Glass standards

The tendency of the color to become darker with time is often indicative of chemical degradation. The test is conducted with the aid of a colorimeter (NF T 60-104 and ASTM D 1500) and by comparison with colored glass standards. The scale varies from 0.5 to 8. The French specifications stipulate that diesel fuel color should be less than 5, which corresponds to an orange-brown tint. Generally, commercial products are light yellow with indices from 1 to 2. 

Color NF T 60-104 ISO 2049 ASTM D 1500 Comparison with colored glass standard references... 

The set of Glass Standard Reference Material NIST SRM 610 - 614 was used for quantification of amount up to 45 trace elements in the synthetic oxide single crystals and natural quartzites. 

In the analysis of solid samples (e.g., LA-ICP-MS, SEM), synthetic standards cannot easily be prepared to the required concentrations, and accurate calibration of such techniques is often challenging. In some cases (e.g., SEM) pure element or single mineral standards are used, ideally with an appropriate standard for each element to be quantified. (It is possible in SEM, within limits, to use fewer standards than the number of elements to be determined, with the calibration for other elements being predicted from the response of the nearest element.) More often, however, multielement primary standards are used as the means of calibrating the instrument, e.g., for LA-ICP-MS of glasses, volcanics, and ceramics, two glass standards, NIST 610 and 612 (Pearce et al. 1996), are often used. It is always advisable to use more than one multielement standard in order to cover as wide a range of concentrations as possible, and to use at least one additional independent reference material as an unknown, for quality assurance purposes (see below). 

Hollocher, K. and Ruiz, J. (1995). Major and trace-element determinations on NIST glass standard reference material-611, material-612, material-614, and material-1834 by inductively-coupled plasma-mass spectrometry. Geostandards Newsletter 19 27-34. 

Figure 6.12 RSCs of two standard reference materials (NIST SRM 612 glass standard and BRC 2G basaltic glass prepared from BCR-2 reference material) measured by LA-ICP-MS.30 (j. S. Becker et ai, Mikrochim. Acta 135, 71 (2000). Reproduced by permission of Springer Science and Business Media.)...

Figure 6.13 LA-ICP-MS results for trace elements on basalt glass (KL2-G from the Kilauea Volcano on Hawaii) using different glass standards (NIST SRM 612 and BCR-2G) compared to recommended value.

For the largest field of application for LA-ICP-MS - geological research - many different geological and glass standard reference materials are available. Using standard reference materials in LA-ICP-MS, analytical results for trace analysis in homogeneous samples can be obtained with an accuracy better than 10%, and a precision of 2-5% is also possible.25 If no suitable CRM... 

Table 9.32 Results of LA-ICP-MS on MPI-DINC Geological Glass Standard Basalt ML3B-G in comparison to reference value (concentration in fjugg )e.

Determine the apparent d of sample (das) in the same manner as described for the glass standard and calc as follows ... 

Tests on glass standard reference materials (SRM) from the National Institute of Standards and Technology (NIST) show that a stable signal is obtained when each isotope is measured using the peak jumping mode and one point per peak with a dwell time of 18,000 ps. The quadrupole mass spectrometer scans the entire mass range three times per replicate and accumulates 9 replicates for a total acquisition time of about 1 minute. For this application, fifty-three isotopes were selected (Table I). 

E. Miscellaneous Tubing Connectors. The variety of tubing couplers is enormous and a comprehensive list would be out of place in this book, but several additional types will be mentioned here which are useful in the laboratory. Metal standard taper and metal ball joints are available, and these will mate with corresponding ground-glass joints to provide one means of connecting parts made of dissimilar materials.4 As with glass standard taper joints, the seal is... 

Fig. 1.13. Variation on the cannula technique. The glass lube with fritted filter and the glass delivery tubes are attached to the glass standard taper joints by means of plastic adaptors (e.g., Kontes K-179800). The flexible plastic tubing connecting the two parts should be impervious to solvents. Teflon tubing is best and. to prevent contamination of the filtrate, Tygon tubing should be avoided when organic solvents are used.

The sample was mounted on a goniometer and rotated about an axis perpendicular to the laser beam. The laser beam was linearly polarized in a direction parallel to the rotational axis. The generated third harmonic was passed through a fundamental wave cutting filter and was detected by a photomultiplier tube. Third harmonic intensities were measured as a function of the incident angle for PAV films and a silica glass standard whose was reported to be 2.8 x 10 14 esu(17). The details of the experiments were reported else where (IS). 

Prior to measurement of reflectance, the sample face is covered with cedar oil or commercial immersion oil and then multiple readings are taken of the maximum reflectance of the coal component (e.g., vitrinite) of interest. These values are compared with readings of high-index glass standards (of known reflectance) that are available with reflectance values typically ranging from 0.302 to 1.815%. 

The mean maximum reflectance of vitrinite was determined in oil (ca. 1.517 index of refraction) and in 546-nm wavelength green light. A photomultiplier photometer was used to measure vitrinite reflectance. Two glass standards were used to calibrate the equipment. A Leitz MPV2 microscope photometer was used. The reflectance values were determined as designated in ASTM D2798-85 (2 5). Twenty-five vitrinite reflectance values were determined for the Rasa coal. 

Component Soda-Lime Soft Glass Standard Flint Pyrex Coming No. 7740 Vycor Coming No. 7900... 

The major limitation of LA-ICP-MS is the need for standards that closely match the properties of the samples. In some cases it is possible to use NIST glass standard reference materials for calibration in the analysis of geological materials [67,68], Internal standardization employing MS signals from elements at known concentrations has been used to improve precision and accuracy. Other techniques, such as acoustic [69] and light scattering [70] measurements, have been used in an attempt to monitor the relative amount of material ablated. These approaches seem to work well for variations in the amount of material sampled for similar sample matrices but not for very different types of solids. Dual-sample introduction systems with either wet [71] or dry [72] aerosol introduction in addition to laser ablation have also been reported. 

Table 3 rf-GDMS Analysis of NIST 610 Trace Elements in Glass Standard... 

The study of this effect in our laboratory proved that high active carbon black, when mixed in low concentrations with polyethylene, colored the polyethylene to ruby and brown shades. Using surface-active agents to enhance its despersion, PVC compounds could also be colored to similar shades. To prepare a reference color chart, glass standards containing different amounts of carbon proved convenient. 

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