Iron specific detection

Although analytical SFC was demonstrated in the early 1960s, it has only been in recent years that the availability of adequate high resolution packed and capillary SFC columns and instrumentation has led to renewed interest in the technique. Plasma emission is a natural development because of its use in GC and HPLC. A surfatron MIP sustained in helium has been employed for SFC detection, giving sulfur-specific detection at 921.3 nm with a 25 pg s limit for thiophene [28]. An argon high efficiency MIP has been interfaced with packed column SFC and the separation and detection of ferrocene and derivatives achieved with iron specific detection. Methanol modifier concentrations to 5% were tolerated in the carbon dioxide mobile phase [29]. 

Application of the phosphorus-specific detection (see Section 3.8.2) described by Vaeth et al. [118] allows the use of the AS7 column for the analysis of higher condensed phosphates. A mixture of potassium chloride and EDTA [119] is used as an eluant. The potassium chloride concentration determines retention EDTA is only added for improving peak symmetry. However, post-column derivatization with ferric nitrate, as mentioned above, cannot be apphed in this case because the Fe(III) ions of the derivatization reagent form iron-chloro complexes with the chloride ions of the mobile phase, which leads to a high background absorbance. Conductivity detection is also impossible due to the high salt concentration in the mobile phase. The detection system developed by Vaeth et aL comprises a post-column hydrolysis of the polyphosphates to orthophosphate... 

More specifically, 2-aminophenol can be detected in solution using an iron(II) sulfate—hydrogen peroxide reagent (94). 3- Aminopheno1 has been analyzed colorimetrically by oxidation in base and subsequent extraction of a violet quinoneimide dye (95). A colorimetric method using... 

Note The dipping reagent, which can also be applied as a spray reagent, can be employed on cellulose and silica gel layers. A 3% solution of 2,2 -bipyridine in 40% thioglycolic acid can be employed as a specific spray reagent for the detection of iron (red coloration) [7],... 

The protein from D. desulfuricans has been characterized by Mbss-bauer and EPR spectroscopy 224). The enzyme has a molecular mass of approximately 150 kDa (three different subunits 88, 29, and 16 kDa) and contains three different types of redox-active centers four c-type hemes, nonheme iron arranged as two [4Fe-4S] centers, and a molybdopterin site (Mo-bound to two MGD). Selenium was also chemically detected. The enzyme specific activity is 78 units per mg of protein. 

A different type of phenomenon is observed for the two specific Rapid signals which are obtained from xanthine (Fig. 3). Whilst the no complex detected types of signal are still seen with very low xanthine concentrations (88), these are replaced at higher xanthine concentration by a different signal (76, 88, see also Section V D and Fig. 4) which seems to represent a mixture of variable amounts of two complexes of reduced enzyme (76, 78). These complexes are, apparently, not with a product derived from the xanthine molecule which originally reduced molybdenum (76). Instead they involve a further xanthine molecule, this remaining un-oxidized in the complex. Ultimately, when molybdenum has been reoxidized (via iron and flavin), this substrate molecule having... 

Recently, another interaction was reported between an intracellular pathogen and the key regulator system of intracellular iron concentration, i.e. the degree of binding of the IRPs to IRE (see Chapter 7). In extracts from Leishmania tarentolae, a protein has been detected that binds specifically to the mammalian IRE. However, the exact nature and function of this protein is unclear up to now. In contrast to mammalian IRPs, the L. tarentolae IRE-binding activity was not induced by growth in iron-depleted medium (Meehan et ah, 2000). 

Other studies in this specific area are also based on the catalytic effect of a variety of metal ions such as copper (II), cobalt (II), nickel (II), iron (III), and manganese (II) on the luminol-hydrogen peroxide reaction providing a rapid and efficient detection mode for these five ions, when an online CL detector is used before separation by CE [88], This contribution combines capillary ion analysis (CIA) and CL detection by means of a postcapillary reactor similar to the one originally developed by Rose and Jorgenson [80] and finally modified by Wu... 

Potassium permanganate and iodine, which are important redox reagents, are both self-indicating, i.e. the colour of the reagent in each case is intense and will impart a perceptible colour to a solution when present in very small excess. One drop of a solution of potassium permanganate (0.02 mol dm 3) can be detected in a titrand solution of 100 cm3, and a similar amount of iodine by shaking the titrand with 5 cm3 of chloroform or carbon tetrachloride to produce an intense purple colour. Specific indicators react in a specific manner with one participant in the reaction. The best examples are starch, which produces an intense blue colour with iodine and potassium thiocyanate, which forms an intense red compound with iron(III). 

ABC transporters involved in the uptake of siderophores, haem, and vitamin B]2 are widely conserved in bacteria and Archaea (see Figure 10). Very few species lack representatives of the siderophore family transporters. These species are mainly intracellular parasites whose metabolism is closely coupled to the metabolism of their hosts (e.g. mycoplasma), or bacteria with no need for iron (e.g. lactobacilli). In many cases, several systems of this transporter family can be detected in a single species, thus allowing the use of structurally different chelators. Most systems were exclusively identified by sequence data analysis, some were biochemically characterised, and their substrate specificity was determined. However, only very few systems have been studied in detail. At present, the best-characterised ABC transporters of this type are the fhuBCD and the btuCDF systems of E. coli, which might serve as model systems of the siderophore family. Therefore, in the following sections, this report will mainly focus on the components that mediate ferric hydroxamate uptake (fhu) and vitamin B12 uptake (htu). 

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