Working calibration standards

Working calibration standards of pentachlorophenol in methylene chloride were prepared by serial dilution of the composite standards with methylene chloride, at five concentrations, 0.1, 1.0, 2.0, 5.0 and lOpg/mH, for the unlabelled pentachlorophenol and lpg/mH for the stable-labelled pentachlorophenol. 

Inject each working calibration standard and standard mixture (including any optional internal standard) individually into the automatic injector. 

Procedure Set up the instrumental method to measure the area of the 0- ig/mL Working Calibration Standard (blank) peaks and then the net intensities of the 0.050- and 0.250-fig/ mL Working Calibration Standards with the yttrium Internal Standard. The calibration curve should be linear. Examine the spectra of the cadmium and yttrium, and make any necessary adjustments to the exact peak locations and baselines to ensure proper integration of the areas under the respective peaks. Analyze the sample and calculate the concentration, in micrograms per milliliter, of the cadmium in the Sample Solution. 

Dilution of stock solutions to prepare the series of working calibration standards that are injected into the gas chromatograph mass spectrometer (GC-MS) to calibrate the instrument for each of the 100 or more semivolatile organics. This series of standards should also contain at least one initial calibration verification... 

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... 

Prepare a set of working calibration standards to include an ICV that brackets the anticipated range for the unknowns. To each calibration standard, add 50 pL of 20 ppm IS so that the concentration of IS in each calibration standard is identical and at 1.0 ppm. 

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. 

Prepare a series of working calibration standards and ICVs according to the following table ... 

Preparation of the Primary Dilution Standard and Working Calibration Standards... 

As an illustration only, working calibration standards could be prepared as suggested below (this scheme assumes that the 1000 ppm certified stock reference standard solution has been carefully diluted to 3 ppm) ... 

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 ... 

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. 

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... 

To prepare working calibration standards for the run Aliquot the appropriate amount of 1.0, 0.1, or 0.01 pg/mL spiking standard into a labeled 16x125 mm test tube (see Table 1). Dilute to 1.0 mL with drug-free urine. Aliquot 1.0 mL of drug-free urine for the negative (carryover) control. 

Quality controls (QC) can be purchased, or a working QC standard can be prepared as described for the working calibration standard. The QC standard should be prepared from a different manufacturer and independently from the calibration standard. 

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

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