Qualitative monitoring

Hydrogen probes are mainly used in refineries to detect the onset of conditions when HjS cracking of carbon-steel equipment could become a real risk. As a qualitative monitoring technique, it has a long and proven service of worth. 

The VX bubbler method suffers from a problem that decreases recovery and contributes to a low bias. Performance is within criteria to allow use as a qualitative monitoring method by setting an action level at 0.56 time-weighted average (TWA). A 3 1 signal to noise ratio is achieved at approximately 0.5 TWA. 

Optical techniques were developed - both in situ and on line - over a broad range of applications and various types of light sources. Main examples are solids concentration measurements in particle fluidisation [6,7], as well as gas-solid flow [8], or sample composition in dry blending operations, this latter beginning from the pioneering work of Harwood et al. [9] up to more recent advances in this scientific field [10-12], The main interest of these techniques lays in the fact that optical probes are easily available on the market, so that qualitative monitoring of mixers is possible at an industrial scale. However, these probes only provide local information of the mixture (typically 1/40 of a tablet), so that in essence, they still sample the powder flow in a way that may be intrusive and not always representative of the overall stream. 

Large CH2/CH3 intensity ratios suggest long alkyl chains and visa versa. CH stretching features for fatty compounds (and proteins) and carbohydrates are significantly different. Frequencies of the iy,(CH2) and Vs(CH2) bands can be used to qualitatively monitor conformational order. 

The results presented here demonstrate that thin films can be characterized based on acoustical monitoring of changes in film mass density, conductivity, and viscoelasticity. Additional sensing mechanisms are available to probe film properties. Some examples are thin-film dielectric constant, stress, and structure (e.g., roughness). Some of these sensing mechanisms will be hard to quantify since they involve a complex interaction (e.g., wave attenuation based on wave scattering due to film roughness) however, they may still be useful to provide a qualitative monitor based on empirical data. 

Perform qualitative monitoring of the coupling reaction using a colorimetric test (see Note 1). 

Cu(II) and Co(II) were the first cations to be chosen for the study because they form complexes that are easy to study by DRS and IR methods. The work may be employed in qualitative monitoring of these adsorbates or their related functional groups in the environment. The characteristic electronic and bonding behavior for particular ligand-... 

GC and HPLC methods, not fully investigated, may be used for qualitative monitoring. It may be noted that exposure to certain chemicals, such as parathion, may also produce p-nitrophenol as a urinary metabolite. A screening test for nitrobenzene exposure may be performed by monitoring methe-moglobin in the blood. 

Henceforth, the operator will base its operations on the unplugging temperature measurement associated with the sodium oxide (low unplugging temperature) and on the duration of the low level which is an effective and simple method of qualitively monitoring the sodium purity and its evolution over time... 

On the other hand, the fact that many metal carbonyl clusters are colored [80] often allows thdr formation in zeolite cages to be qualitatively monitored visually. The color of a zeolite which contains a duster may not be quite the same as that of the duster in the pure solid state. For example, [Ir4(CO)i2] in NaY zeolite is yellow, a odor almost the same as that of the cluster in solution. [3, 5, 66] The color of the [Ir (CO)ig] isomer with edge bridging CO ligands in a NaY zeolite is yellow, [3, S] but the color of this duster in tetrahydrofuran solution is red. [57, 58]... 

Qualitative monitoring techniques include smoke tubes and the dust observation lamp. Smoke tubes generate a white smoke which may be used to indicate the direction of flow of air - this is particularly useful when the air speed is very low or when testing the effectiveness of ventilation ducting. A dust observation lamp enables dust particles which are normally invisible to the human eye to be observed in the light beam. This dust is usually in the respirable range and, although the lamp does not enable any measurements of the dust to be made, it will illustrate the operation of a ventilation system and the presence of such dust. 

DIES can be used both for qualitative monitoring of chemical reactions in organic materials e.g. curing, drying) and for quantitative measurements e.g. determination of the concentration of polar liquids in materials such as water content in polymers). DIES can be combined with other techniques, such as FTIR, to gain specific molecular information on reactions that take place simultaneously and monitor these reactions. However, only conductivity, a macroscopic property, is measured. Consequently, molecular differentiation between combined reactions cannot be made. A lab-scale experiment in combination with more specific techniques (e.g. FTIR) is necessary to determine quantitatively the specific reactions. Dielectric analysis also measures changes in the properties of a polymer as it is subjected to a periodic field. A general problem in interpretation of dielectric and conductive methods is that they are not specific and are affected by many sources of interferences. These factors may explain the relatively slow introduction of this technique in characterisation of elastomer systems. 

Monitoring and evaluation of the crossover reaction in ring-opening metathesis polymerization (ROMP) via MALDI methods were reported recently by Binder et al. [97]. The crossover reactions as well as the polymerization kinetics of the various monomers were studied in the presence of different catalysts by kinetic analysis and MALDI MS. Whereas the classical kinetic analysis enabled the qualitative monitoring of the chain-growth reaction, MALDI method allowed the monitoring of the reaction directly at the point of the crossover reaction, thns enabling a better evalnation of the different monomers and catalysts employed in the polymerization reactions. 

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