Errors reactions

Table 4.6). Specifically, the methods used were to (1) add a tag (type of atom or physical change tracked in these calculations) (2) remove a tag element from the resin during reaction or (3) use a tag element unique to the resin before and after reaction. Error was estimated by accessing limitations of elemental analyses and known resin functionalization error. While the third case listed could not be applied to the phenylacetylene... 

The reaction error is thus expressed as a percentage of the total ion concentration. Positive reaction errors indicate cation excess negative errors indicate anion excess. Reaction errors are caused by the analytical errors of the individual parameters and the fact that not all possible ions are commonly measured. 

In certain cases it is worthwhile to enlarge the list of ions analyzed in order to lower the reaction error, for example, to include NO/, Fe3+, or P044. ... 

At the beginning of each study a decision has to be made as to which reaction errors will be acceptable. A cutoff at 2 or 5% is common. Analyses with high reaction errors are omitted in the data processing and, if possible, they should be discussed with the laboratory personnel. 

The reaction error (section 5.8) is the difference between total cations and total anions, expressed as a percentage of the TDI. For sample 1 of Table 5.4 this would be... 

The data of Table 5.4 have been reworked again in Table 5.6, which includes the total cations, total anions, total ions, and reaction errors. The data in Table 5.4 have been expressed in meq/1. However, most people are used to the mg/1 units for assessment of the degree of salinity of water. The conversion of meq/1 data into mg/1 was discussed in section 5.6, and is here demonstrated on the Wisdom Spring data (Table 5.7) ... 

Table 5.6 Total Ions (meq/1) and Reaction Errors, Calculated for the Wisdom Spring Data (Table 5.4)...

Sample K+ Na+ ca2+ Mg2+ cr hco3 so42 Total cations Total anions Total ions Reaction error... 

As stated, reaction errors are another way to estimate data quality (section 5.8). The reaction error can (and should) be better than 1%, but they are often larger. Many investigators will accept up to 5%. Using the latter criterion the reaction errors calculated in Table 5.6 (4.3%, 3.3%, 2.1%, 1.2%, and 1.6%) are acceptable. This example brings out a major shortcoming of the reaction error quality test the poor reproducibility of the S04 data, demonstrated above, is not reflected in the reaction error because SO4 is a minor compound of the Wisdom Spring water. Low reaction errors indicate acceptable quality of the data for the major ions alone. 

The reaction errors in repeated measurements are expected to be random, that is, in part of the measurements the total cations will exceed the total anions and in the rest of the cases the total cations will exceed the total anions. However, occasionally a systematic pattern is seen. In Table 5.6 all the measurements reveal total cations to be higher than total anions (check it). Possible explanations are ... 

Exercise 5.4 What is the reaction error for the data of sample 73 of the Green Mice Spring reported in Table 6.2 ... 

Sample no. Li Sr K Na Mg Ca Br Cl so4 hco3 Total anions Total cations Total ions Reaction error (%)... 

Answer 5.4 The sum of cations equals the sum of anions in this (synthetic) case. Hence the reaction error is Omeq/1, or 0%. 

A useful method for the generation of molecular diversity starting from a given gene is to use a method of random mutagenesis by error-prone polymerase chain reaction (error-prone PCR) (Figure 10.8). Using error-prone PCR, the mutation rate must be carefully tuned - beneficial mutations are rare but deleterious mutations are common. If the mutation... 

Owing to the exponential dependence of the equilibrium constant on the Gibbs standard enthalpy of reaction, errors in are multiplied exponentially. 

The reverse reaction error was investigated only for the polarization-resistance technique. For the idealized case, the error... 

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