With a large number of pharmaceutical manufacturers competing in the market, quality, safety and efficacy of the end finished product are being given highest priority and are being inspected closely to assess the superiority of a brand over the other. Even minutest difference in quality is considered vital to propel the marketing promotional activities and to have an upper hand in the market space. This is possible only with continuous upgradation and innovation of metal detection technology in the manufacturing and processing lines of the pharma industry.
Product protection within the pharmaceutical industry is tightly controlled by regulatory as well as legislative measures. Therefore manufacturers have to adhere to the requirements of Food and Drug Administration (FDA) and the Medicines Control Agency (MCA) by adopting the safest and most stringent standards and protocols. Quality and integrity are the fundamental requirements for products from the pharmaceutical industry. Effective product protection is pivotal throughout manufacture and packaging in the pharmaceutical and nutraceutical industry, for ethical pharmaceutical formulations, generic equivalents or over-the-counter solid dosage products.
“With increased regulatory reforms and changing pharmaceutical landscape across the globe, pharma industry in India is fast adapting themselves to the global requirements. Particularly, the conscious export -oriented pharmaceutical manufacturers are taking every possible step to ensure quality, for which they are adopting new and advanced systems and innovating their processing and manufacturing lines by installing high end advanced metal detector technology,” Says Ravi Uday Bhaskar, Director General of Pharmexcil.
There are several possible sources of metal object contamination, including ingredient contamination, mixing-process errors, and machinery failures in the tablet- and capsule-forming and filling process. It is vital that all these sources of contamination are identified and removed before the product leaves the factory. Food-processing metal detectors play an important role in detecting magnetic or conductive metal materials in pharmaceutical products.
Functioning of a metal detector
A metal detector employed to detect foreign objects contains a transmitter antenna that sends out a radio-frequency signal ranging from 300 kHz to 1 MHz. Two receiver antennas sit on each side of the transmitter at equal distance from the transmitter.
When the system is balanced and there is nothing magnetic or conductive inside the aperture of the metal detector, the difference of the two signals is zero, signifying that no metal is present. When metal is present and travelling through the detector, a detectable imbalance is created. The accurate performance of this system depends on three factors:
- The closeness of the metal that is being detected to the antennas or coils (i.e., the aperture or opening size)
- The effectiveness of the fields created by the transmitter (i.e., the transmit-antenna design)
- The frequency of the signals used (the higher the frequency, the better the detection of conductive, non-magnetic metals).
The receivers' signals are digitized and analysed by a digital-signal processor (DSP) that filters the signals. The DSP uses signal-processing algorithms to increase the probability of an accurate detection. The signals have two components: one is magnetic (X), and one is conductive (R). These components enable the system to detect metal foreign objects that are mainly conductive and have a small amount of magnetism such as in 316-alloy stainless steel. As a result, detection of conductive metal objects relies on a different signal analysis compared with a ferrous metal containing iron. Most metals exhibit both magnetic and conductive behaviours; these behaviours can change with the size of the metal. An off-line laboratory instrument such as an X-ray fluorescence spectrometer is necessary to determine full metal composition.
In some applications, the ability of the system to ignore the signals that can be caused by the uncontaminated product passing through the metal detector is crucial. For example, some products may have a chemical composition that appears to be slightly magnetic or conductive to the metal detector fields. This type of product effect can be ignored by the system by first learning the magnitude of the product's X and R signals. During production, the system creates a region where any combination of X and R signals with the same ratio and similar magnitude are thereby ignored. This process, called phasing, is only required in pharmaceutical applications using products that have high concentrations of iron or other metallic elements.
“In India, the metal detector industry is fast evolving and the Indian manufacturers are equally competing with leading global players in the manufacture and supply of best of the custom - based metal detectors. Today we are present in every sector relating to science and technology and second to none in the world,” observed P. Satish, Technical Director of PMG equipments.
The metal detection system in the pharmaceutical industry is being used for more than a decade to detect metallic contaminants, and the systems are evolving to offer improved performance and ease of use. One new technology is the inclusion of multi-coil arrangements in metal detectors to improve the signal viewed by the receiver. Compared with a single transmitter with two receivers, multi-coil arrangements can improve detection performance of the instrument by up to 20 per cent.
Metal detectors in food, pharma industries
The role of metal detectors in food and pharmaceutical industries is to detect metal contamination in products or packets. The metal contamination may occur in food and pharmaceutical products due the presence of metallic pieces or components (viz., fasteners, pins, buds, eroded or corroded metallic parts etc.) in ferrous, non-ferrous, or stainless steel 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 product safety. Metal detector also protects equipment and regulates compliance in the food and pharmaceutical industries. Moreover, metal detectors play an important role in maintaining the organization’s reputation.
