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Comparative analysis of mechanical pencil lead by TG-MS

Product: JMS-Q1500GC GC/MS System


Thermogravimetry (TG) is used to measure weight changes of samples under programmed heat conditions. A system combining thermogravimetry/differential thermal analysis (TG/DTA) with mass spectrometry (MS) is called a TG-MS system, and can be used for both qualitative and quantitative mass spectral analysis of evolved gas from the TG furnace.

The TG-MS technique can also be used to analyze the thermal-decomposition process. This application note shows an example of comparative analysis of mechanical-pencil leads of different performances, grades, and manufacturers. These leads are made by baking a mixture of graphite and resin, and then dipping it in oil for hardness and smoothness. Since the resin is carbonized and baked out, the lead is composed of only carbon and oil. In this application note, we show TG-MS analysis results for these mechanical-pencil leads using a “STA2500 Regulus” system (NETZSCH) and a gas chromatography–quadrupole mass spectrometry (GC/QMS) “JMS-Q1500GC” system (JEOL).


Commercially available mechanical-pencil leads (each about 25 mg, 0.5 mm × 60 mm) were measured as samples. These were crushed and put into TG sample cups. Differences in blackness (4H, HB, 4B), grade (2 types), and manufacturers (4 companies) were compared. Table 1 shows the TG-MS measurement conditions.

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