Plasma calibration curves

Fig. 11 Dispersion stabilities of CNTs in water with 0.01 vol.% CNT addition, (a) Optical absorbance of the CNT nanofluids at wavelength of 530 run. (b) Relative concentrations of the CNTs suspended in the fluid phase calculated using the inserted calibration curve. Plasma conditions and CNT sample designation are given in Table 3...

The choice between X-ray fluorescence and the two other methods will be guided by the concentration levels and by the duration of the analytical procedure X-ray fluorescence is usually less sensitive than atomic absorption, but, at least for petroleum products, it requires less preparation after obtaining the calibration curve. Table 2.4 shows the detectable limits and accuracies of the three methods given above for the most commonly analyzed metals in petroleum products. For atomic absorption and plasma, the figures are given for analysis in an organic medium without mineralization. 

Sensitivity Sensitivity in flame atomic emission is strongly influenced by the temperature of the excitation source and the composition of the sample matrix. Normally, sensitivity is optimized by aspirating a standard solution and adjusting the flame s composition and the height from which emission is monitored until the emission intensity is maximized. Chemical interferences, when present, decrease the sensitivity of the analysis. With plasma emission, sensitivity is less influenced by the sample matrix. In some cases, for example, a plasma calibration curve prepared using standards in a matrix of distilled water can be used for samples with more complex matrices. 

An ICP-OES instrument consists of a sample introduction system, a plasma torch, a plasma power supply and impedance matcher, and an optical measurement system (Figure 1). The sample must be introduced into the plasma in a form that can be effectively vaporized and atomized (small droplets of solution, small particles of solid or vapor). The plasma torch confines the plasma to a diameter of about 18 mm. Atoms and ions produced in the plasma are excited and emit light. The intensity of light emitted at wavelengths characteristic of the particular elements of interest is measured and related to the concentration of each element via calibration curves. 

Figure 5.69 Calibration curves obtained from (a) LC-ToF-MS and (b) LC-MS-MS using selected-reaction monitoring for Idoxifene in human plasma, fortified from 5 to 2000 ngml for LC-ToF-MS and 0.5 to 1000 ngml for LC-MS-MS with a triple quadrupole is the correlation coefficient, a measure of the quality of calibration (see...

Watters, R. L., Jr., Carroll, R. J., and Spiegelman, C. H., Error Modeling and Confidence Interval Estimation for Inductively Coupled Plasma Calibration Curves, Anal. Chem. 59, 1987, 1639-1643. 

Pd removal was determined as follows. An aliquot of a representative liquid or solid sample was accurately weighed and subsequently digested by refluxing in nitric and/or hydrochloric acid using a closed vessel microwave procedure (CEM MARS5 Xpress or Milestone Ethos EZ). Cooled, digested samples were diluted, matrix matched to standards, and referenced to a linear calibration curve for quantitation an internal standard was employed to improve quantitation. All samples were analyzed by an Inductively Coupled Plasma Mass Spectrometer or ICP/MS (Perkin Elmer SCIEX Elan DRCII) operated in the standard mode. 

Matrix effect — To demonstrate that the assay performance was independent from the sample matrix, QC samples were prepared using two different lots of matrix. The QC samples were evaluated using the same calibration curve. With regard to analytical recovery, no significant difference was observed for the QCs prepared in two lots of plasma. 

A linear calibration curve for carvedilol in plasma was constructed over a range of 1 to 80 ng/mL. The correlation coefficient exceeded 0.999. Intra-day and inter-day coefficients of variation were 1.93 and 1.88%, respectively. The average carvedilol recovery was 98.1%. The limit of quantification was 1 ng/mL. This high-throughput method enabled the analysis of more than 600 plasma samples without significant loss of column efficiency. 

Standards, controls, and samples (250 fiL each) were treated with 500 fiL acetonitrile-acetic acid (99 1 v/v) containing IS (2.50 jUg/mL), vortexed for 10 sec, incubated for 5 min, and centrifuged at 15,000 g for 5 min. The supernatants (1650 //L) were loaded onto a polypropylene 96-well plate containing 900 fxL HPLC water under low vacuum. The SPE plates were conditioned with 500 fxL methanol followed by 300 jx. acetonitrile-water-acetic acid (30 69.5 0.5 v/v/v) (solvent A), washed with 1000 /xL solvent A, dried under full vacuum for 10 min, wiped dry with paper, eluted with 500 jxL methanol-trifluoroacetic acid (99.9 0.1 v/v) (solvent B) and then with 400 //L solvent B for 2 min, evaporated to dryness at 65°C under a gentle air stream, reconstituted with 200 /xL methanol-hydrochloric acid (0.1 M) (70 30 v/v) and assayed. The injection volume was 50 i L. Figure 11.3 shows chromatograms of blank plasma and spiked plasma with lumefantrine. A calibration curve was constructed in a concentration range of 25 to 20,000 ng/mL. Intra-assay and interassay coefficients of variation were below 5.2 and 4.0%, respectively. The limit of detection was 10 ng/mL. The limit of quantification was 25 ng/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. 

Adrenal Tumours The assay-method is entirely based on the Schwartz-Mann Kit. According to this method, cortisol is first extracted from the plasma using CH2C12 (methylene chloride). In the actual radioimmunoassay the cortisol present in the extract competes with Cortisol-H3 i.e., the radioactive tracer) for the common binding sites on transcortin, which is incidently not an antibody but a cortisol-binding protein. Now, the free cortisol is quantitatively removed by adsorption on dextran-coated charcoal from the one bound to the transcortin. Finally, the bound radioactivity (due to Cortisol-H3) is measured which is then employed to calculate exactly the amount of cortisol present in the sample by the help of a Standard Curve (or Calibration Curve). 