In pharmaceutical industry there is a possibility that the products get contaminated by metallic parts either magnetic or non-magnetic. This is due to metal-object contamination (ingredient contamination, mixing-process errors and machinery failures) and due to the use of various process equipment viz. reactors, agitated and storage vessels, classifiers, dryers, pumps, valves, pipes etc. in the synthesis, processing and storage and most of these equipment, 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 used.
In many pharmaceutical processing, unsaturated organic compounds that contain double and 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. Abrasive materials can wear mill parts and screens. In these operations, a probability always exists that the products may get contaminated with various metallic components. The final food and pharmaceutical products must be free from metal contamination as per GMP standards. Metal detectors are mostly used for US State Department of Agriculture (USDA), Hazard Analysis Critical Control Point (HACCP) or US Food and Drug Administration (USFDA) Certifications in India and other countries.
Depending on the purpose, different types of metal detectors are available for checking metallic contamination in the food and pharmaceutical industries. For examining small and unpacked goods such as vegetables, snack items, frozen foods, sea foods, poultry and packed medicine conveyor type metal detectors are most suitable. Metal detectors with advanced microprocessor-based technology are highly advantageous for checking coarse-grained food stuffs such as popcorn, cornflakes and soup noodles.
These are different types of metal detectors based on certain operating principle. Some commonly used metals detectors are discussed below.
Electromagnetic induction measurement
The electromagnetic induction metal detector system operates based on the principles of electromagnetic induction. Metal detectors contain one or more inductor coils that are used to interact with metallic elements on the food or pharmaceutical products. Metallic contaminant in the product creates high frequency magnetic field within the detector coil, which in turn activates a reject flap by means of a solenoid. The detector is designed in such a way that it automatically removes the metal components from tablets without production interruption. The metallic contaminant is ejected with very little loss of material due to the extremely fast and short activation of the reject flap of the detector. This type of metal detectors is mostly used to detect the presence of metal contamination in continuous tablets manufacturing process.
This type of metal detector can be easily cleaned and are compatible for all tablet press. It has high sensitivity to all metals including the most difficult non-magnetic stainless steel. Its performance is maintained stable throughout the life.
Multi-frequency transmission and receiving
This kind of metal detector works 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 viewed by the receiver. Compared with a single transmitter with two receivers, multi-coil arrangements can improve detection performance (as measured by the diameter of the metal sphere size that can be detected) of the instrument by up to 20 per cent.
Quality and integrity are the fundamental requirements for products from the pharmaceutical industry. Effective product protection is essential throughout manufacture and packaging in the pharmaceutical and food industries, for ethical pharmaceutical formulations, generic equivalents, or over-the-counter solid dosage products.
Radio-frequency signals
Radio-frequency metal detectors contain a transmitter antenna that produces radio-frequency signals ranging from 300 kHz to 1 MHz. Two receiver antennas sit on each side of the transmitter at equal distance from the transmitter. When the system is balanced and there is no magnetic or conductive inside the aperture of the metal detector, the difference of the two signals is zero, signifying that no metal is present. When the metal travels through the detector, a detectable imbalance is created. The accuracy of such metal detectors depends on the closeness of the metal that is being detected to the antennas or coils. The signals have two components: one is magnetic (X), and the other one is conductive (R). These components enable the system to detect metal foreign objects that are mainly conductive and have a small amount of magnetism such as in 316-alloy stainless steel.
As a result, detection of conductive metal objects relies on a different signal analysis compared with a ferrous metal containing iron. Most metals are both magnetic and conductive which change with the size of the metal. An off-line laboratory instrument such as an X-ray fluorescence spectrometer is necessary to determine full metal composition.
In some applications, the ability of the system to ignore the signals that can be caused by the uncontaminated product passing through the metal detector is crucial.
Very low frequency measurement
Metal detectors based on the operating principle of Very Low Frequency (VLF) measurement principle are the most commonly used. The metal detectors contain two sets of coils, namely, transmitter coil and receiver coil. Electricity is passed through the transmitter coil to create a magnetic field. This constantly pushes the electricity into the ground and pulls it back up. The magnetic field so generated interacts with any metallic or conductive object that comes in its way. The receiver coil passes the electric current whenever the metal detector passes over a conductive object. This amplifies and sends the frequency of the current to the control box.