同位素稀释-气相色谱/高分辨质谱法测定食品中的指示性毒杀芬指示性毒杀芬

目的 建立食品样品中P26, P50, P62等三大指示性毒杀芬的检测分析方法,为进一步开展常规监测提供技术平台和基础数据。方法 食品样品使用索式提取系统(Soxtec)提取, 提取液依次由30%酸性硅胶柱和氧化铝柱净化, 利用同位素稀释-高分辨气相色谱/高分辨双聚焦磁式质谱联用(ID-HRGC/HRMS)技术对三种指示性毒杀芬单体P26, P50, P62进行定量定性分析。结果 本研究所建成的检测方法相对标准偏差(RSD)小于25%, 回收率可以达到40%~120%; P26, P50, P62的方法检测限分别为0.08、0.02、0.06 pg/g; 方法性能达到开展食品样品中毒杀芬检测技术的要求。结论 该方法可以对食品样品中毒杀芬进行检测, 检测效率高, 结果准确可靠。     

Determination of epoxidized soy bean oil (ESBO) in oily foods by GC–FID or GC–MS analysis of the methyl diepoxy linoleate

A simplified method is presented for determining epoxidized soy bean oil (ESBO) in food or food simulants, such as olive oil. ESBO is transesterified with methoxide/methanol directly in the homogenated food, i.e. without prior extraction, and analyzed on a cyanopropyl or phenyl polysiloxane stationary phase without formation of dioxolanes. For most foods, flame ionization detection (FID) was appropriate, but for samples with interfering components, GC–MS was needed. Chemical ionization (CI) with ammonia is more sensitive and more selective than electron impact ionization (EI). In CI, positive and negative ion monitoring (PCI and NCI) are similar in sensitivity, but different in selectivity, i.e. the combination of the two is well suited for confirmation. Results are shown to be in agreement with on-line LC–GC–FID.     

Comparison of an individual congener standard and a technical mixture for the quantification of toxaphene in environmental matrices by HRGC/ECNI-HRMS

Both a technical standard and a recently commercially available standard containing 25 congeners were used to quantify toxaphene in a variety of environmental matrices, using high-resolution gas chromatography/electron capture negative ion high-resolution mass spectrometry (HRGC/ ECNI-HRMS). The purpose was to examine the differences between the two standards and to assess how well the congener standard describes the total toxaphene profile. At a resolving power of approximately 11,000 no interferences from other organochlorines were observed. Biotic matrices were enriched in octa- and nonachlorobornanes relative to the technical mixture, whereas abiotic matrices were enriched in hexa- and heptachlorobornanes. The hexa- and heptachlorobornanes were generally overestimated by the weighted response of the technical mixture, whereas the nonachlorobornanes were consistently underestimated. The extent to which the technical mixture over- or underestimates total toxaphene concentrations depends on the distribution of congeners among homologue groups and the abundance of particular congeners. The current 25-congener mixture described only approximately 35-75% of the total toxaphene response: more congeners are needed to adequately describe some matrices. Correction factors were developed that will allow laboratories to report reliable concentrations of individual congeners in samples that were quantified using the technical mixture, but they should be applied with caution, as they may be highly instrument dependent.     

Levels and temporal trends of toxaphene congeners in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary, Canada

Environmentally relevant toxaphene congeners were determined in blubber samples of stranded beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary (SLE), Canada. The purpose of this study was to evaluate the levels and the temporal trends (1988-1999) of a suite of six chlorobornanes (P26, P40/41, P44, P50, and P62) in the SLE belugas. P26 and P50 mean concentrations were in the same range as those reported for animals living in the Arctic environment suggesting that the atmospheric transport represents the main input of toxaphene to the SLE. A general exponential decline of chlorobornane concentrations in belugas was observed, except for P26 and P50 in males. On average, concentrations decreased by a factor of two in 8.5 years during the 1988-1999 time period. This rate of decline is similar to the reduction of toxaphene emission from agricultural soils in the southern United States reported over the same time period. Some differences in decline rates were observed among the studied CHB congeners. For instance, P62 decreased more rapidly than P26 and P50 in both male and female belugas. Several hypotheses were advanced to explain these differences such as selective metabolism of specific chlorobornanes by SLE belugas or their prey. However, a most likely explanation is the selective degradation of the technical product in soils and atmosphere in the source region.     

