Acute enteric-coated sodium bicarbonate has negligible effect on anaerobic performance but affects metabolomics and attenuates the gastrointestinal response.

Sodium bicarbonate ingestion before exercise has a performance-enhancing effect on high-intensity exercise. However, gastrointestinal symptoms can be a problematic side-effect. Enteric-coated sodium bicarbonate can attenuate gastrointestinal symptoms following acute bicarbonate loading. In addition, the subsequent effects on exercise performance and metabolomics have not been investigated. The purpose of this study was to investigate the acute effect of enteric-coated sodium bicarbonate supplementation on the anaerobic performance, physiological profile, and symptoms of gastrointestinal discomfort after severe-intensity intermittent exercise. At the same time, targeted metabolomics was used to study the changes in urine metabolism after ingestion of enteric-coated sodium bicarbonate and to explore the characteristics of biological metabolism. In a randomized crossover design, twelve male college students completed four Wingate anaerobic 30-s cycling tests (WACT) after consuming a placebo (PL) and two experimental conditions: 0.2 g/kg body mass in enteric-coated sodium bicarbonate pills (ES) or general sodium bicarbonate pills (GS). Blood lactate (BLA), heart rate (HR), ratings of perceived exertion (RPE), and gastrointestinal-symptoms assessment questionnaire (GSAQ) were measured pre-exercise and post-exercise. In contrast, mean power (MP) and peak power (PP) were recorded immediately post-exercise. Urine samples were collected before formal tests and 50 min after the third WACT. Our findings indicate the following: 1) mean power and peak power showed no significant difference among conditions (MP: F2.0, 33 = 0.541, p = 0.587, η2 = 0.032; PP: F2.0, 33 = 0.526, p = 0.596, η2 = 0.031). The PP decline of the ES and GS after the third WACT was lower than that of the PL; 2) There were no significant differences in physiological responses, such as BLA (F2.0, 33.0 = 0.191, p = 0.827, η2 = 0.011) and heart rate (F2, 33 = 0.418, p = 0.662, η2 = 0.025), between the three conditions. Although blood lactate concentration after 10 min of the third WACT was lower with ES and GS than with placebo; 3) Fewer participants experienced gastrointestinal symptoms with enteric-coated than with general sodium bicarbonate; 4) The metabolites with differences among the three conditions 50 min after exercise were 3-phospho-d-glycerate, d-Glucose 6-phosphate, pyruvate, cis-aconitate, oxaloacetate, and citrate. ES had higher levels of 3-phospho-d-glycerate, d-Glucose 6-phosphate, pyruvate, and cis-aconitate than GS. The 3-phospho-d-glycerate, d-Glucose 6-phosphate, pyruvate, and cis-aconitate levels in GS were significantly lower than in PL. In contrast, the citrate level in GS was significantly higher than that in other experimental conditions. Compared to PL, the level of oxaloacetate was higher after exercise in ES. This data suggests that supplementation of enteric-coated and general sodium bicarbonate before exercise can alter energy metabolism following anaerobic exercise, involving the metabolism of 3-phospho-d-glycerate, D-Glucose 6-phosphate, pyruvate, cis-aconitate, oxaloacetate, citrate, and lactate. However, they do not affect anaerobic performance and blood lactate. The supplementation of acute enteric-coated sodium bicarbonate and general sodium bicarbonate can enhance some of the weak effects of blood lactate clearance during anaerobic exercise, which may be beneficial for glycolytic energy supply. In addition, enteric-coated sodium bicarbonate intake mitigates gastrointestinal symptoms compared to general sodium bicarbonate.

Effects of serial and acute enteric-coated sodium bicarbonate supplementation on anaerobic performance, physiological profile, and metabolomics in healthy young men.

