Glass sample containers

In the past, the practice has been to take a sample from any depth in a large metal or (better) plastic container and then transfer the sample to another, usually plastic, container for subsequent analysis by appropriate analytical methods. Obviously, a metal container will contribute to the trace metal content of the sample, and even plastic containers will cause problems. Trace analysis studies have shown that plastic or glass sample containers can both absorb trace metal ions from the sample and/or contribute other metal ions to solution by surface dissolution 12, 13), Thus, the sample cannot be analyzed accurately because of the time-dependent effects on concentration which are related simply to the nature of the container and the conditions used to store the sample. 

Glass sample container connected to a water-cooled reflux condenser... 

Figure 6. ESR spectrum of the peptide anion radical derived from electron attachment to fl-alanylglycine at —196°C in a LiCl glass. Sample contained 5 X 10r2M of ft-alanylglycine and the electrons were generated photolutically (64). Spectrum was recorded at —153°C and is attributed to the radical NDS-...

The sample holders in (fc)-(m) are used in Linseis DTA equipment. In (k), removable sleeves made of metal or ceramic are used to contain the sample. This type of sample holder is convenient for cleaning purposes as the sleeve may be easily removed, leaving the exposed sample. A disadvantage of this type of sample holder is that the thermocouple is in direct contact with the sample and may be attacked by corrosive sample materials, thus changing its EMF output characteristics. A similar disadvantage is present for the probe-type sample holders in (/) and C/i). in which the thermocouple is immersed in the interior of the sample. The glass sample container in tei is usually a disposable capillary tube I -2 mm in diameter. A sample holder for horizontal use is illustrated in Iml. 

Raman band (300-550 cm" ) arising from the glass sample container makes this technique particularly suitable for the study of low-frequency vibrational modes. Heat removal by the cold tip minimizes laser-induced damage moreover, the spectra are generally of higher quality because of the... 

The samples D /T 0.5 and D /T 1 have chemical conqwsition of SiC 02(i ) (x = 0.3) and contain almost no free carbon, while 9 glass sample contains excess silicon... 

Tare a glass sample container and its PTFE-faced rubber septum sealing cap. Transfer a quantity of an oxygenate to the sample container and record the mass of the... 

Sample preparation is straightforward for a scattering process such as Raman spectroscopy. Sample containers can be of glass or quartz, which are weak Raman scatterers, and aqueous solutions pose no problems. Raman microprobes have a spatial resolution of - 1 //m, much better than the diffraction limit imposed on ir microscopes (213). Eiber-optic probes can be used in process monitoring (214). 

Natural crystals, synthetic crystals, and glasses often contain small bubbles that preserve samples of the fluid from which the crystals grew or of the atmosphere over the glass melt. Using a long focal length lens, the laser beam can be focused into inclusions at some depth below the crystal or glass surface. The Raman spectra then permit the identification of molecular species dissolved in the aqueous solutions or of components in the gas bubbles. ... 

Similarly, glass sample bottles should never be carried by hand. Workers have been injured when bottles they were carrying knocked against projections and broke. Bottles should be carried in baskets or other containers, such as those used for soft drinks. Bottles containing particularly hazardous chemicals, such as phenol, should be carried in closed containers. 

FIGURE 7.17 Separation of a complex mixture on Fractogel EMD BioSEC (S) with a column dimension of 1000 X 50 mm (Superformance glass column). The sample contained ferritin (I), immunoglobulin G (2), transferrin (3), ovalbumin (4), myoglobin (5), aprotinin (6), and vitamin B, (7). Five milliliters of the mixture was injected onto the column at a flow rate of 3 ml/min (eluent 20 mAI sodium phosphate buffer, 0.1 M NaCI, pH 7.2). 

A thin glass tube containing the sample solution is placed between the poles of a strong magnet and irradiated with rf energy. 

Figure 3. 4f core level spectra for a series of glasses containing Ca, Za, or B oxide additives (glass sample F, G,... 

For the AOAC beer samples, a 2 m x 2 mm glass column packed with 8.57o Carbowax 20 M + 0.857, NaOH on 100/120 mesh Chromosorb G was used at 130 C and a helium flow rate of 20 cc/min. Retention times of NDMA and NDPA were 4.5 and 12.2 min, respectively. For the ASBC collaborative study, a 1 m x 2 mm glass column containing 67, Carbowax 20 M-TPA on 100/120 mesh Chromosorb G was operated at 90 C with 20 cc/min helium flow rate. Retention times were 3.6 and 11.3 min for NDMA and NDPA, respectively. For determination of nitrosamines in amines, a 2 m X 2 mm, 107, Carbowax 20 M-TPA on 100/120 mesh Chromosorb G column was operated at 190 C with a carrier gas flow rate of 20 cc/min. Retention times were NPYR, 6.6 min NMOR, 7.4 min. 

The number of fluorine equivalents (to toluene) was varied the gas and liquid flow velocities were kept constant to maintain the same flow pattern for all experiments. Liquid products were collected in an ice-cooled roimd-bottomed glass flask containing sodium fluoride to trap the hydrogen fluoride. The flask is connected to a cooling condenser to recover the solvent. Samples were typically collected for 1 h. Waste gases were scrubbed in aqueous 15% potassium hydroxide solution. Samples were degassed with nitrogen and filtered before analysis. 

Figure 4.19 shows the p-PIXE X-ray spectra collected simultaneously from a fragment ( 1 mm in diameter) of an archaeological cobalt-blue glass (Uzonyi et al. 2001). This sample contains numerous minor and trace elements from carbon to lead, and the instrument employed both an ultra-thin window (UTW) detector as well as a Be-windowed detector. 

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