Auxiliary gas flow

HR-ICP-MS EEEMENT-2 (Pinnigan MAT, Germany) equipped with a standard introduction system (quartz water-cooled spray chamber, concentric nebulizer, torch with 1.5 mm i.d. injector and nickel cones) was used for measurements. The following operating conditions were used RP power 1150 W, coolant gas flow rate 16 1 min k auxiliary gas flow rate 0.85 1 min nebulizer gas flow rate 1.2 1 min k Sample uptake rate was 0.8-1 ml min k Measurements were performed with low and middle resolutions. Rh was used as an internal standard. Por calibration working standard solutions were prepared by diluting the multielemental stock solutions CPMS (SPEX, USA) with water to concentration range from 5 ng to 5 p.g I k... 

A velocity flame stopper is effective only as long as there is a sufficient gas flow through it. If gas stream can he subject to low flow deviations during normal or upset operating conditions, a highly dependable auxiliary gas flow must be provided. The reliability of this auxiliary gas system will affect the selection of the velocity flame stopper. 

InsAument parameters (sheath and auxiliary gas flows, spray voltage, capillary temperature, collision cell gas flow and offset, etc.) should be optimized while infusing a standard of tebuconazole prior to the Arst attempt at analysis. Optimization should be performed at an HPLC Aow rate and composition simulating those present during elution of tebuconazole using each HPLC condition set employed... 

A desirability function was defined to study all elements simultaneously according to three critical variables (sheath gas flow, pump speed and auxiliary gas flow)... 

The quadrupoles in an MS instrument serve as selective mass filters to isolate ions with m/z-values specific for the analytes of interest. The triple quadrupole MS/MS instrument is typically operated by a pneumatically assisted electrospray source with an additional heated auxiliary gas flow for higher flow rates. There is a trade-off between resolution (favored by lower flow) and sensitivity (favored by higher flow) of the quadrupole analyzers. The biological molecules can be proto-nated or deprotonated at multiple sites to produce ions of n charged states [M nH]n . The MRM-MS/MS scan mode has a high duty cycle for the detection... 

Shen et al. [95] reported the first instance of SFC coupled to ICP-MS for tetraalkyltin speciation. The mobile phase used was C02. Tetramethyltin (TMT), tetrabutyltin (TBT), thetraphenyltin (TPT), tributyltin acetate (TBTA), and dibutyltin diacetate (DBTDA) were all resolved. C02 was also used as the auxiliary gas flow for ICP-MS. The Sn signal was optimized by adjusting the C02 flow and the rf forward power. The compounds were found to interact poorly with the stationary phase thus only TBT and TPT could be separated. No organic modifiers were added, however. Further organotin speciation studies by the same group... 

The combination of GC with olfactometry is another possibility for detection that has been used in essential oil analysis. Olfactometry adapters are commercially available and should include humidity of the GC effluent at the nose adapter and provide auxiliary gas flow. The correlation among eluted peaks with specific odors allows accurate retention indices or retention times to be... 

Plasma gas flow Auxiliary gas flow Spray chamber Radial torch Nebuliser Integration time Delay time Stabilisation time Sample uptake rate Sample read rate PMT... 

Figure 1.21. Schematic description of the sieve-based-device 1 sprayer 2 syringe pump 3 DC power supply 4 auxiliary gas flow regulator 5 N2 cylinder 6 sieve mounted on a stainless steel frame 7 screen 8 beam interceptor 9 sample holder.

The selection of the proper intrinsic (plasma power, argon gas flow rate, auxiliary gas flow rate, powder carrier gas flow rate, etc.) and extrinsic (spray distance, powder feed rate, powder grain size, particle morphology, surface roughness, etc.) plasma parameters is crucial for sufficient powder particle heating, flow and surface wetting on impact and hence development of the desired coating porosity and... 

Carrier gas flow rate Auxiliary gas flow rate Plasma gas flow rate Dwell times... 

The formation of solvent—analyte noncovalently bound complexes (e.g., [M -F H + ACN], [M -F H -F MeOH]", etc.) complicates molecular ion determination in ESI—APCI MS (Table 10.1). The relative abundances of these solvent cluster ions depend on the components in the solution phase, ionization mode, spray voltage, capillary temperature, sheath gas pressure, as well as auxiliary gas flow. Zhao et al. (2004) recently reported that acetonitrile could be reduced to ethyl amine under ESI conditions (Scheme 1). They demonstrated that the M -F 46 ion in the mass spectrum represented the ethyl amine adduction ([M -F H -F CH3CH2NH2] ) when the ESI—MS was performed by infusion of the compound in acetonitrile and water (1% HCOOH -F 1% NH4OH) (1 1 V v). Moreover, they showed the same analyte produced a moderate [M + H + CD3CH2NH2] (M -F 49) signal when acetonitrile-ds was used as the organic solvent (Scheme 1). 

The combination of GC with olfactometry is another possibility for detection that has been used in essential oils analysis. " " " Olfactometry adapters are commercially available and should include humidity of the GC effluent at the nose adapter and provide auxiliary gas flow. The correlation among eluted peaks with specific odors allows accurate retention indices or retention times to be estabhshed for the essential oil components. Some of them can be detected in this way after applying chemometric techniques, such as cluster analysis and principal component analysis, to the data from the sensors. A limitation of GC with olfactometry is that peak coelution in complex samples makes identification of the compound(s) responsible for an odor difficult, particularly where trace odorants coelute with larger odor-inactive peaks. One possible solution for identifying character-impact odorants where coelution occurs is to use comprehensive two-dimensional GC (GC X GC). " ... 

It is also possible to evaporate solvent from the sample applied onto the needle in the injecting cylinder 8 without descending the needle of the injector into the chamber 9 (Fig. 2). This procedure is possible in the case of solvents characterized with low heat of vaporization. In this case, auxiliary gas flows through the inlet 30 over the ball valve... 

Grace and Lim (1987) proposed a simple criterion based on stable spouting correlation by Chandnani and Epstein (1986), as shown in Eq. (154), as a neees-sary but not sufficient condition for permanent flame jet formation in fluidized, spout-fluid, and spouted beds. They also observed that inereasing temperature has a significant destabilizing influence on jet formation, and that a lower ratio of orifiee and particle diameter is required for permanent jet formation at high temperatures. Larger auxiliary gas flow can also lead to unstable jets and absence of permanent flame jets. For jets other than in the vertical direction, the formation of permanent flame jets is less likely. 

Detector MS, PE Sciex API 3000 turbo ionspray, positive ion mode, ionspray needle 5 kV, turbo gas temperature 300°, auxiliary gas flow 8 L/min, m/z 311-259... 

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