Variations in concentrations and compositions of polycyclic aromatic hydrocarbons (PAHs) in coals related to the coal rank and origin.

The release of unburnt coal particles and associated polycyclic aromatic hydrocarbons (PAHs) may cause adverse impacts on the environment. This study assessed variations in the concentration and composition of PAHs in a set of fifty coal samples from eleven coal basins worldwide. The maximum PAH concentrations at high volatile bituminous rank were recorded in samples from a single basin. Considering the entire sample set, the highest PAH concentrations were in fact found outside of this rank range, suggesting that the maceral composition and thus the coal's origin also influenced PAH concentrations. The examination of the PAH compositions revealed that alkylated 2-3 ring PAHs remain dominant compounds irrespective of coal rank or origin. Multivariate analysis based on PAH and maceral content, bulk and maturity parameters allowed the recognition of seven groups with different rank and origin within the coal sample set.

Native polycyclic aromatic hydrocarbons (PAH) in coals - a hardly recognized source of environmental contamination.

Numerous environmental polycyclic aromatic hydrocarbon (PAH) sources have been reported in literature, however, unburnt hard coal/ bituminous coal is considered only rarely. It can carry native PAH concentrations up to hundreds, in some cases, thousands of mg/kg. The molecular structures of extractable compounds from hard coals consist mostly of 2-6 polyaromatic condensed rings, linked by ether or methylene bridges carrying methyl and phenol side chains. The extractable phase may be released to the aquatic environment, be available to organisms, and thus be an important PAH source. PAH concentrations and patterns in coals depend on the original organic matter type, as well as temperature and pressure conditions during coalification. The environmental impact of native unburnt coal-bound PAH in soils and sediments is not well studied, and an exact source apportionment is hardly possible. In this paper, we review the current state of the art.

Method for determination of methyl tert-butyl ether in gasoline by gas chromatography.

A simple method for the determination of methyl tert-butyl ether (MTBE) in gasoline has been developed. The separation of MTBE from other analytes was controlled by the use of gas chromatography-mass spectrometry in the full scan mode using the characteristic primary, secondary and tertiary ions m/z 73, 57 and 43. The sample mass spectrum did not show any superimposition of other analytes. The separation from the common gasoline component 2-methylpentane was sufficient for reliable quantitation. An application of the developed conditions using gas chromatography with flame ionization detection was performed by the analysis of regular, euro super, super premium unleaded and 'Optimax' gasoline from petrol stations in the area of Frankfurt/Main, Germany. Regular unleaded gasoline shows an average MTBE content of 0.4% (w/w), whereas the MTBE content in euro super gasoline varies between 0.4 and 4.2% (w/w). The blending of MTBE to super premium has increased from 8.2% (w/w) in 1998 to 9.8% (w/w) on average in 1999. The recently introduced gasoline 'Optimax' shows an average MTBE content of 11.9% (w/w). The presented method might also be used for the analysis of other ethers, such as ethyl tert-butyl ether, which requires the use of another internal standard.

Sensitive method for determination of methyl tert-butyl ether (MTBE) in water by use of headspace-SPME/GC-MS.

A simple and rapid method for the determination of methyl tert-butyl ether (MTBE) in water by headspace-solid-phase microextraction (headspace-SPME) at sub-microg/L concentrations is described. On using a cooled SPME fiber coated with a 75-microm layer of poly(dimethylsiloxane)/carboxene and heating the sample to 35 degrees C, about 4 times more MTBE is extracted compared to SPME extraction with the fiber placed in the water sample. Stable analytical conditions with a detection limit of 10 ng/L are achieved. By use of a sample volume of 4 mL in a 10 mL vial, a sodium chloride content of 10% (w/w), and an extraction time of 30 min, the total time of an analytical cycle was optimized to 39 min. Precise linearity of R2>0.9991 and R2>0.9916 in the calibration range of 20-5000 ng/L and 20-100 ng/L, both in addition to blanks, respectively, and relative standard deviations of 10% (100 ng/L, long-term) and 11% (20 ng/L, short-term) are presented. The recovery is well within the accepted limits of 83-118% at a concentration of 100 ng/L and even close thereto at trace levels of 20 ng/L (96-125%). The data presented for a concentration of 100 ng/L are examined by statistical methods and show results for the T test at the 95% confidence level. Due to the large concentration range covered, the method is well suited for the monitoring of MTBE in the aquatic environment.

[MR mammography of fatty tissue necrosis]. / MR-Mammographie der Fettgewebsnekrose.

