If mineral oils are found in foods or consumer goods, the main question quickly arises regarding the origin of these contaminants. Hump Inspector® uses the “humps” contained in the LC-GC measuring profiles in order to develop mineral oil reference databases and, through the software-supported comparison, to enable the fast and reliable determination of the origin of the respective contaminant.
Challenges in the identification of the origin
- For fast processing, the manual work steps must be substantially reduced.
- The broad, chromatographically unresolved peak clusters, which are referred to as humps or Unresolved Complex Mixtures (UCM), prevent a comprehensive identification of the individual components.
- Any databases that are created must be suitable for identification purposes across laboratories.
- In addition to a detailed similarity value, an effective visual review of the results must be possible.
In order to design the workflow to be as effective as possible, the manual interventions must be kept to a minimum. For each measurement sequence, the baseline of the blind value measurement for the subsequent blind value subtraction as well as the assignment of the alkanes in the retention time standard are generated automatically and, if required, can be manually adjusted. The subsequent processing of the measurement series – both for the creation of a database as well as for identification purposes – is completed in mere seconds.
Hump Inspector works upon a complementary basis to the Chrolibri evaluation software. If the determination of the MOSH and MOAH content should have been conducted with Chrolibri for the samples to be identified, the data that are relevant for identification purposes can be directly imported. By so doing, any potentially-redundant processing steps can be avoided, e.g. verification of the retention time standard.
Clever modelling of the humps
In order to be able to conduct a robust similarity comparison for the identification of a MOSH/MOAH contamination, one must focus on the characteristics of the existing humps. Through the modelling of the humps via suitable curve functions, transparent retention times for the hump maxima, the shape of the humps (symmetrical/asymmetrical) and the hump surface areas can be determined in an automated fashion. These characteristics are used in order to identify matches and/or similarities with the references in the database.
If very pronounced peaks on the humps distort the shape of the humps, they can be cut off and/or excluded in advance in order to obtain improved modelling.
A comparison against the database generates a list with the best hits based on the similarity measure. The quality of the matches between the contamination to be identified and the references in the database can be verified via visualisation in overlay mode. In this context, available options allowing visual retention time alignment and scaling for example to an internal standard, are of great benefit.
In order to further reduce the number of hit candidates, optionally-stored reference metadata can be used to filter the results.
Keep an overview
Last but not least, Hump Inspector helps to organise your data and offers the option of quickly accessing all MOSH/MOAH measurements and comparing your historical measurement data with each other or with the current measurement sequences of the MOSH/MOAH samples – also in order to, for example, quickly check the retention time stability or the effect of changes to the oven programme.