Steady state and time-resolved fluorimetry of benzo(a)pyrene in liposomes and microsomes

Comparisons of the steady-state fluorescence signals of benzo(a)pyrene (BP) in liposomes and in microsomes indicate that BP molecules involved in the formation of excimers emitting around 520 nm may be the primary species being oxidized during the first 30 min of metabolism. Moreover, these excimers seem to be kinetically differentiable from BP molecules in other locations in the membrane. Since excimers can be formed only when BP molecules are close together, this implies that the metabolizing BP molecules are more likely on the membrane surface than in the midplane region.     

Fast-atom bombardment mass spectrometry of conjugated benzo(a)pyrene metabolites

Fast-atom bombardment mass spectrometry has been used to obtain spectra of conjugated benzo(a)pyrene (bap) metabolites using a 1:1, glycerol + thioglycerol matrix, bap Glucuronides give positive- and negative-ion spectra with peaks due to [M + H]+ and [M - H]- ions and a major fragment peak (base peak) at [bap-OH]+ and [bap-O]-. bap Sulfates (sodium salts) give similar negative-ion spectra with [M - Na]- and [bap-O]- peaks, but the positive-ion spectra are dominated by sodium and glycerol adducts of the bap sulfates.     

超声辅助分散液液微萃取-高效液相色谱法测定环境空气中的苯并(a)芘

建立了超声辅助分散液液微萃取样品前处理技术,结合高效液相色谱测定环境空气中苯并(a)芘的方法。样品用丙酮:水(1∶4,v/v)混合溶液提取,用氯苯萃取,超声,离心后沉积相进行HPLC测定。对分散液液微萃取的因素进行了优化,在最优条件下,苯并(a)芘的富集倍数达到400倍,检出限为0.4μg·L-1,线性范围为2~200μg·L-1,线性相关系数为0.9998,平均加标回收率为98.2%~99.2%,相对标准偏差为1.6%~2.3%。本方法具有简单便捷、准确灵敏、萃取率高、有机溶剂消耗少等特点,可满足环境空气中苯并(a)芘的快速测定。     

Contribution to the fluorometric method of analysis for atmospheric benzo(a)pyrene

Summary The potentiality of the method for the determination of benzo(a)pyrene (BaP) in airborne particulates, based on the fluorescence measurements in H₂SO₄, was investigated. Stability of the BaP fluorescence in H₂SO₄, isolation of the BaP fraction by thin-layer chromatography and the effect of quenchers on the fluorescence intensity of BaP were studied and the results are discussed. The relative standard deviation of the method was determined to be 2.9 and 5.9% for BaP levels of 265 and 68 ng, respectively.

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Beitrag zur fluorimetrischen Analyse von Benzo(a)pyren in der Atmosphäre

Zusammenfassung Die Möglichkeiten der Benzo(a)pyrenbestimmung durch Fluorescenzmessung in schwefelsaurer Lösung wurden untersucht. Die Stabilität der Fluorescenz, die Isolierung der Benzo(a)pyrenfraktion durch Dünnschicht-Chromatographie sowie der Einfluß fluorescenzlöschender Substanzen wurden geprüft und die Ergebnisse diskutiert. Die relative Standardabweichung des Verfahrens beträgt 2,9 und 5,9% für Benzo(a)pyrenmengen von 265 bzw. 68 ng.

     

超高效液相色谱-大气压化学电离-三重四极杆质谱联用法快速测定食品中苯并[a]芘

建立了快速检测食品中苯并[a]芘的超高效液相色谱-三重四极杆质谱联用(UPLC-MS/MS)分析方法。样品用正己烷提取后,经分子印迹固相萃取柱净化,以甲醇和水作为流动相进行梯度洗脱,在XBridge BEH C18柱上实现分离,大气压化学电离(APCI)-三重四极杆质谱正离子MRM方式检测,以苯并[a]芘-d12作为内标的稳定同位素稀释法定量。方法的线性范围为0.07~50μg/kg,定量限为0.07μg/kg。平均加标回收率为86%~104%,相对标准偏差为2.3%~14%。该方法灵敏、准确,适用于食品中苯并[a]芘的测定,已应用于实际样品的检查。     