PURPOSE: To evaluate MR-imaging for the differentiation of fatty necrosis (FN) of the breast. MATERIAL AND METHODS: In 1016 MR mammographies FN was found in 13 patients aged 44 to 69 years. In all studies we used a proton-weighted fat suppressed sequence (STIR) and serial T1-weighted gradient echo sequences before and after bolus injection of Gd-DTPA, MRI was correlated to ultrasound and in 8 cases to mammographic findings. RESULTS: All 15 FN displayed fat-isointense signal on T1-weighted and on proton-weighted, fat-suppressed sequences. They were delineated by a more or less wide rim of low signal intensity with sharp border to the center. After intravenous injection of gadopentetate dimeglumine they showed no increase of signal intensity in the centre and no increase, or only a minor increase, of the rim. Ultrasound could not distinguish FN from recurrent tumour in 6 cases. 7 FN looked like atypical cysts. CONCLUSION: MR-mammography is very promising in the diagnosis of FN.

[MR-mammography assessment of tumor response after neoadjuvant radiochemotherapy of locally advanced breast carcinoma]. / MR-mammographische Beurteilung des Tumoransprechverhaltens nach neoadjuvanter Radiochemotherapie lokal fortgeschrittener Mammakarzinome.

PURPOSE: We investigated the role of magnetic resonance mammography in monitoring tumour response of locally advanced breast cancer (LABC) after neoadjuvant radiochemotherapy. MATERIAL AND METHODS: 17 patients with LABS had a magnetic resonance mammography and ultrasonography before and after neoadjuvant radiochemotherapy. RESULTS: After neoadjuvant radiochemotherapy 14 patients showed in MR-mammography less pronounced and prolonged enhancement without washout. After treatment three patients had signal intensity-time curves still characteristic for tumour. Ultrasonography was true negative in two patients, true positive in 12 and false positive in three patients. CONCLUSION: Magnetic resonance mammography is suitable for monitoring tumour response after radiochemotherapy of LABC. However, a negative MRI does not exclude a residual tumour. Ultrasonography is of limited value in monitoring therapy of LABC.

[Initial experiences with MR-mammography in after-care following surgical flap treatment of breast carcinoma]. / Erste Erfahrungen mit der MR-Mammographie in der Nachsorge bei lappenunterstützter operativer Behandlung des Mammakarzinoms.

PURPOSE: To demonstrate typical MR mammographic findings after plastic surgery of breast cancer. PATIENTS AND METHODS: Postoperative (7-38 months, median 13) MR mammographic examinations of 25 patients operated for breast cancer (11 latissimus dorsi-flaps (LAT), 14 rectus abdominis myocutaneous-flaps (TRAM)), were reevaluated. The examinations were performed with a breast coil at 1 T. The sequences applied were a fat-suppressed 2-D turbo IR-sequence proton-weighted and a T1-weighted FLASH 3-D sequence as dynamic series. RESULTS: Scars between the myocutaneous flap and the remaining breast tissue always appeared in form of a ligament or septum. Signal and perfusion characteristics of scar tissue and muscle stalk in this investigation were clearly different from those of tumour. One tumour recurrence and one fat necrosis was found and rectified by biopsy. CONCLUSION: MR mammography is a very valuable diagnostic method for postoperative evaluation of myocutaneous flap-based therapy of breast cancer.

Effect of topically applied oxymetazoline on tear volume and tear flow in humans.

Vasoconstrictive, alpha-sympathicomimetic eye drops are ophthalmic drugs that are extensively used. However, patients often complain of typical dry eye symptoms, especially after long-lasting application of such eye drops. In the present study, the effect of sympathicomimetic eye drops (0.026% oxymetazoline) on the tear volume and tear flow of 38 healthy individuals was determined quantitatively by means of objective fluorophotometry. Both tear volume and tear flow were found to be significantly (P less than 0.001) decreased up to 6 h after instillation, reaching a minimum 90 min after application (tear volume: -63%; tear flow: -71%). Thus, alpha-sympathicomimetic eye drops containing 0.026% oxymetazoline lead to a marked and protracted decrease in tear volume and tear flow. After frequent or long-lasting application, this fact may be responsible for severe dry eye conditions.

[Effect of vasoconstrictor eyedrops on tear volume and tear secretion]. / Einfluss vasokonstriktiver Augentropfen auf Tränenvolumen und Tränensekretion.

Vasoconstrictive, alpha-sympathicomimetic eye drops are ophthalmic drugs that are extensively used. However, patients often complain of typical dry eye symptoms, especially after long-lasting application of such eye drops. In the present study, the effect of sympathicomimetic eye drops (oxymetazoline 0.026%) on the tear volume and tear flow of 16 healthy individuals was determined quantitatively by means of objective fluorophotometry. Both tear volume and tear flow were found to be significantly (p less than 0.001) decreased 3 h after instillation (tear volume: -52%; tear flow: -31%). Thus, alpha-sympathicomimetic eye drops containing oxymetazoline 0.026% lead to marked and protracted decrease in tear volume and tear flow. After frequent or long-lasting application, this fact may be responsible for severe dry eye conditions.