蒙古族肥胖儿童肠道菌群结构和短链脂肪酸含量的研究

目的 了解蒙古族肥胖和正常体重儿童肠道菌群结构及其代谢产物短链脂肪酸的含量,为蒙古族肥胖的研究提供一定基础数据。方法 采用随机整群抽样的方法按照性别年龄1:1配比,正常体重组和肥胖组各30人,取新鲜粪便提取肠道菌群总DNA,进行总DNA Illumina Miseq测序;用SYBR嵌合荧光法进行实时荧光定量PCR;通过气相色谱法测定各粪便样本中SCFAs的含量。结果 蒙古族肥胖儿童肠道菌群的多样性和丰富度均低于正常体重组（P<0.05）;门水平以Bacteroidetes（正常组56.49%,肥胖组47.08%）和Firmicutes（正常组38.61%,肥胖组48.73%）的相对丰度最高;两组的共同优势菌属有17种,在优势菌属中Pseudobutyrivibrio、 Parasutterella、Ruminococcaceae＿UCG＿014、Bifidobacterium在两组间的差异明显（P<0.05）;SCFAs的含量在正常体重组与肥胖组间差异明显(P<0.05)。结论 蒙古族肥胖儿童肠道菌群的结构及短链脂肪酸含量均发生改变,揭示肠道菌群结构变化对于蒙古族儿童...     

粪便短链脂肪酸的测定方法优化及联合补充纳豆红曲对短链脂肪酸水平的影响

目的 建立液相色谱串联质谱(LC-MS/MS)方法测定粪便短链脂肪酸(SCFAs),并检测经纳豆红曲干预后小鼠粪便中SCFAs的水平。方法 利用2-硝基苯肼盐酸盐(2-NPH·HCl)对粪便样本进行衍生，上清液萃取吹干后初始流动相复溶上机。将41只7周龄～8周龄ApoE^-/-雄性小鼠随机分成4组：低脂饲料组(LFD)、高脂高胆固醇饲料组(HFD)、低脂饲料+0.3 g/kg纳豆红曲组(LFD+NR)和高脂高胆固醇饲料+0.3 g/kg纳豆红曲组(HFD+NR)。干预12周后检测粪便SCFAs水平和空腹血糖水平。结果 目标待测物在LC-MS/MS下分离良好。所有待测物线性相关系数在0.997以上，回收率均在80.95%～119.45%,精密度均在0.2%～5.4%,满足方法学要求。联合补充纳豆红曲12周增加LFD饲养的ApoE^-/-小鼠粪便丙酸和异丁酸水平。粪便中乙酸与空腹血糖水平成负相关，辛酸与空腹血糖水平成正相关。结论 通过LC-MS/MS测定粪便SCFAs水平的方法准确度、灵敏度高，定量准确。粪便SCFAs含量与空腹血糖水平具有相关性，提...     

气相色谱-质谱法测定新鲜食用蘑菇中37种脂肪酸

目的建立新鲜食用蘑菇中同时测定37种脂肪酸的气相色谱-质谱(GC-MS)法,并对市售新鲜蘑菇中脂肪酸进行检测及营养调查。方法样品中的脂肪酸经提取、皂化、甲酯化后,以正己烷提取,采用SP-2560毛细管气相色谱柱(100 m×0.25 mm×0.2μm)进行气相色谱-质谱分析检测,以十九碳酸甲酯为内标定量。结果 37种脂肪酸在其浓度范围内均呈现良好的线性关系,线性相关系数r≥0.999,方法的最低检测限为0.1 mg/100 g~0.4 mg/100 g;回收率为76.3%~108.3%;相对标准偏差为3.17%~7.62%。对采集的6种新鲜蘑菇进行检测,发现竹荪中不饱和脂肪酸含量最高且种类最多。结论本法具有操作简单,灵敏度高,定性定量准确等特点,适用于新鲜蘑菇中37种脂肪酸的检测,为食用菌类植物中营养成分的监测和评估提供了技术支持。     

