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The coupled-column (LC-LC) configuration consisting of a 3 microm C18 column (50 x 4.6 mm I.D.) as the first column and a 5 microm C18 semi-permeable-surface (SPS) column (150 x 4.6 mm I.D.) as the second column appeared to be successful for the screening of acidic pesticides in surface water samples. In comparison to LC-LC employing two C18 columns, the combination of C18/SPS-C18 significantly decreased the baseline deviation caused by the hump of the co-extracted humic substances when using UV detection (217 nm). The developed LC-LC procedure allowed the simultaneous determination of the target analytes bentazone and bromoxynil in uncleaned extracts of surface water samples to a level of 0.05 microg/l in less than 15 min. In combination with a simple solid-phase extraction step (200 ml of water on a 500 mg C18-bonded silica) the analytical procedure provides a high sample throughput. During a period of about five months more than 200 ditch-water samples originating from agricultural locations were analyzed with the developed procedure. Validation of the method was performed by randomly analyzing recoveries of water samples spiked at levels of 0.1 microg/l (n=10), 0.5 microg/l (n=7) and 2.5 microg/l (n=4). Weighted regression of the recovery data showed that the method provides overall recoveries of 95 and 100% for bentazone and bromoxynil, respectively, with corresponding intra-laboratory reproducibilities of 10 and 11%, respectively. Confirmation of the analytes in part of the samples extracts was carried out with GC-negative ion chemical ionization MS involving a derivatization step with bis(trifluoromethyl)benzyl bromide. No false negatives or positives were observed.

Background: Reflux in deep veins is an important pathophysiological factor of post-thrombotic syndrome which can be demonstrated by colour-coded duplexsonography. This study investigates the effect of different compression therapies on the reflux velocity in deep veins in patients with a post-thrombotic syndrome., Patients and Methods: Sixty patients with a post-thrombotic syndrome-confirmed by phlebography, in the deep veins of the calf and the thigh were investigated in two groups: In group A, 30 patients (mean age 58 +/- 10 years) received compression stockings (calf compression class II and III, thigh compression class II) and in group B 30 patients (mean age 58 +/- 14 years) received a Sigg short traction bandage of the calf. The velocity at the time of the greatest reflux in the popliteal vein was determined as reflux parameter with the colour-coded duplex sonography using a cuff applied at the calf. All patients stood upright and were measured with and without different kinds of compression therapies. The reflux velocities were graded as low, moderate and high., Results: A significant decrease of the reflux velocity by about more than 45% with compression therapy was found in both groups. The decrease of the refluxes in group A (mean 47.9%) did not differ significantly from the decrease of refluxes in group B (mean 55.8%). The greatest decrease of the reflux velocity under compression therapy was found in high-grade refluxes in both groups., Conclusion: A significant decrease of the reflux velocity in post-thrombotic syndrome can be readily demonstrated with different kinds of compression stockings as well as with bandages by means of colour-coded duplex sonography.

Reflux in deep veins is accepted as the most important pathophysiologic phenomenon in postthrombotic syndrome. The data proved by colour coded duplex sonography are demonstrated in this summary. As the different methods to provoke reflux yet are not examined we present our own results. A velocity of more than 10 cm/sec. at the time of the greatest reflux, a duration of reflux of more than 2 seconds and the lack of the valve signal are the best criteria to detect and quantify a postthrombotic syndromE by colour coded duplex sonography. Using Valsalva's maneuver, calf compression and cuff compression test to provoke reflux, the cuff compression technique proved to be the best one.

Tris(4-chlorophenyl)methanol (TCP) and tris(4-chlorophenyl)methane (TCPMe) were determined in aquatic organisms and sediment by a method based on Soxhlet extraction, gel permeation chromatography, fractionation over silica and gas chromatography/mass spectrometry (GC/MS) analysis. TCPMe was identified as the 4-substituted isomer after synthesis of this compound. TCP could be determined by GC/MS with negative chemical ionistation (GC/NCI-MS) with a detection limit of 0.02 g kg(-1) and a recovery of 90%. TCP concentrations in marine mammals from the North Sea and Dutch Wadden Sea ranged from 0.2 to 2 mg kg(-1), and those in marine and freshwater fish samples from 0.005 to 0.4 mg kg(-1) on a lipid wt basis. TCP concentrations in two Rhine delta sediment samples were 1.2 and 3.0 microg kg(-1) dry wt, respectively. TCPMe concentrations, determined by GC/MS with electron impact (GC/EI-MS), were 10-50% of the TCP concentration in all samples analysed.

Unlabelled: Comparison of colour-coded Doppler sonography, CW-Doppler and real time sonography in the diagnostics of the postthrombotic syndrome., Method: Colour-coded Doppler sonography, CW-Doppler and real time sonography were studied in 40 legs with postthrombotic syndrome, confirmed by phlebography. In a further step deep veins of patients with primary varicosis (n = 40) and a group of normal veins (n = 40) where compared with the postthrombotic group (n = 40)., Results: The sensitivity of CW-Doppler was 71.2% and that of real time sonography 67.5%, their specificity 92.3% and 92.2%, respectively, while colour-coded Doppler sonography had a sensitivity of 90.9% and a specificity of 88.9%. In addition, colour-coded Doppler sonography in combination with measurement of the peak velocity of venous reflux in deep veins had the highest sensitivity with 92.8% and specificity with 95.4% of all ultrasound methods tested. By means of colour-coded Doppler sonography together with measurement of the peak velocity of venous reflux, healthy persons and patients with varicosis could be distinguished with high significance (p < 0.003) by a peak velocity of venous reflux of more than 10 cm/s., Conclusion: In comparison to real time sonography and CW-Doppler, quantitative analysis of reflux in the deep veins by means of colour-coded Doppler sonography is the most valid ultrasound method in the diagnosis of postthrombotic syndrome.

Until now, the diagnosis of the postthrombotic syndrome is based upon venography. This study compares the diagnostic value of the CW-Doppler with the sonographic signs in the deep venous system observed in B-mode sonography and with the quantitative measurement of venous reflux by color Doppler sonography. 84 venous sections of 21 patients with phlebographically diagnosed PTS and substantial clinical signs were examined. CW- Doppler and B-mode sonography did not show significant differences compared to phlebographic findings. Color doppler sonography, however, showed signs which significantly went beyond those seen in venography.

Both Solubility Parameter (SOLPAR) and Linear Solvation Energy Relationship (LSER) theory utilize molar volume and energies as descriptors for distribution phenomena. They provide powerful methods for the prediction of the GLC retention indices of chlorobenzenes (CBzs) and tetrachlorodibenzo[p]dioxins (TCDDs). Almost complete isomer resolution is obtained with correlation coefficients (r) of greater than or equal to 0.9984 (CBzs) and greater than or equal to 0.9839 (TCDDs). The n-octanol/water partition coefficient (log Kow) of CBzs can be calculated with a standard error of regression of 0.04, which compares favourably with standard deviations of 0.03-0.26 in mean values based on four different experimental methods. The HPLC capacity factor of TCDDs on C18 columns can be predicted by SOLPAR with moderate accuracy (r = 0.9470), allowing for a preliminary calculation of log Kow. A simplified LSER method fails.