Toxicokinetic model assessment on the dechlorination of dietary toxaphene CHB-62 into CHB-44 in Atlantic salmon (Salmo salar L.)

European Union legislation on the upper limits of toxaphene in feed and food include the congeners CHB-26, CHB-62 and CHB-50 and is set at 50 µg kg^?1 feed for the sum of these three congeners. However, due to their elevated presence in fish, the congeners CHB-40 and CHB-41, CHB-44, and CHB-42 should also be included according to the European Food Safety Authority (EFSA) in 2005. Earlier trials with model zebra fish have shown in vivo dechlorination of dietary CHB-62 to CHB-44 and, to a lesser degree, of CHB-50 to CHB-40. Biomagnification patterns of Atlantic salmon, fed with technical toxaphene-enriched feeds, indicated that Atlantic salmon have a similar dechlorination. In the present study, a serial one-compartment physiological kinetic model, which includes differentiated growth of body components, is used to quantify the contribution of dechlorination to the congener-specific fillet accumulation of a mixture of dietary toxaphene congeners in Atlantic salmon. The model is assessed from experimental uptake and elimination kinetics of Atlantic salmon smolt fed with technical toxaphene for 122 days followed by a depuration period of 75 days in which the fish were fed toxaphene-free control feed. The serial one-compartment model shows that about 31% of CHB-44 that accumulated in the fillet originated from dietary CHB-62. In contrast, dechlorination of CHB-50 into CHB-40 is not significant. The results show that previously demonstrated in vivo dechlorination of CHB-62 into CHB-44 in zebra fish also occurs in the farmed fish species Atlantic salmon. This dechlorination can at least partly explain the relatively elevated CHB-44 observed in toxaphene fish surveys.     

气相色谱-质谱法测定生姜中丙炔氟草胺残留量

本文建立了生姜中丙炔氟草胺残留量的分析方法。试样经乙腈提取,活性炭柱净化,目标农药采用气相色谱-质谱/选择离子监测法(GC-MS/SIM)进行定性、定量分析,方法检出限为0.006mg/kg,在0.02、0.04、0.05、0.1、0.2mg/kg添加水平回收率为62%～105%,相对标准偏差(RSD)5.2%～18%。     

Recent declines in PAH, PCB, and toxaphene levels in the northern Great Lakes as determined from high resolution sediment cores

Sediment cores were collected from two sites in Grand Traverse Bay, Lake Michigan in May 1998, dated using 210Pb geochronology, and analyzed for polychlorinated biphenyl (PCB) congeners, polycyclic aromatic hydrocarbons (PAHs), and toxaphene. The extraordinarily high sediment focusing and accumulation rates in these cores relative to other Great Lakes sediments allowed quantification of high-resolution temporal trends in the burial of hydrophobic organic contaminants. The focus-corrected accumulation rate of total PCBs (sum of 105 congeners) in 1998 was 0.50 ng/cm2-year at both sites. Toxaphene and total PAH (t-PAH; sum of 33 compounds) surficial accumulations varied at each site and ranged from 0.08 to 0.41 ng/cm2-year for toxaphene and 25 to 52 ng/cm2-yr for t-PAHs at the two sites. The maximum t-PAH accumulation rate was in sediment dated from 1942, and PAH accumulation decreased from 1942 to 1980 with a first-order rate of decline 0.017 yr(-1). Both toxaphene and t-PCB accumulations peaked in sediment deposited in 1972, afterwhich their accumulations decreased with nearly identical rates of decline (0.027 yr(-1) and 0.028 yr(-1), respectively).     

GC/MS CONFIRMATION OF ETHYLENE DIBROMIDE RESIDUE IN FOODS

Electron impact (EI) and negative ion chemical ionization (NICI) selected-ion-monitoring (SIM) GC/MS techniques are described for the confirmation of ethylene dibromide (EDB) residues in various food products.     

