samples were classified into specific compound classes. Thus, deeper insights into the occur- rence, abundance and molecular weight distri- bution of the individual compound classes were obtained. EXPERIMENTAL Sample material The samples analyzed in this work are two specially modified coal tar pitches that are used as binders for the manufacturing of refrac- tory materials. Carbores® P (P) is present as a fine powder with a softening point of 235 °C. Carbores® F 112M (F) is a granule with a sof- tening point between 109-115 °C. Solvent extraction Fractionation was carried out by se- quential solvent extraction with n-heptane and toluene. For comparable results, granular F was grinded while P was used in its original powder form. CTP powder and n-heptane were mixed with a solute-solvent ratio of 1 g/25 ml. The ex- traction was performed in an ultrasonic bath for 2 h to ensure the complete dissolution. The so- lution was then filtered through a 0.6 µm quan- titative filter to obtain heptane-soluble (HS) and heptane-insoluble (HI) fractions. After dry- ing at 50 °C the HI fraction was extracted with toluene using the same procedure as above. Toluene-soluble (HI-TS) and toluene-insolu- ble (HI-TI) fractions were obtained. Elemental analysis The amount of carbon, hydrogen, nitro- gen and sulphur was determined by inert gas fusion technique with an IR-Detector and ther- mal conductivity measurements (Elementar, Langenselbold, Germany). The oxygen content was calculated by difference. Thermogravimetric analysis Thermogravimetric analysis was per- formed on a STA 449C Jupiter (Netzsch, Selb, Germany). 20 mg of the samples were heated up from 25 °C to 1500 °C with a heating rate of 10 K/min in an atmosphere of argon (flux = 30 ml/min). GC x GC – HR-TOFMS GC x GC measurements were con- ducted using an Agilent 7890A gas chromato- graph (Palo Alto, CA, USA) equipped with a Leco Pegasus HRT 4D (Leco, St. Joseph, MI, USA). As column combination a BPX50 (60 m x 0,25 mm film: 0,25 µm) as the first dimen- sion and a BPX1 (2,4 m x 0,1 mm film: 0,1 µm) as second dimension was used. The sam- ples were vaporized using a temperature gradi- ent from 50 °C up to 350 °C (10 K/s) with a holding time of 10 min in the end (OPTIC 4, GL Science, Eindhoven, Netherlands). Helium was used as carrier gas. The HR-TOFMS was operated at 100 Hz within a mass range of 15 ≤ m/z ≤ 500. Electron ionization took place at 70 eV at a source temperature of 300 °C. DIP – HR-TOFMS DIP-HR-TOFMS were performed on a Leco Pegasus HRT 4D (Leco, St. Joseph, MI, USA) which is equipped with a direct inlet probe system (SIM GmbH, Oberhausen, Ger- many). The solid CTP was transferred directly into the ion source. A temperature gradient from 40 °C up to 400 °C (2 K/s) with a final holding time of 2 minutes was applied. Acqui- sition rate and range were set as 1 Hz and 50 ≤ m/z ≤ 800, respectively. Triple determination was performed. Data processing GC x GC-HRMS data were processed using the ChromaTOF software (Leco, St. Jo- seph, MI, USA) and home-built Matlab-scripts (R2020b, the Mathworks Inc., Massachusetts, USA). Briefly, all mass spectra were postcali- brated based on fragments of the internal stand- ard PFTBA. To reduce spectral noise and pro- cessing time only peaks with a signal-to-noise ratio s/n 10 and within the areas RT1 ∈ [1000 s, 8500 s] & RT2 ∈ [4450 s, 6800 s] or RT1 ∈ [3000 s, 7400 s] & RT2 ∈ [1900 s,