气相色谱-质谱法测定食品中的37种脂肪酸含量

目的建立采用酸水解、皂化、液-液萃取等方式提取样品,气相色谱-质谱法测定食品中37种脂肪酸含量的分析方法。方法试样加入内标经酸水解后用乙醚石油醚混合液提取脂肪,脂肪提取物经氢氧化钠甲醇溶液皂化,三氟化硼甲醇溶液甲酯化,正庚烷提取后GC-MS测定。结果 37种脂肪酸甲酯加标平均回收率为67.6%～109.5%,RSD为2.84%～5.35%,方法的最小检出限在0.000 20 g/100 g～0.000 65 g/100 g。采用气相色谱质谱技术有效避免了假阳性,采用内标法定量,提高定量的准确性,通过与气相色谱法比较,结果无差异。按照脂肪酸甲酯与甘油三酯的转换系数换算得出总脂肪含量,与采用GB 5009.6—2016食品中脂肪的测定方法测出的结果比较,无明显差异。结论该方法快速、准确,能满足食品中多种脂肪酸含量的测定。     

加热对食用植物油中短链脂肪酸含量的影响

目的建立气相色谱-质谱法(GC-MS)直接分析植物油中短链脂肪酸,研究食用植物油经高温加热后油脂短链脂肪酸的含量变化。方法经高温加热的正常食用植物油样品利用皂化、酸化、萃取的方法,提取短链脂肪酸,GCMS定性、定量分析。结果正己酸、正庚酸、辛酸在各自的线性范围内线性关系良好,相关系数分别为0.999 4、0.998 9、0.996 4。以峰面积对样品的浓度建立线性回归方程,检出限分别为2.73×10~(-3)μg/ml、4.07×10~(-3)μg/ml、2.33×10~(-2)μg/ml,定量限分别为9.11×10~(-3)μg/ml、1.36×10~(-2)μg/ml、7.76×10~(-2)μg/ml。结论本法操作简便、快速、准确、检出限低,可用于植物油中短链脂肪酸的检测。食用植物油中的短链脂肪酸的含量与其加热程度、次数密切相关。本法有望作为煎炸老油鉴别的特异方法,同时对地沟油的鉴别检测也有一定的借鉴作用。     

超声波萃取气相色谱法测定土壤样本中16种有机氯农药

目的建立超声萃取-气相色谱法测定土壤中16种典型有机氯农药的方法。方法土壤样本用有机溶剂(V丙酮∶V正己烷=1∶1)超声提取三次,合并提取液,经浓H2SO4除杂质净化后,在优化的测定条件下,用气相色谱进行定量分析,用微池电子捕获检测器检测。结果对土壤样本进行平行处理测定两次,得到了很好的重现性;对样本进行加标回收率的测定,得到了较好的回收率(49.08%~108.98%),利用本法参与土壤样本中有机氯农药的测定的比对,结果准确可靠。结论本法快速、简便、准确地测定了土壤样本中16种有机氯农药,该法的建立为土壤中此类物质的测定提供了参考。     

QuEChERS-在线凝胶渗透色谱-气相色谱/质谱法 同时测定蔬菜中49种常见农药残留

摘要:目的　建立蔬菜中49种农药的QuEChERS-在线凝胶渗透色谱-气相色谱/质谱（GPC- GC/MS）快速检测方法。方法　样品经QuEChERS方法处理,乙腈提取,离心后,上清液通过基质分散固相萃取净化;净化液经氮吹浓缩后,在线GPC-GC/ MS 定量分析。结果　49种待测农药在0.4～16.0 μg范围内时相关系数在0.9912～0.9999之间;3种样品（白菜、南瓜和胡萝卜）的加标回收率范围为66.6%～120.7%,相对标准偏差（RSD）均小于15.0%（n＝6）。结论　本法简单快速、灵敏、准确,具有良好的回收率和稳定性,适用于蔬菜中多种农药残留的测定。     

饮水中57种农药的GC/MS确证检验方法

目的:建立饮水中57种农药的GC/MS确证检验方法。方法:采用液-液萃取(LLE)技术,对水样中57种有机磷类、有机氯类、氨基甲酸酯类、菊酯类农药进行提取、净化、浓缩前处理。采用气相色谱/质谱(GC/MS)联用法进行定性测定。结果:本法回收率为89.1%～112.2%,测定精密度为2.4%～14.5%,SCAN检测模式的检出限为0.3μg/L～4μg/L,SIM检测模式的检出限为0.07μg/L～8μg/L。结论:本法简便、快速、灵敏、定性准确,适合于水样中农药的快速鉴定。     