Structure of the toxaphene compound 2,5-endo,6-exo,8,9,9,10,10-octachlorobornene-2: a temperature-dependent formation of two rotamers

The irradiation of 2,2,3-exo,5-endo,6-exo,8,9,9,10,10-decachlorobornane in n-hexane at 254 nm leads to a spontaneous Cl2 elimination as the major reaction pathway. This results finally in the main product 2,5-endo,6-exo,8,9,9,10,10-octachlorobornene-2, of which the structure could be elucidated with the help of X-ray, 1H and 13C NMR, IR, and MS. Temperature-dependent 1H NMR spectroscopic investigations have shown that the -CHCl2 groups located at C1 and C7 are able to rotate slowly under normal circumstances. If such measurements, however, are exerted at low temperatures (-10 to -60 degrees C), so can be seen that two rotamers are formed due to the hindrance of the free rotation about the bonds C1-C10, C7-C8, and C7-C9, which for the first time could be revealed for a toxaphene compound. Furthermore, as all 1H NMR chlorobornane spectra known so far show only sharp and clear signals, it can be assumed that chlorobornane compounds as main toxaphene components have fixed bonds, which requires to indicate chlorine atoms within the tentacles such as "a", "b", and "c" for characterizing the correct position. Those fixed tentacles are probably the reason that many toxaphene congeners remain very stable in environmental compartments, and particularly the biotic and abiotic transformation may strongly be hindered by the inflexibility of the tentacles.     

A Comparative Study of the Ionization Modes in GC–MS Multi-residue Method for the Determination of Organochlorine Pesticides and Polychlorinated Biphenyls in Crayfish

A gas chromatography–mass spectrometry (GC–MS) multi-residue method with different ionization modes has been developed for the determination of 23 organochlorine pesticides and ten polychlorinated biphenyls (PCBs) in crayfish. The approach was based on an extraction with acetonitrile saturated by hexane (containing 0.1 % acetic acid), followed by a dispersed solid-phase extraction cleanup with primary secondary amine and octadecylsilane, and finally analyzed by GC–MS/MS operated in electron impact (EI) and positive chemical ionization (PCI), and GC–MS in negative chemical ionization (NCI), respectively. An isotope internal standard, DDT-D₈, was used for quantification. These three GC–MS procedures were validated and compared using crayfish samples fortified at three levels (5, 10 and 20 ng/g). Good linearity, accuracy, precision and sensitivity were achieved by all three ionization modes with recoveries in the range of 70 to 112 %, relative standard deviations (RSDs) below 10 % and limits of detection (LODs) in the range of 0.002 to 8 ng/g. Extremely high selectivity was obtained by both EI- and PCI-MS/MS, while PCI was more sensitive to compounds containing nitro and carbonyl groups, and EI was a better choice for dieldrin, endosulfan, and its metabolites. NCI-MS had the highest sensitivity but lower anti-interference ability and was not suitable for the determination of DDTs and PCBs. These three ionization modes can be used as complementary and alternative in routine GC–MS analysis of organochlorine pesticides and polychlorinated biphenyls in food.     

Analytical methods for the determination of polychlorinated dibenzodioxins and dibenzofurans in human milk

A method is described for the determination of polychlorinated dibenzodioxins and dibenzofurans in breast milk. After addition of potassium oxalate, the compounds are extracted, along with fat and other lipophilic compounds, using ethanol, ethyl ether and pentane. An aliquot of the fat is fortified with seven 13C-labelled dioxins and furans. Gel permeation chromatography on Bio-Beads S-X3 is used for removal of fat followed by column chromatography on florisil, charcoal and acid alumina. Except for 2,3,7,8-tetrachlorodibenzodioxin (2,3,7,8-TCDD), all other congeners are determined by combined capillary gas chromatography/mass spectrometry by use of negative chemical ionization employing methane as reagent gas. MS analysis is performed in the SIM mode (selected ion monitoring). For each isomer group two ions are monitored. Octachloronaphthalene is used as a syringe spike for the quantification based on a calibration run of standards. The calibration mixture, which contains the spike as well as all 2,3,7,8-chlorine substituted dioxins and furans and the 13C-labelled surrogates at a concentration level of 3-5 pg/microliters, is injected twice every day. For the determination of 2,3,7,8-TCDD a mass selective detector is used operating in electron impact mode. The MS analysis is also performed in SIM mode monitoring two ions for TCDDs and one ion for 13C-2,3,7,8-TCDD. Dependent on the level of each congener in breast milk, the coefficient of variation of the method varies between 3% for 2,3,4,7,8-pentachlorodibenzofuran and 40.9% for octachlorodibenzofuran. More than 200 human milk samples, mostly from nursing mothers living in North Rhine-Westphalia, have been analysed for residues of polychlorinated dibenzodioxins and polychlorodibenzofurans.(ABSTRACT TRUNCATED AT 250 WORDS)     

