The inside story of how we maintain the industry’s highest QC standards for zinc oxide.
Zochem customers have come to appreciate the quality and consistency of our products, but did you ever wonder how we maintain such tight standards? Certainly, our state-of-the-art manufacturing and packaging technologies are major contributors. However, there is another critical part of our processes that hasn’t received a lot of attention, our QC labs.
Mona Ghanam at Zochem North in Brampton Ontario, and Cheril Norville at Zochem South in Dickson Tennessee head the QC labs, employ advanced instrumentation to confirm that the product shipped always meets or exceeds our customer’s specifications.
Mona explains, “That process begins before manufacturing. An identity test for the zinc metal is performed for every lot received from the zinc supplier. Impurity tests are then performed periodically to ensure that the supplier Certificate of Analysis matches Zochem’s internal testing. Zochem uses special high-grade zinc to produce various grades of zinc oxide. The purity level of the zinc metal must be at 99.995% minimum.” These procedures allow Zochem to ensure that the manufacturing process will begin with zinc metal of known purity. Knowing this up-front is vital for a consistently high-quality production run.05
All customer requirements are entered into an electronic customer profile in the Zochem database. This will include zinc oxide technical specifications, product grade, labeling, packaging type, and shipping information. Many controls are in place to ensure the product has all the necessary properties that the customer requires.
“The Lab is the next handoff,” said Cheril Norville, “and is where the quality control testing is done to confirm the properties and purity of the zinc oxide. Once this is complete, a Certificate of Analysis (COA) is customized for each customer. Before the material is shipped, a final inspection is performed to ensure all shipping and labeling requirements have been met.”
The QC Team
Cheril Norville is both Quality Assurance and Laboratory Manager at Zochem South, in Dickson. An education in chemistry and math led Cheril to spend over 25 years in laboratory work, analyzing and developing analytical methods, and managing/training others how to perform analyses. In addition to her skill with various lab instruments, Cheril has also been deeply emersed in a wide range of regulatory guidelines, including those of the EPA, ASCLAD, and FDA. One look at the certifications page on the Zochem website will illustrate the many agencies and organizations that have their own unique requirements.
Mona Ghanam is Cheril’s counterpart at Zochem North in Brampton. Mona’s impressive qualifications include a Bachelor of Chemical Engineering and 23 years of on-the-job experience including 18 years with Zochem. She is a member of Professional Engineers Ontario (PEO), holds a license in project management (Project Management Professional – PMP), a Six-Sigma Green-Belt certification, and is certified as ISO 9001 auditor.
The main tests performed for the in-process and finished oxide are particle surface area, zinc oxide %, the “retains” on a 325-mesh screen, lead, moisture, and cadmium levels. Other tests are done periodically, such as loss at 110 °C, loss on ignition @ 500 °C, bulk and apparent density tests, full impurity testing, as well as a daily analysis for lead, cadmium, and iron. For zinc oxide USP grades, tests are performed according to the zinc oxide USP current monograph or validated internal test methods.
Labs at both manufacturing facilities are equipped with a comprehensive array of specialized instrumentation, allowing each QC manager and their teams to conduct tests that meet the highest standards of the food and pharmaceutical industries, and more. In addition, every instrument has its calibration verified before each test.
As an example, Zochem’s Quantachrome Monosorb instrument employs the BET method for measuring surface area. Surface area is one of the main properties that customers specify when purchasing zinc oxide. Cheril explains that “surface area can affect product flow, reactivity, and viscosity in our customer processes, so it is an especially important component.” She continued, “Another important component is metal content. Our Thermo ICP-OES is used to analyze very small levels of metals such as lead, iron, cadmium, and aluminum various metal content in our finished product. These components play a significant role in meeting customer specifications.”
Mona describes the importance of lot-number traceability details…“All numbers assigned to lots or batches of zinc oxide are a sequential six-digit number and allow for product traceability. Depending upon the type of product packaging, lot numbers are either stamped directly on the product packaging or are available with a sticker or tag affixed to it. The Certificate of Analysis (CofA) also refers to the lot number.”
Each lot is tested at the start, middle, and end to ensure the properties are consistent for the entire lot. Zochem retains samples from every skid produced. Retains are tested are kept for one year, and those that were not tested are kept for three months. This allows a retest if there is ever a question about one of the certified properties. Test data is entered into an electronic spreadsheet and given a second check to ensure no transcription errors occur.
Furnace logs are used to track raw materials and furnace readings during the production of every lot. Each furnace has electronic limit control settings that provide a layer of control for the finished products.
As a final QC check, Certificates of Analysis are created for each lot that is sold. Every certificate is checked by a second person to ensure no errors are made, customer specifications are met, and profile requirements are included.
Production packing sheets document and verify, scale checks, lot number, who packed the lot, date of manufacture, weights of every skid are within tolerances, and the location in the warehouse where the material is being stored.
An additional inspection of every order occurs at the time of shipping. This ensures the correct lot is selected, the material is labeled correctly, the skids are clean and neat, and the load weight is correct.