微波辅助衍生化-气相色谱法测定烟草中非挥发性有机酸

在气相色谱法测定烟草中非挥发性有机酸中,提出了用硫酸-甲醇(1+7)混合溶液作衍生试剂,在微波炉中于选定的条件下对所测定的有机酸进行衍生化.经酯化的溶液用二氯甲烷萃取,萃取液蒸缩至2 mL,分取1μL进样作气相色谱分析.测定中采用AC 20毛细管柱及火焰离子化(FID)检测器并用戊二酸作内标,对7种非挥发性有机酸用标准...     

烟草中挥发性和非挥发性有机酸的快速测定

建立了气相色谱-质谱(GC-MS)法快速测定烟草中22种非挥发性、挥发性有机酸的分析方法。采用对甲苯磺酸-硫酸-甲醇(PTSA/H2SO4/CH3OH)酯化试剂对烟草样品进行一次酯化,生成的有机酸酯用GC-MS进行分析。结果表明,酯化时间从20 h缩短到1 h,非挥发酸回收率在93.4%~103.2%之间,相对标准偏差(RSD)小于4.2%;挥发性有机酸回收率在89.2%~99.1%之间,RSD小于3.5%。该方法具有简便、快速,结果准确等特点,用于测定部分烟草样品的挥发性、非挥发性有机酸,取得了满意的结果。     

色质联用分析葡萄酒中有机酸

用树脂将葡萄酒中有机酸吸附分离后,在不洗脱的情况下直接酯化,然后进行色质联用分析,共测出葡萄酒中19种有机酸。方法新颖、快速、简便、有效。     

固相萃取-离子色谱/气相色谱-质谱法联合检测油田水中的有机酸和酚类化合物

建立了固相萃取-离子色谱(IC)/气相色谱-质谱(GC-MS)联合检测高矿化度油田水中低相对分子质量的有机酸和酚类化合物的方法。在中性pH条件下,样品经Waters Oasis HLB柱萃取后,萃取液经稀释、Ag2O沉淀和Ag-H柱处理除去大部分氯离子,再用IC测定有机酸;将萃取柱真空冷冻干燥,然后经甲基叔丁基醚/甲醇(9:1, v/v)脱附并用无水硫酸钠除水,再用GC-MS检测酚类化合物。在优化的实验条件下,4种低相对分子质量的有机酸以及5种酚类化合物的平均加标回收率达到80%以上,相对标准偏差(RSD, n=6)为2.38%～9.45%,定量限均低于88.9 μg/L。该方法测定结果准确可靠,适用于氯离子含量高达150 g/L左右水样中低相对分子质量的有机酸和酚类化合物的检测。     

柱前衍生-气相色谱法同时测定功能食品中8种有机酸

建立了功能食品中8种有机酸同时测定的方法。样品中的有机酸(乙酸、丙酸、丁酸、草酸、乳酸、丙二酸、丁二酸、柠檬酸)经体积分数15%的硫酸甲醇提取酯化,三氯甲烷萃取,最后用气相色谱法测定。色谱条件:SPB-5毛细管柱(30 m×0.53 mm×0.5μm)为分离柱,火焰离子化检测器检测,进样口温度为250℃,检测器温度为300℃,程序升温。载气(N2)流速为0.8 mL/min,分流比为10:1,富马酸二甲酯内标法定量。8种有机酸衍生物达到基线分离,检测限范围为0.01~0.04 mg/L,精密度(RSD)范围为2.4%~5.5%,平均回收率范围为79.5%~106%。方法适合于功能食品中8种有机酸的快速测定。     

金属有机钛化合物对脂肪酸与芳香醇酯化反应的催化作用

酯的合成方法很多,常用的方法是有机酸和醇的直接酯化,催化剂一般有H_2SO_4,分子筛等.但对于羧酸和苄醇的直接酯化,其产率往往不高,这是因为苄基有着较大的空间阻碍.为提高产率,一般是采用酰卤醇解法或羧酸钠盐与氯苄反应,或通过季胺盐热分解法制备羧酸苄酯.本文用己酸和苄醇在二氯二茂钛催化剂作用下直接酯化,其酯产率与文献中的正丁酸苄酯相近.以有机钛化合物为催化剂的酯化,具有催化剂用量少,装置简单,操作方便,且后处理简便,产率较高等优点.     

