Helping you Know the Unknowns
Eurofins Advinus Limited, Bangalore
For registering the agrochemicals, thorough information on the composition of the technical grade material must be provided to the regulatory authorities. This includes the content of active ingredient, relevant impurities, significant impurities, and other possible constituents like residual solvents, metal contaminants, etc. This information is usually provided to the regulatory authorities in the form of a 5-batch analysis report. Hence, this 5-batch analysis report becomes a core requirement for any registration of the technical material. Due to this criticality, the quality of the 5-batch analysis report becomes very important.
This quality comes from a thorough screening of the material for all the impurities at significant levels, confidently assigning the structural information to each impurity and providing the most reliable quantitative data.
To achieve this, at Eurofins Advinus Limited, we usually start the 5-Batch analysis with a pre-screening of the material for its total composition which includes, active ingredient content analysis, impurity profiling, and analyzing for toxicologically significant impurities, where relevant. After this, the regular 5-batch analysis of the technical material will be conducted.
Initial Impurity Screening for Batch Analysis Studies
The most important part of the five-batch analysis is the initial impurity screening. The HPLC instruments with PDA / DAD detectors are used for the initial screening of the UV active compounds. While studying for the impurities on HPLC-PDA, which are ≥ 0.1%, it is important to have it in mind that the response of some impurities may be less/more as compared to that of the active ingredient at a particular wavelength. To overcome this, we do screen for impurities at varying wavelengths, covering the entire UV-Vis range. The identification of impurities that are at a significant level of more than 0.1% is carried out based on mass spectra of these impurities recorded on LC-MS or GC-MS and other information, like the process adopted for synthesizing the technical material, etc.
Most of the time the obtained mass spectra leads us to more than one probable impurity structure. At times, it may be required to take MS/MS spectra to get more fragmentation information for predicting the plausible structure of the impurity. A look at the synthetic process adopted for manufacturing the technical material will let us know the probability of the formation of the predicted impurity.
When the ionization of the impurity is low on LCMS/ GC-MS, the obtained spectra do not give much information. In such cases, we need to use the prep-HPLC technique to isolate the impurity to get a small quantity for recording NMR spectra.
Once the impurity structures are confirmed, synthesizing the predicted impurities is an ideal way. If the synthesis is difficult, we can isolate the impurities from the technical material or corresponding crude material (material before final purification) using prep-HPLC. The obtained impurities need to be thoroughly characterized to use them as standards for the 5-Batch analysis.
To identify the volatile impurities / residual solvents in the test item, Headspace GC with a mass detector is used. In the case of inorganic pesticides, the impurities in the test item are identified and quantified using the analytical ‘technique/s like ion chromatograph (IC), inductively coupled plasma-mass-spectrometry (ICP-MS), etc. The higher concentrations of the inorganic salts residues in the technical materials are quantified with chemical titrations.
The 5-Batch analysis study must comply with the GLP principles of OECD, US-EPA, EC, etc. All the 5-Batch analysis studies include different parameters, like, method validation of active ingredient and impurities, 3D screening, characterization of reference standards, and each batch of the test item.
The method validation parameters are performed to fulfill the requirements of the following guidelines – SANCO/3030/99, ABNT NBR 14029, JMAFF, and APVMA with according to US-EPA 40 CFR Part 160.
The validation of the analytical method involves the following parameters – Specificity & selectivity, detector linearity, the limit of detection (LOD), the limit of quantification (LOQ), precision, intermediate precision, and accuracy.
The reference standards and each batch of the test item are thoroughly characterized for its chemical identity. The structure of the active ingredient and the impurities are confirmed using NMR (1H and 13C), Mass, and IR.
The analytical results of the active ingredient and all components present in quantities of more than 0.1 % m/m must be summarized and the mass balance also to be presented in the report. This data is also used to select the most impure batch for the toxicology studies. All this data which is vast and requires various instrumentation and technical expertise are carried out in-house at Eurofins Advinus Limited.