Calibration curve construction

Using a newly developed, transversely heated graphite atomizer and D2-back-ground correction (for details see Sections 2.2 and 4.3), Cd, Pb and Cr were determined in cement and river sediment samples. Of the various calibration approaches applied the best results, also in comparison with wet chemical procedures, were achieved with calibration curves constructed by means of different BCR CRMs with different analyte concentrations and usually n = to individual intakes (Nowka and Muller 1997). 

Figure 3 Layout of competitive solid-phase antibody immunoassay format in an incubation step antigen (Ag) and labeled antigen (Ag-L) compete for the solid-phase antibodybinding sites (Ab) after the solid-phase antibodies are washed, the activity of the bound labeled antigen is measured, and a calibration curve constructed. The measured signal is inversely proportional to the antigen concentration.

Fig. 4.13 Univariate calibration curves constructed at 770 nm for four tested vapors over 0 0.1 PI P0 concentration range. Reprinted from Ref. 15 with permission. 2008 Institute of Electrical and Electronics Engineers...

Figure 21-4 Atomic fluorescence from Pb at 405.8 nm. Water containing parts per billion (ppb) of colloidal PbC03 was ejected from a capillary tube and exposed to a 6-ns pulse of 1 064-nm laser radiation focused on the drop. This pulse created a plume of vapor moving toward the laser. After 2.5 xs, the plume was exposed to a 193-nm laser pulse, creating excited Pb atoms whose fluorescence was measured for 0.1 ps with an optical system whose resolution was 0.2 nm. The figure shows a calibration curve constructed from colloidal PbC03 standards and the signal from tap water containing 2 ppb Pb. /From S.K.H0 and N. H. Cheung, Sub-Part-per-Billion Analysis of Aqueous Lead Colloids by ArF Laser Induced Atomic Fluorescence," Anal. Chem. 2005, 77, 193.]...

Route 2 (a) Using the retention volume calibration curve in conjunction with the polystyrene HDV calibration curve, construct an ap-... 

The free enzymes FIA system permitted analysis in a linear range of 0.05-1.0 g of ethanol/L, a sampling frequency of 15 analyses/h, and a relative SD of 3.5%. The total volumetric flow was 5 mL/min, and the six-channel injection valve permitted the introduction of 0.185 mL (loop volume) of enzymes-reagents solution per analysis (4). Ethanol solutions of different concentrations were used to determine the linear working range and for the calibration curve construction (Fig. 4), presenting a linear relation up to 1 g of ethanol/L with a correlation factor of 0.9899 for six samples. 

The first change is, of course, to increase the sensitivity of the detector. Most HPLC detectors contain range switches that make this a simple matter. When range switching is carried out, it is useful to determine whether calibration curves constructed at one range setting are still valid at another. 

The measurement method is comparative. All the measurements are made by comparison with a calibration curve constructed from standards of accurately known concentration... 

Figure 2. (a). In situ XANES spectra for PtMo catalyst collected at the Mo k-edge (20,000 eV) at the indicated electrode potentials, (b). XANES Calibration curve constructed using the change in edge energy as a function of oxidation state of Mo. 

The linear region for a calibration curve by the Stewart assay is between 10 and 100. g of PC (DPPC, DSPC, or mixtures with Ars (see below) can also be used at this range). The Stewart assay was found to detect arsonolipids (when present in high concentrations in the ARSL dispersions). Thereby, known concentrations of phospholipids mixed with arsonolipids (at the specific analogy used in the ARSL samples measured, in each case), are initially measured and their values are used for calibration curve construction. 

Quantitation was made through the use of external standards. The calibration curve, constructed from measurement of the total area under the chromatogram versus known weights of standard LAS, was linear from 0 to 3 ug LAS injected. The sensitivity for total LAS was 10 ppb for aqueous samples and 100 ppb for solid samples when using the suggested sample volumes. The reproducibility of the entire method expressed as a relative standard deviation, was 4 % for aqueous samples and 10 % for solid samples. Recovery of standard additions of LAS was 94% minimum. 