Background: Previous studies have reported that sodium bicarbonate ingestion may enhance high-intensity exercise performance and cause severe gastrointestinal distress. However, enteric-coated sodium bicarbonate may reduce gastrointestinal symptoms of sodium bicarbonate after oral administration. This remains to be confirmed. This study aimed to verify the effects of serial and acute enteric-coated sodium bicarbonate supplementation on anaerobic performance, physiological profile, and metabolomics in healthy young men. Methods: Healthy young males (n = 12) ingested 0.2 g/kg body mass of enteric-coated sodium bicarbonate (ES) in serial enteric-coated sodium bicarbonate (SES, continuous ES supplementation for 5 days) and acute enteric-coated sodium bicarbonate (AES, acute ES supplementation before exercise) or a placebo (PL) in a randomized crossover design. After each supplement protocol, the participants completed four Wingate anaerobic tests (WAT). The first three Wingate tests (testing anaerobic capacity) were performed with a 5-min passive recovery between each. After the third Wingate test, participants were required to complete a 50-min recovery followed by a fourth WAT test (testing the recovery of anaerobic capacity after 50-min intervals). Blood lactate (BLA), heart rate (HR), and ratings of perceived exertion (RPE) were measured in all conditions during the test, as was the subjective gastrointestinal-symptoms assessment questionnaire (GSAQ). Mean power (MP) and peak power (PP) were recorded after four WATs. Urine samples were collected before the test and 50 min after the 3rd WAT. Results: Serial enteric-coated sodium bicarbonate supplementation improved anaerobic capacity in the third bout of WATs, as observed based on an increase in mean power (SES vs. PL (613 ± 57 vs. 542 ± 64 W), P = 0.024) and peak power (SES vs. PL (1,071 ± 149 vs. 905 ± 150 W), P = 0.016). Acute ES supplementation did not affect anaerobic capacity. The occurrence of gastrointestinal symptoms after enteric-coated sodium bicarbonate supplementation was minimal and no difference compared to placebo in the current study. In particular, serial enteric-coated sodium bicarbonate supplementation had no gastrointestinal side effects before the test. The AES and SES groups had a trivial effect on blood lactate compared to the PLA group. There was no significant difference in HR and RPE among the three groups. Based on targeted metabolomics analysis, the 50 min after the third WAT, the levels of lactate (P < 0.001), L-Malic acid (P < 0.05), and oxaloacetate (P < 0.05) were significantly higher in the SES group than in the PL group. Compared with the AES group, the levels of lactate and fumarate in the SES group were significantly increased (P < 0.05). Conclusions: Our study indicates that serial enteric-coated sodium bicarbonate supplementation positively improves anaerobic performance among healthy young men. However, acute ingestion of enteric-coated sodium bicarbonate did not improve anaerobic exercise performance. Either with serial or acute supplementation doses, enteric-coated sodium bicarbonate produced fewer gastrointestinal symptoms and no difference compared to placebo, especially with no gastrointestinal side effects after serial supplementation. Serial and acute supplementation of enteric-coated sodium bicarbonate might tend to promote lactate clearance. Furthermore, serial enteric-coated sodium bicarbonate ingestion may cause changes in the metabolism of lactate, L-Malic acid, oxaloacetate, and fumarate 50 min after exercise, which presumably may promote the tricarboxylic acid cycle and lactate clearance.

[Effects of annual distribution difference of precipitation on evapotranspiration characteristics of dry orchard in Loess Plateau, China]. / é»„åœŸé«˜åŽŸé™æ°´å¹´å† åˆ†å¸ƒå·®å¼‚å¯¹æ—±ä½œæžœå›­è’¸æ•£ç‰¹å¾çš„å½±å“.

Precipitation is the main driving factor for hydrological cycle in rain-fed agricultural areas, which determines the water-related ecological environment and affects the evapotranspiration characteristics of crops. By analyzing the annual distribution characteristics of precipitation across different years, this study clarified the concentrated trend of precipitation in Jingning County. Based on a field experiment in 2018 and 2019, the changes of soil moisture with precipitation and the response process of orchard evapotranspiration characteristics to the annual distribution differences of precipitation were explored. The results showed that the concentration degree of precipitation was high in the study area over the years. The concentration period was mainly distributed in July and August, with the proportion of August being up to 75%. Moreover, the time of precipitation concentration period varied greatly among years. The response of soil moisture to precipitation was mainly concentrated in the 0-40 cm layer, while moisture in deep soil layer would change significantly only in response to heavy and continuous rain. Both 2018 and 2019 were water-rich years. The precipitation concentration degree in 2018 was high, and the concentration period was earlier and shorter, with the diurnal water consumption of apple trees showing a single peak with large amplitude. In 2019, the distribution of precipitation was uniform, the concentration period was late, and the diurnal water consumption showed double-peak with a small amplitude and a lagged large peak. The maximum water demand period of apple trees lasted a long time. The concentrated distribution of heavy rain in 2018 could not meet the physiological water demands of apple trees in the later period, which damaged the yield, and the utilization efficiency of precipitation decreased by 30.2% compared with 2019. In the Loess Plateau region, there is often a brief drought during the young fruit growth period, which would affect fruit quality. Therefore, water management during this period should be strengthened.

