Silver ion high-performance liquid chromatography of the triacylglycerols ofCrepis alpina seed oil

The triacylglycerols ofCrepis alpina oil were characterized because this oil has a high concentration of crepenynic (cis-9-octadecen-12-ynoic) acid, a fatty acid useful in the chemical synthesis of deuterated fats for human metabolism studies. The triacylglycerols were separated from the crude oil by solid-phase extraction. Resolution, quantitation and isolation of the individual triacylglycerols were performed by silver ion high-performance liquid chromatography on a commercial column, an acetonitrile in hexane isocratic mobile phase and flame-ionization detection. Isolated triacylglycerols were identified by capillary gas chromatography of their fatty acid methyl esters. Of the eleven eluted triacylglycerols ofCrepis alpina oil, 85% included 35% tricrepenynoyl, 34% linoleoyldicrepenynoyl and 16% dilinoleoylcrepenynoyl glycerols. Triacylglycerols eluted according to the numbers of alkene and alkyne bonds. Elution times, resolution and quantitation were reproducible over a three-month period. The flame-ionization detector response required no response factors for quantitation of the triacylglycerols present inCrepis alpina oil. The silver ion chromatography system permitted the identification of 95% of the triacylglycerols compared to 70% of the triacylglycerols previously identified with reversed-phase high-performance liquid chromatography.     

The triacylglycerol structure of olive oil determined by silver ion high-performance liquid chromatography in combination with stereospecific analysis

The compositions of positionssn-1,sn-2 andsn-3 of triacylglycerols from “extra-virgin” olive oil (Olea europaea) were determined. The procedure involved preparation of diacyl-rac-glycerols by partial hydrolysis with ethyl magnesium bromide; 1,3-, 1,2- and 2,3-diacyl-sn-glycerols as (S)-(+)-1-(1-naphthyl)ethyl urethanes were isolated by highperformance liquid chromatography (HPLC) on silica, and their fatty acid compositions were determined. The same procedure was also carried out on the five main triacylglycerol fractions of olive oil after separation according to the degree of unsaturation by HPLC in the silver ion mode. Although stereospecific analysis of the intact triacyl-sn-glycerols indicated that the compositions of positionssn-1 andsn-3 were similar, the analyses of the molecular species demonstrated marked asymmetry. The data indicate that the “1-random, 2-random, 3-random” distribution theory is not always applicable to vegetable oils.     

The structure of the triacylglycerols of meadowfoam oil

The triacylglycerols of meadowfoam oil have been resolved by HPLC in the silver ion and reversed-phase modes, and by the two techniques used in a complementary fashion. The fractions obtained were collected and quantified by gas chromatography of their methyl esters in the presence of an internal standard. Silver ion chromatography gave a distinctive resolution in which fractions differing solely in the position and chain-length of a single monoenoic fatty acyl group were resolved, the order of elution being 11−20∶1, 5−20∶1, 13−22∶1, 5−18∶1 and 9−18∶1. Reversed-phase chromatography also gave fractions containing single positional isomers, (11−20∶1<5−20∶1<13−22∶1<5−22∶1), but the pattern was more difficult to discern since fractions containing 22∶2 tended to overlap with those containing 20∶1. The species (5−20∶1)(5−20∶1)(22∶2), (5−20∶1)(5−20∶1)(5−20∶1) and (5−20∶1)(5−20∶1)(13−20∶1) were found to be the most abundant, and together comprised 67% of the total. A small but significant trilinolein fraction was detected and its presence may have biosynthetic implications.     