Toxaphene deposition to Lake Ontario via precipitation, 1994-1998

Precipitation samples collected continuously at Point Petre on Lake Ontario from November 1994 through December 1998 were analyzed for total toxaphene (=sum of hexa-, hepta-, octa-, and nonachloro bornanes) and chlorobornane congeners (1997-98 only). Composite triplicate samples were collected during 4-week intervals throughoutthe 4-year study using heated wet-only samplers. These results represent the first detailed data for toxaphene in Great Lakes precipitation. Seasonal volume-weighted mean concentrations for total toxaphene in precipitation ranged from 0.25 to 1.5 ng/L. Highest concentrations were found during the four spring (March-May) periods at roughly twice the annual means. The pattern for hexathrough nona-homologues over the 4 years did not vary appreciably with average ratios (relative to hepta-) of 0.08: 1.0:1.3:0.2. The volume-weighted mean concentrations for individual chlorobornane congeners were consistent in their season pattern with maximums seen in the spring. The major chlorobornane in precipitation, B8-2229 (Parlar 44), which was present at concentrations ranging from 0.016 to 0.079 ng/L, constituted 28 and 29% of the congener sum for 1997 and 1998, respectively. Lakewide loadings of toxaphene for Lake Ontario via precipitation were estimated to be 12, 17, 12, and 13 kg/year for 1995-1998, respectively. Previous toxaphene loading estimates were calculated for the individual Great Lakes on the basis of the only concentration data available, a single precipitation estimate of 0.2 ng/L from early work in northwestern Ontario. The loading estimates in this study indicate that precipitation inputs of toxaphene are 3-4 times higher than previously reported for Lake Ontario. The 1998 estimates of Lake Ontario wet deposition flux are 50% of the estimated gas deposition flux. However, wet flux values from this study exceed the net gas-phase mass transfer of toxaphene across the air-water interface.     

An historical record of toxaphene and its congeners in a remote lake in western Europe

Historical trends in the concentrations of toxaphene, its component homologue groups, and individual chlorobornane congeners were determined in a dated sediment core from a mountain lake, Lochnagar, in Scotland, U.K., representing the first such profiles outside of North America. The profile of total toxaphene showed a bimodal distribution with maxima in the mid-1970s and early 1990s unlike the unimodal PCB profile (maximum 1973) in the same core. The earlier toxaphene peak shows agreement with the U.S. source curve and therefore may correspond to modeled global patterns while the later peak may be dueto long-rangetransportfrom eastern and southern Europe or from still lower latitudes. Sediment toxaphene concentrations (14 ng/g dry wt (dw) at surface; 40 ng/g dw at maximum) and accumulation rates (surface 0.42 ng cm(-2) yr(-1); maximum 1.6 ng cm(-2) yr(-1)) were considerably higher than levels in untreated sites in the Great Lakes region and the Canadian Arctic and are equivalent to those reported for the Great Lakes themselves where there have been additional riverine inputs. Two toxaphene congeners, B6-923 and B7-1001, accounted for most of the hexa- and heptachlorobornanes, respectively. B6-923 and B7-1001 abundance ratios (relative to the sum of 12 chlorobornane congeners) had doubling times of 17 +/- 3 and 12 +/- 3 yr, respectively. Given the remoteness of the site from areas of toxaphene production and usage, the high sediment levels raise concerns over toxaphene levels in areas of Europe closer to sources, especially where sites are fished for human consumption. Further European data are needed for comparison.     