13C-NMR. Studies on ion-selective liquid membranes (author's transl)]

¹³C-NMR. Studies on Ion-Selective Liquid Membranes. A method for the ¹³C-NMR. study of solvent polymeric membranes in equilibrium with aqueous salt solutions is described. Neutral ion carriers incorporated in these membranes maintain a high degree of rotational mobility. The complexation by group IA and IIA cations of macrotetrolide antibiotics as well as of carriers of the type 3,6-dioxa-octanedioic diamides in the membrane phase was followed by ¹³C-NMR. chemical shift and spin-lattice relaxation studies.     

Synthesis of nonactin (author's transl)]

Synthesis of Nonactin. The macrotetrolide antibiotic nonactin (I), containing four units of a C₁₀ hydroxy acid, has been synthesized starting from two adequately protected derivatives (III and IV) of nonactic acid (II). The 32-membered ring of the macrotetrolide is built up by a sequence of condensation and deprotection steps leading first to a product with two, and subsequently to one with four nonactic acid residues (VIII) which is then cyclized in the presence of Ag⁺-ions. Two reactions forming ester bonds have been developed to condense the hydroxy acids and to effect the final cyclization. In one the activation of the carboxyl group is achieved by conversion into the mixed anhydride with 2,4,6-trimethylbenzene sulfonyl chloride in pyridine. In the other the Ag⁺-ion induced reaction of a S-(2-pyridyl) hydroxy carbothioate is used to form the corresponding macrocyclic lactone. In the case of nonactin the ring closure is promoted by the coordinating effect of Ag⁺-ions present in the reaction mixture.     

High-pressure liquid chromatography of free and conjugated 17-ketosteroids (author's transl)]

High-pressure liquid chromatography (HPLC) should be used more frequently in biomedical research because heavy molecules can be analysed at ambient temperature without derivatisation to volatile compounds. In this paper the separation of four free 17-ketosteroids, their ester sulfates and glucuronides by reversed-phase HPLC on a Micropak CH column is described. In order to improve the separation several parameters have been studied. Retention data allow comparison of the hydrophilic behaviour of free and conjugated steroids.     

Identification and quantitation of impurities from benorilate (Salipran) by high-performance liquid chromatography (author's transl)]

High-performance liquid chromatography is used for identification and quantitation of impurities which may be encountered in a new antalgic, benorilate (or Salipran), an ester of aspirin with paracetamol. Gradient elution is carried out using a stationary phase consisting of porous 10-micron silica beads bonded to alkylnitrile (Micropak CN), and a mixture of hexane-methylenechloride-methanol-acetic acid with varying methanol percentage as mobile phase. The following impurities were separated from benorilate: acetylsalicylic anhydride, aspirin, acetylsalicylsalicylic acid, salophene, amino-4-phenylacetoxy-2-benzoate, paracetamol, p-aminophenol. The repeatability of the quantitative analysis is good with a standard variation of 0.54% for benorilate (7 injections). Detection is by UV absorption at 254 nm, and detectability is between 2-10(-9) moles for p-aminophenol and 4-10(-11) moles for salophene.     

Evaluation of the reproducibility in radioactivity measurements with liquid scintillation counters--effect of anomalous count rate-dependent photomultiplier gain variations (author's transl)

Time variations in count rate were measured for prolonged period of time using a set of 3H samples and a few other specially prepared samples of 14C, 32P, and 137Cs. Besides, beta-ray spectra of a particular 3H sample were measured as a function of time with a multichannel pulse height analyzer. These measurements lead to the following conclusions: (1) Anomalous count rate variations are attributed to strong dependence of photomultiplier gain on count rate. (2) Different steady state count rates can be observed for 3H samples having activities of approximately 10(5) dps when they are measured immediately after the measurements of background and 3H samples of higher activities. (3) The count rate-dependent effect on photomultiplier gain can be described properly by the current flowing through the tube rather than the count rate. (4) The measurement of the external standard channel ratio using the built-in 137Cs source can affect seriously the successive measurements on 3H samples, while the channels ratio itself exhibits strong time dependence.