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This paper reports on a novel method for rapid determination of the degree of deacetylation (DD) of chitosan samples by headspace gas chromatography (HS-GC). In this method, overdose of an acid is added to protonate the free amino groups in chitosan, which further reacts with bicarbonate (as an alkali titrant) in a close vial. Based on measuring the HS-GC signal for CO 2 vs. the volume of HCO 3 − added by a stepwise titration, two transition points can be obtained. The DD value is calculated by net volume of HCO 3 − consumed, i.e., by the R NH 3 + groups in chitosan. The results showed that the present method has a good measurement precision (RSD < 0.82%) and accuracy (relative differences < 6.46% when compared with the results measured by a reference method). Since the HS-GC can perform an automated sample reaction equilibration and measurement, it could be much more efficient than the existing methods in the batch sample analysis. Image 1 • A novel HS-GC technique was developed to quantify the DD value of chitosan. • The resulting product CO 2 is used as the indicator. • The method was based on determining two transition points from CO 2 releasing curve. • This method is accurate and suitable to be used in the batch sample analysis. [ABSTRACT FROM AUTHOR]

Abstract This paper reports on a practical method for rapid determination of the degree of substitution of sodium carboxymethylcellulose (CMC-Na) by a headspace gas chromatography (HS-GC). In this method, CMC-Na was treated with a strong acid cation exchange resin to completely convert it to CMC-H form in 30 min at a room temperature, which was further reacted with bicarbonate in a close vial for 15 min at 60 °C. The resulting product, i.e. CO 2 , was then determined by HS-GC, from which the DS of CMC-Na can be calculated. The results showed that the present method has a good measurement precision (RSD < 4%) and accuracy (relative differences < 7% when compared with the results measured by a reference method). Since the HS-GC can perform an automated sample reaction equilibration and measurement, it could be much more efficient than the existing methods in the batch sample analysis. Graphical abstract Image 1 Highlights • A practical method for rapid determination of the degree of substitution of sodium carboxymethylcellulose was proposed. • CMC-Na was pretreated with strong acid cation exchange resin. • The conditions of ion exchange were explored. • Compared with a reference method, the present method had improved measurement precision and accuracy. [ABSTRACT FROM AUTHOR]

Abstract This paper proposed a new method for the determination of the viscosity average molar mass of guar gum, based on a volatile tracer assisted twice headspace extraction gas chromatographic technique. The feasibility study showed that n-butanol was a suitable tracer to be used in this method. The results showed that the present method had a good precision (with the relative standard deviation < 0.86%) and good accuracy (in which the relative differences were within 7.94% when compared with the reference method). The present method is simple and practical. It can conduct an automated measurement when a batch sample testing is required. Highlights • Establish a new method for measuring the average molecular weight of guar gum. • n-Butanol as Tracer for twice headspace extraction. • Good linear relationship between the logarithm of ( M ¯ v) of guar gum and the headspace signal value. [ABSTRACT FROM AUTHOR]

Abstract: We report on a headspace gas chromatographic method for determining the content of 3‐chloro‐1,2‐propanediol in polyamideamine epichlorohydrin resin solution. It was based on quantitatively converting 3‐chloro‐1,2‐propanediol to formaldehyde by periodate oxidation in a closed headspace sample vial at a room temperature for 10 min, and then to methanol by borohydride reduction at 90°C for 40 min followed by the headspace gas chromatographic measurement. The results showed that the present method has an excellent measurement precision (relative standard deviation < 2.60%) and accuracy (recoveries from 96.4–102%) in 3‐chloro‐1,2‐propanediol analysis. The limit of quantitation was 0.031 mg/mL. It is simple and suitable for determining the 3‐chloro‐1,2‐propanediol content in polyamideamine epichlorohydrin resin solution. [ABSTRACT FROM AUTHOR]

This paper reports on an ionic-liquid assisted headspace gas chromatographic (HS-GC) for the determination of the content of alkyl ketene dimer (AKD) in its latex samples, in which the GC system was equipped with a thermal conductivity detector (TCD). The method was based on the AKD hydrolysis conducted in 1-butyl-3-methylimidazolium chloride (ionic-liquid) added medium at 100 °C for 10 min in a closed headspace sample vial, and the measured CO 2 (the resulting product of the hydrolysis) by HS-GC. The results showed that the present method has a good measurement precision (RSD <2.3%) and accuracy (recoveries from 96 − 105%), and the limit of quantitation (LOQ) is 0.9%. The present method is very suitable to be used for the routine check of AKD content in its latex sample in mill applications. The study also showed that the content of AKD in the tested commercial latex samples were in the range of 3.5–12%. [ABSTRACT FROM AUTHOR]

This study demonstrated a headspace gas chromatographic (HS-GC) method for the determination of residual epichlorohydrin (ECH) and the by-product 1,3-dichloro-2-propanol (DCP) in polyamine epichlorohydrin (PAE) solution. It was based on the vapor-liquid phase equilibrium of these analytes at 60 °C for 30 min in a closed headspace sample vial before GC measurement. It was found that matrix of the PAE solution had the effect on the headspace equilibrium of these species and therefore a standard addition must be applied in the method validation. The results showed that the present method has a good measurement precision (RSD <2.90%) and accuracy (recoveries from 93.6 to 105%), and the limit of quantitation (LOQ) is 3.75 mg/L for ECH and 0.8 g/L for DCP. The present method is suitable to be used for analyzing the chlorinated volatile organic compounds in the commercial PAE resin solutions. [ABSTRACT FROM AUTHOR]