Onzo Alberto, Acquavia Maria A, Cataldi Tommaso R I, Ligonzo Mattia, Coviello Donatella, Pascale Raffaella, Martelli Giuseppe, Bondoni Marcella, Scrano Laura, Bianco Giuliana
Dipartimento di Scienze, Università degli Studi della Basilicata, Via dell'Ateneo Lucano 10, Potenza, 85100, Italy.
ALMAGISI s.r.l, Corso Italia, 27, Bolzano, 39100, Italy.
Rapid Commun Mass Spectrom. 2020 Oct 30;34(20):e8884. doi: 10.1002/rcm.8884.
The anionic surfactants, among which are alkyl ether sulfates (AESs), are the most used class of surfactants in cleansing applications. The negatively charged head group of AESs is a sulfate moiety linked with a variable number of ethylene oxide units, i.e. a polyethylene glycol chain. The hydrophobic part of an AES is constituted by a linear alkyl chain of carbon atoms, generally obtained from natural fatty acids. Coconut oil fatty acids, including the sodium salts of coceth sulfate (CES) with chemical formula C H (OCH CH ) OSO Na, are widely used as feedstock for AESs synthesis. CES is added to many cleaning products and detergents defined as non-aggressive. Currently, no detailed structural information concerning the alkyl chain length x and, more importantly, the degree of ethoxylation n has been reported.
A commercial standard solution of CES was characterized by tandem mass spectrometry, employing direct injection into the electrospray ionization (ESI) source of a a linear quadrupole ion trap mass spectrometer.
Two series of oligomeric species, characterized by a C12 and C14 alkyl chains, i.e. [C H (OCH CH )nOSO ] and [C H (OCH CH ) OSO ] with n ranging from 0 to 7, were successfully identified. The interpretation of these data was very useful for CES identification in three commercial dishwasher cleaning products.
Direct injection MS/MS analysis of CES revealed a well-defined molecular weight distribution and allowed the alkyl chain composition and the number of ethylene oxide units to be to identified.
阴离子表面活性剂，其中包括烷基醚硫酸盐（AESs），是清洁应用中使用最广泛的一类表面活性剂。AESs带负电荷的头部基团是与可变数量的环氧乙烷单元相连的硫酸根部分，即聚乙二醇链。AES的疏水部分由碳原子的直链烷基构成，通常由天然脂肪酸制得。椰子油脂肪酸，包括化学式为C₁₂H₂₅(OCH₂CH₂)ₙOSO₃Na的椰油醇硫酸酯钠（CES），被广泛用作AESs合成的原料。CES被添加到许多被定义为无刺激性的清洁产品和洗涤剂中。目前，尚未有关于烷基链长度x以及更重要的乙氧基化程度n的详细结构信息的报道。
采用直接进样到线性四极杆离子阱质谱仪的电喷雾电离（ESI）源中，通过串联质谱对商业标准CES溶液进行表征。
成功鉴定出两个系列的低聚物种，其特征在于具有C12和C14烷基链，即[C₁₂H₂₅(OCH₂CH₂)ₙOSO₃]⁻和[C₁₄H₂₉(OCH₂CH₂)ₙOSO₃]⁻，其中n范围为0至7。这些数据的解释对于三种商用洗碗机清洁产品中的CES鉴定非常有用。
CES的直接进样MS/MS分析揭示了明确的分子量分布，并能够确定烷基链组成和环氧乙烷单元的数量。
