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01 Microbiology
Microbiological quality is one of the most important properties of cosmetic and technical products containing water. It is usually taken for granted. Nonetheless, experience teaches that this is often difficult to achieve, especially given the many limitations that legal frameworks and product concepts that are customer protection oriented. In particular, modern, "mild" preservation systems have inefficiencies that require a particularly careful design of the protection system. Testing its efficiency under the changing circumstances of the respective product matrix is therefore very important.
Biochema-Method
Semiquantitative germ count
Spiralplater
Quantitative germ count
Filtration
Quantitative germ count
The central element for evaluating the biological stability of chemical-technical products is the preservative loading test (KBT). Here, in principle, a product is inoculated with germs and then observed the further development of the germs by microbiological methods, the aim of which is their complete reduction. Numerous methods exist for performing such tests, including parameters such as inoculated germ species, added germ count, frequency of inoculation (s), germ count times, storage temperatures during the test, and the like. differ.
The standard tests for chemical-technical and cosmetic products have been established as a single-use procedure based on the methodology (Pharm.Eur.-method) described in the various pharmacopoeias as well as a repetitive loading procedure. Both methods are available - even in modified versions. It is necessary to agree on the respective product and its field of application in order to assess with which method a safe, practical assessment can be achieved. In addition, it may be important to include problematic germs (e.g., "housekeeping") in the trials to safely capture the microbial contamination risk actually present under production or operating conditions.
Ongoing investigations are kept under constant control. In the case of emerging microbiological instabilities, we contact the client to discuss possibilities for improvement in a timely manner. Canceled checks are calculated at a reduced cost rate.
The development of products requires careful selection and testing of a preservative to prevent spoilage of the product.
There is evidence from the literature or one's own experience that can be used as a guide, but the empirical laboratory test is always the necessary and definitive proof of whether a preservative is suitable and works in the given matrix.
In the development of an effective conservation system we support you extensively and on an individual basis. We are happy to offer you screenings or stress tests with special parameters tailored to your needs.
We can develop these together with you based on our many years of experience and thus ensure your product safety.
If a biocidal system is not only intended to ensure the shelf life of a product, but also to provide active protection after and during use, surface-oriented testing methods must be used. Such requirements can be found e.g. in paints and plasters which are meant to have fungicidal protection on the facade, but also to textiles or foils that are to be preserved in an outdoor application against fungal attack and mold. Furthermore, coating systems, which are meant to reduce bacterial germs as "antimicrobial surfaces," are also playing an increasing role.
Depending on the application, tests can be carried out according to various standards. Again, the test program to be performed depends strongly on desires of the customer - whether, upstream washing/leaching, or UV exposure is desired prior to the microbiological challenge. This can all be arranged on an individual basis.
Anwendungsspezifisch können Prüfungen nach verschiedenen Normen durchgeführt werden. Auch hier hängt das durchzuführende Prüfprogramm stark von den Wünschen des Kunden ab – ob z.B. vorgeschaltete Auswaschvorgänge gewünscht sind, oder UV-Belastungen benötigt werden.
Disinfecting products, such as hand disinfectants, disinfectant cleaners or disinfectant cleaning wipes, usually require a rapid germ reduction, since the exposure times under conditions of use are short. Accordingly, efficacy tests of such products are usually applied in suspension tests with correspondingly short vaccination times. These investigations are carried out in agreement with the client under definition of the desired examination parameters (time, germs, etc.)
Dementsprechend werden Wirksamkeitsprüfungen solcher Produkte üblicherweise in Suspensionstests mit entsprechend kurzen Abimpfungszeiten angelegt.
Diese Untersuchungen werden in Absprache mit dem Auftraggeber unter Definition der gewünschten Untersuchungsparameter (Zeit, Keime, etc.) durchgeführt.
Further we can provide surface testing after the DIN 13697 regulations.
The diagnosis of microbial contaminants can - depending on the task - be carried out at different levels. Among others, the following are used for the primary characterization.
- Assessment of the macroscopically recognizable growth behavior, also on selective nutrient media
- simple reactions, such as Gram stain, oxidase test
- microscopic methods
For this purpose, a powerful microscope is available, which also allows fluorescence analysis measurements.
Ultimately, a mass spectrometric analysis, in an accredited partner laboratory, can help to elucidate the germ identity.
After evaluating the microbiological risk of a product (e.g. via DIN EN ISO 29621), a low risk profile may be assumed for products that have the following properties.
Examples:
- Products with an alcohol content of > 20 %
- Products based on organic solvents
- Products with a very high or very low pH-vlaue
- Products with an aW-value < 0,75 ("water free")
For products that fulfill these criteria we offer a so called challenge test exclusion in which we confirm the low risk profile and examine the product for microbiological threshold values.
