Flatbed scanners

Dilute the DAB concentrate (10X stock) with stable peroxide buffer to IX following the manufacturer s protocol. Submerse the membrane in the DAB solution and develop for approx 3 min (Fig. 1). Rinse membrane with H20, incubate in a dark place until it is completely dry, and scan the image using a flatbed scanner. 

Figure 10.14. Scheme 1 depicts the formation of the three-component sandwich assay discussed in the text. (a) and (b) show flatbed scanner images of microarrays treated with gold nanoparticles before and after silver enhancement, respectively, (c) shows a typical Raman spectrum acquired from one of the silver spots. (d) shows a profile of the Raman intensity at 1192 cm-1 as a function of position on the chip the laser beam from the Raman instrument is moved over the chip from left to right as defined by the line in (b). (With permission from Ref. 40.)... 

If possible, use a flatbed scanner, where the art rests flat on a glass surface and is scanned by a moving scanner s eye, rather than a sheet-fed scanner, where the art is rolled past the scanner s eye. Flatbed scanners are less likely to distort your figure. 

The major advantage of these scanners is that they produce adequate quality at less than half the price of a flatbed scanner. The major downside is that they are slow and the quality depends on how steady the hand of the operator is. 

A. The flatbed scanner gives the best quality and highest resolution over a handheld scanner. This is due to several reasons, such as that the scanning hardware is enclosed in a special casing and the scanning arm is moved by a motor instead of by a human hand. 

An example of these 2D bar codes scanned from a flatbed scanner can be seen in Figure 18.2. Reliable and cost-efficient radio-frequency identification devices (RFID) are used in highly industrialized processes and have potential application in pharmaceutical laboratories [15],... 

High-resolution flatbed scanner (Epson Perfection Scanner series 1640, Long Beach, CA or UMAX PowerLook 1120, Dallas, TX, USA). 

Marty S, Baker K, Dibildox-Alvarado E, IN R. Monitoring and qnantifying of oil migration in cocoa butter using a flatbed scanner and fluorescence light microscopy. Food Res Int. 38 (2005) 1189-1197. 

Strains for nse in dairy applications are examined for their ability to acidify milk at varions temperatnres in microtiter plates. The change in the pH of the milk is followed by the inclnsion of pH indicators (bromocresol pnrple and bromocresol green) in the milk and scanning on a flatbed scanner typically at 6-min intervals. The data are exported to a snitable spreadsheet such as Microsoft Excel (Microsoft Corporation, Redmond, WA, USA) for ease of calculation. Acidification curves are obtained, and descriptors like total pH drop, maximum acidification rate, and specific time intervals snch as time to acidify from pH 6.0 to pH 5.5 are easily derived in the spreadsheet. The formation of volatile organic compounds in the acidified milk is measured by head space gas chromatography, allowing quantitative assessment of the production of relevant metabolites such as acetaldehyde, acetoin, and 3-methyl-butanal. Tolerance to NaCl is also tested in milk by following the acidification in the presence and absence of 4% (w/v) NaCl. 

Documentation of a TLC chromatogram as an image is conveniently possible. Traditionally photographs have been taken but the availability of electronic devices such as flatbed scanners or digital cameras have simplified the process. The principal advantage of electronic images is their durability. Added benefit is the possibility of qualitative and quantitative densitometric evaluation. 

Densitometry was first used to directly measure the amount of light absorbed by radioactive spots on films or stained protein bands on electrophoresis gels in the transmission mode. TLC slit scanners were then developed to directly measure the diffuse reflectance of colored, ultraviolet (UV) absorbing, and fluorescent zones on a layer, followed by videodensitometers for documentation and quantification of layer images. Most recendy, a commercial diode array scanner and office flatbed scanners (as purchased or modified) have been used for quantitative TLC. 

Zones on TLC plates can also be measured with a flatbed scanner. As with a CCD camera, chromatogram images are stored in digital form, and tracks and zones are detected and quantified with specialized software. Commercial office scanners can be used for naturally colored zones or colored zones produced by postchroma-tographic derivatization. Modified flatbed scanners have been described for use in quantification of fluorescent and fluorescence-quenched zones. As CCD cameras, flatbed scanners, and associated specialized software improve, quantification by image analysis will become increasingly competitive with slit scanners in the future. 

Mustoe, S.P. McCrossen, D. A comparison between slit densitometry and video (flatbed scanner) densitometry for quantitation in thin layer chromatography. Chromatographia 2001, 53 (Part 2, Suppl. S 2001), S474— S477. 

Gerasimov, A. V. Use of the software processing of scanned chromatogram images (flatbed scanner) in quantitative planar chromatography. J. Anal. Chem. 2004,59 (4), 348-353. 

Johnson, M.E. Rapid, simple quantitation in thin layer chromatography using a flatbed scanner. J. Chem. Educ. 2000, 77 (3), 368-372. 

Campbell, A. Chejlava, M. Sherma, J. Use of a modified flatbed scanner for documentation and quantification of thin layer chromatograms detected by fluorescence quenching. J. Planar Chromatogr.-Mod. TLC 2001, 16 (3), 244-246. 

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