The Secrets of Quality Control in Fragrances
In the world of fragrances, perfumes, aromas, and essential oils, ensuring excellent quality control of scented products is essential. Behind the allure of perfumes lies precision work, carried out in the laboratory, which combines both technological expertise, delicate manual control, or automated control with Artificial Intelligence (AI) programs. At the heart of this process are gas chromatography and mass spectrometry (GC-MS).
Gas Chromatography: A Key Technology
Gas chromatography is a separation analysis method used to distinguish and quantify the different substances present in a sample. In this field, it involves distinguishing the various components of essential oils or perfume mixtures, which can contain between one and hundreds of compounds!
The gas chromatography apparatus includes several modules: the injector, the column, and the detector. The sample is introduced into the injector, which transforms it into vapor. It is then carried into the column by the carrier gas. The different components of the sample separate based on their volatility: the most volatile components exit first and are detected by the detector.
However, optimizing a chromatographic separation is a compromise between three criteria: resolution, analysis time, and the amount to be injected. For example, if sensitivity is prioritized, a large amount of product must be injected, which can saturate the column and increase the analysis time.
Meticulous Control of Chromatographic Peaks
Even though technology plays a key role in analysis, manual or automatic control remains essential. Each peak on the chromatogram represents a component of the sample. Measuring the area of the peaks allows for estimating the quantity of each component. This task must be carried out with great precision, as even a small error can lead to an incorrect estimation of the sample’s composition.
In the absence of an automatic chromatogram comparison tool, this work must be done manually. It requires extensive expertise and a thorough knowledge of the substances likely to be encountered in the samples. Indeed, the position and shape of the peaks can vary depending on numerous factors, such as the type of column, temperature, and the flow rate of the carrier gas.
The Challenges of Quality Control for Scented Products: Technical Aspects and Peak Control
Manual Approach to Chromatographic Peak Control
Quality control also requires a certain degree of manual and subjective approach, particularly when it comes to analyzing the peaks on a chromatogram. It is crucial to monitor the shape, area, and position of the peaks in the chromatogram to determine the composition of the analyzed mixture and ensure the quality of the final product. This task can be challenging, especially in the absence of an automatic chromatogram comparison tool.
The measurement of peak areas is performed automatically by integration software from all chromatography brands (e.g., Chemstation / Openlab / Masshunter from Agilent, Totalchrom from Perkin Elmer, Chromeleon from Thermofisher, Labsolutions / GCMSsolution from Shimadzu, Empower from Waters , CompassCDS from Scion). However, this requires optimized parameter settings: peak start, valley-to-valley integration, or from the baseline, number of points in the peak envelope, peak stop, point smoothing, etc.
Nonetheless, it is sometimes necessary to perform specific integration on certain peaks of the chromatogram to handle issues such as coelutions or other integration problems.
This task must be performed with precision to ensure the reliability of the results. It requires significant expertise and attention to detail and can be prone to errors if the operator is not adequately trained or attentive.
Automatic Approach to Chromatographic Peak Control
A software based on neural algorithms can compare two reference chromatograms with a sample within a second, displaying in an analysis report all missing peaks and surface variations of each peak in the chromatograms for quality control, working according to standards. This is an arduous task if done manually! Indeed, cosmetic products and perfumes comprise a mixture of many raw materials and can contain several hundred peaks.
When the quality control laboratory wants to qualify the peaks, the ability to work with retention indices or mass spectrometry allows for easy identification of the molecules.
The Importance of Anomalies and Issues
Quality control also involves managing anomalies and issues that can arise during analysis. This can range from detecting contaminants or unexpected compounds to more technical problems like distorted peaks or degraded resolution. A thorough understanding of chromatography and its principles is therefore essential to identify and resolve these issues.
Gas Chromatography with FID Using Retention Indices for Molecule Identification
The identification of molecules, especially problematic ones such as allergens, can be achieved using retention indices, often referred to as Kovats indices. Indeed, thanks to the performance of software tools coupled with current computing power, the automatic identification of molecules on a complex chromatogram can be accomplished in a few seconds. The accuracy of the identification is further enhanced by cross-referencing results from two databases using two columns of different polarities, such as a non-polar column (DB5, DB1, OV101) and a polar column (Carbowax: C20M, DBWax).
Identification of Molecules by Mass Spectrometry
In laboratories, gas chromatography is often coupled with mass spectrometry (GC-MS). While this is a costly solution, mass spectrometry allows for the identification of different substances present in a sample by measuring their molecular mass. This precise technique is beneficial in research and development, as it not only helps control scented products but also detects the slightest trace of an undesirable component that could affect the fragrance of the final product.
Conclusion
In summary, the work of a quality control professional in a laboratory, working with gas chromatography and mass spectrometry (GC-MS), is a complex blend of technical expertise, attention to detail, problem-solving, and decision-making based on experience and judgment. While many aspects of this work can be automated, the human component remains indispensable to ensure the quality and reliability of the results. It is a demanding yet highly rewarding profession that plays a crucial role in guaranteeing the quality of the products we use daily (perfumes, beauty products…).
Learn more about Chromatography on Wikipedia
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FAQ
What is the difference between perfume and fragrance?
Perfume is a specific type of fragrance with a high concentration of aromatic compounds, designed for long-lasting wear and is generally more expensive.
Fragrance is a general term that refers to any scent and can be found in a wide range of products with varying concentrations of aromatic compounds.