Determination of molecular species of oil triacylglycerols by reversed-phase and chiral-phase high-performance liquid chromatography

A method is described for the determination of molecular species of oil triacylglycerols. The method is based on the analytical separation of the enantiomericsn-1,2-andsn-2,3-diacylglycerols, derived from triacylglycerols, by high-performance liquid-chromatography (HPLC) on a chiral column containing N-(R)-1-(α-naphthyl)ethylaminocarbonyl-(S)-valinecarbonyl-(S)-valine as stationary phase. Model triacyl-glycerol molecules comprising three known fatty acids were isolated from peanut oil and cottonseed oil by a combination of argentation-TLC and reversed-phase HPLC and submitted to partial chemical deacylation. The derivedsn-1,2(2,3)-diacylglycerols were analyzed and fractionated as 3,5-dinitrophenyl urethane derivatives by reversed-phase HPLC according to chainlength and unsaturation. From thesn-1,2(2,3)-diacylglycerol composition and the diacylglycerolsn-1,2-andsn-2,3-enantiomer composition, the individual molecular species of four peanut oil triacylglycerols and one cottonseed oil triacylglycerol were identified and quantitated. The method can be applied to triacylglycerols of any other oil or fat.     

Soybean oil triacylglycerol analysis by reversed-phase high-performance liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry

Soybean oil triacylglycerols from genetically modified soybean lines were conclusively identified by reversed-phase high-performance liquid chromatography coupled with mass spectrometry with atmospheric pressure chemical ionization. Atmospheric pressure chemical ionization is a soft ionization technique which gives simple spectra for triacylglycerols. Spectral identification of the triacylglycerols was based on the molecular [M+1]⁺ ion and the 1(2)-, 2(3)- and 1(3)-diacylglycerol fragments. Triacylglycerols identified in high-stearic and high-palmitic soybean varieties were quantitated by reversed-phase high-performance liquid chromatography with flame-ionization detection. There was excellent agreement between the fatty acid composition calculated from the triacylglycerol composition and the fatty acid composition obtained by gas chromatography of the transmethylated oils. The oils of the modified soybean varieties, compared to typical soybean oil, contained increased content of triacylglycerols known to be more oxidatively stable, such as linoleoyloleoylstearoyl, linoleoylpalmitoylstearoyl, and linoleoyldipalmitoyl glycerols, and less triacylglycerols like trilinoleoylglycerol, known to decrease oxidative stability. This study showed that the atmospheric pressure chemical ionization technique is suitable for mass spectral identification of neutral molecules, such as triacylglycerols, which do not contain a chargeable functional group.     

反相高效液相色谱法测定化妆品中羟基喹啉

采用反相高效液相色谱法测定化妆品中羟基喹啉的含量.色谱条件为:Kromasil C18色谱柱(250 mm×4.6 mm i.d.,5μm),流动相为V(甲醇):V(0.01 mol/L癸烷磺酸钠溶液(磷酸调pH=2.25))=62:38的混合溶液,流速1.0 mL/min,检测波长240 nm,柱温25℃,进样量20μL.结果表明,该方法的检出限为2.254 μg/g,线性范围为1.0～100.0μg/mL,回收率为95.5％～100.1％,RSD为0.07％～2.18％.     

反相高效液相色谱法测定化妆品中的几种防晒剂

采用反相高效液相色谱法测定化妆品中的10种防晒剂,用色谱柱为Waters Symmetry shield C18柱(250mm ×4.6 mm i.d,5 μm),V(甲醇):V(水)=85:15为流动相,检测波长310 nm,回收率为98.1%～101.0%,相对标准偏差小于5%.     

Analysis of triacylglyceride hydroperoxides in vegetable oils by nonaqueous reversed-phase high-performance liquid chromatography with ultraviolet detection

Triacylglyceride hydroperoxides (HPO-TAG), the primary autoxidation products of triacylglycerides (TAG), have been analyzed in polyunsaturated vegetable oils by means of nonaqueous reversed-phase high-performance liquid chromatography (HPLC) with ultraviolet detection. Using a retention time model based on equivalent carbon numbers, mono- and bishydroperoxy TAG and hydroxy TAG could be identified. The correlation between the peroxide value (POV) determined by iodometric titration and quantitative HPLC results for HPO-TAG was established for sunflower oil samples with POV between 0.5 and 50 meq/kg. The recovery of HPO-TAG in the HPLC procedure was found to be close to 100% in the POV range of 4 to 71 meq/kg. Absolute quantitative results for HPO-TAG in sunflower oil samples could not be obtained accurately, as molar extinction coefficients of HPO-TAG occurring in natural oils deviate from those of available HPO-TAG reference compounds.     

