It is extremely difficult to remove completely all the elemental impurities present in the pharmaceutical products. But, these quantities may be reduced as low as possible and normally they are allowed to be present as low as achievable. The impurities will directly harm the consumers of the products due to their toxicity and can function as a catalyst for the degradation and contamination of the pharmaceutical products.
Various types of contaminations can happen during the production of pharmaceutical products. Metal contamination is one of them. The identification and detection of metal contamination should be given the greatest priority in final quality check of the pharmaceutical products.
Metal contamination gets generated during process of pharmaceutical manufacturing. To identify and eliminate it at initial level of processing is very significant, and it also important to identify the source of it. However it would be practically difficult to install metal detector at each and every stage of manufacturing process of pharmaceutical products.
Detection of metals even in trace quantities in drugs, medicines, nutrients is very important in pharmaceutical industry.
The facilities for production of pharmaceutical products must be so designed and to be situated to have measures to avoid risk of various types of contamination and degradation. However it often happens unknowingly even if tight precautions are made.
Pharmaceutical products get contaminated and degraded by presence of metallic parts either magnetic or non-magnetic. This is due to metal-object contamination, ingredients and excipients contamination, mixing-process errors, and machinery failures, and due to the use of various process equipments such as reactors, agitated and storage vessels, classifiers, dryers, pumps, valves, pipes, etc. in the synthesis, processing and storage.
Most of the equipment like pipes, valves and pumps are made up of different types of metal materials. For example, in large-scale dehydrogenation processes nickel (Ni), cobalt (Co), platinum (Pt), palladium (Pd) and mixtures containing potassium (K), chromium (Cr), copper (Cu), aluminum (Al) and many other metals are also employed.
In pharmaceutical processing, unsaturated organic compounds that contain double bonds and triple bonds need to be hydrogenated. Platinum black, palladium black, copper metal, copper oxide, nickel oxide, aluminum and other metal materials have subsequently been developed as hydrogenation catalysts. Abrasive materials can wear mill parts and screens. In these activities, there a probability exists that the products to get contaminated with various types of metallic components. The final pharmaceutical products must be free from metal contamination as per current good manufacturing practice standards.
Metal detector is very significant in quality control system of pharmaceutical products and it is employed in pharmaceutical sector to detect metal contamination in products. The metal contamination can occur in pharmaceutical products due the presence of fasteners, pins, buds, eroded or corroded metallic parts either ferrous or non-ferrous, or stainless steel materials or tramp metals such as axe heads, digger teeth. Detection of such components is vital and in this detection, high accuracy and reliability are desirable features. Thus a metal detector plays very significant role to ensure safety of the pharmaceutical products. Metal detector also protects processing equipment and regulates compliance in the pharmaceutical sector.
Implementation of metal detector in pharmaceutical processing facility has become mandatory as metal contamination in pharmaceutical products can be harmful to the products consumers. Fragments of metals are hard and can be quite sharp, so this can cause dangerous and risk situations such as injuries to the digestive system and other parts of human. Some metals are very toxic and even a little amounts can be hazardous.
The installation of metal detectors can also save a lot of processing equipment. For example, some hard pieces of metals can destroy processing equipment such as cutters’ teeth, blades in grinding machines and blending machines. A little piece of broken equipment can create a situation to close down the complete production system till it is restored, thereby happening huge loss in productivity.
More than one century back, the first method to find out heavy metals such as lead (Pb), mercury (Hg), arsenic – a poisonous metallic element, etc. in pharmaceutical products was introduced in the United States, under the name or known as ‘elemental impurity analysis method’. The drug makers and regulators across the globe are willing to modernize this method, but reaching on it has been a difficult task.
Spectroscopic methods
The chapter 231 of United States Pharmacopeia describes the method of heavy metal limit test. This test is based on the reaction of metal impurities with thio-acetamide (C2H5NS). The chapter also describes the analytic limits, while chapter 233 describes sample preparation options containing closed vessel microwave digestion utilizing multi element inductively coupled plasma mass spectroscopy (ICP-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES techniques. Either inductively coupled plasma mass spectroscopy or inductively coupled plasma optical emission spectroscopy techniques are applied to enable low levels e.g. parts per billion (ppb) or lower in solution) of metal detection. These are the new analytical methods and one of the most powerful analytical tools to determine the trace metal elemental levels in a variety of various sample matrices and the inductively coupled plasma optical emission spectroscopy test method is based on the identification of elements in the sample by the method of emission of photons of characteristic wavelengths.
The samples are directed into the core of the inductively coupled plasma, where the highest degree of temperature liberates the elements as free atoms in the excited condition and these atoms then relax into the stable condition and releasing a characteristic wavelength of a photon that is used to identify them. There are different types of metal detectors; some are suitable for self-monitoring online metal detection. Nowadays there are several other techniques also for trace metal measurement. Some of them are - stripping voltammetry, X-ray fluorescence, atomic emission spectrometry with inductively coupled plasma excitation, atomic absorption spectrometry and neutron activation analysis.
According to a global expert, inductively coupled plasma mass spectroscopy works almost the same as inductively coupled plasma optical emission spectroscopy, with the difference being that the former identifies the metal elements using mass spectroscopy method. Both techniques will provide more consistent results across a wide variety of testing laboratories.
(The author is a chemical engineer based in Mumbai)