Correlation calibration-curve detection

It can be seen that in both cases a well correlating calibration curve in the shape of a straight line is obtained. It is also evident that for equal applied quantities the peak heights on the HPTLC plate are slightly more than twice as high as on the TLC plate. For this reason and on account of the fact that the baseline noise is markedly less on the HPTLC plate evaluated in reflectance mode as a result of its more homogeneous and smoother surface, the detection limit for S-BHC under the given conditions on the HPTLC pre-coated plate silica gel 60 is considerably less at 18 ng than on the TLC pre-coated plate silica gel 60 at 40 ng. 

Well correlating calibration curves in form of straight lines are obtained on both types of HPTLC plate for all three sample substances in the range of quantities examined. Although the applied quantities are identical, the peak heights on the HPTLC pre-coated plate cellulose are somewhat higher than those obtained on the HPTLC pre-coated plate silica gel 60. The detection limits determined by the peak heights and by the baseline noise for the three substances examined are listed in Table VII. 

Calibration curves for anthracyclines were constructed for the concentration range of 0.4 to 10,000 ng/mL. Correlation coefficients exceeded 0.999. Within-day and between-day coefficients of variation were less than 10%. Recoveries ranged from 89 to 109%. Accuracies were 91 to 107%. Limit of detection and limit of quantification were both 0.4 ng/mL. 

Calibration curves for voriconazole were constructed in concentration ranges of 0.1 to 10 jUg/mL. Correlation coefficients exceeded 0.9998. Intra-day and inter-day coefficients of variation were less than 3.8 and 6.1%, respectively. The average extraction recovery was 94.6%. The limit of detection and the limit of quantification were 15 and 50 ng/mL, respectively. 

A calibration curve was constructed over a concentration range of 1 to 50 fig/mL with a correlation coefficient of 0.998. Intra-assay and inter-assay coefficients of variation were less than 7.9 and 9.5%, respectively. Mean absolute recoveries at 10 and 20 fig/mL were 72 and 76%, respectively. Limit of detection was 0.3 fig/mL. Limit of quantification was 1.0 fig/mL. 

A linear calibration curve for epirubicin ranged from 0.50 to 100.0 ng/mL with a correlation coefficient of 0.999. Intra-day and inter-day coefficients of variation were less than 5.2 and 11.7%, respectively. Limit of detection and limit of quantification were 0.1 and 0.5 ng/mL, respectively. The extraction recoveries ranged from 89.4 to 101.2%. The validated method was successfully applied to the routine analysis of plasma samples from patients treated with epirubicin. 

Based on the 96-well format, OCT-PAMPA was proposed and has proved its ability to determine (indirectly) log Poet [87]. PAM PA is a method, first developed for permeability measurements, where a filter supports an artificial membrane (an organic solvent or phospholipids) [88, 89]. With this method, the apparent permeability coefficient (log P ) of the neutral form of tested compounds is derived from the measurement of the diffusion between two aqueous phases separated by 1-octanol layer (immobilized on a filter). A bilinear correlation was found between log Pa and log Poct> therefore log Poet of unknown compounds can be determined from log Pa using a calibration curve. Depending on the detection method used a range oflog P within —2 to +5 (with UV detection) and within —2 to +8 (with LC-MS detection) was successfully explored. This method requires low compound amounts (300 pi of 0.04 mM test compound) and, as for the previous method, samples can be prepared in DM SO stock solutions. For these experiments, an incubation time of 4h was determined as the best compromise in term of discrimination. The limitation of the technique lies in the lower accuracy values... 

Calibration curves for all BAs subjected to the sample work-up procedure were linear in the range 5-200 pmoles. The linear regression correlation coefficients varied from 0.991 to 0.999 and the slopes varied from 0.83 to 1.32, when the measured isotope ratios were plotted against the calculated ratios. Detection limits for all BAs investigated were 1 pg (2.5 fmol) injected onto the column. 

Fig. 18.5. Calibration curve obtained by the immunoassay procedure for the detection of anti-CTB using the ITO-PPB-coated optical fibers. The curve was fitted according to the equation y = A+B ln(.r), where x is the anti-CTB dilution value and y is the chemiluminescence response. The obtained correlation coefficient is R2 = 0.95.

