Sensitivity and Reproducibility

For a soluble lignin sample, the standard deviation for the yield of main C6C3 monomeric products is less than 2%. For lignocellulosic materials, it is higher (5-10%) owing to the greater complexity of the chromatogram. 

The limit of detection (LOD) of the candidate reference HPLC method for CDT in % AUC for asialo- and monosialotransferrin was approximately 0.05% of total serum transferrin in the normal concentration range ( 2.0-3.5 g L ). For routine use, a limit of quantification (LOQ) of 0.1 % is applied. It should be noted that the LOD and LOQ depend in part on the transferrin concentration in the serum sample. Furthermore, as all glycoforms except tetrasialotransferrin occur at low concentrations, and the absorbance of the transferrin-iron complex at 460-470 nm is only 10% compared with its absorbance at 280 nm, the performance of the photometric detector is very important. However, in dilution studies, using a serum sample containing a very high transferrin concentration and water as diluent (tested range 

5 gL ), the AUC for total transferrin was linear and the calculated relative amount of disialotransferrin was not markedly changed at the lower total transferrin concentrations (CV 6.0%). The intra- and inter-assay imprecision for serum samples containing normal and elevated disialotransferrin levels (range 1-5.6%) were below 5% (CV) and the retention times for the transferrin glycoforms were also stable over time. 

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The methods for detection and quantitation of radiolabeled tracers are deterrnined by the type of emission, ie, y-, or x-rays, the tracer affords the energy of the emission and the efficiency of the system by which it is measured. Detection of radioactivity can be achieved in all cases using the Geiger counter. However, in the case of the radionucHdes that emit low energy betas such as H, large amounts of isotopes are required for detection and accurate quantitation of a signal. This is in most cases undesirable and impractical. Thus, more sensitive and reproducible methods of detection and quantitation have been developed. 

Selenium is required, but levels must fall into a narrow window. Both deficiency and toxicity symptoms occur. The element is also used therapeutically in cancer treatment. It is the co-factor of the enzyme glutathione peroxidase which is thought to play an important role in oxygen toxicity. The determination of Se in blood or serum is not easy, as many incorrect, inaccurate and imprecise methods have been published (Magee and James 1994). A suggested procedure for Se in body fluids is based on GF-AAS (Thomassen et al. 1994)- For tissues SS-AAS may be used (Fler-ber 1994a). Recent developments by Turner et al. (1999) show that LC-ICP-MS is sensitive and reproducible at low levels. 

Biological, individual, and variations between individuals (such as gender, age, and nutrition) affect peptidomes and require careful consideration in order to find valid biomarkers. A few, equally important factors for successful proteomic biomarker research are high sample quality, high sensitivity, and reproducibility that depend on proper selection of the high quality samples. 

Currently, LC-MS is widely used for the analysis of polar compounds, such as medicinal metabolites and bioactive peptides, since the interface has been improved and several new ionization methods have been developed. The sensitivity and reproducibility are sufficient for a daily quantitative analysis. The usefulness of the LC-MS has been demonstrated for studies on Type II pheromones using a time-of-flight MS with electrospray ionization (ESI) [180]. Each epoxydiene derived from the (Z3,Z6,Z9)-triene shows three ion series of [M+NHJ+, [M+H]+, and [M-OH]+ with high resolution and good sensitivity, indicating its molecular formula. In addition to these, characteristic fragment... 

Niclosamide and other some antiamebic and anthelmintic drugs were determined spectrophotometrically in pharmaceuticals based on the formation of colored species with p-N,N-d i met hyI phenyicncdiaminc 2HCI and chloramines-T [48]. The method was simple, sensitive, and reproducible within 1%. 

Usof et al. [59] utilized the derivatizing agent NPM and reversed-phase HPLC as a method for analysis of (/))-pcnicillamine. The relative standard deviation for within-precision and between-precision of 500 nM standard (z>)-penicillamine were 2.27% and 2.23%, respectively. Female Sprague-Dawley rats were given 1 g/kg (/+penicillamine I.P., and the amounts of (iff-penicillamine in the samples were subsequently determined. The assay is rapid, sensitive, and reproducible for determining it in biological samples. 