Nuclear magnetic resonance spectroscopy and reversed-phase high-performance liquid chromatography of peracetylated digalactosyldiacylglycerols

A simple method for the peracetylation of digalactosyldiacylglycerols is described. The peracetylated compounds were isolated by thin-layer chromatography and subjected to nuclear magnetic resonance spectroscopy for structure elucidation. The proton signals at acetylated sites are shifted downfield compared to the nonderivatized compounds, resulting in improved resolution. The peracetylated compounds were also subjected to molecular species analysis by reversed-phase high-performance liquid chromatography. The chromatography behavior of the peracetylated compounds was similar to that of triacylglycerols, displaying narrow and symmetrical peaks yielding a highly resolved molecular species profile.     

The regiospecific position of 18∶1 cis and trans monoenoic fatty acids in milk fat triacylglycerols

TAG of butterfat were fractionated according to the type and degree of unsaturation into six fractions by silver-ion HPLC. The fractions containing TAG with either cis-or trans-monoenoic FA were collected and fractionated further by reversed-phase HPLC to obtain fractions containing cis TAG of ACN:DB (acyl carbon number:double bonds) 48∶1, 50∶1, and 52∶1 as well as trans 48∶1, 50∶1, and 52∶1. The FA compositions of these fractions were elucidated by GC. The MW distribution of each fraction was determined by ammonia negative-ion CI-MS. Each of the [M-H]⁻ parent ions was fractionated further by collision-induced dissociation with argon, which gave information on the location of cis-and trans-FA between the primary and secondary positions of TAG. The results suggest that the sn-positions of the monoenoic cis-and trans-FA depend on the two other FA present in the molecule. With 14∶0 FA in the TAG molecule, the 18∶1 FA in the sn-2 position are mostly present as cis-isomers. When there is no 14∶0 in the TAG molecule, the trans-18∶1 isomers seem to be more common in the sn-2 position. Also when other long-chain FA are present, the trans-isomers are more likely to be located in the secondary (sn-2) position.     

反相高效液相色谱法测定化妆品中防腐剂

采用反相高效液相色谱法测定化妆品中山梨酸、苯甲酸、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯和对羟基苯甲酸丁酯等6种防腐剂,用ZorbaxODS(5μm,4 6mmi d ×150mm)柱,V(磷酸二氢钾)∶V(乙腈)为90∶10作流动相,加入磷酸调pH值为2 0,检测波长为254nm。样品用乙醇-水-冰乙酸(体积比为70∶29 5∶0 5)提取,回收率为90 8%～105 7%,相对标准偏差为3 1%～8 5%。     

Triacylglycerols of winter butterfat containing configurational isomers of monoenoic fatty acyl residues. I. Disaturated monoenoic triacylglycerols

The triacylglycerols of winter butterfat were fractionated according to the type and degree of unsaturation into six fractions by silver ion high-performance liquid chromatography (Ag-HPLC). The acyl carbon number distribution of the triacylglycerols in each fraction was elucidated by reversed-phase HPLC and mass spectrometry (MS). The MS analysis of each fraction gave deprotonated triacylglycerol [M - H]⁻ ions which were produced by chemical ionization with ammonia. The daughter spectrum of each of the [M - H]⁻ ions provided information on its fatty acid constituents. Successful fractionation of triacylglycerols differing in the configuration of one fatty acyl residue by Ag-HPLC was important because geometrical isomers could not be distinguished by the MS system used. In addition to the fatty acid compositions, reversed-phase HPLC analysis demonstrated the purity of the collected fractions: molecules having acis-trans difference were separated nearly to the baseline. Triacylglycerols differing in the configuration of one fatty acyl residue were not equally distributed in relation to their acyl carbon numbers. This indicates that during the biosynthesis of triacylglycerols,cis- andtrans-fatty acids are processed differently. Although the fatty acid compositions of the corresponding molecular weight species of disaturatedtrans- and disaturatedcis-monoenoic triacylglycerols were similar, there may be differences in the amounts of different fatty acid combinations or in the distribution of fatty acids between the primary and secondary glycerol positions. In addition to the main components, it was possible to analyze minor triacylglycerols, such as molecules containing one odd-chain fatty acid, by the MS system used.     

