Pharmaceutical applications, high-sensitivity

Water adsorbed on the surface of pharmaceutical or food powders, even at low levels, has a significant impact on the behavior of such powders during processing, and ultimately on the quality and performance of the final product. Bakri (1993) reported the application of heat conduction microcalorimetry to study the adsorption of water vapor onto solid pharmaceuticals. The high sensitivity of the calorimeter permits detection, even at low humidities, of heat flow as a result of interaction of solvent vapor with the solid. The heat flow (Pj ) can be described by ... 

Nowadays, many organic materials used in pharmaceuticals, dyes, or pesticides have become hazardous wide spread pollutants in the effluent. These organic species which exhibit electrochemical activities can be determined by mercury electrodes, especially trace amounts of organic compounds in pharmaceutical and biomedical applications. High sensitivity is easily achieved by employing adsorptive accumulation as the preconcentration step in the stripping technique. The determinations of common organic compounds are summarized in Table 3. 

Ion chromatography has become an essential tool of the pharmaceutical analytical chemist. The high sensitivity of the technique, coupled with the wide dynamic operating range made possible with modern high-capacity stationary phases makes it ideal for the analysis of ions in pharmaceutical applications. The combination of gradients and suppressed conductivity detection provides a powerful screening... 

A good example of using adsorptive separation in a non-refining/petrochemical application is the separation of fructose from an aqueous solution of mixed sugars. This process allows the production of high concentration fructose which has a much higher sweetness to calorie ratio than simple glucose or sucrose. As in fine chemical and pharmaceutical applications we can often use adsorption when distillation is not possible or feasible or when the material is thermally sensitive. 

The earliest applications for quantitative analysis of liquid samples and solid preparations entailed sample dissolution in an appropriate solvent. A number of moisture determinations in APIs and pharmaceutical preparations based on both reflectance and transmission measurements have been reported. Their results are comparable to those of the KF method. The high sensitivity provided by the NIR technique has fostered its use in the determination of moisture in freeze-dried pharmaceuticals. ° The noninvasive nature of NIR has been exploited in determination of moisture in sealed glass vials. " " ... 

The development of microbore chromatography and nano-flow HPLC has greatly increased interest in detectors suitable for sub-microliter peak volumes. These include LIE, EC, and MS spectrometry detectors. Zare first described the application of lasers for detection in analytical chemistry in 1984, outlining the potential for the use of lasers in analytical science, especially their application to HPLC [20]. This was followed in 1988 by another review that focused more on HPLC applications and provided examples of the high sensitivity possible with LIE detection [21], Another good review was written by Rahavendran and Karnes outlining the usefulness of LIE in pharmaceutical analysis [22],... 

The main advantage of using a fluorimetric detector is its inherently high sensitivity for pharmaceutical analysis, but very often application of this method to nonfluorescent drug substances requires derivatization with a strong fluorophore. The derivatization process can be performed either precolumn or postcolumn to increase the detection sensitivity [14]. 

The analysis of compounds of pharmaceutical relevance is one of the most promising application areas for CEC—MS, because it offers high sensitivity, high selectivity and structural information [38,98,99,105], Paterson et al. [105] utilized CEC—ESI-MS for the analysis of potential drug candidates down to the 1 ng/ml level in solid-phase extracts of plasma samples. Relative standard deviations of retention time and peak area of 0.4-1.7% and 2.6-10.7%, respectively, were achieved, which proves, that the method is also applicable to quantitative analysis. The analysis of a pair of... 

NMR has been an integral part of the chemist s analytical toolbox for decades. The most common and fundamental experiment is the one-dimensional (ID) H experiment. The relatively high sensitivity of the H nucleus makes this a very useful start, but for a complex molecule the ID spectrum can be crowded and often uninterpretable. In these cases more advanced techniques can be used to provide increased resolution and specific types of structural information. In this section we will describe a range of NMR techniques from the simplest ID experiments to complex multidimensional, multinuclear experiments. The focus of this section will be on the general principles underlying these experiments and their applications to molecules of pharmaceutical interest. Further details on these experiments can be found in the references. 

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