Determination Of Orginic Acids And Furfural In Biomass Hydrolysate By Headspace Gas Chromatography

The hydrolysis pretreatment of biomass materials prior to pulping is an important step in converting a tradition pulp into an integrated forest biorefinery.After pre-extraction of hemicelluloses,the materials still can be used to make pulp.During hydrolysis pretreatment,formic acid,acetic acid and furfural were generated,which can influence the pulp's properties and inhibit the activity of fermentation microorganisms during ethanol production.In addition,the dissolution of carbohydrates and lignin in the hydrolysate was significantly affected by the organic acids.Besides,the acetic acid and furfural both are high-valued chemicals.Therefore,it is of great significance to quantify formic acid,acetic acid and furfural in the biomass hydrolysate.In this paper,the poplar chips and wheat straw were used as raw materials.Frist of all,hydrolysis pretreatment was performed with acid and autohydrolysis pretreatment,and then the content of original acids?mainly formic and acetic acids?and furfural was determined by headspace gas chromatography?HS-GC?.For formic and acetic acids,prior to GC analysis,they are converted to corresponding esters in the HS thermostat.In order to get satisfactory detection effect,the optimization of derivatization conditions,headspace and gas chromatography settings was performed.For furfural,prior to GC analysis,it is extracted by SPME at the headspace of HS-vial.In order to select the main parameters that affected the efficiency of SPME extraction and desorption,the orthogonal experiments were designed and performed.The linearity,precision,LOD,LOQ and recovery of the newly developed methods were evaluated.In addition,for investigating the methods'application and reliability,cross-validation with the commonly used HPLC method was performed.The results showed that,in I-HS-GC method,using ethanol couple with NaHSO₄ has obtained the most satisfactory achievements,and the optimal dosage of NaHSO₄ was 3.5 g.The optimal equilibration temperature and time of HS sampler were 80? and 30 min,respectively.The validation results of HS-GC showed excellent linearity?R²>0.9991?and precision?RSD<1.21%?.Besides,the recovery ranged from 97.1%to 103.1%,and LOQs were 2.02 and 2.38 mg/L for formic and acetic acids,respectively.When using HS-SPME-GC method to measure furfural,the optimal temperature and time of SPME extraction were 50 ? and 40 min,respectively.The validation results showed excellent linearity?R²>0.9991?and precision?RSD<3.63%?.The LOQ was 22.3?g/L and the recovery was ranged from 98.1%to 103.0%.A cross-validation with the HPLC method demonstrated that the present HS-GC and HS-SPME-GC methods have lower LOQs and better separation effect.The present methods are simple,sensitive and automated for the determination of formic acid,acetic acid and furfural in the multifarious biomass hydrolysates in pulping and biorefinery industries.