Triacylglycerols of winter butterfat containing configurational isomers of monoenoic fatty acyl residues. II. Saturated dimonoenoic triacylglycerols

Triacylglycerols of Finnish winter butterfat containing one saturated and two monoenoic fatty acyl residues were studied. With silver ion high-performance liquid chromatography (HPLC), molecules were separated according to the difference in the configuration of one fatty acyl moiety. The distribution of the saturatedcis,trans-dimonoenoic and saturatedcis,cis-dimonoenoic triacylglycerols according to their acyl carbon numbers was compared by means of reversed-phase HPLC and tandem mass spectrometry. Furthermore, two examples of the fatty acid composition of a specified molecular weight species were shown. The fatty acid compositions of corresponding saturatedcis,trans-dimonoenoic and saturatedcis,cis-dimonoenoic triacylglycerols were similar; however, there may be differences in the proportions of different fatty acid combinations or in the distribution of fatty acids between primary and secondary glycerol positions.     

反相高效液相色谱法测定化妆品中巯基乙酸

采用反相高效液相色谱法测定化妆品中巯基乙酸的含量。色谱条件为:Kromasil C18(250 mm×4.6 mm,5μm)色谱柱,流动相为V(乙腈)∶V(0.01 mol/L KH2PO4溶液(磷酸调pH=2.5))=10∶90的混合溶液,流速1.0 mL/min,检测波长215 nm,柱温30℃,进样量20μL。结果表明,此条件下巯基乙酸在5.0～150.0μg/mL质量浓度范围内与峰面积线性良好,线性回归方程为Y=5 100X-13 400(r=0.999 8),平均回收率在98.4%～100.8%,RSD为0.09%～0.84%。     

Detection of olive oil adulteration with canola oil from triacylglycerol analysis by reversed-phase high-performance liquid chromatography

The objective of this study was to explore the use of reversed-phase high-performance liquid chromatography (RP-HPLC) as a means to detect adulteration of olive oil with less expensive canola oil. Previously this method has been shown to be useful in the detection of some other added seed oils; however, the detection of adulteration with canola oil might be more difficult due to similarities in fatty acid composition between canola oil and olive oil. Various mixtures of canola oil with olive oils were prepared, and RP-HPLC profiles were obtained. Adulteration of olive oil samples with less than 7.5% (w/w) canola oil could not be detected.     

Analysis of sn-1(3)- and sn-2-short-chain acyl isomers of triacylglycerols in butteroil by gas-liquid chromatography

The aim of the study was to determine major triacylglycerols (TG), and sn-1(3) and sn-2 isomers of butyryl and caproyl TG in butteroil (BO) and interesterified butteroil (IBO) by gas-liquid chromatography (GLC) and silver ion column chromatography. Altogether, 112 molecular species of TG were synthesized by interesterification and their retention indices were determined. Molar empirical correction factors for TG were determined using linear calibration. Retention indices showed that sn-1(3) and sn-2 isomers of the TG containing one short-chain acyl (butyrate, caproate) and two long-chain acyls (lauroate, myristate, palmitate, stearate, and oleate) were separated on a phenyl (65%) methylsilicone column. The difference between retention indices of 1(3)- and 2-short-chain acyl isomers ranged from 14 to 19, and from 9 to 16 for butyrates and caproates, respectively. The proportion of sn-2 isomers of butyrates averaged 1.4%, but only traces of sn-2 isomers of caproates were detected in butteroil. The ratio of sn-1(3)- to sn-2-butyrates and caproates in interesterified butteroil averaged 2.0:1. The most abundant molecular species of mono-short-chain TG in butteroil were BPP + BMS (5.6 mol%), BPO + BSPo (4.8 mol%), BMP + BLaS (3.4 mol%), BMO + BPPo (2.7 mol%), BPS (2.5 mol%), and CoPP + CoMS (2.3 mol%).     