实时直接分析-四极杆飞行时间质谱法快速分析青果槟榔和烟果槟榔代谢物差异

目的 基于实时直接分析-四极杆飞行时间质谱(direct analysis in real time -quadrupole time-of-flight mass spectrometry, DART-QTOF-MS)技术结合非靶向代谢组学,快速实现青果槟榔与烟果槟榔代谢物差异分析。方法 通过单因素实验,考察影响DART离子源电离效率的关键因素;结合Q-TOF MS以TOF MS和信息依赖采集模式分别在正离子和负离子模式下获得质谱数据,采用多元统计学软件建立有监督和无监督的判别模型并筛选差异化合物。采用MarkerView 1.3.1、PeakView软件及在线数据库对差异化合物进行初步鉴定。结果 在正负两种扫描模式下,DART离子源的最佳工作条件为：离子化温度500℃,样品传输速度0.2 mm/s。在此条件下发现两种食用槟榔化学成分存在差异,获得了25种差异化合物;烟果槟榔中有20种化合物的相对含量高于青果槟榔,有5种化合物的相对含量低于青果槟榔。结论 该研究从代谢组学角度初步揭示了青果槟榔与烟果槟榔代谢物的差异性,可为食用槟榔的加工工艺研究及品质提升提供参考依据。同时,本研究采用实时直接分析质谱技术,具有操作方便、分析速度快、准确度高和稳定性好的优点。     

UHPLC‐ESI‐MS/MS for the Quantification of Eight Major Gingerols and Shogaols in Ginger Products: Effects of Ionization Polarity and Mobile Phase Modifier on the Sensitivity

We developed and validated an improved ultra high performance liquid chromatography (UHPLC)‐electrospray ionization (ESI)‐tandem mass spectrometry (MS/MS) method for the fast separation and quantification of 8 major gingerols and shogaols (4‐, 6‐, 8‐, 10‐, and 12‐gingerols, and 6‐, 8‐, and 10‐shogaols) in gingerol products. The ionization polarity and mobile phase modifier greatly affected the mass ion profiles and sensitivity of the analytes. A mobile phase modifier of 0.05 mM ammonium formate dramatically decreased the sodium adduct ions and greatly increased the protonated ions of the gingerols and shogaols. Positive ion UHPLC‐MS/MS with the ammonium formate in mobile phase showed greatly higher (4.5‐ to 15.7‐fold) sensitivities than negative ion UHPLC. The positive ion UHPLC‐MS/MS method showed excellent linearities (r² > 0.999), low limits of detection (LOD = 2.5 to 8.2 pg), high accuracy and precision, and no considerable matrix effect. Baseline separation of the 8 target compounds was achieved in 1 min by the UHPLC with a short C18 core‐shell column. The method was successfully applied to analyze the compounds in fresh and dried powdered gingers, and dietary supplements. The total contents of the major compounds in the fresh gingers, dried powdered gingers, and dietary supplements were in the range of 1114 to 1478, 4380 to 11324, and 2915 to 29998 mg/kg, respectively. There was about 10‐fold variation of the content in the dietary supplements with the commercial brands. This represents the 1st report on the ionization polarity and mobile phase modifier on the sensitivity of gingerols and shogaols in LC‐mass spectrometry. Furthermore, the established method provided great improvement in chromatographic separation of the target gingerols.     

Screening method for the determination of 199 pesticides in agricultural products by gas chromatography/ion trap mass spectrometry (GC/MS/MS)

A screening method is described for determining 200 pesticides, except dimethipin, divided into four groups by means of gas chromatography/tandem mass spectrometry (GC/MS/MS) using an ion trap mass spectrometer equipped with automated gain control (AGC). The quantitation limit for 194 pesticides was 0.01 mg/kg on a crop basis, except for allidochlor, dimethoate, hexythiazox, methamidophos and triadimenol. The calibration curve of each pesticide was linear in the range of 0.04-5.0 microg/mL. One hundred and ninety-nine pesticides were added to matrix of potato, spinach, cabbage, apple, orange, soybean and unpolished rice at twice the limits of quantitation. The recoveries of 194 pesticides from all crops were satisfactory (50-150%) for screening purposes. Although some pesticides in apple and orange were not determined by selected ion monitoring (SIM) analysis at the limits of quantitation, all of them were identified by ion-trap GC/MS/MS at the same concentration. Thus, the ion trap GC/MS/MS technique is useful for the screening of residual pesticides present at low levels in agricultural products.     

