Working calibration standards using

Use the following table to prepare a series of working calibration standards using MeOH as the dilution solvent. Transfer the standards to a 2-mL GC vial, cap, and either place on autosampler or store for future use. 

Prepare the working calibration standards using the stock solution as described in 8.5 and 8.6. 

The accuracy of interference microscopy depends on the calibration standards used. For measurements in the secondary wall, these values are 1.604 for Nb and a range of values for Na depending on the specimen. The variation in Na arises presumably from variation in microfibril angle (Hermans 1946). The need to measure Na for each sample is one disadvantage of this technique that increases the amount of work necessary to perform the measurement. If Na is not measured for each sample, an error of 11% is introduced compared to the usual error of 2% (Donaldson 1985a). Na does not vary between earlywood... 

Initial Calibration Verification (ICV) Standard prepared in a similar manner as for the working calibration standards, however, at a different concentration than any of the working standards. Used to evaluate the precision and accuracy for an interpolation of the least squares regression of the calibration curve. This standard is run immediately after the calibration of the working standards. 

We see that a direct proportionality exists between the emitted fluorescence intensity denoted by F and the sample absorbance denoted by If a standalone spectrofluorimeter is used to conduct a quantitative analysis, the error introduced by neglecting the term should be considered. However, for a fluorescence HPLC detector where a set of working calibration standards are used (refer to Chapter 2) and where the concentration of fluorophore is relatively low, it is sufficient to ignore the higher-order terms. Upon substituting for A, we obtain... 

Using the 2000-ppm BTEX stock reference solution, prepare a series of calibration standards in which the BTEX is present in 10 mL DDI contained in a 22-mL HS vial with PTFE/silicone septa and aluminum crimp caps. Refer to the calibration in Step 2 for reference as you prepare a series of working calibration standards for HS GC analysis. Following the development of a calibration curve, inject the ICV (only one injection per vial is acceptable in HS GC) and then one or more of the gasoline-contaminated aqueous samples. 

The detailed instructions on how to set up and operate a FIAA using the Model 3110 AA will be made available in the laboratory (6). The burner-nebulizer attachment will need to be installed and the energy throughput optimized using either the Ca or Mg HCL. Proceed to aspirate the working calibration standards. An instrument calibration verification (ICV) standard should be prepared whose concentration should be approximately between the low and high standards. It should be sufficiently aspirated so that triplicate determinations of the absorbance from the same ICV solution can be... 

Calibrate the Model 1600 FTIR (Perkin-Elmer) by first preparing a series of working calibration standards. The following table serves as a useful guide and yields concentrations that are compatible with the software which operates the instrument. 

Using the stock solution, proceed using the following table as a guide to prepare a set of working calibration standards ... 

All the reagents were of analytical grade and were used without further purification. Working calibration standard solutions of desired concentrations of Cu, Cd, Pb and Zn were prepared fresh from stock solutions (100 ppm) prepared in double distilled water. 

The biggest problem with the configuration in Figure 10.79 is calibration. Because external calibration methods are used, it is critical that calibration standard solutions are correctly prepared and stored. Working calibration standards at submicrogram/Liter levels, however, cannot be prepared by diluting higher concentrated stock standards due to the likelihood of contamination. A second... 

Calibration Cahbration entails the adjustment of a measurement device so that the value from the measurement device agrees with the value from a standard. The International Standards Organization (ISO) has developed a number of standards specifically directed to cahbration of measurement devices. Furthermore, compliance with the ISO 9000 standards requires that the working standard used to cahbrate a measurement device must be traceable to an internationally recognized standard such as those maintained by the National Institute of Standards and Technology (NIST). 

For solutions which do not follow Beer s Law, it is best to prepare a calibration curve using a series of standards of known concentration. Instrumental readings are plotted as ordinates against concentrations in, say, mg per lOOmL or lOOOmL as abscissae. For the most precise work each calibration curve should cover the dilution range likely to be met with in the actual comparison. 

To obtain the calibration standards, take aliquots ranging from 50 /xL to 300 juL As, from the working standard solution, using an Eppendorf micropipette. Add the appropriate microlitre quantities to the reaction vessel of the vapour generation system, together with 10 mL of hydrochloric acid (AM), delivered from a calibrated dispenser. 

A series of calibration standards (CS) is made up that covers the concentration range from just above the limit of detection to beyond the highest concentration that must be expected (extrapolation is not accepted). The standards are made up to resemble the real samples as closely as possible (solvent, key components that modify viscosity, osmolality, etc.). A series of blinded standards is made up (usually low, medium, high the analyst and whoever evaluates the raw data should not know the concentration). Aliquots are frozen in sufficient numbers so that whenever the method is again used (later in time, on a different instrument or by another operator, in another laboratory, etc.), there is a measure of control over whether the method works as intended or not. These so-called QC-standards (QCS) must contain appropriate concentrations of all components that are to be quantified (main component, e.g., drug, and any impurities or metabolites). 

Laser ablation ICP-MS (LA-ICP-MS) was established in the early 1990s as a potential routine tool for the measurement of trace and ultra-trace elements in silicate systems for geology. Early studies (Perkins et al. 1993) used sample preparation techniques identical to that used to prepare rock samples for WDXRF, i.e., either a pressed powder disk or a glass bead fusion method (see Appendix VIII). Such studies concluded that LA-ICP-MS had the potential to surpass XRF in terms of the limits of detection achieved and INAA in terms of the speed of analysis (Perkins et al. 1993 481). It has long been recognized that the main limit on the quantitative performance of LA-ICP-MS is the homogeneity at the trace and ultra-trace level of the solid calibration standards available. Subsequent work (e.g., Hollecher and Ruiz 1995, Norman et al. 1996) has demonstrated that some of the international... 

Since certified reference materials for seawater nutrient analysis are currently unavailable, individual laboratories must prepare their own standard solutions for instrument calibration. Standard stock solutions are prepared at high concentrations (mM) so that they can be used for months without significant alterations in concentration. Working low-concentration standard solutions are unstable and need to be prepared daily by diluting stock solutions with distilled water or low-nutrient seawater. In this case, the accuracy of nutrient analysis at a given laboratory is highly dependent upon the accuracy of the daily preparation of the calibration solutions. 

Working with blank matrix, the calibration standards are spiked into the matrix to avoid false estimations. It should be checked if the same sensitivity is obtained using different batches of blank matrix. 

SEC calibration methods which employ a series of narrow MWD standards are based upon a peak position method and traditionally have been the most widely practiced calibration procedures. The peak position method simply correlates the peak elution volume of each standard to its nominal molecular weight or size value. A curve fitting procedure (usually a least squares regression) is used to obtain a working calibration curve. The serious limitation of polymer chemical types for which a series of narrow MWD standards covering a wide molecular weight range can be obtained led to the development of experimental approaches which could be applied to polymer chemical types other than that of the narrow MWD standards employed in calibration. 

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