Pharmaceutical products, metal analysi

The selectivity and sensitivity offered by atomic spectroscopy techniques can be used for direct and indirect determination of metals in a range of pharmaceutical preparations and compounds. Metals can be present in pharmaceutical preparations as a main ingredient, impurities, or as preservatives which can be prepared for analysis using non-destructive (direct or solvent dilution) or destructive methods (microwave acid digestion, bomb combustion, extraction, etc.) and the metal of interest measured against standards of the metal prepared in the same solvents as the sample. Methods associated with some pharmaceutical products are already described in the international pharmacopoeias and must be used in order to comply with regulations associated with these products, e.g titration techniques are carried out according to methods that are the same for all pharmaceutical products. 

Sample preparation of pharmaceutical products is an important step in the analysis methodology and must be carefully carried out to avoid contamination, loss of metal(s) or addition of interferences that could result in errors in the measurements. Modem versions of the international pharmacopoeias contain methods involving atomic emission methods, and some replace tedious titration, spectrophotometer or gravimetric methods. 

The methods of metal analysis of pharmaceuticals include X-ray fluorescence spectroscopy, AA spectroscopy, and ICP. Most pharmaceutical products are organic substances or biological materials. Active drug molecules rarely contain inorganic or metallic elements, but metallic pharmaceutical compounds such as ferrous sulfate, ferrous gluconate, zinc undecylenate, and magnesium stearate (a commonly used excipient) still exist in the market. 

However, the presence of metal in pharmaceuticals, even in trace amounts, is a form of contaminant. For example, metallic ions may act as a catalyst in oxidation that may be detected in drug products. High-sensitivity methods and techniques for metal analysis are essential for quality control. The classical method of detecting metal contamination is the heavy metal testing described in the USP. This method is a precipitation test with H2S. The limit is observed by comparing with the standard solution. 

The analytical measurement of elemental concentrations is important for the analysis of the major and minor constituents of pharmaceutical products. The use of atomic spectroscopy in this regard has been the subject of several reviews (2,3,35,36). Metals are major constituents of several pharmaceuticals such as dialysis solutions, lithium carbonate tablets, antacids, and multivitamin-mineral tablets. For these substances, spectroscopic analysis is an important tool. It is indispensable for the determination of trace-metal impurities in pharmaceutical products and the qualitative and quantitative analysis of metals, essential and toxic, in biological fluids and tissues (37). Beyond this, several drugs which do... 

Despite the problems discussed above, LIPS has been successfully applied in a number of process analysis applications. In some cases, the LIPS system has been used off-line as in the application described by Ottesen in which air cooled metallic substrates were used to collect fly ash deposits from a pulverised coal combustion for subsequent analysis off-line [70]. Calibration standards were prepared by spraying aqueous solutions onto heated substrates using an air brush and the method was found to work well provided that the deposits were sufficiently thin to permit complete ablation. Other workers have proposed on-line LIPS systems for process control. An example is the apparatus proposed by Sabsabi [71] for in situ analysis of pre-selected components of homogeneous solid compositions. In particular, the author proposed that the system could be used for measurement of the concentration of active ingredients (e.g. drugs) in pharmaceutical products such as tablets, by monitoring an element present in the active component (e.g. 

All fields of modern industry that depend on the composition of products has to use the methods of analytical chemistry. In earlier periods of this century only the final products were analysed. In this respect the analysis of pharmaceutical products was important as well as the material characterisation in metallurgy. Later on manufacturers realised the financial importance of process control in addition to the analysis of the products. Based on process analysis the technology can be controlled in order to ensure the required product properties. Metal industry was among the first to implement process analysis. 

Activation analysis can be applied to most types of material, including food products, urine, feces, air pollution particulates, river water, marine samples, vegetation, soils, sediments, ores, plastics, petroleum products, pharmaceuticals, coal, metals, alloys, semiconductor materials, clays, ceramics, and glasses. Variations in the analytical procedures for multielemental analysis are dictated by the matrix and so are detection Hmits. Table 2 compares the detection limits for an air particulate sample on filter paper and those for a deep-sea sediment to the detection limits in the ideal situation. Petroleum products, pharmaceuticals, plastics, carbon products, and air filters are not activated to produce y-rays, so the spectrum is free of any interferences from the matrix. This means that detection limits are low and over 60 elements can be determined simultaneously. Soils, sediments, clays, and glasses have elements such as sodium and scandium in their matrices that can produce backgroimd activities that result in poorer detection limits for most elements. 

Porphyrin-modified electrodes were widely utilized for quantification of low concentrations of metals, pharmaceutical products, and species of environmental and industrial importance in association with flow techniques. This strategy enhances the amperometric response and sensitivity (the capacitive current is virtually reset), while reducing significantly the time necessary for analyses. Flow injection analysis (FIA) has been extensively explored for this purpose and a revision on the application of porphyrins and derivatives was published some years ago [203]. Alternatively, batch injection analysis (BIA) can be an interesting way for fast analyses utilizing a similar mass transport process to the electrode surface [204]. For example, citric acid was electrochemically determined by BIA using cobalt phthalocyanine modified carbon paste electrodes [205]. 

Part—I has three chapters that exclusively deal with General Aspects of pharmaceutical analysis. Chapter 1 focuses on the pharmaceutical chemicals and their respective purity and management. Critical information with regard to description of the finished product, sampling procedures, bioavailability, identification tests, physical constants and miscellaneous characteristics, such as ash values, loss on drying, clarity and color of solution, specific tests, limit tests of metallic and non-metallic impurities, limits of moisture content, volatile and non-volatile matter and lastly residue on ignition have also been dealt with. Each section provides adequate procedural details supported by ample typical examples from the Official Compendia. Chapter 2 embraces the theory and technique of quantitative analysis with specific emphasis on volumetric analysis, volumetric apparatus, their specifications, standardization and utility. It also includes biomedical analytical chemistry, colorimetric assays, theory and assay of biochemicals, such as urea, bilirubin, cholesterol and enzymatic assays, such as alkaline phosphatase, lactate dehydrogenase, salient features of radioimmunoassay and automated methods of chemical analysis. Chapter 3 provides special emphasis on errors in pharmaceutical analysis and their statistical validation. The first aspect is related to errors in pharmaceutical analysis and embodies classification of errors, accuracy, precision and makes... 

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