离子色谱法测定乙二醇中微量有机酸和无机阴离子

建立了以YSA-8阴离子交换柱的离子色谱法分析乙二醇中微量有机酸和无机阴离子的方法,比较了进样乙二醇浓度对F-及有机酸测定结果的影响,进样乙二醇质量分数低于8.5%时,能够得到较准确的数据.用本法对所测的有机酸和无机阴离子检出限均在8.9 μg/L以下,线性相关系数r在0.996～0.999范围内,标准样中各物质的离子峰面积的相对标准偏差(RSD)在4.2%以下(n＝11),对乙二醇质量分数约为8.5%的样品中F-及有机酸的加标回收率在91.6%～100.0%之间,乙二醇含水料直接测定无机阴离子的加标回收率在91.8%～104.8%之间.     

固相萃取-高效液相色谱法测定蜂蜜中的有机酸

建立了固相萃取-高效液相色谱(SPE-HPLC)同时测定蜂蜜中5种有机酸(L-苹果酸、马来酸、琥珀酸、柠檬酸、D-苹果酸)含量的方法。蜂蜜经制样后过Bond Elutes SAX固相萃取(SPE)小柱净化,用C18-MS-II反相色谱柱(250 mm×4.6 mm, 5 μm)进行分离,流动相为2%偏磷酸溶液,流速为0.7 mL/min,检测波长为210 nm。在此条件下5种有机酸在相应的线性范围内其线性相关系数均大于0.9967;方法的回收率为86.0%～103.9%,相对标准偏差为5.7%～9.8%(n=6),检出限为0.06～9.4 mg/kg。所建立的方法可用于蜂蜜样品中有机酸的测定。     

高效液相色谱法测定1,3-丙二醇发酵液中的有机酸

采用高效液相色谱法在Kromasil C18色谱柱(5 μm,250 mm×4.6 mm i.d.)上测定了1,3-丙二醇发酵液中的有机酸,流动相为0.2%(V/V)磷酸和乙腈混合溶液(体积比为96.53.5),发酵液经氯仿处理后直接分离定量,8 min内可将发酵液中的甲酸、乳酸、乙酸、琥珀酸、柠檬酸及延胡索酸完全分离定量.流动相流速为1.0 mL/min,紫外检测波长为214 nm,柱温为20℃.方法的回收率为97.7%～100.5%;RSD为0.98%～2.35%.实验结果表明,该法是测定发酵液中有机酸的快速、有效的定量分析方法.     

离子色谱法分析磷脂纯化工艺回收乙醇中的乳酸、甲酸和乙酸

建立了同时分析磷脂纯化工艺回收乙醇中乳酸、甲酸和乙酸的离子交换色谱法。采用阴离子交换柱,以4 mmol/L NaHCO3溶液作流动相,样品中的有机酸(乳酸、甲酸和乙酸)在13 min内达到基线分离。采用抑制型电导检测,有机酸的检出限在0.03～0.04 mg/L之间。加标回收率在87.5%～102.4%之间。方法可用于磷脂纯化工艺监控和产品质量监测。     

Capillary electrochromatographic enantioseparations using a packed capillary with a 3 microm OD-type chiral packing

A technique for separating methyl esters of monounsaturated fatty acids by argentation chromatography using silver nitrate-impregnated TLC plates is described. Monounsaturated fatty acid methyl esters are separated from polyunsaturated and saturated fatty acid methyl esters and the monounsaturated fatty methyl esters are resolved according to chain length. cis isomers are well resolved from the corresponding trans isomers. R(F) values for individual monounsaturated fatty acids are very reproducible. The potential of the technique in metabolic studies is demonstrated in the chain elongation of [14C]-18:1(n-9) and delta-9 desaturation of [14C]-18:0 by human skin fibroblasts. Recoveries of individual [14C]-fatty acids for scintillation counting exceed 94%.     

Acids and their functionally substituted esters fromAmaranthus cruentus seed oil

The acid composition of seed oil ofAmaranthus cruentus and the synthesis of their glycidyl and pyridinecontaining esters are studied. It is demonstrated that 67% of the total acids are C₁₈-polyunsaturated linoleic and linolenic. A new method for preparing glycidyl esters of C₁₈-unsaturated carboxylic acids is developed by reacting their salts with ECG in an aprotic medium to produce the corresponding glycidyl esters. The reaction of the glycidyl esters and pyridine salts with carboxylic and phosphonic acids produces the propanolpyridine esters of the acids that combine the properties of the acids and pyridinium salts and are promising in the search for biologically active compounds.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 217–219, May–June, 2000.     

