Harmonization of the quantitative determination of volatile fatty acids profile in aqueous matrix samples by direct injection using gas chromatography and high-performance liquid chromatography techniques: Multi-laboratory validation study

Abstract

A b s t r a c tThe performance parameters of volatile fatty acids (VFAs) measurements were assessed for the first time by a multi-laboratory validation study among 13 laboratories. Two chromatographic techniques (GC and HPLC) and two quantification methods such as external and internal standard (ESTD/ISTD) were combined in three different methodologies GC/ESTD, HPLC/ESTD and GC/ISTD. Linearity evaluation of the calibration functions in a wide concentration range (10-1000 mg/L) was carried out using different statistical parameters for the goodness of fit.Both chromatographic techniques were considered similarly accurate. The use of GC/ISTD, despite showing similar analytical performance to the other methodologies, can be considered useful for the harmonization of VFAs analytical methodology taking into account the normalization of slope values used for the calculation of VFAs concentrations. Acceptance criteria for VFAs performance parameters of the multi-laboratory validation study should be established as follows: (1) instrument precision (RSDINST≤ 1.5%); (2) linearity (R 2 ≥ 0.998; RSDSENSITIVITY≤ 4%; REMAX≤ 8%; REAVER≤3%); (3) precision (RSD ≤ 1.5%); (4) trueness (recovery of 97-103%);(5) LOD (≤3 mg/L); and (6) LOQ (10 mg/L).

Validation and application of an ultrahigh-performance liquid chromatographic-Orbitrap mass spectrometric method for the simultaneous detection and quantification of volatile and non-volatile organic acids in human faecal samples

“…The determination of SCFAs in faecal samples is generally performed by gas chromatography in combination with flame-ionization [18] or MS detection without [19] or with derivatization to improve chromatographic behaviour or to increase molecular weight [20]. Alternatively, SCFA determination can be performed by capillary electrophoresis [21] and liquid chromatography coupled to refractive index [22][23], conductivity [24], electrochemical [15], spectrophotometric [25][26] or mass spectrometer [27] detector. More recently, Raposo and colleagues [23] published a multi-laboratory study regarding the quantitative determination of volatile fatty acids in aqueous matrix by GC-FID and HPLC coupled to conductivity, RI and UV.…”

“…Alternatively, SCFA determination can be performed by capillary electrophoresis [21] and liquid chromatography coupled to refractive index [22][23], conductivity [24], electrochemical [15], spectrophotometric [25][26] or mass spectrometer [27] detector. More recently, Raposo and colleagues [23] published a multi-laboratory study regarding the quantitative determination of volatile fatty acids in aqueous matrix by GC-FID and HPLC coupled to conductivity, RI and UV. Short-chain fatty acids have no chromophore group, thus their detection occur only at short ultraviolet wavelengths (200-210 nm), and this can compromise method selectivity.…”

A Multiproduct Biorefinery Approach for the Production of Hydrogen, Methane and Volatile Fatty Acids from Agricultural Waste

“…The PO4-P determination was carried out using an ion chromatography system (Dionex ICS-900 with AS14 column), with a previous centrifugation of samples and filtration through membrane filters (Whatman, 0.45 μm). For VFA determination an ion chromatography system (Dionex ICS 1100 with AS23 column) was employed [20]. Samples were previously filtered at 0.20 μm.…”

Strategies for recovery of imbalanced full-scale biogas reactor feeding with palm oil mill effluent

“…The VFA samples were collected by syringe (one mL) and filtered through a nylon membrane (0.2 µm). The filtrated samples were acidified to pH 3.0-3.2 with 30% (v/v) phosphoric acid for VFAs analysis Raposo et al (2015). Buswell's equation was used to calculate theoretical methane yield, assuming the total stoichiometry conversion of the organic matter to methane and carbon dioxide (Buswell & Mueller, 1952).…”