Analysenverfahren zur Bestimmung von polychlorierten Dibenzodioxinen und Dibenzofuranen in Frauenmilch

Zusammenfassung Es wird eine Methode zur Bestimmung von polychlorierten Dibenzodioxinen (PCDD) und Dibenzofuranen (PCDF) in Frauenmilch beschrieben. Die PCDD und PCDF werden mit dem Fett und anderen lipophilen Verbindungen nach Zusatz von Kaliumoxalat mit Ethanol, Diethylether und Pentan extrahiert. Einem aliquoten Fettanteil werden sieben¹³C-markierte Dioxine und Furane zugesetzt. Nach gelchromatographischer Abtrennung des Fettes an Bio-Beads S-X3 erfolgt eine weitere Reinigung des Extraktes an einer Florisil-, Aktivkohle- und an einer Aluminiumoxidsäule. Mit Ausnahme von 2,3,7,8-TCDD werden alle anderen Verbindungen durch kombinierte Capillargaschromatographie/Massenspektrometrie mit Hilfe der negativen chemischen Ionisation (NCI) und Methan als Reaktantgas bestimmt. Für die Registrierung wird die SIM-Technik (selected ion monitoring) eingesetzt, wobei für jede Isomerengruppe zwei Fragmente gemessen werden. Zur Kompensation der Volumenungenauigkeit beim Injizieren wird Octachlornaphthalin (OCN) zugesetzt. Über diese Substanz erfolgt auch die quantitative Auswertung nach der für gaschromatographische Analysen üblichen Peakflächenmethode. Für die Ermittlung der Korrekturfaktoren wird eine Standardlösung, die OCN, alle 2,3,7,8-chlorsubstituierten PCDD und PCDF sowie die¹³C-markierten Verbindungen enthält, zweimal täglich eingespritzt. Die Bestimmung von 2,3,7,8-TCDD erfolgt mit Hilfe der Elektronenstoßionisation (EI) an einem massenselektiven Detektor, ebenfalls unter Verwendung der SIM-Technik. In Abhängigkeit von der Konzentration des jeweiligen Analyten in der Frauenmilch beträgt der Variationskoeffizient der Methode zwischen 3% für 2,3,4,7,8-Pentachlordibenzofuran und 40,9% für Octachlordibenzofuran. Insgesamt wurden bisher über 200 Frauenmilchproben, hauptsächlich von stillenden Müttern aus Nordrhein-Westfalen, isomerenspezifisch auf Rückstände von polychlorierten Dibenzodioxinen und Dibenzofuranen untersucht. Die dabei erhaltenen Ergebnisse werden ebenfalls mitgeteilt.

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Procedure for the determination of polychlorinated dibenzodioxins and dibenzofurans in breast milk

Summary A method is described for the determination of polychlorinated dibenzodioxins and dibenzofurans in breast milk. After addition of potassium oxalate, the compounds are extracted, along with fat and other lipophilic compounds, using ethanol, ethyl ether and pentane. An aliquot of the fat is fortified with seven¹³C-labelled dioxins and furans. Gel permeation chromatography on Bio-Beads S-X3 is used for removal of fat followed by column chromatography on florisil, charcoal and acid alumina. Except for 2,3,7,8-tetrachlorodibenzodioxin (2,3,7,8-TCDD), all other congeners are determined by combined capillary gas chromatography/mass spectrometry by use of negative chemical ionization employing methane as reagent gas. MS analysis is performed in the SIM mode (selected ion monitoring). For each isomer group two ions are monitored. Octachloronaphthalene is used as a syringe spike for the quantification based on a calibration run of standards. The calibration mixture, which contains the spike as well as all 2,3,7,8-chlorine substituted dioxins and furans and the¹³C-labelled surrogates at a concentration level of 3–5 pg/l, is injected twice every day. For the determination of 2,3,7,8-TCDD a mass selective detector is used operating in electron impact mode. The MS analysis is also performed in SIM mode monitoring two ions for TCDDs and one ion for¹³C-2,3,7,8-TCDD. Dependent on the level of each congener in breast milk, the coefficient of variation of the method varies between 3% for 2,3,4,7,8-pentachlorodibenzofuran and 40.9% for octachlorodibenzofuran. More than 200 human milk samples, mostly from nursing mothers living in North Rhine-Westphalia, have been analysed for residues of polychlorinated dibenzodioxins and polychlorodibenzofurans. The results of this investigation are also reported.