Evaluation of the peak variance in gradient liquid chromatography.

The peak variance obtained under single stepwise (SS), single linear (SL) and ladder-like (LL) gradient conditions was evaluated by taking into account the variation of plate height with mobile phase composition. LC tests were performed on a C18 column using a mixture of methanol and water as the mobile phase and six aromatic compounds (anisole, o-cresol, biphenyl, phenol, aniline and acetophenone) as the model samples. It was found that the relationship between the retention factor and mobile phase composition could be described by the linear solvent strength model. The plate height that was measured under isocratic conditions varied with mobile phase composition. This variation could be described by a quadratic polynomial in this work. Under gradient conditions, the experimental and predicted values of peak variance were found to be well consistent. The discrepancy between the experimental and predicted values in the SS gradient was larger than that in the SL or LL gradient. This may be ascribed to the distortion of the gradient profile as a result of dispersion that occurred in the mobile phase. By using the dispersive gradient profile that was obtained at the column inlet for the calculation, the discrepancy between the experimental and predicted values in the SS gradient may be minimized.

[Application of general retention time formula for gradient liquid chromatography in the studies of ladder-like gradient elution].

By not explicitly specifying the type of solvent strength model, the features of ladder-like gradient elution were studied based on the general retention time formula that was derived in our previous work. For the case where the solute is eluted at like gradient, we derived the expression that connects the mobile phase composition (phiR), at which the solute is eluted from the column, with the gradient slope (B). It was shown that phiR will increase with the increase of B in this case. For the case where the solute is eluted at the last isocratic segment of the ladder-like gradient, it was proven that the retention time (tR) will correlate linearly with the reciprocal of the gradient slope (1/B) when the initial and final mobile phase compositions are set to be constant. In experiments, by taking biphenyl as the sample, the values of retention time in isocratic and gradient elution were measured on a C18 column by using a mixture of methanol and water as the mobile phase. The experimental values were found to be well consistent with the theoretical values that were calculated from the expressions. These expressions will be helpful to understand the features of the ladder-like gradient in practice.

Study of the peak variance in isocratic and gradient liquid chromatography using the transport model.

The expressions accounting for the peak variance in isocratic and gradient liquid chromatography is derived from the transport model. In mathematical treatments, the dwelling time is taken into account, and the type of solvent strength, gradient profile and the variation of plate height (H) with mobile phase composition (φ) is not specified. By applying a coordinate transformation, the transport model is solved by using the Laplace transform approach. A plate height equation that is suited for both isocratic and gradient elution is obtained. Based on this equation, the plate height equations for any combination of stepwise and linear gradients are derived. These equations will be algebraic when the solvent strength is linear and the H-φ plot is parabolic. The plate height equations for single stepwise, single linear and the ladder-like gradients are also given.

[General retention time formulae for gradient liquid chromatography with any combination of isocratic, linear and stepwise gradients].

The ideal model of liquid chromatography in gradient elution was solved by using the characteristic approach on the assumption of a linear solvent strength model. By considering the influence of the dwelling time of the chromatographic system on retention time, the retention time formulae suited for any combination of isocratic, linear and stepwise gradients were obtained. It was found that the values of the retention time obtained from these formulae were in well accordance with those computed by using the finite-difference method, which confirms the validity of the formulae. Due to the simplicity and broad scope of applications, these formulae can be easily applied in practice.

[Study on thermal decompositon properties of hexafluoropropane clean gaseous fire-extinguishing agent].

The thermal decomposition properties of hexafluoropropane clean gaseous fire-extinguishing agent were studied in tubular reactor from 500 to 750 degrees C and the decomposed gas was characterized by gas chromatography(GC), Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS). Hydrogen fluoride was detected after the decomposed gas was analyzed by pH testing, while pentafluoropropylene was found by GC-MS. The results showed that hydrogen fluoride eliminated from hexafluoropropane was the main reaction, while pentafluoropropylene was the primary product during hexafluoropropane decomposition under high temperature. GC and FTIR results indicated that the reaction temperatures had significant effects on the thermal decomposition of hexafluoropropane. Haxafluropropane was steady at 500 degrees C, whereas started to decompose weakly at 600 degrees C. The degree of the thermal decomposition of hexafluoropropane was enhanced with the temperature increase. And hexafluoropropane underwent intense decompositon at 750 degrees C. FTIR can be used as a new method to study extinguishing mechanism of fluorine-containing fire extinguishing agent online.