For common product these should be the following (also refer to DIN EN ISO 17516):
max. 2000 cfu/mL aerobic total germ count (Bacteria, Yeast and Moulds) and none of the following germs in 1 gramm of the product
Escherichia coli
Pseudomonas aeruginosa
Staphylococcus aureus
Candida albicans
We offer these examinations under the following numbers.
M02.05.01 (confirmation of low risk and determination of total aerobic count)
M02.05.02 (M02.05.01 + confirmation/examination according to DIN EN ISO 17516)
Further literature:
02 Analytic
The analytical analytical methods implemented primarily serve to quantify the measurement of antimicrobial substances or their degradation products.
Thus, questions of dosage, phase distribution or drug stability can be illuminated.
If necessary, however, other issues that can be solved with the listed methods, can be treated.
Modern high-pressure gradient technology with UV / VIS detection in a diode array detector is the heart of the HPLC system. Furthermore, the system is equipped with post column derivatization with reactor furnace and UV-Cracker, which extends the analytical possibilities to several important areas. Standard examinations include:
- Determination of the concentration of common preservatives such as parabens, isothiazolones, bronopol, IPBC, benzoate, sorbate, alcohols, quaternary ammonium compounds and amines and many more.
- Determination of free formaldehyde from formaldehyde donors even in complex matrices by post-column derivatization.
- Determination of nitrosamines in different matrices
- Chemical stability tests on preservatives in product matrix.
With a broadband sample preparation technique simple as well as complex systems can be investigated. Typical systems are e.g. Cosmetics (surfactant products, creams, lotions, wipes), paints and binders, cooling lubricant baths, PVC films and the like.
For conducting ion chromatographic investigations, an IC system with conductivity detector and upstream dialysis unit is available. The latter allows ion analysis also from complex matrix. Standard applications are:
- Determination of organic acids (benzoic acid, sorbic acid, formic acid etc.)
- Determination of standard anions from water and in complex matrix.
- Further applications can be worked out if necessary.
- Determination of standard cations and amines
A modern high-resolution dual-beam photometer and a multiwell photometer allows photometric analysis in the UV as well as in the visible wavelength range. For this purpose, a number of investigation procedures have been developed.
In particular:
- Trace analysis of metals such as iron, copper, lead, cadmium
- Anion analysis (phosphate, silicate)
- Determination of formaldehyde as total formaldehyde. This process is mainly used in the paint industry and has been described in guideline VdL03. For this purpose, the sample material is first subjected to an acidic steam distillation and the distillate is then quantified using the "acetylacetone method" on formaldehyde. An in-house improved version of this method allows more precise statements about release rates and quantities. By means of an adapted equipment, even large quantities of samples can be examined inexpensively.
Further applications can also be prepared for photometric investigations.
Modern titration technology allows us to determine typical product parameters even in complex matrices.
That includes:
- Acid/base parameters, e.g., acid/base capacity, corrosivity
- Iodometric measurable quantities, e.g., peroxide number
- argentometric determination of halogenide contents
- redox titrations
03 Physics
In addition to conservation experiments, product parameters such as pH and density can be measured as part of the main investigation. Photometric methods are used to control raw materials and finished products.
Furthermore, we offer comprehensive investigations of storage stability including graphic elaborations and photo documentation.
Water activity is a measure that reflects the "free water concentration" in a final product. This is not equal to the amount of water incorporated, but a value that describes the availability of this water. It can be crucial for the biological stability of technical products as well as food. Thus, e.g. Sugar and related substances Water, which leads to a decrease in water activity - and consequently leads to an increase in microbiological stability. The preparation of preservative-free products can therefore be e.g. by formulation of larger amounts of sugars, such as sorbitol or xylitol done.
By measuring the water vapor partial pressure, it is possible for us with a special apparatus to measure the water activity of a product and to obtain an indication of possible biological stability.
Among the determinable physical parameters are e.g.:
- Density
- pH
- refractive index (Brix)
- turbidity measurement
- optical rotation
Particularly in the field of cosmetic products, but also in the case of paints, plasters or pastes, viscosity and flow behavior are important quality-determining product parameters. This can be influenced by microbiological influences as well as by recipe-related galenic factors.
To round off the assessment profile for such products, we have set up a rheology measuring station, with which numerous additional examinations can be carried out. These include:
- Measurement of product viscosity (according to Brookfield) as product parameter.
- Observing the viscosity of products before and after a germ load test.
- Determination of the rheological properties of products. Measurement of intrinsic viscosity, yield point or non-linear viscosity phenomena.
- Measurement of the rheological profile e.g. a cream after storage to detect any segregation phenomena.
- Observing the galenic stability of products by repetitive rheological measurements during and after storage tests under defined conditions, e.g. with repeated temperature changes.
- Such stability studies may also help to better understand microbiological sensitivities of products.
- The rheological examinations are designed after consultation with the client to the respectively desired parameters.