Quantification procedures solutions

Calibration and quantification procedures are easier in LA-ICP-MS compared to other solid-state mass spectrometric techniques because the laser ablation and the ICP ion source operate at normal pressure and the laser ablation of solid samples and ionization of analytes are separated in space and time. Therefore the advantage of solution calibration in ICP-MS can be applied in this solid-state analytical technique. The introduction of solution based calibration, which is only possible in LA-ICP-MS, was an innovative step in the development of this sensitive mass spectrometric technique. A number of different calibration approaches using aqueous standard solutions in the dual gas flow technique have been discussed by various authors.74 75 In the dual gas flow injection technique , the nebulized standard solution and the laser ablated sample material are mixed in the -piece and the two gas flows from the nebulizer (e.g. ultrasonic nebulizer) and laser ablation chamber are added. Using solution based calibration with the addition of a standard solution, Leach et alP determined minor elements in steel reference materials with a relative accuracy of a few %. In comparison to the so-called dual gas flow technique proposed in the literature, where the argon flow rates through the nebulizer and ablation cell add up to 11 min-1 (e.g. 0.451 min-1 and... 

Bings77 quantified 11 trace metals in lubricating oil with the aid of solution based calibration in LA-ICP-MS using a ToF mass spectrometer. It has been shown that good analytical performance in terms of precision (6 % on average) and low detection limits in the ng g-1 range can be obtained with this easy and fast quantification procedure in LA-ICP-MS.77... 

Trace impurities in noble metal nanoclusters, used for the fabrication of highly oriented arrays on crystalline bacterial surface layers on a substrate for future nanoelectronic applications, can influence the material properties.25 Reliable and sensitive analytical methods are required for fast multi-element determination of trace contaminants in small amounts of high purity platinum or palladium nanoclusters, because the physical, electrical and chemical properties of nanoelectronic arrays (thin layered systems or bulk) can be influenced by impurities due to contamination during device production25 The results of impurities in platinum or palladium nanoclusters measured directly by LA-ICP-MS are compared in Figure 9.5. As a quantification procedure, the isotope dilution technique in solution based calibration was developed as discussed in Chapter 6. 

Relatively few studies have been made on the feasibility of quantitative FAB analysis. Riley et al. [217] have described a quantification procedure to monitor the paint additive Tinuvin 770 in two coating systems (acrylic melamine and a hydroxy ester melamine). Tinuvin 770 proved to be well suited for FAB analysis in coating extracts on glycerol basis using an internal standardisation procedure. Lay et al. [218] have developed a FAB-MS method for the quantitative analysis of plasticisers (DEHP, including any isomeric dioctyl phthalates) in baby PVC pacifiers that does not require sample extraction, clean-up, or chromatographic separation. A reference material, didecylphthalate (DDP), was added to a solution of the PVC sample in THF as an internal standard. Quantitation was based on the relative... 

The Folin-Denis assay is used as a procedure for the quantification of total phenolics in plant materials, food, and beverages. Reduction of phosphomolybdic-phosphotungstic acid (Folin-Denis reagent) to a blue-colored complex in an alkaline solution occurs in the presence of phenolic compounds (Folin and Denis 1912). 

Quantitative analysis of AP/APEO by HPLC-FL can be performed with external standard solutions of mixtures of AP or APEO. Initially quantification of oligomeric mixtures was based on the elaborate procedure of normal-phase analysis with subsequent quantification of all oligomeric peaks [27]. Kiewiet et al. [28] have described the general principle of quantification of ethoxymers in reversed-phase LC with spectroscopic detection in detail using the example of derivatised alcohol ethoxylates. Based on this method the quantitative analysis of... 

For all these techniques, the general qualitative correlation between the measured parameter and the iron concentration was established. However, the measurements are too sensitive to the parameters of the experimental procedures and to physiological data beyond the iron content to allow for routine use in hospitals (43). Indeed, the relaxivity of ferritin is different in solutions, in the liver, in the spleen, in the brain, etc., which implies that MRI quantification protocols must be developed separately for each organ. 

In solution, vitamin D (both D2 and D3) isomerizes to previtamin D and forms a temperature-dependent equilibrium mixture [520], which leads to quantification problems. Previtamin D is difficult to quantify because of interference from co-eluted contaminants. The reversibility of the isomerization is very slow, therefore the percentage of previtamin can be considered constant during the entire analysis. The quantification of the potential vitamin D can be performed using an external standard that has undergone saponification procedure as the sample [521]. Vitamin D2 and D3 can be used as an internal standard to quantify the other one. Indeed, the isomerization rates of vitamins D2 and D3 are virtually the same thereby the previtamin D/vitamin D ratio will be the same for both vitamers at any temperature. The isomerization problem can be resolved by... 

This procedure has been developed for quantification of the three types of macromolecules in tissue extracts, where other hiomolecules are also present. Small dissolved amounts of DNA, RNA, or protein, especially when no material should be consumed and no interfering substances are in the solution, maybe estimated by UV photometry, but a discrimination between DNA and RNA is impossible by reading absorbencies (cf. Protocol 1.2.5). 

According to the modified procedure (602), milk is thoroughly mixed in its storage container immediately before transfer of the 1 ml aliquot in the extraction tube. This is necessary because approximately 50% of phenylbutazone in milk is associated with the cream. The sample is extracted with 2.4 ml diethyl ether and 2.4 ml petroleum ether in presence of 1 ml ethanol and 100 1 25% ammonia solution. The organic layer that contains the milk lipids is discarded. Five ml hexane-tetrahydro furan (4 1) is added to the aqueous layer, which is tiien acidified with hydrochloric acid and the layers are mixed. Under the acidic conditions, phenylbutazone partitions quantitatively into tlie organic layer, which is collected, evaporated, and dissolved in the mobile phase to be analyzed by liquid chromatography. Separation is performed on a reversed-phase column using an isocratic 0.02 M phosphate buffer/methanol mobile phase, and determination is by ultraviolet detection at 264 nm (Fig. 29.18.2). The limit of detection and limit of quantification were 3.0 and 5.4 ppb, respectively (Table 29.17). 

The partitioning of Fluka humic material was studied at pH 3 and pH 7 to ascertain the amount of potential interference with subsequent GC analysis (19). Water-methylene chloride partition coefficients were determined by quantification of the humic concentration in pH 3 and pH 7 salt solutions by UV analysis at 254 nm of the humic material before and after methylene chloride extraction. The method followed the procedure of Suffet and Faust (7) in which p-values (fraction recovered in methylene chloride at 1 1 water methylene chloride) and E-values (fraction recovered in methylene chloride at any specified water-to-solvent ratio) were calculated. Watenmethylene chloride (10 1) was used for all E-value calculations. The values obtained were as follows for pH 3, p-value = 0.48 and 10 1 E-value = 0.07 for pH 7, p-value = 0.19 and 10 1 E-value = 0.02. 

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