[Emission spectroscopy diagnostics of plasma electron temperature].

Electron temperature is one of the important parameters of plasma. It is very difficult to measure the electron temperature exactly and instantly owing to its complexity during discharge. As a plasma diagnostics technique, emission spectroscopy is widely applied in the study and diagnosis of any kind of plasma, because of its simple instrument system, noninterference of measurement, high sensitivity and fast responsibility. In the present paper, some methods for plasma electron temperature diagnosis, such as two lines method, multiline slope method, isoelectronic line method, Saha-Boltzmann equation, absolute intensity method, were introduced. And the applications of these methods were reviewed to provide reference for choosing appropriate methods in practice.

Effect of spectral resolution on the measurement of monoaromatic hydrocarbons by DOAS.

The excellent response characteristics and detection sensitivity with much lower operational cost and the capability to discriminate between the isomer of some monoaromatic hydrocarbons (MAHCs) make differential optical absorption spectroscopy (DOAS) a powerful tool to trace concentration variation of MAHCs. But due to the similarity in chemical structure, those MAHCs have the similar overlapped characteristic absorption structures, which make the selection of instrumental parameter critical to the accurate detection of MAHCs. Firstly, the spectral resolution used in DOAS system determines the nonlinear absorption of O2 and the mass dependence of characteristic absorption structure; thereby it determines the effect of elimination error of O2 absorption in the atmospheric spectra for the detection of MAHCs. Secondly, spectral resolution determines the differential absorption characteristics of twelve MAHCs representing major constituents in technical solvents used in the automobile industry and the interference of spectral overlapping. Thirdly, the spectral resolution determines the sensitivity, time resolution and linear range. So the spectral resolution range with the best ratio of signal to noise is used to determine the most suitable spectral resolution range, as well as the spectral resolution range that ensure the characteristic absorption structure of MAHCs and the minimization of O2 absorption interference. Finally, 0.15-0.16 nm (FWHM: full width at half maximum) is assumed to be closest to the optimum spectral resolution and it is confirmed by the results of practical measurement of MAHCs by DOAS.

[The effect of resolution on the measurement of carbon bisulfide by DOAS].

Featuring excellent response characteristics and detection sensitivity and with much lower operational cost, differential optical absorption spectroscopy (DOAS) can be a powerful tool to trace the concentration variation of carbon bisulfide (CS2), a kind of poisonous gas with bad smell. In the DOAS measurement, the accuracy of the carbon bisulfide results is determined by the selected spectral resolution. The present paper focuses on the effect of resolution on the detected characteristic absorption structure of CS2 and the variation in differential cross section of CS2 with the change in resolution, from which the effect of resolution on the detection limit of CS2 is deduced. In the end, the functional dependence of the ratio of signal to noise (S/N) on the resolution is reduced by studying the relationship between light intensity and resolution. And the optimized resolution is determined as 0. 41-0. 50 nm (FWHM) with the lowest S/N. The optimized resolution range can yield high sensitivity, good selectivity and a reasonable time resolution for the accurate qualitative and quantitative analysis of CS2 (the results of five different concentration cells show linear correlation with r = 0.999 9 and all the relative standard deviations are less than 0.3% with n = 10). In the end, the long time, real time and continuous monitoring of CS2 was carried out in the Fengtai District of Beijing, and a good result was obtained.

A new membrane inlet interface of a vacuum ultraviolet lamp ionization miniature mass spectrometer for on-line rapid measurement of volatile organic compounds in air.

