Online headspace chromatographic method for measuring VFA in biogas reactor

2005 ◽  
Vol 52 (1-2) ◽  
pp. 473-478 ◽  
Author(s):  
K. Boe ◽  
D.J. Batstone ◽  
I. Angelidaki
Keyword(s):  
Fatty Acids ◽  
Organic Acid ◽  
Gas Phase ◽  
Volatile Fatty Acids ◽  
Chromatographic Method ◽  
Negative Impact ◽  
Automated System ◽  
Liquid Volume ◽  
Strong Impact ◽  
Short Period

A headspace chromatographic method has been applied to measure volatile fatty acids in anaerobic digesters using gas phase extraction at pH less than 2 and temperature higher than 65 °C. The concentration of volatile fatty acids in liquid and gas phase can be correlated in the form of Henry's coefficient. Analysis of different factors in the batch indicated that pH, temperature, and salt addition had a strong impact on apparent solubility, while liquid/gas volume ratio and organic acid concentration had little impact. Larger liquid volume had a positive impact on extraction efficiency, while increased gas headspace had a negative impact, indicating that the system was total mass-limited. The best conditions were at pH < 2.0, and temperatures above 75 °C. The advantage of an automated gas-extraction system for organic acid analysis, compared to an automated liquid system is that it contains no filter element, which is susceptible to fouling in manure samples or samples with high solid content. An automated system which included a valerate pulse to the parent reactor was implemented, and operated for a short period.

A rapid gas chromatographic method for the quantitation of volatile fatty acids in urine

1973 ◽  
Vol 81 (1) ◽  
pp. 65-69 ◽  
Author(s):  
B.F. Gibbs ◽  
K. Itiaba ◽  
J.C. Crawhall ◽  
B.A. Cooper ◽  
O.A. Mamer
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Chromatographic Method ◽  
Gas Chromatographic Method

scholarly journals Absorption of volatile fatty acids from the rumen of lactating dairy cows as influenced by volatile fatty acid concentration, pH and rumen liquid volume

1993 ◽  
Vol 69 (2) ◽  
pp. 385-396 ◽  
Author(s):  
Jan Dijkstra ◽  
Huug Boer ◽  
Jaap Van Bruchem ◽  
Marianne Bruining ◽  
Seerp Tamminga
Keyword(s):  
Fatty Acids ◽  
Dairy Cows ◽  
Acid Concentration ◽  
Butyric Acid ◽  
Absorption Rate ◽  
Volatile Fatty Acids ◽  
Liquid Volume ◽  
Lactating Dairy Cows ◽  
Volatile Fatty Acid Concentration ◽  
Fractional Absorption

The effect of rumen liquid volume, pH and concentration of volatile fatty acids (VFA) on the rates of absorption of acetic, propionic and butyric acids from the rumen was examined in lactating dairy cows. Experimental solutions introduced into the emptied, washed rumen comprised two different volumes (10 or 30 1), four levels of pH (4.5, 5.4, 6.3, 7.2) and three levels of individual VFA concentrations (20, 50 or 100 mM-acetic, propionic or butyric acid). All solutions contained a total of 170 mM-VFA and an osmotic value of 400 mOsmol/l. Absorption rates were calculated from the disappearance of VFA from the rumen corrected for passage with liquid phase to the omasum. An increase in initial fluid pH caused a reduction in fractional absorption rates of propionic and butyric acids. Increasing the initial pH from 4.5 to 7.2 reduced fractional absorption rates of acetic, propionic and butyric acids from 0.35, 0.67 and 0.85 to 0.21, 0.35 and 0.28/h respectively. The fractional absorption rates of all VFA were reduced (P < 0.05) by an increase in initial rumen volume. The fractional absorption rate of acetic acid was lower (P < 0.05) at an initial concentration of 20 mM than of 50 mM. The fractional absorption rate of propionic acid tended (P < 0.10) to decrease as the level of concentration increased while fractional absorption rate of butyric acid was not affected by butyric acid concentration. These results indicate that relative concentrations of VFA in rumen fluid might not represent relative production rates and that attempts to estimate individual VFA production from substrate digestion must take account of pH and VFA concentration.

scholarly journals Measurement of Acetate in Aqueous Solutions and Plasma by Gas Phase Chromatography using a Porous Polymer Stationary Phase

1978 ◽  
Vol 15 (1-6) ◽  
pp. 228-232 ◽  
Author(s):  
M. F. Laker ◽  
M. A. Mansell
Keyword(s):  
Fatty Acids ◽  
Stationary Phase ◽  
Gas Phase ◽  
Retention Time ◽  
Healthy Subjects ◽  
Volatile Fatty Acids ◽  
Reference Range ◽  
Porous Polymer ◽  
Plasma Samples ◽  
Apparently Healthy

Summary A method of acetate determination by gas phase chromatography using a porous polymer stationary phase is reported that is suitable for use with aqueous and plasma samples. It is linear up to 100 mmol/l and has a coefficient of variation of less than 4 % for acetate values of greater than 1 mmol/l. The recovery of acetate from plasma is 92 % and sample retention time is 3 minutes. The reference range of plasma acetate in a group of 40 apparently healthy subjects was from less than 0·1 to 0·35 mmol/l. The frequently encountered problem of adsorption and ghosting of volatile fatty acids is overcome without the addition of formic acid vapour to the carrier gas.