The fluctuation of the temperature in the mixing device, reaction coil, and flow cell affects the CL reaction velocity and emission duration thus affecting the sensitivity and reproducibility. Therefore, it is preferable to keep a constant temperature [11],... 

One problem associated with this design is that the Ru(bpy)32+ reservoir evaporates over time and the Ru(bpy)33+ concentration changes as the CE capillary effluent dilutes it, which affect both sensitivity and reproducibility of the CL response. To overcome this problem, recently a new in situ-generated Ru(bpy)33+ CL cell has been proposed [98], In this design, Ru(bpy)32+ is continuously delivered to the cell and Ru(bpy)33+ is then generated at the interface of the separation capillary and the working electrode. Electrochemical control of the production of Ru(bpy)33+ at the distal end of the separation capillary without interference from the CE current is provided and finally the ECL process is cou-... 

The analysis for tracer should be convenient, sensitive, and reproducible. 

Pregnalatto and Sabino200 incorporated glycerine into the ninhydrin solution and reported an improved sensitivity and reproducibility enabling neomycin concentrations as low as 4 yg/ml to be determined. An automated ninhydrin assay has been described by Kaptionak, Biernacka and Pazdera O based on a modified Moore and Stein methodl l. 

The high sensitivity and reproducibility of currently used instruments also allows to directly monitor the binding of small ligands, i.e. disaccharides or monosaccharides, to immobilized lectins.75 77 Fig. 3 illustrates the binding of small glycans to BclA lectin from Burkholderia cenocepacia.26... 

Results obtained for the application of HPLC—APCI—MS to the quantification of M2D—C3—O—(EO ) —CH3 recoveries from Chenopo-dium album plant foliage are shown in Table 2.8.5, as compared with HPLC-LSD analysis [29], The improvements in the sensitivity and reproducibility were obtained with the use of HPLC—APCI—MS as the analytical method and the HPLC—APCI—MS method also enabled detection of the n = 3 M2D-C3-0-(E0) -CH3 molecule. 

A direct method has been developed for the spectrophotometeric determination of Pd(II) with sodium-1-methyl-l-propylthioxanthate as a complexing reagent in the micellar media. Beer s law was obeyed in the concentration range 0.84-7.5pg/mL for Pd(II) under the optimized conditions. Calibration curve was constructed at the absorption maxima (/.m(ix) i.e. 370nm for Pd(II). Sandell s sensitivity and molar absorptivity have been found to be 0.0060pg/cm2 and 8.6xl04 L/mol/cm for Pd(II). The developed method has been found to be quite simple, rapid, sensitive and reproducible results were obtained. 

Radioimmunoassay (RIA) was among the first methods used for Lp(a) quantifications (A6). This method is sensitive and reproducible its major drawback remains the radioactive tracer and the high sample dilution required. 

Pagliarulo V, George B, Beil SJ, Groshen S, Laird PW, et al. 2004. Sensitivity and reproducibility of standardized competitive RT-PCR for transcript quantitation and its comparison with real time RT-PCR. Mol Cancer 3 5... 

Our RIA was developed to optimize the main criteria of simplicity, sensitivity and reproducibility. The format which was eventually developed was based on the addition of a "second antibody". This procedure separates the bound from the free label by precipitation of the anti-STXOL antibody, which was raised in rabbits, with an antibody produced in goats against rabbit IgG. The source of the labeled hapten was H-STXOL. 

In this work, we adapted a method for the analysis of beer aldehydes using solid-phase microextraction (SPMF) with on-fiber derivatization. This extraction technique does not require solvents, consists of a one-step sample preparation procedure, and provides high sensitivity and reproducibility. It enabled a detailed study of aldehyde level changes during packaged beer storage. 

All detection methods have limitations. The most severe are sensitivity and reproducibility. Happily, the past few years have seen a flurry of technologies developed specifically to detect cells at rather low environmental concentrations. The most prominent of these methods are outlined here, along with notes of their merits and reported sensitivity. Several excellent reviews have recently dealt with this topic (Drahos, 1991b Atlas et al., 1992 Edwards, 1993 Prosser, 1994). 

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