A novel membrane inlet interface coupled to a single-photon ionization (SPI) miniature time-of-flight mass spectrometer has been developed for on-line rapid measurement of volatile organic compounds (VOCs). The vacuum ultraviolet (VUV) light source for SPI was a commercial krypton discharge lamp with photon energy of 10.6 eV and photon flux of 10(10) photons/s. The experimental results showed that the sensitivity was 5 times as high as obtained with the traditional membrane inlet. The enrichment efficiency could be adjusted in the range of 10 to 20 times for different VOCs when a buffer cell was added to the inlet interface, and the memory effect was effectively eliminated. A detection limit as low as 25 parts-per-billion by volume (ppbv) for benzene has been achieved, with a linear dynamic range of three orders of magnitude. The rise times were 6 s, 10 s and 15 s for benzene, toluene and p-xylene, respectively, and the fall time was only 6 s for all of these compounds. The analytical capacity of this system was demonstrated by the on-line analysis of VOCs in single puff mainstream cigarette smoke, in which more than 50 compounds were detected in 2 s.

[The rapid and nondestructive identification and infrared spectra visualization of Banlangen granule].

Banlangen granule is the main medicament of Banlangen, and is widely used for the prevention and cure of flu and viral infection. In the present article, Fourier transform infrared (FTIR) spectroscopy was used in the identification and analysis of the traditional Chinese medicine, Banlangen granule. The FTIR spectra of Banlangen granule samples coming from different companies and different batches of the same company were obtained. The curves of original absorbance and the second derivatives of the absorbance were analyzed for identification, and compared with those of indigowoad root and indigowoad leaf, which are their raw medicine materials. In addition, the infrared fingerprint spectra were visualized in the form of color bar figure. Results showed that characteristic fingerprint spectra of Banlangen Granule could be picked up effectively, and the products quality of different pharmaceutical factories and the spectra of different batch numbers from the same factory could be revealed directly by FTIR spectroscopy combined with the second derivative spectrum and fingerprint spectrum visualization of analytical data. Thus they were differentiated conveniently, accurately, quickly and directly with this method, providing a simple and effective technique in supervising and examining the quality of the traditional Chinese medicine.

[Preparation and characterization of magnetic photocatalysts TiO2/Fe3O4].

Magnetic photocatalysts (TiO2/Fe3O4), which are liable to be separated and recovered, were prepared using Fe3O4 as the support. The surface morphology and crystal pattern were investigated by means of XRD, SEM, XPS and FTIR. The results showed that TiO2 wraps on the surface of Fe3O4. The photocatalytic activity of the catalysts was investigated by photocatalytic decolorization of (TNR). The photocatalytic activity of the catalysts is high and the separating ratio is good.

[Principal component extraction used for the interpretation of RS-FTIR spectra].

A method for interpretation of remote sensing FTIR spectra was set up based on ANN model. Considering long training time and over-fitting problem of ANN, two methods, partial least squares (PLS) and principal component analysis (PCA), were utilized to extract principal components of spectra, process time decrease from about 30 minutes to a few seconds. Meanwhile, the idea of calibration transfer was used to overcome the limitation of calibration model in remote sensing FTIR spectra analysis. With the optimization of ANN model, four-component mixtures of acetone, benzene, chloroform and methanol were predicted in a remote sensing and real-time way while the calibration model was built with EPA data. The best performance was yielded with PLS-ANN model, and the root mean square error (RMSE) of acetone, benzene, chloroform and methanol were 0.043, 0.031, 0.034 and 0.051 respectively, which confirm the real-time, correct and quick analysis of remote sensing FTIR in air monitoring.

[Multicomponent quantitative analysis using near infrared spectroscopy by building PLS-GRNN model].

The present paper introduces an application of near infrared spectroscopy(NIRS) multi-component quantitative analysis by building partial least squares (PLS)-generalized regression neural networks (GRNN) model. The PLS-GRNN prediction model for chlorine, fibre and fat in 45 feedstuff samples was established with good veracity and recurrence. Eight peak values in principal components compressed from original data by PLS and four in original spectra were taken as inputs of GRNN while 4 predictive targets as outputs. 0.1 was chosen as smoothing factor for its good approximation and prediction with the lowest error compared with 0.2, 0.3, 0.4 and 0.5. Predictive correlation coefficient and Standard error of the estimate of three components by the model are 0.984 0, 0.987 0 and 0.983 0, and 0.015 89, 0.154 1 and 0.115 1, while the Standard deviations of an unknown sample scanned 8 times are 0.003 26, 0.065 5 and 0.031 4. The results show that PLS-GRNN used in NIRS is a rapid, effective means for measuring chlorine, fibre in the fat in feedstuff powder, and can also be used in quantitative analysis of other samples. A settlement in the high error of prediction of other samples with lower contents was also shown.

