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Metal detectors play a vital role in detecting elemental impurities in pharmaceutical processing and production units. They are normally used in pharmaceutical production facilities for identifying or to trace out the presence of metallic objects, such as ferrous, non-ferrous, or stainless-steel contaminants in intermediates and in final pharmaceutical products. Various intermediates and final pharmaceutical products are being contaminated by these metal or metallic substances from processing equipment used in the manufacturing activities and many other various potential sources.
Categories of sources of elemental impurities include: residual impurities resulting from elements intentionally added (e.g., catalysts) in the formation of the drug substance, excipients or other drug product components; elemental impurities that are not intentionally added but may be present in the drug substance, water or excipients used in the preparation of the drug product; elemental impurities that may be introduced into the drug substance and/or drug product from manufacturing equipment contact; and elemental impurities that have the potential to be leached into the drug substance and drug product from container closure systems.
It is critical to ascertain the quantum of elemental impurities included in the pharmaceutical products, so that they can be kept very low. Metal detector plays vital role to trace out elemental impurities in products of pharmaceutical industry.
Contamination occurs in medicinal products due the presence of ferrous and non-ferrous materials. Detection of such metal contamination is important and in this detection process, high accuracy and reliability are desirable. Thus, a metal detector plays an important role in ensuring quality and safety of medicinal product. The presence of metal pieces even in a minute quantity, it has abnormal capacity to degrade the medicinal products.
In pharmaceutical sector, contamination by metallic parts can be termed as it is due to metal-objects - ingredient contamination, mixing-process errors, and machinery failures - and due to the use of various process equipment such as reactors, agitated and storage vessels, classifiers, dryers, pumps, valves, pipes etc. in the synthesis, processing and storage most equipment, viz. pipes, valves and pumps are made up of metals. For example, in large-scale dehydrogenation processes nickel, cobalt, platinum, palladium, and mixtures containing potassium, chromium, copper, aluminium and other metals are employed.
In many pharmaceutical processing, unsaturated organic compounds that contain double-bonds or triple-bonds need to be hydrogenated. Platinum black, palladium black, copper metal, copper oxide, nickel oxide, aluminium and other materials have subsequently been developed as hydrogenation catalysts, and the abrasive materials can wear mill parts and screens. In these operations, there is a probability existing to the products get contaminated with various metallic components.
There are different types of metal detectors working on various principles, for example multi-frequency transmission and receiving type. This type detector is working on the principle of multi-frequency transmission and receiving. Multi-coil arrangements are used for the transmission and receiving of multi-frequency in metal
detection.
The multi-frequency created by the multi-coil arrangement improves the signal system viewed by the receiver. Depending on the purpose, different types of metal detectors are available for checking metallic contamination.
Ultraviolet–visible spectroscopy or ultraviolet–visible spectrophotometry refers to absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region. This means it uses light in the visible and adjacent ranges.
Ultraviolet/visible detector coupled to high performance liquid chromatography or as a stand-alone, ultraviolet/visible is widely used and is the primary technique for the detection of the qualitative and quantitative analysis of metal/metallic impurities in pharmaceutical analysis and quality control.
Many pharmaceutical compounds absorb light in the ultraviolet region, especially in the low wavelength ultraviolet region. Ultraviolet detector is sensitive, robust, compatible with liquid chromatography, and has a wide linearity range. It is also easy to use, low maintenance, and relatively more affordable than other detectors.
Instrumental neutron activation analysis
Instrumental neutron activation analysis is a relatively straight forward analytical technical method for determining elemental abundance (abundance in physics the ratio of the number of atoms of a specific isotope of an element to the total number of isotopes present) in a wide range of materials.
This technical method relies on the measurement of characteristic radiation from radio-nuclides formed directly or indirectly by neutron irradiation of the material of interest.
The energy of the emitted gamma rays is used to identify the nuclide and the intensity of the radiation can be used to determine its abundance. The last 50 years, this analytical technique has been found to be extremely useful in the determination of trace and minor elements in pharmaceutical materials.
Following are some of the generally used metal detectors for pharmaceutical sector: Radiofrequency metal detectors; balanced coil metal detectors; magnetic field metal detectors; electromagnetic induction measurement type detector; very low frequency measurement metal detectors; pulse induction metal detectors; multi-frequency transmission and receiving detectors.
Conclusion
Regardless of whether the contaminants are exposed or embedded in the drug products - is made of iron, steel, stainless steel or non-ferrous metals, such as aluminium, copper and brass, a genuine metal detection system can identify all metallic contaminants using innovative technology. They send a signal to the process controls and, together with a separation unit, remove the contaminated products – entirely automatically.
The role of metal detector is considered very important in quality controlling of pharmaceutical products. Pharmaceutical metal detectors are used in tablets and capsules manufacturing units. These metal detecting devices are installed online to the compression
machines.
Pharmaceutical sector like other industries need very highly accurate metal detection device to meet the requirements of demanding consumers and stringent legislation to compliance with cGMP mandated by the regulatory to meet the needs for safety and efficacy.
(The author is a retired chemical engineer)
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