Hao C, Croley T R, March R E, Koenig B G, Metcalfe C D
Water Quality Centre, Trent University, Peterborough, ON, Canada.
J Mass Spectrom. 2000 Jul;35(7):818-30. doi: 10.1002/1096-9888(200007)35:7<818::AID-JMS6>3.0.CO;2-P.
A mass spectrometric study was carried out on two nonylphenoxycarboxylic acids, NP1EC and NP2EC (where 1 and 2 indicate the number of ethoxylate units attached to the nonylphenoxy moiety), that are persistent metabolites of widely used nonionic surfactant nonylphenol ethoxylates. In a gas chromatographic/mass spectrometric (GC/MS) study of the methyl esters of NP1EC and NP2EC, two series of fragment ions were observed in electron ionization (EI) mass spectra; m/z (179 + 14n, n = 0-7) and m/z (105 + 14n, n = 0-4) for NP1ECMe and m/z (223 + 14n, n = 0-7) and m/z (107 + 14n, n = 0-5) for NP2ECMe. Similarity indices were used to compare quantitatively the mass spectra of isomers. The mass spectra of two isomers were found to be similar whereas those of the remaining isomers were readily distinguishable from each other. The abundant fragment ions of the two NPECMes were investigated further by GC/MS/MS; product ions resulting from cleavage in the alkyl moiety, cleavage in the ECMe moiety and cleavage in both moieties were detected. Possible structures of the nonyl groups in the two esters were inferred. GC/chemical ionization (CI) mass spectra of the NPECMes with isobutane as reagent gas showed characteristic hydride ion-abstracted fragment ions shifted by 1 Da from those in the corresponding EI mass spectra. The sensitivity of a selected ion monitoring quantitation method for the NPECMes is enhanced under CI conditions compared with that under EI conditions. With electrospray ionization MS/MS, M - H ions of NP1EC (m/z 277) and NP2EC (m/z 321) were observed and, upon collision-induced dissociation of M - H of each of the two acids, fragment ions of m/z 219 corresponding to deprotonated nonylphenol, were observed in each case. Based on this observation, a rapid, simple and reliable selected product ion quantitation method is proposed for NP1EC and NP2EC.
对两种壬基苯氧基羧酸NP1EC和NP2EC（其中1和2表示连接在壬基苯氧基部分的乙氧基单元数）进行了质谱研究，它们是广泛使用的非离子表面活性剂壬基酚乙氧基化物的持久性代谢产物。在对NP1EC和NP2EC甲酯的气相色谱/质谱（GC/MS）研究中，在电子电离（EI）质谱中观察到两个系列的碎片离子；NP1ECMe的m/z（179 + 14n，n = 0 - 7）和m/z（105 + 14n，n = 0 - 4），以及NP2ECMe的m/z（223 + 14n，n = 0 - 7）和m/z（107 + 14n，n = 0 - 5）。相似性指数用于定量比较异构体的质谱。发现两种异构体的质谱相似，而其余异构体的质谱则很容易相互区分。通过GC/MS/MS进一步研究了两种NPECMes的丰富碎片离子；检测到了在烷基部分裂解、在ECMe部分裂解以及在两个部分都裂解产生的产物离子。推断了两种酯中壬基的可能结构。以异丁烷作为反应气的NPECMes的GC/化学电离（CI）质谱显示，特征性的氢化物离子提取碎片离子比相应EI质谱中的碎片离子偏移了1 Da。与EI条件相比，CI条件下NPECMes的选择离子监测定量方法的灵敏度有所提高。在电喷雾电离MS/MS中，观察到了NP1EC（m/z 277）和NP2EC（m/z 321）的M - H离子，并且在对这两种酸各自的M - H进行碰撞诱导解离时，每种情况下都观察到了对应于去质子化壬基酚的m/z 219的碎片离子。基于这一观察结果，提出了一种针对NP1EC和NP2EC的快速、简单且可靠的选择产物离子定量方法。