Distribution of Δ5-olefinic acids in the triacylglycerols fromPinus koraiensis andPinus pinaster seed oils

Purified triacylglycerols (TAG) fromPinus koraiensis andP. pinaster seed oils, which are interesting and commercially available sources of Δ5-olefinic acids (i.e.,cis-5,cis-9,cis-12 18:3 andcis-5,cis-11,cis-14 20:3 acids) were fractionated by reversed-phase high-performance liquid chromatography, and each fraction was examined by capillary gas-liquid chromatography for its fatty acid composition. A structure could be assigned to more than 92% of TAG from both oils. In both instances, ca. 48% of the TAG were shown to contain at least one δ5-olefinic acid. In the great majority of TAG, our data showed that there is only one molecule of δ5-olefinic acid per molecule of TAG. This is compatible with theoretical calculations based on the proportion of total δ5-olefinic in the oils. Thecis-5,cis-9,cis-12 18:3 acid (14.2 and 8.6% of total fatty acids in the seed oils ofP. koraiensis andP. pinaster, respectively) and thecis-5,cis-11,cis-14 20:3 acid (1.1 and 8.1% of total fatty acids in the seed oils ofP. koraiensis andP. pinaster, respectively) are preferentially associated with two molecules of linoleic acid, and to a lesser extent, to one molecule of linoleic acid and one molecule of oleic acid, or two oleic acid molecules. However, several other combinations occur, each in low amounts. The distribution of δ5-olefinic acids in TAG is evidently not random. Combining these results with the known preferential esterification of δ5-olefinic acids to the 1,3-positions of TAG would suggest that most of these acids are present at only one of these positions at a time.     

Quantitative determination of diesel oil in contaminated edible oils using high-performance liquid chromatography

A simple and reliable high-performance liquid chromatography method for the analysis of diesel oil in contaminated edible oils is described. Analysis performed using a diol column with a mobile phase of heptane and isopropanol (94∶6, vol/vol). Although baseline separation between diesel and other background fluorescent components was not achieved, quantitation was still possible using baseline integration. The method is linear over the range of 5–1000 μg/g with a correlation coefficient (r ²) of 0.9984. Average recoveries from spiked edible oils were 94.4–101.3%, with a limit of quantitation (LOQ) of 5 μg/g for sunflower oil, palm olein, and groundnut oil. Corn oil has a higher content of ester components, thus, LOQ was slightly worse (40 μg/g). The applicability of the method was confirmed by gas chromatography-mass spectroscopic detection to show the presence of diesel hydrocarbons in the suspected contaminated crude palm oil. This procedure provides a simple and sensitive method for determining diesel oil concentration in contaminated edible oils without prior sample cleanup or extraction.     

Gas chromatography of triacylglycerols in palm oil fractions with medium-polarity wide-bore columns

Wide-bore (WBOT, 0.53 mm i.d.) capillary columns, operated with helium carrier gas, are a viable alternative to narrow-bore (0.25 mm i.d.) equivalents operated with hydrogen carrier gas in high-resolution gas chromatography (HRGC) of triacylglycerols (TAG). Resolution and quantitation proved to be similar for the two types of columns. WBOT HRGC with automatic cold-on-column injection has strong potential for precise real-time control of oils and fats processing and offers a reliable approach to automated HRGC of TAG. The technique has been used to characterize palm oil and palm oil fractions.     

化妆品中抗坏血酸磷酸镁的色谱分析

建立了化妆品中抗坏血酸磷酸镁(Vc—PMG)的反相高效液相色谱法(RP—HPIC)。以四氢呋喃-磷酸盐缓冲液(30：70,体积比)溶解并稀释样品,采用乙腈-0．3mol／L磷酸盐缓冲溶液(pH4)(35：65,体积比)为流动相,选择检测波长255nm,Vc—PMG在氨丙基柱上获得了良好分离。该方法的检出限为0．4mg／L,回收率为96．97％～102．78％,相对标准偏差为1．28％。