Sites of organic acid production and absorption in gastrointestinal tract of the pig

1975 ◽  
Vol 228 (2) ◽  
pp. 454-460 ◽  
Author(s):  
RA Argenzio ◽  
M Southworth
Keyword(s):  
Fatty Acids ◽  
Gastric Mucosa ◽  
Organic Acid ◽  
Intestinal Mucosa ◽  
Volatile Fatty Acids ◽  
Control Diet ◽  
Organic Acid Production ◽  
Rumen Epithelium ◽  
High Concentrations ◽  
Digesta Passage

The relationship between diet, pH, and microbial digestion of carbohydrate was examined in 24 pigs fed either a conventional or a low-protein, high-cellulose experimental diet and sacrificed 2, 4, 8, or 12 h after a meal. In animals fed the control diet contents of the cranial half of the stomach demonstrated marked, cyclic fluctuations in pH and high concentrations of organic acids. Contents of the caudal (glandular) half were lower in both pH and organic acid concentration. Despite concentrations of volatile fatty acids (VFAs) as high as 250 meq/liter in the large intestine, the pH remained relatively neutral. The VFA levels remained relatively constant throughout the length of the colon. The VFA transport across isolated gastric and large intestinal mucosa also was examined. All four types of gastric mucosa absorbed and transported VFA at substantial rates. Mucosa of pig cecum and colon transported VFA at much greater rates than gastric mucosa and greater rates than previously determined in equine large intestinal mucosa or even bovine rumen epithelium. Comparison with results of earlier studies in the pony suggested that the higher concentration of VFA in the large intestinal contents of pigs was due to the more rapid rate of digesta passage rather than to less efficient absorption of fatty acids.

scholarly journals Optimizing the impact of temperature on bio-hydrogen production from food waste and its derivatives under no pH control using statistical modelling

2015 ◽  
Vol 12 (21) ◽  
pp. 6503-6514 ◽  
Author(s):  
C. Arslan ◽  
A. Sattar ◽  
C. Ji ◽  
S. Sattar ◽  
K. Yousaf ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Hydrogen Production ◽  
Food Waste ◽  
Volatile Fatty Acids ◽  
Negative Impact ◽  
Glucose Consumption ◽  
Statistical Modelling ◽  
Effect Of Temperature ◽  
Coefficient Of Determination ◽  
The Impact

Abstract. The effect of temperature on bio-hydrogen production by co-digestion of sewerage sludge with food waste and its two derivatives, i.e. noodle waste and rice waste, was investigated by statistical modelling. Experimental results showed that increasing temperature from mesophilic (37 °C) to thermophilic (55 °C) was an effective mean for increasing bio-hydrogen production from food waste and noodle waste, but it caused a negative impact on bio-hydrogen production from rice waste. The maximum cumulative bio-hydrogen production of 650 mL was obtained from noodle waste under thermophilic temperature condition. Most of the production was observed during the first 48 h of incubation, which continued until 72 h of incubation. The decline in pH during this interval was 4.3 and 4.4 from a starting value of 7 under mesophilic and thermophilic conditions, respectively. Most of the glucose consumption was also observed during 72 h of incubation and the maximum consumption was observed during the first 24 h, which was the same duration where the maximum pH drop occurred. The maximum hydrogen yields of 82.47 mL VS−1, 131.38 mL COD−1, and 44.90 mL glucose−1 were obtained from thermophilic food waste, thermophilic noodle waste and mesophilic rice waste, respectively. The production of volatile fatty acids increased with an increase in time and temperature in food waste and noodle waste reactors whereas they decreased with temperature in rice waste reactors. The statistical modelling returned good results with high values of coefficient of determination (R2) for each waste type and 3-D response surface plots developed by using models developed. These plots developed a better understanding regarding the impact of temperature and incubation time on bio-hydrogen production trend, glucose consumption during incubation and volatile fatty acids production.

scholarly journals Effects of Organic acid Blend on Growth Performance, Nutrient Digestibility and Concentration of Volatile Fatty Acids in the Faeces of Young Pigs

2021 ◽  
Vol 65 (2) ◽  
pp. 42-47
Author(s):  
L. Bujňák ◽  
P. Naď ◽  
T. Mihok
Keyword(s):  
Fatty Acids ◽  
Organic Acid ◽  
Growth Performance ◽  
Crude Protein ◽  
Volatile Fatty Acids ◽  
Average Daily Gain ◽  
Live Weight ◽  
Nutrient Digestibility ◽  
Control Group ◽  
Young Pigs

Abstract The objective of this experiment was to evaluate the effects of a feeding diet containing a dry organic acid blend (lactic acid—ammonium formate—ammonium propionate—citrate—sorbate) in young pigs on their: performance, the apparent total tract digestibility of nutrients and the concentration of volatile fatty acids in their faeces. A total of 12 crossbred pigs (Slovakian White × Landrace) with an initial live weight of 12.78 ± 1.86 kg were divided into two dietary treatments. The experimental period lasted 28 days. Pigs were fed a control diet (control group) or a diet supplemented with a dry organic acid (OA) blend, 0.6 g per 100 g feed (experimental group). Compared with the control group, the average daily gain (ADG) was improved (P < 0.05) by OA blend over the period of the investigation (0—28 days). For the apparent total tract digestibility determination, ash which is insoluble in hydrochloric acid was used as a marker. The apparent total tract digestibility of crude protein and total ash was improved (P < 0.05) by the OA blend in the experiment. Compared with the control group, the concentration of the total volatile fatty acid in the faeces increased (P < 0.05) in pigs supplemented with the OA blend. The concentration of butyric acid in the faeces tended to be higher (P < 0.01) in pigs supplemented with the OA blend compared with the control group. In conclusion, the addition of 0.6 g per 100 g feed had a positive effect on: growth performance, total tract digestibility of crude protein and the concentration of volatile fatty acids in the faeces of young pigs.

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