Field Analytical Chemistry & Technology最新文献

A two-channel fluorometric sensor system for the detection of the waterbloom phytoplankton Microcystis aeruginosa has been developed. Excitation wavelengths of 620 and 440 nm were used, the former for detecting the cyanobacteria themselves, and the latter for subtracting the interference due to eukaryotic algae present in the sample. The fluorescence of the cyanobacteria and eukaryotic algae was measured at 645 and 680 nm, respectively. A linear relationship between phycocyanin fluorescence was established for the species examined in the range of 10⁻⁴ to 10⁰ g/ml⁻¹ chlorophyll a. Furthermore, upon ultrasonic treatment of a colony of cyanobacteria, the relationship between fluorescence intensity and cell concentration was improved. Applied to real samples in Lake Kasumigaura, Japan, after ultrasonication, this fluorometric method could detect waterbloom. This system is capable of the rapid determination of phycocyanin; the time required for one measurement cycle is approximately 25 min including sonication and rinsing for 5 min. The detection limit of this method is suitable for detecting phycocyanin in the early stage of waterbloom formation. Furthermore, a device based on this system was used for the continuous in situ monitoring of phycocyanin in lake water. © 2000 John Wiley & Sons, Inc. Field Analyt Chem Technol 4: 53–61, 2000

Both vehicle-portable and man-portable GC/MS techniques and applications are currently undergoing rapid further development. Vehicle-portable GC/MS technology is expanding into the area of temporally and spatially resolved mapping, formerly accessible only to stand-off methods. Also, unmanned vehicles such as UAVs and drones are expected to play an increasingly important role as experimental platforms for the future. Man-portable instrumentation appears to be evolving from the unwieldy “luggables” to the readily wearable backpacks and, possibly, even handhelds. In the next 5 to 10 years this may open the way for the “chemical Geiger counter” or “definitive electronic nose”. The above developments are discussed from the perspective of field-portable, mobile GC/MS, with special emphasis on performance breakthroughs leading to potentially new applications, rather than from a strictly historical point of view. © 2000 John Wiley & Sons, Inc. Field Analyt Chem Technol 4: 3–13, 2000

Pyrolysis mass spectrometry (Py-MS), incorporating an in situ thermal hydrolysis and methylation (THM) step, was used to profile methylated lipids (e.g., fatty acids and cholesterol) from pathogenic viruses and bacteria by means of a field-portable ion-trap MS instrument referred to as the chemical/biological mass spectrometer (CBMS). The CBMS has been successfully tested for biological warfare agents to give correct classification (three classes—spore, vegetative cell, and toxin) in both field and chamber tests. Incorporating an in situ THM step in the CBMS will improve its capabilities to better identify biomarkers from bacteria and viruses. Mass spectra of one bacterial and two viral pathogens (grown by cell cultures) were produced with a total analysis time of 3 min per profile and could be separated when examined by principal-component analysis (PCA).© 1999 John Wiley & Sons, Inc. Field Analyt Chem Technol 3: 357–374, 1999

Comparison between a standard toxicological test with luminous bacteria based on DIN 38 412 L 341, 2 and a rapid test yield similar results. However, the standard deviation of the rapid test was lower than that of the standard test. Costs for material and instruments are low; the test is easy to handle and can be used on site. By appropriate choice of the dilution steps and proper timing by intercalating the individual sets of assays, the overall time required to obtain results can be shortened considerably compared to the standard test. In combination with a recently developed method for aqueous extraction this allows assessment of the risk in contaminated soil on site within 30–45 min. © 1999 John Wiley & Sons, Inc. Field Analyt Chem Technol 3: 329–337, 1999

This article provides an overview of the development and application of surface-enhanced Raman scattering (SERS) for the detection of vapors of organic chemicals with the use of personal dosimetry. The approach used with this personal dosimeter requires no sample desorption or wet-chemical extraction procedure. The dosimeter employs the SERS technique for direct measurement of the amount of analyte collected on the sample substrate. SERS substrates based on nanoparticles developed in our laboratory have been incorporated in this dosimeter design. Polymers applied to these solid-based SERS substrates can further enhance dosimeter shelf life, ruggedness, and chemical selectivity. Use of this SERS dosimeter for the determination of time-weighted average exposures to chemical vapors has been demonstrated. © 1999 John Wiley & Sons, Inc. Field Analyt Chem Technol 3: 346–356, 1999

A new all-season passive sampling system for monitoring NO₂ in air has been developed. This passive sampling system employs the same approach as the all-season sampling system for monitoring SO₂ reported in FACT [Vol. 1(5), 1997] before, but a new collection medium (CHEMIX™) for sampling NO₂ has been developed and is used. Compared to the existing collection media used for NO₂ passive samplers, such as a triethanolamine (TEA)-coated cellulose fiber filter, CHEMIX™ is less affected by temperature and relative humidity, and has a higher sampling rate. This system has been extensively tested in the lab (temperature from −27 to 20 °C, relative humidity from 4 to 80%, and wind speed from 0.5 to 150 cm/s) and validated in the field in all climates. Comparing measurements obtained with the use of the new passive sampling system with equivalent measurements with the use of a continuous NO₂ analyzer yielded an accuracy of greater than 85%. The new NO₂ passive sampling system can be used to measure ambient NO₂ concentrations ranging from 0.1 to 50 ppb based on a 1-month exposure period. © 1999 John Wiley & Sons, Inc. Field Analyt Chem Technol 3: 338–345, 1999

The dithiocarbamate fungicides and the organophosphorus and carbamate insecticides are two families of pesticides of environmental concern used on a very large scale worldwide. The need for increasing numbers of analyses has created a demand for the development of rapid, simple, and low cost methods. Enzyme sensors based on the abilities of these compounds to inhibit enzymes are described. An enzyme sensor with immobilized aldehyde dehydrogenase is described allowing the detection of 9 ppb of zineb, whereas the classical method allows the determination of 400 ppb. Using screen-printed electrodes with acetylcholinesterase, it is possible to detect 0.5 ppb of paraoxon in aqueous buffer and 1.4 ppb of paraoxon in a mixture of hexane and water (80/20). © 1999 John Wiley & Sons, Inc. Field Analyt Chem Technol 3: 171–178, 1999