分散液液微萃取-气相色谱/质谱法测定松茸中18种邻苯二甲酸酯

目的 建立松茸中18种邻苯二甲酸酯类（PAEs）的分散液液微萃取-气相色谱/质谱分析方法（DLLME-GC/MS）,并用于松茸中邻苯二甲酸酯的污染调查。方法 样品经乙腈超声提取后,经三氯甲烷分散液液微萃取,氮吹干、甲醇复溶后进样测定,内标法定量。结果 方法线性范围为0.001～1.00mg/L（DBEP和DCHP为0.005～1.00mg/L）,相关系数均大于0.9995。方法检出限为0.10～0.85μg/kg,定量限为0.33～2.84μg/kg。在3个加标浓度水平下的加标回收率为80.23%～118.0%,相对标准偏差为1.38%～14.7%。用本法检测了18个松茸样品,检出多种PAEs,总含量范围（∑PAEs）为12.62~5430μg/kg。结论 该方法具有简单、快速、灵敏、价廉等优点,适用于松茸中18种邻苯二甲酸酯的测定。     

缓冲QuEChERS气相色谱电子捕获检测法测定蔬菜中52种含卤素农药残留

目的:建立快速测定蔬菜中常见的52种含卤素农药残留的气相色谱电子捕获检测方法。方法:10 g样品用10 ml 0.1%乙酸的乙腈快速提取、无水醋酸钠和无水硫酸镁盐析后,经Florisil柱固相萃取净化,气相色谱电子捕获检测器检测,基体标准定量。结果:52种含卤素农药的加标回收率在60%~124%,相对标准偏差在1%~18%之间,检出限为0.0005~0.005 mg/kg。结论:本法灵敏、准确,适合于蔬菜中含卤素农药多残留分析。     

不同提取方法对粪便中短链脂肪酸含量及稳定性的影响

目的 测定粪便中乙酸、丙酸、丁酸和戊酸等短链脂肪酸的含量,研究不同提取方法和不同计算方法对SCFA含量和稳定性的影响。 方法 采用HPLC法测定粪便中SCFA的含量,采用高通量测序方法测定粪便菌群。 结果 在超纯水提取法中,以粪便湿重计算SCFA含量时,第4天测定的丙酸含量与第1天相比具有较大差异( t =-4.30, P =0.05);以OUT计算时,第4天测定的丁酸含量与第2天相比具有显著差异( t =5.63, P =0.03),而以属数目计算时,第4天测定的丙酸含量显著高于第1天( t =7.03, P =0.02)。在硫酸过滤法中,当以OUT计算时,第2天测定的丁酸含量高于第1天( t =-4.67, P =0.04),第4天测得的总SCFA含量低于第2天( t =5.98, P =0.03);而分别以湿重和属数目计算的各SCFA含量间均无显著差异。对超纯水提取法和硫酸过滤法进行比较后发现,两种提取方法间无显著差异。 结论 两种SCFA提取方法间无统计学差异,但采用硫酸过滤法提取、以粪便湿重计算时获得的SCFA含量具有较好的稳定性。     

Characteristic chromatographic fingerprint study of short-chain fatty acids in human milk,infant formula,pure milk and fermented milk by gas chromatography–mass spectrometry

Human milk, infant formula, pure milk and fermented milk as food products or dietary supplements provide a range of nutrients required to both infants and adults. Recently, a growing body of evidence has revealed the beneficial roles of short-chain fatty acids (SCFAs), a subset of fatty acids produced from the fermentation of dietary fibers by gut microbiota. The objective of this study was to establish a chromatographic fingerprint technique to investigate SCFAs in human milk and dairy products by gas chromatography coupled with mass spectrometry. The multivariate method for principal component analysis assessed differences between milk types. Human milk, infant formula, pure milk and fermented milk were grouped independently, mainly because of differences in formic acid, acetic acid, propionic acid and hexanoic acid levels. This method will be important for the assessment of SCFAs in human milk and various dairy products.     