     

液相色谱-质谱联用测定蛋粉中胆固醇含量

建立了液相色谱-大气压化学电离-同位素稀释质谱法测定蛋粉中的胆固醇含量的方法。本方法采用选择离子模式检测,用括弧法对蛋粉胆固醇进行定量计算。通过胆固醇一级标准物质保证测量过程的溯源性,通过采用添加胆固醇同位素标记物作为内标减少了样品前处理过程和液相色谱-质谱测定时物质响应所产生的误差,提高了测量结果的准确性。本方法具有较高的测量准确度和精密度,可作为复杂基体胆固醇测定的高准确度测定方法。     

Persistent organic pollutants in two dolphin species with focus on toxaphene and polybrominated diphenyl ethers

Assessing trends of persistent organic pollutants (POPs) in marine mammals is difficult due to age, gender, and metabolism influences on accumulation. To help elucidate these effects in dolphins, POP concentrations were determined in the Atlantic white-sided dolphin, Lagenorhynchus acutus, a pelagic delphinid inhabiting North Atlantic waters, and in the rough-toothed dolphin, Steno bredanensis, a pelagic delphinid inhabiting tropical and subtropical waters. The specific objectives of this study were to determine baseline POP concentrations in L. acutus and S. bredanensis blubber samples and to examine the effects of age, gender, and metabolism on POP concentrations in dolphin blubber. Focus was aimed at contaminants of emerging concern, specifically, toxaphene and polybrominated diphenyl ethers (PBDEs). Samples collected from L. acutus (n = 47) stranding events in Massachusetts (1993--2000) and S. bredanensis samples (n = 15) were analyzed for PCBs, toxaphene, and other organic pesticides by gas chromatography/mass spectrometry (GC/MS). Age and gender influences were similar between the two species, with adult females having significantly lower POP concentrations as compared to adult males and juveniles. Mean sigma toxaphene concentrations were highest in juvenile L. acutus, 13.0 (6.7) microg/g wet mass (1 SD), and lowest in adult female S. bredanensis, 1.49 (1.4) microg/g wet mass. sigma PBDE (sum of congeners 47, 99, 100, 153, and 154) concentrations were highest in juvenile L. acutus, 2.41 (1.2) microg/g wet mass, and lowest in adult female S. bredanensis, 0.51 (0.6) microg/g wet mass. POP concentrations did not significantly differ between adult males and juveniles, suggesting metabolism of congeners and/or dilution with growth. PBDE concentrations in juvenile white-sided dolphins were not significantly related to collection year, suggesting that there may be a lag period for higher concentrations to be detected in pelagic marine mammals such as L. acutus or that concentrations have already peaked in this species prior to the first collection in 1993.     

Study on detection of drugs in slimming health foods using GC-MS/MS

The determination of five drugs, fenfluramine (FEN), N-nitrosofenfluramine (NFE), sibutramine (SIB), mazindol (MAZ) and phenolphthalein (PHP), was studied in slimming health foods using GC-MS/MS. These drugs have been detected at high rates, especially in slimming health foods. Prolonged or excessive consumption of non-approved or unauthorized pharmaceuticals may cause serious adverse health consequences. In this study, samples were extracted with methanol and ultrasonication. Analyses were performed by GC-MS/MS, using established MS/MS parameters in the electron ionization (EI) mode and chemical ionization (CI) mode. In the EI mode, the recoveries of five drugs from several types of slimming health foods such as tablets, capsules and tea-bags spiked at 1 μg/mg (except PHP, spiked at 4 μg/mg) were in the range of 85.0-110.7% and 100 μg/mg (except PHP, spiked at 200 μg/mg) were 94.9-102.9%, respectively. In the CI mode, good recoveries of 80.3-102.2% (spiked at low concentration) and 92.8-103.2% (spiked at high concentration) were also obtained. We evaluated the present method using four slimming health foods, in which drugs had previously been detected. The results were similar to the previous results. These findings indicate that the present procedure for evaluating five drugs in slimming health foods by means of GC-MS/MS is useful.