A constant volume of control human plasma is added to a constant volume of each standard of chlordiazepoxide to produce a calibration curve of 2 to 100 ng per tube,... 

A radioimmunoassay method has been reported for the monitoring of therapeutic concentration of chlorpromazine and its 7-hydroxy metabolite in plasma by [184]. The limit of detection for chlorpromazine was reported to be 0.1 ng, and its calibration curve linear up to 2 ng. The limits of detection for the 7-hydroxy metabolite was reported as 0.1 ng, and the calibration curve linear up to 1.2 ng. 

In a flame, as the concentration of atoms increases, the possibility increases that photons emitted by excited atoms in the hot region in the centre will collide with atoms in the cooler outer region of the flame, and thus be absorbed. This self-absorption effect contributes to the characteristic curvature of atomic emission calibration curves towards the concentration axis, as illustrated in Fig. 4.4. The inductively coupled plasma (ICP) tends to be hotter in the outer regions compared with the centre—a property known as optical thinness—so very little self-absorption occurs, even at high atom concentrations. For this reason, curvature of the calibration curve does not occur until very high atom concentrations are reached, which results in a much greater linear dynamic range. 

The peak area ratio of the blank is due to the endogenous BA concentration in plasma samples. In the reported paper the 95% confidence limits of the calculated average concentrations were calculated as x0 tsx0, where sx0, the standard error for both the sample and the calibration curve, was determined using equation 5.10 from Miller and Miller [39]. This calculated average concentration was then compared to the actual concentration using a f-test. 

Figure 9. Calibration curves of glucose sensor I before (— —) and after (—O—) human plasma test.

As an example, Fig. 36.5 presents a calibration curve for the determination of Interleukin IB in plasma sample. The insert in Fig. 36.5 shows the row data obtained for the parallel detection of p-aminophenol in a series of eight individually addressable microchannels as a function of time, and the resulting calibration points are given by the slope at the origin of these different curves. 

Calibration curves obtained by spiking various concentrations of fexofenadine into blank human plasma... 

Fexofenadine mean plasma concentration-time profile obtained using corresponding calibration curves on opposite column... 

Figure 1.6. Fexofenadine calibration curves and mean plasma concentration-time profiles following a single oral administration of (a) 100 pug (microdosing) or (b) 60 mg (clinical dosing) fexofenadine to healthy volunteers. (Reprinted with pemnission from Yamane et al., 2007.)...

To run a patient sample, you will need to go through exactly the same deproteination, SFE cartridge extraction, IS addition, mobile phases dilution, and injection steps (Fig. 12.4f). From the peak heights relative to the IS height, we can now quantitate the amount of each drug in the patient s blood. To insure linearity, you may need to dilute our windowed plasma blank and spike it with different levels of each standard and plot calibration curves for each compound, but basically, our methods development is done. 

To establish a sensitive and specific liquid chromatography-mass spectrometry (time-of-flight) [LC-MS (TOF)] method for the determination of donepezil in human plasma after an oral administration of 5 mg donepezil hydrochloride tablet [29]. Alkalized plasma was extracted with isopropa-nol-n-hexane (3 97) and loratadine was used as internal standard (IS). Solutes were separated on a Cis column with a mobile phase of metha-nokacetate buffer (pH 4.0) (80 20). Detection was performed on a TOF mass spectrometry equipped with an electrospray ionization interface and operated in positive-ionization mode. Donepezil quantitation was realized by computing the peak area ratio (donepezil-loratadine) (donepezil m/z 380 [M + H]+ and loratadine m/z 383[M + H]+) and comparing them with calibration curve (r = 0.9998). The linear calibration curve was obtained in the concentration range of 0.1-15 jUg/1. The detection limit of donepezil was 0.1 /zg/1. The average recovery was more than 90%. The intra- and inter-run precision was measured to be below 15% of RSD... 

A selective, sensitive, and rapid hydrophilic interaction liquid chromatography with electrospray ionization tandem mass spectrometry was developed for the determination of donepezil in human plasma [32], Donepezil was twice extracted from human plasma using methyl-ferf-butyl ether at basic pH. The analytes were separated on an Atlantis HILIC Silica column with the mobile phase of acetonitrile ammonium formate (50 mM, pH 4.0) (85 15, v/v) and detected by tandem mass spectrometry in the selective reaction monitoring mode. The calibration curve was linear (r = 0.9994) over the concentration range of 0.10-50.0 ng/ ml and the lower limit of quantification was 0.1 ng/ml using 200 /d plasma sample. The CV and relative error for intra- and inter-assay at four quality control levels were 2.7% to 10.5% and —10.0% to 0.0%, respectively. There was no matrix effect for donepezil and cisapride. The present method was successfully applied to the pharmacokinetic study of donepezil after oral dose of donepezil hydrochloride (10 mg tablet) to male healthy volunteers. 

Zarghi et al. [76] developed an HPLC method, using a monolithic column, for quantification of omeprazole in plasma. The method is specific and sensitive with a quantification limit of 10 ng/ml. Sample preparation involves simple, one-step extraction procedure, and analytical recovery was complete. The separation was carried out in reversed-phase conditions using a Chromolith Performance (RP-18e, 100 x 4.6 mm) column with an isocratic mobile phase consisting of 0.01 mol/1 disodium hydrogen phosphate buffer-acetonitrile (73 27) adjusted to pH 7.1. The wavelength was set at 302 nm. The calibration curve was linear over the concentration range 20-1500 ng/ml. The coefficients of variation for intra- and interday assay were found to be less than 7%. 

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]. 

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