[Determination of four contents of feedstuff powder using near infrared spectroscopy by PLS-BP model].

Partial least squares (PLS) and artificial neural networks (ANN) prediction model for four components of feedstuff has been established with good veracity and recurrence. The spectra put into the model should be processed by second derivative and standard normal variate (SNV). Ten principal components compressed from original data by PLS and two peak values were taken as the inputs of Back-Propagation Network (BP), while four predictive targets as outputs, according to Kolmogorov theorem and experiment, and twenty three nerve cells were taken as hidden nodes. Its training iteration times was supposed to be 10,000. Prediction deciding coefficient of four components by the model are 0.9950, 0.9980, 0.9990 and 0.9670, while the standard deviation of an unknown sample scanned parallelly are 0.02774, 0.04853, 0.03292 and 0.02204.

[Study on the multicomponent quantitative analysis using near infrared spectroscopy based on building elman model].

The present paper introduces an application of near infrared spectroscopy (NIRS) multi-component quantitative analysis by building a kind of recurrent network (Elman) model. Elman prediction model for phenylalanine (Phe), lysine (Lys), tyrosine (Tyr) and cystine (Cys) in 45 feedstuff samples was established with good veracity. Twelve peak value data from 3 principal components straight forward compressed from the original data by PLS were taken as inputs of Elman, while 4 predictive targets as outputs. Forty seven nerve cells were taken as hidden nodes with the lowest error compared with taking 43 and 45 nerve cells. Its training iteration times was supposed to be 1000. Predictive correlation coefficients by the model are 0.960, 0.981, 0.979 and 0.952. The results show that Elman using in NIRS is a rapid, effective means for measuring Phe, Lys, Tyr and Cys in feedstuff powder, and can also be used in quantitative analysis of other samples.

[Calibration transfer used for the interpretation of RS-FTIR spectrum].

A technique of analysis for RS-FTIR (Remote Sensing Fourier Transform Infrared) spectrum was built based on the principle of calibration transfer. A system of four-component gas mixtures, whose FTIR spectra were overlapped seriously, was determined as the object in the present research. Its FTIR data from EPA and field measurement were used to set up calibration and prediction models, respectively. With OSC (orthogonal signal correction), the model built with data of EPA predicted values of field measurement. The RMSEP values of acetone, methanol, benzene and chloroform were 0.0085, 0.0180, 0.0640 and 0.0028, respectively, while without OSC correction the corresponding values were 0.0856, 0.0479, 1.0653 and 0.0142, respectively. With optimization, the Kennard-Stone method was used for subset selection, and the iteration in the process of OSC was carried out 3 times, yielding the best performance. The result indicates that this technique can overcome the limitation of background and calibration model, which restricts the application of RS-FTIR in air monitoring.

[Analysis of the impurity of bacterium source of standard endotoxin by gas chromatography/mass spectrometry].

To analyse the impurity of bacterium source of standard endotoxin, 3-hydroxy fatty acid species in different endotoxin standards was determined by gas chromatography/mass spectrometry (GC/MS) using N, O-bis (trimethylsilyl) trifluoroacetamide as the silanizing reagent. GC/MS analysis was performed using a gas chromatograph equipped with a 60 m x 0.25 mm i. d. DB-5 fused silica capillary column and an injector at 250 degrees C. Helium was used as the carrier gas under a constant pressure of 206 kPa. The oven was programmed at a rate of 5 degrees C /min from 90 degrees C (held for 5 min) to 280 degrees C (held for 5 min). The sample size was 1 microL. The transfer line was kept at 280 degrees C. The quadrupole mass spectrometer was operated in electron impact (EI) ionization mode, and the temperature of the source was kept at 250 degrees C. The kind of 3-hydroxy fatty acids in 9 000 EU/tube national standard endotoxin, 20 EU/tube working standard endotoxin, Escherichia coli, Pseudomonas aeruginosa and deionized water were determined to study the purity of bacterium source of the standard endotoxin. It was shown that 9 000 EU/tube endotoxin standard and Escherichia coli only contained 3-hydroxytetradecanoic acid. There was 3-hydroxydodecanoic acid in 20 EU/tube working standard endotoxin, which indicated the presence of impurity of bacterium source.