Determination of specific surface area of biomass activated carbon vial headspace gas chromatography technique.

This paper introduces a method for determining the specific surface area (SSA) of biomass activated carbon (BAC) using a tracer-based headspace gas chromatography (HS-GC) technique. The method relies on the adsorption equilibrium of methanol on BAC samples at elevated temperature. A mathematical model allows for the calculation of SSA from the methanol signal obtained during the headspace analysis. The results demonstrate high precision (relative standard deviation < 2.44%) and strong accuracy (correlation with the conventional BET-N2 adsorption method, R² = 0.986). This method offers several advantages over traditional techniques, including ease of operation, significant time efficiency, and the the ability to perform batch determinations of SSA, as multiple samples can be processed simultaneously during the phase equilibrium step.

Determination of starch gelatinization temperatures by an automated headspace gas chromatography.

This paper reports on an automated temperature-programmed headspace GC technique for the determination of gelatinization temperature of starch. 1-butanol was used as a tracer and added to the starch-solution for the test. Based on measuring the GC signal of 1-butanol in the headspace with the temperature increasing, two transition points (corresponding to the onset temperature and the ending temperature of starch gelatinization) were observed by plotting the GC signal of 1-butanol vs. the temperature. The results showed that the method has a good measurement precision (the standard deviation < 1 °C) and accuracy (the average relative differences = 3.9%, compared to a standard reference method). The present method is simple and suitable for the gelatinization temperature testing for starch samples.

Determination of the softening point of rosin by a simple and automated headspace gas chromatographic technique.

We report a simple and automated headspace gas chromatographic technique for the determination of the softening point of rosin. A lumpy solid of rosin is added into a headspace vial, then an automated stepwise temperature ramping and headspace sampling was performed at each temperature stage and gas chromatography measurement. By plotting the gas chromatography signal for an impurity in rosin versus the temperature, a transition point (corresponding to the rosin softening point) was determined. The results show that the present method has a good precision (<0.76%), and good accuracy (the relative differences compared to the ring and ball method was <4.0%). The present method is simple, accurate, and automated. It is practical and suitable for testing the softening of rosin and derivatives in mills.