银离子固相萃取-气相色谱法检测乳脂肪中的反式脂肪酸

建立了分离反式油酸(C18:1)、亚油酸(C18:2)、亚麻酸(C18:3)的银离子固相萃取-气相色谱(Ag+-SPE/GC)方法,并应用于乳脂肪中反式脂肪酸的检测。采用自制的银离子固相萃取柱对样品进行预分离,总脂肪酸甲酯化后上样,依次经9 mL甲苯-正己烷(体积比5:95)、8 mL甲苯-正己烷(体积比17:83)、6 mL甲苯-乙酸乙酯(体积比17:83)、10 mL甲苯-乙酸乙酯(体积比30:70)洗脱并分别收集洗脱液,采用气相色谱分别进行检测。结果显示,除了反式亚麻酸的回收率为69.9%～101.0%、相对标准偏差(RSD)为11.0%～18.1%外,其余的反式脂肪酸的回收率均为88.4%～107.2%、RSD为1.2%～11.9%。该方法通过特异性固相萃取的方法对样品进行前处理,较好地避免了样品中顺式及饱和脂肪酸对反式脂肪酸检测的干扰。     

糖基修饰的氨基酸类化合物的合成

通过对5种氨基酸酯化和氨基保护得到苄氧羰基氨基酸甲酯, 经肼解制备苄氧羰基氨基酸酰肼, 然后分别与3种不同的糖基异硫氰酸酯反应, 制备了相应的目标化合物15个, 且产率均在60%以上. 所有新化合物均经元素分析, IR, MS和¹H NMR确证. 同时探索了苄氧羰基氨基酸甲酯肼解的最佳反应条件.     

气相色谱/质谱法分析孔石莼中的脂肪酸

建立了孔石莼脂肪酸的气相色谱/质谱(GC/MS)测定方法。使用Folch法提取了孔石莼中的总脂,经过2 mol/L HCl-甲醇溶液的甲酯化处理后,采用GC/MS法对其脂肪酸组成进行了分离分析,同时结合有机质谱学规律,分别对饱和脂肪酸甲酯、单不饱和脂肪酸甲酯和多不饱和脂肪酸甲酯的裂解规律和质谱特征进行了分析归纳。通过质谱数据库检索和标准品对照,鉴定出孔石莼中的24种脂肪酸,其中9,12,15-十八碳三烯酸、4,7,10,13-十六碳四烯酸和6,9,2,15-十八碳四烯酸3种主要多不饱和脂肪酸占总脂肪酸含量的45.14%。通过对孔石莼中脂肪酸的分析,表明特征离子在脂肪酸甲酯尤其是多不饱和脂肪酸甲酯的定性方面具有很好的应用价值。     

羟肟酸法快速测定食用油主要营养必需脂肪酸

建立了用ＨＰＬＣ简便快速测定食用油主要营养必需脂肪酸的羟肟酸法。样品一步衍生成羟肟酸上机分析,不需分离纯化。线性范围为０．０５～０．６０ｇ／Ｌ,回收率９６．９３％,ＲＳＤ＝１．８０％（ｎ＝４）,日内和日间ＲＳＤ分别为１．２４％和１．６２％（ｎ＝６）。比较１８∶３,１８∶２和１８∶１的甲酯与相应的三脂肪酸甘油酯标准品衍生的标准曲线,发现二者转化率均相差近一倍,回收率实验和样品实测结果亦证实,选取甲酯标准品衍生作标准曲线用于油脂定量是不合理的。     

Gas-liquid chromatographic determination of fatty acid composition of cholesteryl esters in human serum using silica Sep-Pak cartridges

A simple and fast analytical procedure for separation and purification of cholesteryl esters of human serum is described. A single lipid extract, together with spiked cholesteryl pentadecanoate, as an internal standard, was passed through a Silica Sep-Pak cartridge. 1.5% diethyl ester in light petroleum was used to elute cholesteryl esters from the column. The separation was verified with thin-layer chromatography on silica gel using light petroleum-diethyl ether-glacial acetic acid (80:20:1) as a solvent. A very clean thin-layer chromatogram of cholesteryl esters without any additional spots of other lipids was obtained. The cholesteryl esters were quantitated by analyzing their fatty acid composition as methyl esters by gas-liquid chromatography. The coefficients of variation were 0.8--4.9% for the major fatty acids (C16:0, C16:1, C18:1, C18:2, C20:4) and 6.7--30.8% for the minor fatty acids (C18:0 and C20:0). The recoveries for cholesteryl palmitate, cholesteryl oleate and cholesteryl linoleate were 90.7, 92.3 and 91.0%, respectively.     