Lin and Wu [137] established a simple capillary zone electrophoresis method for the simultaneous analysis of omeprazole and lansoprazole. Untreated fused-silica capillary was operated using a phosphate buffer (50 mM, pH 9) under 20 kV and detection at 200 nm. Baseline separation was attained within 6 min. In the method validation, calibration curves were linear over a concentration range of 5-100 /iM, with correlation coefficients 0.9990. RSD and relative error were all less than 5% for the intra- and interday analysis, and all recoveries were greater than 95%. The limits of detection for omeprazole and lansoprazole were 2 fiM (S/N = 3, hydroxynamic injection 5 s). The method was applied to determine the quality of commercial capsules. Assay result fell within 94—106%. 

A sensitive and rapid chromatographic procedure using a selective analytical detection method (electrospray ionization-mass spectrometry in SIM mode) in combination with a simple and efficient sample preparation step was presented for the determination of zaleplon in human plasma. The separation of the analyte, IS, and possible endogenous compounds are accomplished on a Phenomenex Lima 5-/rm C8(2) column (250 mm x 4.6 mm i.d.) with methanol-water (75 25, v/v) as the mobile phase. To optimize the mass detection of zaleplon, several parameters such as ionization mode, fragmentor voltage, m/z ratios of ions monitored, type of organic modifier, and eluent additive in the mobile phase are discussed. Each analysis takes less than 6 min. The calibration curve of zaleplon in the range of 0.1-60.0 ng/ml in plasma is linear with a correlation coefficient of >0.9992, and the detection limit (S/N = 3) is 0.1 ng/ml. The within- and between-day variations (RSD) in the zaleplon plasma analysis are less than 2.4% (n = 15) and 4.7% (n = 15), respectively. The application of this method is demonstrated for the analysis of zeleplon plasma samples [14]. 

A typical chromatogram obtained using this method is shown in Figure 12, and the retention times (Rt) and the relative retention time (Rrt) for pantoprazole sodium and some of its related compounds are shown in Table 6. The calibration curve for the assay determination, obtained over a concentration range of228-670 pg/mL, was found to be linear with a correlation coefficient of0.999. The recovery and relative standard deviation for various assays were 97.3-101.5 and 1.1, respectively. A calibration curve was also developed for pantoprazole sodium related compounds, covering a concentration range of 1 to 3 pg/mL, and which was found to be linear with a correlation coefficient of more than 0.999. The limits of detection and limits of quantitation were calculated as 0.15 pg/mL and 0.49 pg/mL, respectively. 

Fig. 4.16 shows a typical chromatogram for a standard 42pg L 1 phosphate solution and hypoxanthine peaks resulting from various phosphate samples after reaction with the enzyme. The calibration curve had a slope of 0.043 0.002 and an intercept of 0.124 0.033 with a correlation coefficient of 0.998. Linearity up to 30mg L 1 was observed. Relative standard deviation of triplicate runs was 10% or less. The detection limit, twice the signal of the blank, was determined to be 1.5mg L 1. 

Results after microscopy are expressed as the ratio between total number of positive nuclei (BrdU staining) and total number of nuclei (DAPI staining) counted in 10 or more randomly selected fields, averaged on the number of replicates per each experimental point. This kind of analysis thus allows to express a proliferative index for the cell population. Results after ELISA detection are simply expressed as o.d. values, vs. an untreated control. A calibration curve can be prepared, to correlate the acmal o.d. readings with the number of cells per well, so that cell numbers can be extrapolated on the linear portion of the curve. 

Gao described the use of CPMAS NMR to quantitate binary mixtures of crystalline forms of dela-virdine mesylate, with calculated limits of detection (LODs) of 1-1.5% and observed LODs of 2-3%. Mass fractions ranging from 2%i to 50%i of the minor component were analyzed, and a linear correlation was found between the calculated and NMR-measured values. The methods used here, similar to those described above for neotame, benefit from the fact that no calibration curve or internal standard is needed however. 

Under these conditions, the product exhibits a broad absorption band between 560 and 580 nm, and a microtiter plate reader set at 575 nm may be used for measurement. Correlation of absorbance with protein concentration has been performed using several protein standards, as shown in Figure 1.4, which also shows results obtained with the same protein standards by the Bradford method. These data demonstrate much better sensitivity with the ninhydrin method, and suggest an 10-fold improvement in detection limit. An important advantage of this method is that the differences in calibration curves obtained using different protein standards are relatively small. Interferences include free amino acids as well as other compounds containing amine groups. 

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