High-performance liquid chromatography method for simultaneous determination of aliphatic acid, aromatic acid and neutral degradation products in biomass pretreatment hydrolysates.

Multi-analyte biosensors may offer the opportunity to perform cost-effective and rapid analysis with reduced sample volume, as compared to electrochemical biosensing of each analyte individually. This work describes the development of an enzyme-based biosensor system for multi-parametric determination of four different organic acids. The biosensor array comprises five working electrodes for simultaneous sensing of ethanol, formate, d-lactate, and l-lactate, and an integrated counter electrode. Storage stability of the biosensor was evaluated under different conditions (stored at +4 °C in buffer solution and dry at −21 °C, +4 °C, and room temperature) over a period of 140 days. After repeated and regular application, the individual sensing electrodes exhibited the best stability when stored at −21 °C. Furthermore, measurements in silage samples (maize and sugarcane silage) were conducted with the portable biosensor system. Comparison with a conventional photometric technique demonstrated successful employment for rapid monitoring of complex media.

Application of a Portable Multi-Analyte Biosensor for Organic Acid Determination in Silage

The configuration and applicability of a system for on-line determinations of media components by high performance liquid chromatography (HPLC) is described, assembled only from commercial available stand-alone devices. The fermentation broth is circulated in a bypass through a magnetically stirred filtration unit. The clear filtrate is injected at preset intervals by an electrically actuated valve into the HPLC analysis system. Excess filtrate is circulated back to the fermenter to minimize liquid loss. The system offers aseptic operation, an excellent long-term stability and a relatively short response time. A wide range of media components is detectable by appropriate choice of analytical HPLC columns and detectors. The system was tested for the analysis of carbohydrates in cultivations of Saccharomyces cerevisiae, Streptomyces olivaceus and Arthrobacter sp.

A simple and versatile system for fermentation control by on‐line HPLC analysis of medium components

This work is focused on developing a new chromatographic method with UV detection for the separation and determination of thirty-two carboxylic aliphatic and/or aromatic acids in a single run. Ion-exclusion chromatography with a silica based, modified with C18, analytical column Alltech Prevail™ organic acid 5 µm (150 mm × 4.6 mm I.D) was used for the solving of this problem. The developed method was based on ion-exclusion and/or hydrophobic interaction chromatographic separation mechanism. The effect of the concentrations of phosphate buffer and its pH as well as the column temperatures on the retention of the test acids has been investigated. Gradient elution of the mobile phase composed of aqueous phosphate buffer and methanol was used to achieve a required separation of carboxylic acids within 45 min. All measurements were done at 220 nm. Column temperature was set at 25 ± 0.1 °C. The LOD values for organic acids range from 0.002–2.224 mg L−1. The repeatability of the procedure developed is characterized by the RSD, which varied between 0.52 and 2.85 % for the peak area. The proposed method was successfully applied for the determination of aliphatic and aromatic acids in dry white wine and human urine samples.

Single-Run Separation and Determination of Aliphatic and Aromatic Carboxylic Acids in Wine and Human Urine Samples by Ion-Exclusion Chromatography

Carbohydrates, acetic acid, furfural, 5-hydroxymethylfurfural (HMF) were analyzed in sulphite liquor using HPLC with refractive index detection.



Pentoses (xylose, arabinose) and hexoses (glucose, galactose, mannose) were separated on an Aminex HPX-87P column as wel as by means of a self-made glass cartridge packed with a piperazine impregnated silica gel. Before injecting into the HPLC apparatus the sulphite liquors were purified using a presep column packed with a cation-exchange resin. The sugar quantification between the two different separation systems was satisfactory.



Using an Aminex HPX-87P column and an UV monitor set at 283 nm connected in parallel with the RI detector also furfural and HMF could be analyzed in sulphite liquor.



Furthermore, an Aminex HPX-87H column and an UV detector set at 210 nm were most suitable to quantify ethanol.



These modified and optimized liquid chromatographic separation systems are the basis for further investigations of the utilization of hexoses as well as pentoses in sulphite liquors by means of suitable microorganisms.

Characterization of biotechnological processes and products using high‐performance liquid chromatography (H P L C). VII. Determination of organic compounds in sulphite liquor

Suitable and optimized chromatographic separation systems for HPLC analyses of mono-, di- and oligomeric carbohydrates, organic acids (e.g. gluconic acid, α-ketoglutaric acid), phospholipids (PE, LPE, LPC, PC, SPH) and neutral lipids (squalene, cholesterol) are demonstrated.



Applications of HPLC technique are separation examples of sugars from hydrolyzed starches which were isolated from potatos, calculations of organic acids in fermentation mediums and determinations of neutral lipids and phospholipids which were isolated from microbial biomass.



The liquid chromatographic separations are based on self-packed highly efficient (approximately 80 000 theoretical plates per meter, N/m) glass columns.

Characterization of biotechnological processes and products using high‐performance liquid chromatography (HPLC). I. Separations of carbohydrates, organic acids and lipids

M. Gey

Papers

Characterization of biotechnological processes and products using high‐performance liquid chromatography (HPLC). I. Separations of carbohydrates, organic acids and lipids