Soyoligosaccharide increases fecal bifidobacteria counts, short-chain fatty acids, and fecal lipid concentrations in young Korean women

The effects of soyoligosaccharide intake on human fecal characteristics were investigated by measuring the fecal water content, bifidobacteria counts, pH, and concentrations of short-chain fatty acids (SCFAs) and lipids. Sixteen young women were randomly assigned to one of two groups: (1) 1.5 g/day soyoligosaccharide intake group [low soyoligosaccharide (LSO)] or (2) 3 g/day soyoligosaccharide intake group [high soyoligosaccharide (HSO)]. The experimental period was 30 days, and fecal samples were collected every 7 days. The number of bifidobacteria in feces was increased significantly in the HSO group. Of the fecal SCFAs, propionate and butyrate concentrations were significantly increased in the HSO group. The excretions of total lipids in feces were significantly increased in both the LSO and HSO groups. These results demonstrate that a soyoligosaccharide intake of 3 g/day increases fecal bifidobacteria counts, SCFA concentrations, and fecal lipid output in Korean young women.     

Fecal short-chain fatty acid (SCFA) analysis by capillary gas-liquid chromatography

A new method is described for short-chain fatty acid (SCFA) analysis in stool samples. After sample purification by acid vacuum transfer and concentration by alkaline freeze-drying, SCFAs were measured by gas-liquid chromatography using a capillary column. Peak resolution and reproducibility were superior to SCFA analysis on a conventional glass column. With this new technique SCFA were quantitated in stool samples of six healthy volunteers on a basal diet with and without a fermentable dietary fiber preparation; fiber had no effect on fecal SCFA concentration. In two patients with a short-bowel syndrome, SCFA could be demonstrated in stool samples, indicating active fermentation.     

Efficiencies of three common lipid extraction methods evaluated by calculating mass balances of the fatty acids

Efficiencies of three common lipid extraction methods have been evaluated by analyzing fatty acids in residues and extracts and calculating the mass balance for the fatty acids. Fatty acids were analyzed by an acid catalyzed direct methylation procedure followed by gas chromatography of fatty acid methyl esters. This procedure was also used as the benchmark for the calculation of mass balances. The three extraction principles investigated were Soxhlet extraction with petroleum ether, Soxhlet extraction after acid hydrolysis, and the Bligh and Dyer method. All samples were dry powders of marine origin; most samples had high ratios of polar to nonpolar lipids. Significant amounts of fatty acids were detected in the residues after extraction. The lowest extraction efficiencies were 30% for the Soxhlet method, 83% for the acid hydrolysis method and 90% for the Bligh and Dyer extraction. The lowest extraction efficiencies were typically found in samples with high ratio of polar to nonpolar lipids.     

Effects of Different Concentrations of Ganpu Tea on Fecal Microbiota and Short Chain Fatty Acids in Mice

Ganpu tea is composed of tangerine peel and Pu-erh tea. Current research suggests that both products can interact with gut microbes and thus affect health. However, as a kind of compound health food, little information is available about the effect of Ganpu tea on intestinal microorganisms. In this study, the basic physiological parameters (body weight, white adipose tissue and serum fat), the regulation of intestinal microorganisms and content of short-chain fatty acids (SCFAs) in feces of healthy mice were studied. The Ganpu tea can reduce the weight gain of mice and the increase in white adipose tissue (p < 0.01). After the intake of Ganpu tea, the abundance of Bacteroidetes increased (p < 0.05), whereas that of Firmicutes decreased (p < 0.01), indicating the latent capacity of Ganpu tea in adjusting the gut microbiota. Moreover, Ganpu tea differentially affected the content of different types of SCFAs in feces. Ganpu tea at the lowest concentrations showed positive effects on the concentrations of SCFAs such as acetic acid and propionic acid, whereas the concentration of butyric acid was decreased. For branched short-chain fatty acids (BSCFAs) such as isobutyric acid, isovaleric acid, etc., Ganpu tea reduced their concentrations. Our results indicated that Ganpu tea may have positive effects on preventing obesity in humans, but further research is needed before introducing such dietary therapy.     

