Calibration linearity

Equation 19 utilizes the Y-residuals, 1) — Y, where 1) are the points on the calculated best-fit line or the fitted 1) values. The appropriate number of degrees of freedom is A — 2 the minus 2 arises from the fact that linear calibration lines are derived from both a slope and an intercept which leads to a loss of two degrees of freedom. 

When the internal standard s concentration cannot be held constant the data must be plotted as (SA/Sis)stand versus Ca/Cis, giving a linear calibration curve with a slope of K. 

A calibration curve shows us the relationship between the measured signal and the analyte s concentration in a series of standards. The most useful calibration curve is a straight line since the method s sensitivity is the same for all concentrations of analyte. The equation for a linear calibration curve is... 

PSS-SG composite film was tested for sorption of heme proteins hemoglobin (Hb) and myoglobin (Mb). The peroxidaze activity of adsorbed proteins were studied and evaluated by optical and voltammetric methods. Mb-PSS-SG film on PG electrode was shown to be perspective for detection of dissolved oxygen and hydrogen peroxide by voltammetry with linear calibration in the range 2-30 p.M, and detection limit -1.5 p.M. Obtained composite films can be modified by different types of biological active compounds which is important for the development of sensitive elements of biosensors. 

Following this procedure urea can be determined with a linear calibration graph from 0.143 p.g-ml To 1.43 p.g-ml and a detection limit of 0.04 p.g-ml based on 3o criterion. Results show precision, as well as a satisfactory analytical recovery. The selectivity of the kinetic method itself is improved due to the great specificity that urease has for urea. There were no significant interferences in urea determination among the various substances tested. Method was applied for the determination of urea in semm. 

The following polyvitamin prepai ations were analyzed Kal tsid (OAO Comfort Plus , Russia), Asvitol (OAO INC Marbiofarm , Russia), Pikovit (KRKA, d.d. The New Place, Slovenia), Yeast with vitamin C (000 EKKO Plus , Russia). Chromatographic experiment has been carried out using Silufol UV-254 (Kavalier, Czech Republic) and acetone - ethyl acetate - acetic acid - ethanol (3 5 1 1) - CTAB (2T0 M) as a mobile phase mixture. The linearity calibration plot, built in coordinate S = f (IgqAC), is valid in the interval 5-25 p.g. Correctness of the determination has been checked by photometry. The obtained results for the ascorbic acid determination are presented below. 

In the experiment was determined that for linear calibration curve for CrKa in GSO PG24-PG31 the standai d error was 0.045%. The application of theoretical corrections method enables a decrease of that value to the level of 0.013%. In case when for the analytical parameter is taken the ratio L /L the standai d deviation decreases to 0.002%. 

The same results were gained for Cr analysis in high alloyed steels. The error of linear calibration in this case is 0.28%. The application of theoretical corrections decreases this error to 0.07%. The standard error of the linear calibration on the base of the analytical pai ameter Ici.j,yipj,j,p is 0.23% and the application of the theoretical corrections in this case gives error 0.04%. 

Rapid, quantitative measurement of trace to minor elemental composition of solids and solutions excellent detection limits, with linear calibration over 5 orders of magnitude... 

BS ISO TR 7066-1 1997. Assessment of Uncertainty in Calibration and Use of Flow Measurement Devices Linear Calibration Relationships. British Standards Institution, 1997. 

The intensity of the emitted fluorescence In is, therefore, directly proportional to the amount of substance applied a This relationship is much simpler than the Kubelka-Munk function and always leads to a linear calibration curve passing through the origin If this is not true then interference is occurring [5]... 

Polysaccharides TSK-GEL GMPWxl TSK-GEL GSOOOPWxl -I- TSK-GEL G3000PWxi Large pore size, linear calibration curve, small particles, high resolving power... 

Small TSK-GEL G2500PWxi TSK-GEL Super SW2000, TSK-GEL G2000SWXL or SW Linear calibration curve, high resolving power... 

Synthetic polymers TSK-GEL GMPWxi TSK-GEL GSOOOPWxl G3000PWxl Large pore size, low adsorption, linear calibration curve... 

