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Method Comparison (method + comparison)
Selected AbstractsMicrofluidic chip-capillary electrophoresis for two orders extension of adjustable upper working range for profiling of inorganic and organic anions in urineELECTROPHORESIS, Issue 18 2010Wen Peng Guo Abstract To meet the need for onsite monitoring of urine anions, a microfluidic chip-capillary electrophoresis device was designed, fabricated and tested to extend the upper CE working range for an enhancement up to 500 fold (100 fold for sample dilution and 5 folds for CE injection) in order to analyze highly variable anionic metabolites in urine samples. Capillaries were embedded between two PMMA plates with laser-fabricated microchannel patterns to produce the microfluidic chip-capillary electrophoresis to perform standard/sample dilution and CE injection with adjustable dilution ratios. A circular ferrofluid valve was incorporated on-chip to perform cleanup and conditioning, mixing and dilution, injection and CE separation. Under optimized conditions, a complete assay for four samples can be achieved within an hour for 15 anions commonly found in urines. Satisfactory working ranges (0.005,500,mM) and low detection limits (0.5,6.5,,M based on S/N =2) are obtained with satisfactory repeatability (RSD, n=5) 0.52,0.87% and 4.1,6.5% for migration time and peak area, respectively. The working ranges with two orders adjustable upper extension are adequate to cover all analytes concentrations commonly found in human urine samples. The device fabricated shows sufficiently large experimentally verifiable enhancement factor to meet the application requirements. Its reliability was established by more than 94% recoveries of spiked standards and agreeable results from parallel method comparison with conventional ion chromatography method. The extension of the upper CE working range enables flexible onsite dilution on demand, a quick turn-around of results, and a low-cost device suitable for bedside monitoring of patients under critical conditions for metabolic disorders. [source] Determination of tryptamine derivatives in illicit synthetic drugs by capillary electrophoresis and ultraviolet laser-induced fluorescence detectionELECTROPHORESIS, Issue 12 2005Carolin Huhn Abstract A method based on separation by capillary electrophoresis combined with UV-laser-induced fluorescence detection (,ex,=,266,nm) was developed for the determination of nine tryptamine derivatives of forensic interest and potential matrix constituents. The composition of the separation electrolyte was optimized with respect to the resolution of solutes of interest and to the sensitivity of fluorescence detection. Native ,-cyclodextrin was employed as a complex forming modifier of the electrophoretic separation and fluorescence-enhancing agent. With the help of a stacking procedure, limits of detection of 0.1,6,µg/L for all analytes were obtained. The repeatability for the peak area (at a concentration of the analyte about 100 times the LOD) was less than 2.3%,RSD. A second HPLC method was developed, and its analytical parameters were evaluated for an estimation of the accuracy of the CE-LIF method and for method comparison. The results of the determination of tryptamine derivatives in the samples of forensic interest obtained with the two independent methods are in good agreement. [source] Evaluation of Ves-Matic Cube 200 , an automated system for the measurement of the erythrocyte sedimentation rateINTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 1p2 2010E. PEROVIC Summary Ves-Matic Cube 200 is fully automated analyzer that performs erythrocyte sedimentation rate (ESR) measurement using the standard ethylenediaminetetraacetic acid blood sample tube, thus markedly reducing the analytical time and avoiding the need for an extra blood sample. The aim of this study was to assess the automatic Ves-Matic Cube 200 system for the measurement of ESR in comparison with the original International Council for Standardization in Hematology reference method (Westergren). The evaluation comprised accuracy which was established using a 95% confidence interval (CI) for the mean difference between Ves-Matic Cube 200 and Westergren method (mean of difference: 0.47 ± 6.84 mm/h; 95% CI: ,0.376 to 1.325 mm/h), within-run imprecision for samples with ESR values of 9, 42 and 95 mm/h (coefficients of variation: 9.19%, 13.88% and 5.66%, respectively) and method comparison (, = 0.95; Passing-Bablok regression equation: Y = ,0.0435 + 1.0435 X; bias: ,0.5; limits of agreement: ,13.9 to 12.9). Stability was estimated after 24 h storage either at 4 °C