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This paper presents the design and evaluation of a tubetype diffusive sampler, the Personal Aldehydes and Ketones Sampler (PAKS). The sampler employs dansylhydrazine (DNSH)-coated solid sorbent to collect aldehydes and ketones (carbonyls). The DNSH-carbonyl derivatives are analyzed using a sensitive HPLC-fluorescence technique. The PAKS was evaluated using test atmospheres containing eight carbonyls for a range of face velocity, temperature, relative humidity, concentration, and sampling duration. The PAKS was also evaluated in the field by comparing results obtained from the PAKS method to those from a conventional DNPH method. The evaluation results indicate that the PAKS is a valid passive sampler for 24-48-h collection of carbonyls in indoor, outdoor, or personal air. The fluorescence detection of DNSH-carbonyl derivatives substantially enhances the sensitivity of the PAKS method as compared to the DNPH method when the sampling rates for the two methods are comparable. The PAKS exposure detection limits for the eight tested carbonyls of relatively large health risk importance (formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, benzaldehyde, and hexaldehyde) range from 0.4 to 1.6 (ppb) (day).

Aldehydes are ubiquitous constituents of the atmosphere. Their concentrations are elevated in polluted urban atmospheres. The present study was carried out to characterize three aldehydes of most health concern (formaldehyde, acetaldehyde, and acrolein) in a central Beijing site in the summer and early fall of 2008 (from June to October). Measurements were made before, during, and after the Beijing Olympics to examine whether the air pollution control measures implemented to improve Beijing's air quality during the Olympics had any impact on concentrations of the three aldehydes. Average concentrations of formaldehyde, acetaldehyde and acrolein were 29.34 ± 15.12 μg/m³, 27.09 ± 15.74 μg/m³ and 2.32 ± 0.95 μg/m³, respectively, for the entire period of measurements, all being the highest among the levels measured in cities around the world in photochemical smog seasons. Among the three measured aldehydes, only acetaldehyde had a substantially reduced mean concentration during the Olympic air pollution control period compared to the pre-Olympic period. Formaldehyde and acrolein followed the changing pattern of temperature and were each significantly correlated with ozone (a secondary product of photochemical reactions). In contrast, acetaldehyde was significantly correlated with several pollutants emitted mainly from local emission sources (e.g., NO₂, CO, and PM_2.5). These findings suggest that local direct emissions had a larger impact on acetaldehyde than formaldehyde and acrolein

Heat processing semi-rigid packages with a steam/air mixture requires an overpressure t o ensure seal integrity. A method was developed t o calculate the overpressure needed t o ensure seal integrity, during thermal processing, o f semi-rigid packages t h a t contain a liquid food or drug. An equation was derived relating total retort pressure (steam and air) required during sterilization t o retort temperature, product water activity and tensile seal stress a t the sterilization temperature. The proposed method was tested, under commercial sterilization conditions (1 23-1 27% for 30 min), with individual packages containing a dilute saline solution. The method was found useful for predicting the total retort pressure (steam and air overpressure) needed t o ensure seal integrity and t o prevent leakage o f packages.

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