A linear calibration curve achieved using PLgel mixed gel columns infers several key advantages in SEC analyses. 

Establishing a calibration function with one single broad distributed sample is an alternative to traditional peak postion calibration of SEC systems with a set of narrow distributed standards. An obvious advantage of this technique is time for peak position calibration elution profiles for the set of standards need to be determined for broad standard calibration the elution profile of one sample needs to be determined only. Establishing a linear calibration function with a broad distributed standard includes startup information [M (true), Mn(true)] and an iterative (repeat.. . until) algorithm ... 

D. Comparison of Linear Calibration Curves of Shodex and TSK Columns... 

Due to the limitation of space, only the linear calibration curves for TSK, PSS, APSC, and PL PEO standards in water/methanol for the Shodex SB-806M... 

TABLE 17.7 Coefficient of Determination (R ) for Linear Calibration Curves for Four Linear Columns and Four Sets of PEO Standards... 

For all four sets of PEO standards the coefficient of determination (R ) for the linear calibration curves for the four linear columns in water and in water/methanol are better than 0.99, except for the PL PEO standards and the TSK GM-PWxl column in water/methanol. The coefficient of determination for the TSK GM-PWxl column in general is not as good as the other three linear columns. The coefficient of determination for the TSK PEO standards showed the least dependency on columns and mobile phases. The TSK GM-PWxl column has a lower exclusion limit in the high molecular weight range than TSK GM-PW, Shodex SB-806, and SB-806MHQ columns. 

External standard method (linear calibration curve of peak areas)... 

Purpose Generate a data set that superimposes normally distributed noise on a linear calibration model to study the effects of the adjustable parameters. A whole calibration—measurement—evaluation sequence can be optimized for quality of the results and total costs. 

Option (Valid) presents a graph of relative standard deviation (c.o.v.) versus concentration, with the relative residuals superimposed. This gives a clear overview of the performance to be expected from a linear calibration Signal = A + B Concentration, both in terms of (relative) precision and of accuracy, because only a well-behaved analytical method will show most of the residuals to be inside a narrow trumpet -like curve this trumpet is wide at low concentrations and should narrow down to c.o.v. = 5% and rel. CL = 10%, or thereabouts, at medium to high concentrations. Residuals that are not randomly distributed about the horizontal axis point either to the presence of outliers, nonlinearity, or errors in the preparation of standards. 

Cardone, M. J., Palermo, P. J., and Sybrandt, L. B., Potential Error in Single-Point-Ratio Calculations Based on Linear Calibration Curves with Significant Intercept, Ana/. Chem. 52, 1980, 1187-1191. 

An added benefit of the direct SEC-[n] calibration approach is that a new independent way of determining K and a values, using only broad MW standards, has also resulted. As few as three standards (or four, if all are narrow MWD) are needed to obtain both MW and [x]] calibration curves for a particular polymer-solvent system by using the broad-standard, linear calibration approach. From the experimental calibration constants of the two calibration curves, one can calculate K and a directly as described later. 

Equation 7 shows that linear calibration using bimodal colximns can be applied to simplify the SEC-In I calibration procedure as has been done for the SEC-MW calibration. The objective of this [n] calibration then is to determine E and E2 values of the SEC column set for the particular polymer-solvent system of interest. The approach is the same as that for SEC-MW calibration. The similarities between the and the [n] formulations are summarized in Table... 

The broad-standard linear calibration curves for polystyrene in THF in Figure 1 and 4 are used to illustrate the K and a calculations as follows. The particular calibration curves are found to correspond to the following calibration equations ... 

Figure 4. Molecular weight calibration curves for polydextran obtaimd u g linear calibration and two broad M WD standards and by plotting Mrm ( / Mif Mw) vs, peak retention volume ((%) Mrms, (---------) M(v) = 0,37 X exp(—OJ v))...

Table V. Results of Case Study 2 - Linear Calibration with Two Broad MWD Polydextran Standards with Known Mj and...

---