Sample prep

Today, most modern data systems provide a comprehensive array of quantitation methodologies. In general, chromatographic peaks may be quantitated using area, height, % area, and % height. Within these basic techniques, the chromatographic assay may also require the use of an Internal Standard to help correct for injector variability or sample-prep... 

Figure 4.9 SEM image ofY zeolite taken with field emission SEM, operated atO.SkV. Sample prep was by dispersing powder in isopropyl alcohol and placing a droplet of the...

Precision Repeatability Ruggedness Reproducibility Sample prep replication Injection replication Factorial designs Intra-laboratory study Inter-laboratory study... 

C. A rule of thumb in small-molecule GPC is that it is possible to analyze two compounds whose molecular weight differs by 10% or more by the judicious selection of the mobile phase. For instance, the separation of tolnaftate (the active ingredient of an antifungal preparation) (MW = 302) and BHT (which is present as an antioxidant) (MW = 220) can be accomplished using methylene chloride, a nonhydrogen bonding solvent as shown in Figure 11-4. For this assay, sample prep-... 

Dilute suspensions Subject to quenching at high colloid loads Little/no sample prep Poor resolution for polydisperse suspensions... 

If tiie sample is a potential oxidising agent, other techniques of sample prep ation should also be used in order to check the reliability of the spectra obtained from the [Pg.245]

GA Smith, TL Uoyd. Automated solid-phase extraction and sample preparation—finding the right solution for your laboratory. LC-GC Curr Trends Dev Sample Prep May S22-S31, 1998. 

David A. Wells, Sample Prep Solutions Company, Saint Paul, MN 55119... 

Sample type total sediments Sample prep. Open digestion with HN03, and HF. 

Matrix Ref.. Sample Prep. Repeatability coeff. of variation Accuracy percent recovery Levels Height Comments Comp,... 

Technique Isotopes, Minerals Sample Prep. Typical Sample Size Spatial Resolution Precision (1 sd) References... 

Sample Prep. gum homogenized In blender with (1 1) H20 CH2Cl2 CH2CI2 phase passed through 0.45 urn Milllpore filter. MVL-built SFC with PE 3920B gas chromatograph oven J W Scientific DB-1,10 m x 50 urn I.D., 0.1 urn film... 

Sample Prep. 0.12 g sample stirred in 4 ml toluene for two hour... 

We now turn our attention to sample preparation techniques to quantitatively determine volatile organic compounds (VOCs) in environmental samples, and after this, we return to a discussion of the more recently developed sample prep techniques for SVOCs. Because we have been discussing LLE and LSE techniques, it is appropriate for us to ask at this point the following question. 

We next move back to a consideration of semivolatile organics by introducing two alternative sample prep techniques that have been developed during the past 20 years and, at present, enjoy widespread popularity, supercritical fluid extraction for solids and solid-phase extraction for aqueous environmental samples. 

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