Absorbent Derivatives

Adenosine deaminase O.IM KCl and O.IM phosphate, pH 7.0 2mM mercaptopurine riboside (substrate analogue) 

Aspartate aminotransferase 5mM phosphate, pH 5.5 lOOmM phosphate, pH 5.5 or 1 mg/ml pyridoxal phosphate 

Carbonic anhydrase 0.01 M Tris, pH 8.0 O-IO M gradient of acetazolamide (enzyme inhibitor) 

O matrix beads (SELECTIVE ADSORBENT) specific enzyme to be purified 

Wilchek and W. B. Jakoby, The Literature on Affinity Chromatography, in Methods of Enzymology, Vol. 34 (W. B. Jakoby and M. Wilchek, Eds.), Academic Press, New York, 1974, p. 3. 

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Derivatization of primary and secondary amines using 9-fluorenylmethyl chloroformate to form a nonpolar, uv-absorbing derivative has been reported (90,91). Amphetamine and catecholamine were used as probes to evaluate this procedure. The derivatives were well behaved and allowed separation in a short time. 

Uses Travelers D (noninvasive strains of E. coli) in pts >12 y Action Not absorbed, derivative of rifamycin. Dose 1 tab PO daily x 3 d Caution [C, /-] Hx aUergy pseudomembranous cohtis Contra AUergy to rifamycins Disp Tabs SE Flatulence, HA, abd pain, GI distress, fevCT Interactions None significant EMS Monitor ECG and BP for signs of hypovolemia and electrolyte disturbances d/t D used primarily for D caused by contaminated food while traveling OD Sxs unknown symptomatic and supportive... 

Biotin does not exhibit UV absorbance. It neither shows fluorescence nor electrochemical activity. Therefore, it needs to be derivatized. 4-Bromomethylmethoxiycoumarin (BMMC) [590], 9-anthryldiazomethane (ADAM) [591], and 1-pyrenyldiazomethane (PDAM) [592] have been used as precolumn reagents to convert biotin to fluorescent absorbing derivatives. Instead, to obtain derivatives that are UV detectable, hydrazines are used, such as 2-nitrophenylhydrazine hydrochloride... 

To this effect, the measurement of absorbance is preceded by a chemical transformation (derivatisation) that has to be specific, total, rapid, reproducible and yield a UV/VIS absorbing derivative that is stable in solution. This is the principle of colorimetric tests. 

Supercritical fluid chromatography (sfc) combines the advantages of gc and hplc in that it allows the use of gc-type detectors when supercritical fluids are used instead of the solvents normally used in hplc. Carbon dioxide, n-petane, and ammonia are common supercritical fluids, For example, carbon dioxide employed at 7.38 MPa (72 9 atm) and 31.3°C has a density of 448 g/mL. Derivatization of primary and secondary amines using 9-fluorenylmethy] chlorofomiate to form a nonpolar, uv-absorbing derivative lias been reported. 

In liquid chromatography, derivatization for detection enhancement is frequently needed, since no universal, sensitive, and simple-to-operate detector exists (the preparation of UV-absorbing derivatives is essential to obtain the sensitivity required for samples in the nanogram range). Since most fatty acids do not absorb UV radiation (at least not in the wavelength ranges of most commercial UV monitors), detection of quantities in the 1-ng range can be difficult. Tag-... 

The post-column derivatization of amino acids by the ninhydrin technique is a well known method for routine analysis of amino acids [7-9]. The amino acids are usually separated by ion-exchange chromatography and then converted into UV-absorbing derivatives for quantitation. The ninhydrin reaction is often used for TLC detection of amino acids and proteins. 

The formation of highly UV-absorbing derivatives of estrogens with azobenzene-4-sulfonyl chloride [29] has been examined for analysis in biological extracts. The derivatives are separated by TLC arid are quantitated by direct densitometry of the chromatoplates. 

The use of benzoylation for the formation of UV-absorbing derivatives of non-UV absorbing hydroxy steroids has been reported for the analysis of these compounds by liquid chromatography [33]. This reaction may prove useful for the separation of steroids which cannot be separated as their DNPH derivatives. Molar absorptivities of many steroid benzoates are normally greater than 100001/mole cm at 230 nm. 

Figure 3. System characterization for shape and position of absorbance-derived signals for urea unfolding gradients alone. Upper panel depicts me average of 8 runs measured at each detector and the associated high/low statistical error limits computed at a confidence interval of 99.9%. Inset to upper panel depicts measured urea phase delay between the averaged runs. The lower panel depicts the averaged data phase-corrected. The lower panel inset depicts the residual differences in urea concentrations between the two absorbance detectors.

Vinyl acetate concentrations were calculated on the basis of the carbonyl band with a maximum absorbance at 1738 cm-1 and a baseline absorbance derived from linear interpolation between absorbance values at 1850 and 1650 cm-1. Vinyl chloride concentrations were calculated on the basis of the net absorbance of the C-Cl band with a maximum absorbance at 691 cm-1 with respect to a baseline drawn horizontally from the absorbance at 750 cm-1. Peak area for the vinyl acetate carbonyl absorption was evaluated between 1752 and 1723 cm l. Peak area for vinyl chloride was evaluated between 750 and 658 cm"l. 

Wide applicability. Enormous numbers of inorganic, organic, and biochemical species absorb ultraviolet or visible radiation and are thus amenable to direct quantitative determination. Many nonabsorbing species can also be determined after chemical conversion to absorbing derivatives. It has been estimated that more than 90% of the analyses performed in clinical laboratories are based on ultraviolet and visible absorption spectroscopy. 

Bodin, N. O., Ekstrom, B., Eorsgren, U., Jalar, L. P., Magni, L., Ramsey, C. H., Sjoberg, B. Bacampicillin a new orally well-absorbed derivative of ampicillin. Antimicrob. Agents Chemother. 1975, S, 518-525. 

Shaikh, B., Pontzer, N. J., Molina, J. E., and Kelsey, M. I., Separation and detection of UV-absorbing derivatives of fecal bile acid metabolites by bigh-performance liquid chromatography. Anal. Biochem. 85, 47-55 (1978). 

The analyte to be measured has no exploitable chromophore once again this problem is overcome by the creation of an absorbing derivative of the initial species following the same principle (Figure 9.22, curves c and d). 

An absorbing derivative of a nonabsorbing analyte can often be prepared. 

Advances in GC separation and ionization detection techniques during the 1960 s generated a great deal of interest and justifiable excitement for endocrinologists, due to the new possibilities of following hormones and their metabolites in body circulation. In particular, the development of electron-absorbing derivatives... 

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