithm was tested include a two-lane undivided rural road and four-lane divided highways. The highway geometry varied, as did vegetation and tree density. Success rates ranged from 93% to 100%, and the algorithm performed better on highways without overhead signs. Results indicate that the proposed method is simple but effective for creating an accurate inventory of traffic signs.