marius
第1楼2007/11/28
帮助文件是这样的(只有英文的,翻译出来太难为我了):
Calibration Mode
Figure 4-16. Analysis Preferences, Calibration Mode
The Calibration Mode field is used to select the desired type of calibration that should be used in the method.
Concentration mode compares instrument response to standards of known concentration. Instrument response typically is corrected for background and may additionally be corrected using an internal standard or inter-element correction. In addition, there are two special calibration modes.
These are called Concentration Ratio and Summation to 100%. These may be used to analyze samples for ALL elements present. The results must always add up to 100 percent. In essence, the whole sample becomes its own internal standard.(不能理解,样品本身可以作内标?)
Typically, when these methods are used, only one line for each element will be used, as the concentrations are reasonably well known. If a wide concentration range is expected, line switching can be used. Multiple lines can also be used and, in some special circumstances, this can provide improved accuracy. iTEVA uses a special algorithm which rejects any lines reporting errors, then averages the valid lines if multiple lines are reported in either of these two modes.
The calibration mode is selected in the method within the Analysis Preference Window. The selected calibration mode appears in the field to the left of the options bar. Using the dropdown menu displays the options. Moving the cursor to each option will highlight that option and a left-click will insert the option as the selected calibration mode.
Concentration - The concentration of each element in the calibration standards is entered.
Concentration Ratio - The concentration of each element is indicated with reference to the internal standard. The base element is the sole internal standard for the method and the sum of all of the element concentrations must be 100%. If this requirement is not met, the method will default to Concentration Mode.
To use the Concentration Ratio mode, a Standards Table is created which uses a Base Concentration. This appears with a value of 100 percent. The major element in the material is omitted from the list of elements in the standard. This major element is designated as the Internal Standard.
When inserting the concentrations of the various elements, the value for the Base is reduced, so that the total always adds to 100%. After inserting all element concentrations (other than the major constituent), the Base Concentration should equal the major constituent concentration. If not, there may be a small concentration of undetermined species present. These undetermined elements should constitute less than 1% of total composition (preferably less than 0.1%). Provision is made for the inclusion of a "residual concentration"; this residual is an approximation of the concentration of undetermined species.
Thus:
C[is] + C[a] + C + ... = 100% - C[r]
Where: C[is] is the concentration of the Internal Standard element
C[a], C, ... are concentrations of elements a, b, ...
C[r] is the residual concentration (if any)
If both sides of the equation are now divided by C(is), the result is:
1 + CR[a] + CR + ... = 100 - C[r]C[is]
Where CR[a], CR, ... are Concentration Ratios of elements a, b, ...
Remember that the calibration curve is now relating SIR to concentration ratio; i.e., the value obtained in each case when the concentration of each element in the Standard is divided by the Base Concentration, or the concentration of the Internal Standard element:
CR [a] = C[a]/C[is]
During analysis, the instrument determines intensity ratio values, which are then related to concentration ratios calculated from a calibration curve which has been established in concentration ratio mode. The equation above may then be solved for C[is], the Internal Standard Concentration.
Once this is known, The equation may be solved for all the individual element concentrations.
Summation to 100% - The standard concentrations for all elements add up to 100% including the base element. If this requirement is not met, the method will default to Concentration mode.
Note The Summation to 100% is generally used in the metals industry (钢铁分析战线上的朋友可否来讲讲课?多谢了先)where the major elements have to be measured as well as the minors and traces.