and room temperature (mean of differences: ,1.91 mm/h; 95% CI: ,4.852 to 1.037 mm/h and mean of differences: ,12.48 mm/h; 95% CI: ,16.580 to ,8.390 mm/h, respectively). The obtained results suggest that the Ves-Matic Cube 200 automated analyzer is reliable system for the measurement of ESR in clinical laboratories. [source] Implementation of three-dimensional wavelet encoding spectroscopic imaging: In vivo application and method comparisonMAGNETIC RESONANCE IN MEDICINE, Issue 1 2009Richard Young Abstract We have recently proposed a two-dimensional Wavelet Encoding-Spectroscopic Imaging (WE-SI) technique as an alternative to Chemical Shift Imaging (CSI), to reduce acquisition time and crossvoxel contamination in magnetic resonance spectroscopic imaging (MRSI). In this article we describe the extension of the WE-SI technique to three dimensions and its implementation on a clinical 1.5 T General Electric (GE) scanner. Phantom and in vivo studies are carried out to demonstrate the usefulness of this technique for further acquisition time reduction with low voxel contamination. In wavelet encoding, a set of dilated and translated prototype functions called wavelets are used to span a localized space by dividing it into a set of subspaces with predetermined sizes and locations. In spectroscopic imaging, this process is achieved using radiofrequency (RF) pulses with profiles resembling the wavelet shapes. Slice selective excitation and refocusing RF pulses, with single-band and dual-band profiles similar to Haar wavelets, are used in a modified PRESS sequence to acquire 3D WE-SI data. Wavelet dilation and translation are achieved by changing the strength of the localization gradients and frequency shift of the RF pulses, respectively. The desired spatial resolution in each direction sets the corresponding number of dilations (increases in the localization gradients), and consequently, the number of translations (frequency shift) of the Haar wavelets (RF pulses), which are used to collect magnetic resonance (MR) signals from the corresponding subspaces. Data acquisition time is reduced by using the minimum recovery time (TRmin), also called effective time, when successive MR signals from adjacent subspaces are collected. Inverse wavelet transform is performed on the acquired data to produce metabolite maps. The proposed WE-SI method is compared in terms of acquisition time, pixel bleed, and signal-to-noise ratio to the CSI technique. The study outcome shows that 3D WE-SI provides accurate results while reducing both acquisition time and voxel contamination. Magn Reson Med 61:6,15, 2009. © 2008 Wiley-Liss, Inc. [source] Comparison of methods for determining the numbers and species distribution of coliform bacteria in well water samplesJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2001R.M. Niemi R.M. NIEMI, M.P. HEIKKILÄ, K. LAHTI, S. KALSO AND S.I. NIEMELÄ. 2001. Aims: Enumeration of coliform bacteria and Escherichia coli is the most widely used method in the estimation of hygienic quality of drinking water. The yield of target bacteria and the species composition of different populations of coliform bacteria may depend on the method. Three methods were compared. Methods and Results:,Three membrane filtration methods were used for the enumeration of coliform bacteria in shallow well waters. The yield of confirmed coliform bacteria was highest on Differential Coliform agar, followed by LES Endo agar. Differential Coliform agar had the highest proportion of typical colonies, of which 74% were confirmed as belonging to the Enterobacteriaceae. Of the typical colonies on Lactose Tergitol 7 TTC agar, 75% were confirmed as Enterobacteriaceae, whereas 92% of typical colonies on LES Endo agar belonged to the Enterobacteriaceae. LES Endo agar yielded many Serratia strains, Lactose Tergitol 7 TTC agar yielded numerous strains of Rahnella aquatilis and Enterobacter, whereas Differential Coliform agar yielded the widest range of species. Conclusions: The yield of coliform bacteria varied between methods. Each method compared had a characteristic species distribution of target bacteria and a typical level of interference of non-target bacteria. Identification with routine physiological tests to distinct species was hampered by the slight differences between species. High yield and sufficient selectivity are difficult to achieve simultaneously, especially if the target group is diverse. Significance and Impact of the Study: The results showed that several aspects of method performance should be considered, and that the target group must be distinctly defined to enable method comparisons. [source] | |||||||||||||