Similar to conventional CE, HT-CE and HT-ME are applicable to quantitative analyses, as the calibration curve constructed from the transformed data shows good linearity even at concentrations less than the concentration limit of detection obtained using conventional CE (18, 29). HT-CE has been used in the analysis of actual samples. For instance, McReynolds et al. have successfully applied the HT-CE method with UV detection to the analysis of nitrates and nitrites in biological samples (30). We have also shown that the HT... 

Near-IR spectroscopy is quickly becoming a preferred technique for the quantitative identification of an active component within a formulated tablet. In addition, the same spectroscopic measurement can be used to determine water content, since the combination band of water displays a fairly large absorption band in the near-IR. In one such study (68), the concentration of ceftazidime pentahydrate and water content in physical mixtures has been determined. Due to the ease of sample preparation, near-IR spectra were collected on 20 samples and subsequent calibrations curves constructed for active ingredient and water content, respectively. An interesting aspect of this study was the determination that the calibration samples must be representative of the production process. When calibration curves were constructed from laboratory samples only, significant prediction errors were noted. However, when calibration curves were constructed from laboratory and production samples, realistic prediction values were determined ( 5%). 

Linearity or dynamic linear range, the concentration range over which the detector response is linear, should be of at least four orders oFmagnitude. If the concentration of sample is outside this range, then the sample should be diluted or an extended calibration curve constructed. 

The separation of dairy proteins by CE has been generally carried out by CZE and has been exhaustively covered in several review papers, - - thus Table 30.8 only presents the key methodologies that offer the reader an overview of their most distinctive features. Basically, dairy protein analysis has been performed in whole milk for the simultaneous determination of caseins and whey proteins, or in fractions isolated from milk after casein precipitation. The first approach being used when the quantitative determination of the major proteins is required for the calculation of casein/whey protein ratios or for authentication purposes where an analysis of the whole protein profile is required. In both cases, accurate quantitative data must be derived. However, few studies have addressed the analysis of both groups of proteins in a single run by presenting quantitative data based on calibration curves constructed with analytical standards and good recovery of all proteins from milk samples. 

Results of analysis of VO in presence of IO3 or 10 at pH 2.2 and under the optimum conditions are summerized in Table 2. The observed concentrations are based on the calibration curve constructed for VOJ alone in the solution. 

Calibration Curves Construction calibration curves were constructed for both catechin and gallic acid using solutions of 8, 16, 24, 32 and 40 pg/ml and applying the procedure above described for the extract samples. Three replicates for each point were used. 

As mentioned previously, at the Y-shaped junction droplet formation takes place in a one-step mechanism that is determined by the viscous shear force and the interfacial tension force [11]. Because of this special feature, it was possible to directly measure the effect of interfacial tension on the droplet size using various systems with different static interfacial tensions. Water/ ethanol mixtures were used as continuous phase, and hexadecane and silicon oils as to-be-dispersed phase. The size of the droplets was recorded and a calibration curve constructed, and based on that curve, the dynamic interfacial tension could be estimated in systems that contain surfactants. 

As described in Chapter 1, a calibration curve constructed for polystyrene can be used to determine the molecular weight of a second polymer if the Mark-Houwink coefficients of the two polymers in the solvent used for SEC analysis are known. The Mark-Houwink coefficients for cellulose in a variety of solvents have been tabulated (138). 

Empirical approach. In SEC, a calibration curve of log molecular mass (log M) V. retention volume (Fr) must first be constructed in order to calculate molecular mass averages of the polymers in question. It is usual to report the results as polystyrene equivalent molecular masses, using a calibration curve constructed with polystyrenes of known molecular masses having narrow MMD. For accurate estimation of copolymer molecular weight, one must use a calibration curve for the copolymer in question. Therefore, it is necessary and important to estimate molecular mass of the copolymer species eluted at retention volume i. 

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