Fiber blank

MS mode (quadrupole) Full-scan mode (40-300 amu) for column blank, fiber blank, and retention time determination of the substances involved. SIM mode for calibration and analysis (see Table 29.3)... 

If the first blank fiber contains peaks that can interfere with the detection of the compound investigated, then another fiber blank must be performed. If the contamination persists, then the fiber must be reconditioned following the specific instructions. Finally, if a carryover due to the previous analysis has been observed, then a longer desorption time and/or higher injector temperature must be set (see Section 29.3.4). 

Otherwise, the possible contamination (e.g., IS solution, methanol used to prepare IS solution, blank column, and fiber blank) must be checked, and corrective measures must be applied. 

Field blank analysis also helps to demonstrate fiber blank and the absence of carryover effects. 

In the event of contamination or carryover effects, check the source (s) of contamination by running a fiber blank and eventually a column blank (see Section 29.1). 

Fiber Blank This is the GC/MS chromatogram obtained for desorption of a freshly conditioned fiber. 

Reinforced Thermoplastic Sheet. This process uses precombined sheets of thermoplastic resin and glass fiber reinforcement, cut into blanks to fit the weight and size requirements of the part to be molded. The blanks, preheated to a specified temperature, are loaded into the metal mold and the material flows under mol ding pressure to fiU the mold. The mold is kept closed under pressure until the temperature of the part has been reduced, the resin solidified, and demolding is possible. Cycle time, as with thermosetting resins, depends on the thickness of the part and the heat distortion temperature of the resin. Mol ding pressures are similar to SMC, 10—21 MPa (1500—3000 psi), depending on the size and complexity of the part. 

Blank and spiked samples were created by pipeting standard amounts of TRIS and Decabrom onto 10 cm2 areas (2x5 cm) of glass fiber filter leaving blank (2x5 cm) blocks between each spiked area. The filter was then used to collect a 2038 m3 air sample in the Research Triangle Park, NC. This filter was shipped to the field and returned for analysis. The results of analysis of areas of the filter are shown in Table IV. These results indicate the overall recoveries for sampling, shipping and storage as well as extraction recovery from this filter. 

For blank value mix 2x10 cells in 850 pi of Soln. A with 150 pi Soln. C and incubate at 37 °C for 60 min. Precipitate with Soln. D and filter on glass fiber filter as described above (t = 0 -> Bo ). 

Dilute 2 X 10 cells in 17 ml Soln. A and warm up to 37 °C. Prepare a solution of H-PN 200-110 (about 1 600 000dpm) in 3 ml. Mix both solutions and continue incubation at 37 °C. Take 1-ml probes in duplicate at timet = 0,l,2,4>6,8,10,12,15,and20 min after mixing (- Bt ). Precipitate the probes with 2 ml of ice-cold Soln. D immediately after sampling and filter on Whatman GF/C glass fiber filters. Prepare a blank ( Bo ) by incubation of a mixture of 850-pl cell suspension and 150 pi Soln. C at 37 °C for 20 min. Wash the filters with Soln. D. Dry the filters at air and count for radioactivity. 

The analytical sensitivity is limited by uncertainties in the response to blank filters. For glass fiber filters (Gelman A/E) the blank values are 2.811.4 pgC/cm for organic carbon and 0.2 pgC/cm for elemental carbon. For Pallflex QAST the respective values are 1.010.5 and 0.310.2 pgC/cm. ... 

---