This document outlines a laboratory analytical procedure for determining sugars, byproducts, and degradation products in liquid fraction process samples. The procedure uses high-performance liquid chromatography (HPLC) with refractive index detection. It includes steps for sample preparation, calibration standards, and analysis of monomeric sugars, cellobiose, total sugars, and degradation products like HMF and furfural. The procedure also covers the preparation of calibration verification standards (CVS) and sugar recovery standards (SRS) to ensure accuracy and reliability of results. The method is applicable to liquid process samples, including pretreatment liquors, fermentation samples, and liquid fractions of process solids. It is suitable for biomass containing the components listed in the procedure, but samples with interfering components require further investigation. All analyses should follow a laboratory-specific Quality Assurance Plan (QAP). The procedure includes detailed apparatus, reagents, and materials required for analysis. It also addresses potential interferences, such as co-eluting compounds like arabitol and xylitol, and the need to verify the absence of artifact peaks in the HPLC system. The method involves preparing calibration standards, analyzing samples, and using HPLC to quantify the components. Calculations for calibration curves, recovery percentages, and correction factors for dilution and acid hydrolysis are provided. The procedure also includes guidelines for reporting results, including concentrations in mg/mL, relative percent difference (RPD), and root mean square deviation (RMS deviation). The procedure emphasizes the importance of proper sample handling, storage, and quality control measures to ensure accurate and reliable results. It also includes references to related procedures and methods for determining acid soluble lignin and structural carbohydrates in biomass.This document outlines a laboratory analytical procedure for determining sugars, byproducts, and degradation products in liquid fraction process samples. The procedure uses high-performance liquid chromatography (HPLC) with refractive index detection. It includes steps for sample preparation, calibration standards, and analysis of monomeric sugars, cellobiose, total sugars, and degradation products like HMF and furfural. The procedure also covers the preparation of calibration verification standards (CVS) and sugar recovery standards (SRS) to ensure accuracy and reliability of results. The method is applicable to liquid process samples, including pretreatment liquors, fermentation samples, and liquid fractions of process solids. It is suitable for biomass containing the components listed in the procedure, but samples with interfering components require further investigation. All analyses should follow a laboratory-specific Quality Assurance Plan (QAP). The procedure includes detailed apparatus, reagents, and materials required for analysis. It also addresses potential interferences, such as co-eluting compounds like arabitol and xylitol, and the need to verify the absence of artifact peaks in the HPLC system. The method involves preparing calibration standards, analyzing samples, and using HPLC to quantify the components. Calculations for calibration curves, recovery percentages, and correction factors for dilution and acid hydrolysis are provided. The procedure also includes guidelines for reporting results, including concentrations in mg/mL, relative percent difference (RPD), and root mean square deviation (RMS deviation). The procedure emphasizes the importance of proper sample handling, storage, and quality control measures to ensure accurate and reliable results. It also includes references to related procedures and methods for determining acid soluble lignin and structural carbohydrates in biomass.