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Solution for material quality control utilizing mass detector

Increasing yields and reducing defective products benefits both profitability and brand reputation. For this reason, it is indispensable to analyze, recognize and control the factors that become critical in the development and manufacturing stage. To achieve the highest quality of product greater demands are made on the analytical techniques used, with more complex questions asked and greater sensitivity required. This analytical trend also applies to quality control. By adopting analytical technology that can accurately and reliably analyze factors to be managed, stable shipments of product with quality as designed can be improved.

Analysis of organic materials using liquid chromatography (LC)

UV and PDA detectors are commonly used for analysis of additives in synthetic polymers and impurities in organic materials using HPLC since their concentrations in materials are relatively high and they contain chromophores.

In recent years, with the diversification and sophistication of advanced materials, the use of new compounds and similar structural compounds has expanded, and the impurity concentration limit has become lower. This is the result of a focus to produce high quality materials with high yield at the development and manufacturing stages, and analysis accompany with this requires more advanced analysis and higher sensitivity. In the analysis of materials in which diversified compounds are used, an analytical system is required which offers the following:

  1. Method versatility : Capability for diverse LC conditions
  2. Chromatographic resolution : Separation of analogous substances with same chromophores
  3. Detector selectivity : Separation of co-elution components
  4. Detector sensitivity : Detection of trace amount of impurities

Easy to use mass detector

In order to cope with material analysis that become complicated and at lower concentrations, a mass spectrometer with higher selectivity and higher sensitivity than the optical detector can be used. Since a mass spectrometer is a detector that separates and detects ionized components in mass-to-charge ratio units, selectivity capable of separating on a mass basis; detection of a compound without a chromophore; and high sensitivity detection due to selectivity become possible. The mass spectrometer can replace the optical detector or used in combination with the UV/PDA. This provides flexibility in methods run as well as from a maintenance and operability perspective. ACQUITY QDa detector is a quadrupole mass detector designed for optical detector users and is a mass detector whose maintenance and operability are similar to that of an optical detector. In addition, a strong organic solvent such as tetrahydrofuran (THF) widely used as a mobile phase for organic material analysis can also be used with the QDa detector by adding an Extended Solvent Compatibility kit (ESC kit).Here are three examples showing the usefulness of mass separation in organic material analysis using ACQUITY QDa detector.

Example application

1)  Impurity analysis in OLED materials

In organic EL displays where low concentration impurities may lead to product degradation and shorten the lifetime of device, permissible impurity concentrations are decreasing to the order of 0.001% in the material. For example, when an organic EL material is dissolved in an organic solvent at 1000 ppm, the 0.001% impurity in the material corresponds to 10 ppb in this solution. In addition, since the impurity often has the same chemistry and therefore chromophore as the main component has, the absorption wavelength at the PDA detector is the same, and/or with a similar retention time, so it may be difficult to separate them in the PDA chromatogram.

Figure 1 shows an example of impurity analysis in organic EL materials E709 acquired in SIR (Selected Ion Recording) mode. In commercialized OLED materials, several impurities were detected at concentration of 0.001 to 0.13%. Also by using THF as mobile phase, chromatographic selectivity is improved and impurities containing isotopes can be separated. Separation of impurities by ACQUITY Arc UHPLC system and highly sensitive mass detection by QDa detector can meet requirement that is demanded more strictly in the OLED market.

Figure 1. Chromatograms of impurities in OLED material E709

Example application

2)  Multiple-additives analysis for synthetic polymers

In the field of polymer materials, from the standpoint of polymer material development and quality assurance, it is a challenge to grasp the influence of additives on quality. Since additives in the same group have similar base structure and many additives with the same absorption wavelength are used, both LC resolution and detector selectivity are important to accurately distinguish them. As there are also additives in use that do not include a chromophore, capability of compound identification improves by using PDA detector and mass detector together.

Figure 2 and 3 show examples of analysis of additive standards and sample extracted from polymer materials by Supercritical Fluid Extraction (SFE), MV-10 ASFE system acquired on PDA and QDa (Scan mode).

Although many kinds of additives are not used for one polymer material, but in order to avoid erroneous identification as analogous additives, adoption of chromatography system and detector that provide high chromatographic resolution, repeatability and selectivity is required. In addition, identification is improved by using both PDA and MS spectra. Adoption of ACQUITY UPLC H-Class system and QDa detector can solve the problem of synthetic polymer additives on development and quality assurance.

Figure 2. UV and mass chromatograms of polymer additive standards.
Mass chromatograms are example of additives without chromophore.

Figure 3. UV chromatograms of polymer additive standards and sample

Example application

3)  High MW HALS (Hindered Amine Light Stabilizer) analysis

HALS are additives which are used widely in recent years due to their resistance against weather, and further, when used in combination with other stabilizers, it is possible to further improve the light stabilizing function and to improve other details depending on polymer and application. However, it is difficult to extract high moleculer weight HALS from polymer materials because of its high hydrophobicity and this hydrophobicity has strong interaction with reverse phase columns making it difficult to elute. Therefore, it is a compound with few quantitative analysis methods. Figure 4 shows an example of analysis of HALS standards. Since the Mobile phase condition with high elution power that can elute high molecule HALS is adopted, it is expected that analogous compounds will co-elute when these are coexisting.

By hyphenating ACQUITY QDa detector with the ACQUITY UPLC H-Class system, it becomes possible to separate, identify and quantify based on molecular weight information even for high MW HALS.

Figure 4. Mass chromatogram of HALS polymer additives

By adding a mass detector in addition to the conventional detectors, you can control factors that become more critical in product quality in more detail and contribute to maximizing profit at each stage from development to production.

< BEH (Ethylene Bridged Hybrid) Technology column >

  • Intrinsic chemical stability of hybrid particle technology
  • Wider usable pH range [pH 1-12]
  • Available in HPLC, UHPLC and UPLC particle sizes [1.7, 2.5, 3.5, 5 and 10 µm]

< ACQUITY Arc UHPLC /PDA >

  • Perfect method transfer to HPLC / UHLC that can produce same chromatographic picture as obtained by UPLC
  • Continuous blending of four solvents
  • Photo Diode Array detector that realizes highly accurate profile by peak-purity test

< ACQUITY UPLC H-Class / PDA >

  • UPLC column with high physical and chemical strength for expanding chromatographic selectivity
  • Ultra high speed and resolution for method development and effective impurity separation.
  • Photo Diode Array detector that realizes highly accurate profile by peak-purity test
  • Continuous blending of four solvents

< ACQUITY QDa detector >

  • Easy-to-use Single Quadropole detector compatible with strong organic solvent
  • Mass detection that can obtain mass information with same operation as optical detector.
  • Intuitive operation

< Empower 3 software >

  • Embedded functionality of purity test and spectrum match with PDA spectrum
  • Customized calculation and reporting function
  • Effective workflow from acquisition, processing to reporting for every operator.
  • Regulatory compliance

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Advanced Polymer Chromatography System

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Method Development on the ACQUITY APC System

Increasing the Speed, Resolution and Flexibility of Polymer Separations

ACQUITY Advanced Polymer Chromatography System