CD Accompanying This Book

Figure 8.14 Temperature changes as a result of depressurization (1) isenthalpic rapid expansion as through a valve, and (2) very slow depressurization, as in a large-volume pipeline. Note that for the rightmost case, a fluid system can be expanded into the hydrate region, as calculated by the methods in Section 4.2.1.1 and the programs of CSMGem on the CD accompanying this book.

The increasing threat of international terrorism was one motivation for development of ISE for the determination of Cs+ in environmental samples [80]. In an event such as a Chernobyl-type disaster or the explosion of a dirty bomb , cesium is one of the most important reaction products and is expected to be the most significant threat to public health [81]. With a detection limit of 10 8M, the developed electrode is sensitive enough for this application and the successful detection of cesium activities in spiked water samples has been demonstrated (see Procedure 2 in CD accompanying this book). In addition, the electrode shows excellent selectivity to cesium in the presence of high levels of strontium, an important interferent originating from nuclear explosions. 

Details on the fabrication of a LAPS for the detection of the pH value and the cadmium-ion concentration in aqueous solutions are given in Procedure 6 (see CD accompanying this book). 

Further details on the application of biosensors for environmental permanence measurements can be found in Procedure 11 (in CD accompanying this book). 

The generic approach to modifying electrodes with peptides for the detection of metal ions is depicted in Fig. 10.1 and outlined in Procedure 13 (in CD accompanying this book). The essential feature is an electrode modified with an SAM, which contains a carboxylic acid moiety at the distal end. The carboxylic acid moiety is activated using carbodiimides, typically l-ethyl-3-(3-dimethylaminopropyl)... 

Results obtained with the electrochemical biosensor were compared to those obtained from the colorimetric PPI assay with the enzyme in solution and by HPLC (see Table 21.1 of Procedure 21 in CD accompanying this book). All real samples contained microcystin at levels detectable by the amperometric biosensor and the colorimetric PPI... 

Wash, hand-peel, chop and lyophilize each plant tissue material for 3-4 h at 25°C (e.g., soybean (Table 17.1), potato, banana, eggplant, sweet potato and artichoke (Table 17.2). Grind the dry tissue to obtain a fine powder and select the particle size using sieves of lower than 200 pm mesh. Store the dry powder in a desiccator at 25°C and use it as the enzymatic source of PPO or peroxidase in the preparation of biosensor. Determine enzymatic activity and total protein content as described in Procedure 22 (in CD accompanying this book). Prepare the carbon paste electrode with dry tissue as described in the same procedure. 

Procedure 27 (see in CD accompanying this book), related to this chapter, gives some details on the use of disposable graphite sensors for DNA detection. 

Differential pulse (DP) voltammetry, a voltammetric technique with high sensitivity, is normally performed and the equipment as well as the electrochemical procedures used for the voltammetric studies of DNA-drug interaction are described (see Procedure 29 in CD accompanying this book). 

DNA-Cu(II)-quercetin interactions can be followed electrochemically using a DNA-electrochemical biosensor [29,35]. This knowledge about the electrochemical behaviour of the dsDNA incubated with quercetin-Cu(II) complexes at GC electrode [45] is an important feature to understand quercetin-DNA interactions at a DNA-electrochemical biosensor. The preparation of the solutions and the quercetin-Cu(II) complex used during the characterization of in situ electrochemical DNA damage promoted by the quercetin-Cu(II) complex using a DNA biosensor is described (see Procedure 29 in CD accompanying this book). 

GCE surface. Such kinds of devices have been shown to be inappropriate since they do not ensure a complete coverage of the GCE surface allowing the non-specific adsorption of the compound. However, a new type of biosensor-multi-layer dsDNA-electrochemical biosensor obtained by successive additions of small quantities of dsDNA on the GCE surface has been developed (see Procedure 29 in CD accompanying this book) and further used to study the interaction between dsDNA and the quercetin-Cu(II) complex. 

In order to obtain information about the origin of the peak at + 0.45 V, the GCE surface was modified with DNA-like sequences (po-lyguanylic and polyadenylic acids) that contain or not guanine residues [35]. These new types of biosensors were incubated in a quercetin solution and then conditioned (see Procedure 29 in CD accompanying this book). In this way, it was shown that the peak at + 0.45 V is directly related with the presence of guanine residues in the polynucleotidic chain and that it is due to the formation of 8-oxodGuo. 

For all the aforementioned reasons, it is possible to conclude that GEC-based platforms are very suitable for the immunological analysis of food residues according to the food management programs on Hazard Analysis Critical Control Point (HACCP). Procedures 33 and 34 (see in CD accompanying this book) give experimental details on the detection of pesticide atrazine and sulfonamide residues in food samples. 

Progesterone in milk See Procedure 35 in CD accompanying this book Chronoamperometric detection of 1-naphthol +0.3V 5-50 ngml-1 7ngml-1 Pemberton et al. [71]... 

Screen-printed electrodes used for the PB modification were home produced. A detailed description of the electrodes used and of the procedure adopted for PB modification is found in Procedure 17 (in CD accompanying this book). The most important thing to note about this procedure is that it does not involve any electrochemical step and, for this reason, it has been designed as chemical deposition . This procedure is also very easy to perform and could be adapted to mass production of modified electrodes (see Procedure 17 in CD accompanying this book). The suitability of the proposed deposition procedure was carefully evaluated with different electrochemical techniques and its application in real samples has been summarised and discussed here. 

All these results were obtained using screen-printed electrodes with batch amperometric or continuous flow techniques (for more details see Procedure 17 in CD accompanying this book). 

As already pointed out in our previous papers [48-50], the high stability is probably the result of the newly developed chemical modification procedure which may lead to a stronger adsorption of the PB particles on the electrode surface. In contrast to the PB layer obtained with the more commonly used electrochemical procedures, these modified electrodes are in fact more stable at basic pH and their continuous use is possible with a minimal loss of activity after several hours. Moreover, with respect to the electrochemical procedure, our chemical deposition is much more suitable for mass production since no electrochemical steps are required and a highly automated process could be adopted (see Procedure 17 in CD accompanying this book). 

An extraction procedure performed by sonication method for dried marine sediments and soil followed by the analysis of the extracts using an electrochemical immunosensor based on magnetic beads and carbon screen-printed electrodes is described in the protocol (see Procedure 25 in CD accompanying this book). 

Reference and auxiliary electrodes are coupled in a micropipette tip. The reference electrode consists of an anodised silver wire introduced in a tip through a syringe rubber piston. The tip is filled with saturated KC1 solution and contains a low-resistance liquid junction. The platinum wire that acts as auxiliary electrode is fixed with insulating tape. For measurement recording the tip is fixed on an electrochemical cell Metrohm support allowing horizontal and vertical movement (see Fig. 36.1 of Procedure 36 in CD accompanying this book). 

Repeatability is checked under the experimental conditions explained in Procedure 36 in CD accompanying this book, 1 h of hybridisation and a 2 x SSC buffer containing 50% of formamide. The value of the RSD was 11% for nine measurements. 

When the PCR products are labelled using the FITC labelled 5 -primer the analytical signals are higher and more reproducible than those obtained using the ULS labelling kit. Moreover, the PCR blank is higher in the latter case (see Fig. 37.2 of Procedure 37 in CD accompanying this book). 

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