Multiple standard method

The multiple standard method uses mixtures of all components at known concentrations in combination with the following expression ... 

The standard semiclassical methods are surface hopping and Ehrenfest dynamics (also known as the classical path (CP) method [197]), and they will be outlined below. More details and comparisons can be found in [30-32]. The multiple spawning method, based on Gaussian wavepacket propagation, is also outlined below. See [1] for further infomiation on both quantum and semiclassical non-adiabatic dynamics methods. 

In Section 8.2.8 we have discussed the standard addition method as a means to quantitate an analyte in the presence of unknown matrix effects cf. Section 13.9). While the matrix effect is corrected for, the presence of other emalytes may still interfere with the analysis. The method can be generalized, however, to the simultaneous analysis of p analytes. Multiple standard additions are applied in order to determine the analytes of interest using many q > p) analytical sensors. It... 

Walters [24] examined the effect of chloride on the use of bromide and iodide solid state membrane electrodes, and he calculated selectivity constants. Multiple linear regression analysis was used to determine the concentrations of bromide, fluorine, and iodide in geothermal brines, and indicated high interferences at high salt concentrations. The standard curve method was preferred to the multiple standard addition method because of ... 

Probably the best way to overcome the problem of poor selectivity is via the multiple standard addition approach in which known amounts of analyte are added to the sample in increasingly high concentrations. Using this method, a... 

The multiple standard addition method is time-consuming although it usually yields superior results to those of the other methods outlined in Table 3.3. 

Add additional analyte to the solution to swamp the interferent. The ratio of analyte to interferent will therefore increase, thus improving the precision of the measurement. This method is termed multiple standard addition... 

Employing the method known as multiple standard addition helps when trying to discern the effects of the sample matrix in which an analyte is dissolved. In this technique, the emf is determined as a function of the amount of standard solution added to the sample. 

Confidence bands are direct precision data, and the maximum reportable concentration can be defined as the maximum concentration at which the method yields adequate precision ( ) (excluding measurements near the minimum reportable concentration, where poor precision is unavoidable). Table III shows RCB for the determination of iron in water by AAS. The analyst may consider a RCB of say, 15% to be adequate. The maximum reportable concentration would be 15 pg/ml from a single, weighted least-squares curve, and 20 pg/ml by the multiple-curve method. Samples containing > 20 pg/ml should be diluted to 1-10 pg/ml and analyzed using standards containing 0.05 - 15 pg/mL. (Note that it is always better to include a standard above the maximum desired concentration. The precision of this standard measurement will be poor, but poor data at this level are better than none.)... 

Cx = (CsFo//xF3)(1-10- ) = Ac (1-10- ) (ASM). (5.20) The double and multiple addition methods are introduced in an attempt further to improve the measuring precision, because with three or more experimental potential values the slope value S need not be knowa Under the same assumptions and with the same symbols as above, provided the same volumes are always added, it holds for the nth addition of the determinand standard solution that... 

In potentiometry with ISEs, however, the second Gran method [46] has found especially wide use, not only in titrations, but also in multiple addition methods in general. In these methods, the concentration of the test substance is plotted against the volume of the titrant or of the standard solution and thus the curve is linearized. The end-point in the titration or the determinand concentration in a multiple addition method is found as the intercept of the straight line with the volume axis. Linearization is attained by taking the antilogarithm of the Nernst equation ... 

Solvent extraction reduction is most frequently performed mainly in connection with the extraction of solid and biological samples by liquid partition. Extractions are typically accomplished using a Soxhlet apparatus that provides the benefits of multiple extractions. By repeated distillation and condensation of the solvent, the apparatus allows multiple extractions using the same (small) volume of solvent. Soxhlet extraction has been a standard method for many decades, and it is often the method against which other extraction methods are measured and verified [14]. 

Suppose you estimate a multiple regression first with then without a constant. Whether the R2 is higher in the second case than the first will depend in part on how it is computed. Using the (relatively) standard method, R2 = 1 - e e/y M°y, which regression will have a higher/ 2 ... 

Due to the possible toxic effects of Hg, alternative electrodes have been sought, such as bismuth, which has recently been used by Kadara and Tothill [155,156] for the determination of Pb2+ and Cd2+ at an SPCE. In this investigation, stripping chronopotentiometric measurements were carried out by depositing a metallic film of bismuth in situ with the target metal ions (lead and cadmium). A deposition potential was applied to preconcentrate the analytes, after which, a constant current was applied to strip the preconcentrated analytes until a limit of —0.2 V. The concentrations for Pb2+ and Cd2+ in the wastewater samples and acetic acid extracts of soils were quantified by the use of a multiple standard addition method. 

Multiple standard addition method (three additions of 50ppb of Cd and Pb solution) is used to detect Cd and Pb in the sample. 

Multiple standard addition method (three additions of 50 ppb of Cd and Pb solution) was utilised to recover two concentration levels of 40 and 80 mg/L of spiked metals into the solution composed of lmL tap water and 24 mL electrolytic cell (0.1M acetate buffer, pH 4.5). 

To satisfactorily meet and address these regulatory and market needs, standard methods for emissions testing need to be both robust and repeatable for competent laboratories to carry out, and practical and affordable for manufacturing industry. Uniformity of test methods, between countries and markets is also important if manufacturers are to avoid having to submit the same products for emissions testing by multiple different emissions certification protocols. 

The coefficients ay can be accurately determined from experimental data by standard linear multiple regression methods. 

---