Quantitative Determination of Isostearic Acid Isomers in Skin Creams by GC-MS-SIM

“Isostearic acid” is frequently listed as an ingredient of skin creams and other cosmetics. In the four skin creams analyzed, “isostearic acid” was esterified with isopropanol, as well as sorbitan or polyglycerols. “Isopropyl isostearate” was isolated by HCl treatment and saponification whereas emulsifiers (sorbitan or polyglycerol isostearates) were enriched by means of a C₁₈-cartridge. Fatty acids in the resulting lipid fraction were transferred into methyl esters. 25:0 and 19:0 methyl esters were used as internal standards. GC-EI-MS was used to determine that “isostearic acid” was a mixture of many methyl-branched isomers of stearic acid (18:0) in all four skin creams. Thus, it may be better termed “isostearic acids”. The branched-chain nature of isostearates was verified by formation and analysis of picolinyl esters of skin cream fatty acids by GC-EI-MS. Twenty-five 18:0 isomers were detected and the main products had one methyl branch on carbons C₁₀–C₁₄. Two late eluting isostearic acid isomers were identified as 16-methyl heptadecanoic acid (i18:0) and 15-methyl heptadecanoic acid (a18:0). GC-EI-MS in the selected ion monitoring (SIM) mode with m/z 87 as quantification ion was used for the determination of i18:0 methyl ester. The quantities of i18:0 in the samples amounted to 10–20 mg g^?1 skin cream. The contribution of i18:0 to the sum of all 18:0 isomers in the four skin cream samples was 8.5 ± 1.1%. Instead of determining all individual isostearates in a product, we suggest the quantitative determination of i18:0 followed by multiplication with factor 11.75 (~reciprocal value of 8.5%, see above) as a simple method for the quantification of isostearates in cosmetics.     

R(-)四氢噻唑-2-硫酮-4-羧酸对D,L-氨基酸酯拆分的研究

以新手性拆分试剂R(-)四氢噻唑-2-硫酮-4-羧酸[简称R(-)TTCA]对D,L-氨基酸酯进行手性拆分,分别得到(R)TTCA氨基酸酯盐1a_1f([α]_D²⁰＝-30.40°～-42.70°)及光学活性氨基酸酯2a-2f,其光学纯度为35.4%～75.8%.由1a_1f在碱存在下分解出2a-2f的对映体3a-3f,光学纯度为39.50%～69.10%.用半经验的量子化学PM3方法研究了氨基的碱性、中间产物铵盐生成热和稳定性.     

Analysis of amino acids as formamidene butyl esters by electrospray ionization tandem mass spectrometry.

Amino acid formamidene butyl esters are optimally prepared by heating amino acids with dimethylformamide dimethylacetal (DMF-DMA) for 2 minutes at 65 degrees C and then with n-butanol/hydrogen chloride for 15 minutes at 65 degrees C. The formamidene butyl esters of simple alpha-amino acids and beta-amino acids afford between 1.1 and 20 times the signal intensity of the corresponding butyl esters during electrospray ionization tandem mass spectral analysis. Complex alpha-amino acids, such as ornithine, arginine and citrulline, and gamma-amino acids are better analyzed as butyl esters. Secondary alpha-amino acids, such as proline and sarcosine, give a mixture of two iminium salts with the DMF-DMA derivatization method. A derivative incorporating two molecules of the amino acid predominates at higher derivatization temperatures. Contrary to a previous report, N-formylamino acids were not detected. The presence of secondary amino acids in amino acid mixtures, derivatized as formamidene butyl esters, affords derivatives that incorporate two different amino acids. The new formamidene butylation method is unlikely to replace the butylation procedure used by neonatal blood spot screening programs for amino acid disorders, since a much poorer response was obtained with formamidene butyl esters of arginine and citrulline, important in the diagnosis of arginase deficiency and citrullinaemia.