Fructooligosaccharides exhibit more rapid fermentation than long-chain inulin in an in vitro fermentation system

This study investigated how chain length affects fermentation properties of fructooligosaccharides (FOSs) and inulin (IN). Chain lengths of FOSs and IN vary from an average degree of polymerization (DP) of 3 to greater than 20. Three samples classified as FOSs (samples A, B, and C) and 3 samples classified as IN (samples D, E, and F) were fermented via an in vitro batch method with human fecal inoculum as the source of microbes. Samples were removed at 0, 4, 8, 12, and 24 hours for total short-chain fatty acid (SCFA), acetate, propionate, and butyrate measurement via gas chromatography. Sample chain length did not affect SCFA concentrations in a predictable manner. Sample E (90%-94% DP > 10, 6%-10% DP = 1-2), a mixture of long-chain IN and short-chain FOS, produced significantly more total SCFA and acetate than the other samples. Sample F (DP > 20), the longest-chain IN, produced the lowest concentration of butyrate at 24 hours. The rate of FOS fermentation was higher than IN fermentation during 0 to 4 hours for all SCFAs, and the rate of IN fermentation was higher than FOS fermentation during 12 to 24 hours for all SCFAs. Chain length affects in vitro fermentability, with short chains being rapidly fermented and long chains being steadily fermented. Clinical studies should follow this work to verify if these differences exist in vivo.     

全自动固相萃取-气相色谱-质谱法测定水中6种苯氧羧酸类除草剂

目的建立全自动固相萃取-气相色谱-质谱法检测水中6种苯氧羧酸类除草剂的方法。方法取水样1 L,加抗坏血酸除余氯,经浓盐酸调节p H <1.0,加D3-2,4二氯苯氧乙酸(D3-2,4-D)内标后混匀,经全自动固相萃取仪上HLB固相萃取柱萃取,用二氯甲烷洗脱固相萃取柱上吸附的待测物,洗脱液氮吹至1 ml,用三甲基氢氧化硫溶液衍生,GC-MS分离检测。结果水样中的苯氧羧酸类除草剂的浓度在10μg/L~100μg/L线性良好,方法检出限为0.003μg/L,平均加标回收率为90.0%~103.1%,相对标准偏差(RSD)为3.15%~5.82%。结论该方法简便、准确,适用于水中6种苯氧羧酸类除草剂的检测。     

The Combined Effects of Magnesium Oxide and Inulin on Intestinal Microbiota and Cecal Short-Chain Fatty Acids

Constipation is a common condition that occurs in many people worldwide. While magnesium oxide (MgO) is often used as the first-line drug for chronic constipation in Japan, dietary fiber intake is also recommended. Dietary fiber is fermented by microbiota to produce short-chain fatty acids (SCFAs). SCFAs are involved in regulating systemic physiological functions and circadian rhythm. We examined the effect of combining MgO and the water-soluble dietary fiber, inulin, on cecal SCFA concentration and microbiota in mice. We also examined the MgO administration timing effect on cecal SCFAs. The cecal SCFA concentrations were measured by gas chromatography, and the microbiota was determined using next-generation sequencing. Inulin intake decreased cecal pH and increased cecal SCFA concentrations while combining MgO increased the cecal pH lowered by inulin and decreased the cecal SCFA concentrations elevated by inulin. When inulin and MgO were combined, significant changes in the microbiota composition were observed compared with inulin alone. The MgO effect on the cecal acetic acid concentration was less when administered at ZT12 than at ZT0. In conclusion, this study suggests that MgO affects cecal SCFA and microbiota during inulin feeding, and the effect on acetic acid concentration is time-dependent.     

饮水中多种农药残留的气相色谱-质谱检验方法

目的 建立饮水中45种农药的气相色谱-质谱( GC/MS)检验方法.方法 采用液-液萃取方法,对水样中有机磷类、有机氯类、氨基甲酸酯类、菊酯类等45种农药进行提取.优化了气相色谱-质谱(GC/MS)仪器工作参数.结果 本法回收率在88.0％ ～ 116.0％之间,测定精密度RSD在2.4％ ～ 12.5％之间,检出限在0.000 2 ～0.032 mg/L之间.结论 本法灵敏、快速、可靠.