Determination of levoglucosan in atmospheric fine particulate matter

A microanalytical method suitable for the quantitative determination of the sugar anhydride levoglucosan in low-volume samples of atmospheric fine particulate matter (PM) has been developed and validated. The method incorporates two sugar anhydrides as quality control standards. The recovery standard sedoheptulosan (2,7-anhydro-beta-D-altro-heptulopyranose) in 20 microL solvent is added onto samples of the atmospheric fine PM and aged for 1 hr before ultrasonic extraction with ethylacetate/ triethylamine. The extract is reduced in volume, an internal standard is added (1,5-anhydro-D-mannitol), and a portion of the extract is derivatized with 10% by volume N-trimethylsilylimidazole. The derivatized extract is analyzed by gas chromatography/mass spectrometry (GC/MS). The recovery of levoglucosan using this procedure was 69 +/- 6% from five filters amended with 2 microg levoglucosan, and the reproducibility of the assay is 9%. The limit of detection is approximately 0.1 microg/mL, which is equivalent to approximately 3.5 ng/m3 for a 10 L/min sampler or approximately 8.7 ng/m3 for a 4 L/min personal sampler (assuming 24-hr integrated samples). We demonstrated that levoglucosan concentrations in collocated samples (expressed as ng/m3) were identical irrespective of whether samples were collected by PM with aerodynamic diameter < or = 2.5 microm or PM with aerodynamic diameter < or = 10 microm impactors. It was also demonstrated that X-ray fluorescence analysis of samples of atmospheric PM, before levoglucosan determinations, did not alter the levels of levoglucosan.     

Studies on the lipid metabolism of some oceanic crustaceans

Mid-water, oceanic crustaceans were either fed food labelled with (¹⁴C) palmitic acid under controlled conditions, or injected directly with (¹⁴C) palmitic acid. Lipid classes and their constituent fatty acids and fatty alcohols were subsequently separated and assayed for radioactivity. Significant levels of radioactivity were present in the 16:0¹ alcohols and 18:1 acids of wax esters, and in the 16:0/16:1, 18:0/18:1, 20:5 and 22:6 acids of both triglycerides and phospholipids. It was concluded that these crustaceans were capable of biosynthesis of wax esters and higher polyunsaturated fatty acids.     

Prenatal diagnosis of tetrasomy 12p by in situ hybridization: Varying levels of mosaicism in different fetal tissues

Prenatal diagnosis of tetrasomy 12p is complicated by the discrimination of the 12p isochromosome from the duplication 21q as well as the level of mosaicism demonstrated in the particular tissue sampled. In this disease, a high percentage of chromosomally abnormal cells are generally found in fibroblastic cells, but lymphocyte karyotypes from the same individual may be normal. We report on the pregnancy of a 37-year-old female who presented to our centre at 16 weeks' gestation for genetic amniocentesis. Sonography of the fetus revealed dextrocardia and diaphragmatic hernia. Chromosome analysis of amniocytes demonstrated mosaicism of a 47,XY,+i(12p) line in 80 per cent of cells and a normal male line (20 per cent), consistent with the Pallister-Killian syndrome. Following termination, a 220 g male fetus of 18 weeks was examined. A flattened nose and low-set ears were noted. In situ hybridization with a chromosome 12 centromeric probe in lymphocytes and skin cells unequivocally confirmed the karyotype and showed the presence of a single centromere in the abnormal chromosome, suggesting a true isochromosome. Chromosome analysis of various fetal tissues was performed and the following percentages of abnormal cells were found: skin 100 per cent, chorion 50 per cent, placenta 30 per cent, and blood 80 per cent. The high frequency of tetrasomic cells in fetal blood at this early gestational age is noteworthy, since most reports of this syndrome show a very low percentage of abnormal cells postnatally.     

Polynuclear Aromatic Hydrocarbons In Urban Atmospheres in Ontario

A comprehensive program comprising the collection of particulate samples at some 20 sampling sites throughout the Province of Ontario afforded seasonal or monthly composites of airborne particulates which were extracted for determinations of polynuclear hydrocarbons. Results indicated that concentrations of airborne carcinogens or potential carcinogens in urban air throughout Ontario are much lower than values reported in the literature for urban atmospheres in England. The project served as a test of the practicability of methods recommended for extractive, chromatographic, and spectroscopic aspects of a complex routine, and the experience gained should be useful as a guide in the ultimate establishment of standardized methods. The work has identified areas in the province where more detailed sampling would be useful, and has indicated analytical problems requiring investigation.     

Rollback Modeling: Basic and Modified

The rollback or proportional model is widely used in pollution control calculations and included in the guidelines for preparing and evaluating state implementation plans. Its basis and limitations are not widely known or understood. In this paper, the basis and limitations of rollback are listed and discussed, and extensions of basic rollback are proposed.     

Factors Affecting Resistivity in Electrostatic Precipitation

The following material is taken from a new book, “The Art of Electrostatic Precipitation,” authored by Mr. Katz and based on his 30 years of field experience with the subject. The book provides practical information on maintaining and upgrading precipitators; chapter titles include fundamentals, operation and maintenance, trouble solving, corrosion factors, methods to improve performance, test evaluation techniques, gas distribution and conditioning, case histories, and optimum designs.     

The UK landfill tax and the landfill tax credit scheme: operational weaknesses

The UK Landfill Tax and the related Landfill Tax Credit Scheme have now been in operation since October 1996. There have been a number of reviews to assess its operation and effectiveness that have led to some minor amendments. However, there continue to be concerns about operational weaknesses of the tax and the credit scheme. In particular, there is the risk that the tax may be evaded and there are fears that a lack of transparency and independence may undermine the fundamental principles of the Landfill Tax Credit Scheme. Following a recent report, the Secretary of State for the Department of the Environment, Transport and the Regions has set up an inquiry. This paper looks at some of the specific concerns that have been raised and the implications for waste management.