Measurements of Linear Alkylbenzenes by GC/MS with Interference from Tetrapropylene-Based Alkylbenzenes:  Calculation of Quantitation Errors Using a Two-Component Model

Abstract

Linear alkylbenzenes (LABs) and tetrapropylenebased alkylbenzenes (TABs) are often used as molecular tracers of domestic waste inputs. Due to the overlapping usage of LABs and TABs in the past, these compounds have been found to co-exist in environmental samples. They elute closely under normal gas chromatographic conditions and contain similar mass spectral ion fragments, which makes it difficult to separate contributions from LABs and TABs even by the gas chromatography/mass spectrometry (GC/ MS) method. This paper presents a two-component model that deals with the quantitation error (E) in measurements of LABs (or TABs) because of the interference from TABs (or LABs). By taking advantage of the GC/MS chromatographic characteristics of LABs and TABs, a simple equation derived from the model can calculate E with the knowledge of relative abundances of m/z 91 and m/z 119 in samples, LAB standards, and TAB standards. The model was applied to a sediment core collected from Santa Monica Bay near the Hyperion 7-mi sludge outfall. This model is also applicable to other similar twocomponent systems, as long as they satisfy the assumptions made under the present study.

Validity of using linear alkylbenzenes as markers of sewage contamination with interference from tetrapropylene‐based alkylbenzenes

“…The detection limit for individual LAB compounds was estimated to be 200 ng for 1 g of dry sample. Linear alkylbenzene concentrations were determined on the basis of the response factors of individual components in an LAB mixture that was quantified previously; detailed procedures are described elsewhere [6]. The surrogate standard recoveries were 90 ± 38% in 15 samples.…”

“…The quantitation error ( E ) for measurements of individual LAB components is defined by Substituting Equation 1 into Equation 2 yields with β = A/A′. As described previously [6], β can be acquired directly from the GC‐MS measurements and X from analyses of a pure LAB mixture.…”

“…An average X value was obtained for each of the LAB components in four measurements of the LAB mixture; the overall relative SD (RSD) was 6.2%. X ′ values were obtained from analyses of a TAB mixture, but instead of assuming an identical value for all TABs [6], we estimated X ′ for individual TAB contributions. Procedurally, four measurements of the TAB mixture were performed, and the abundances of m/z 91 and 119 were summed around the retention times of LAB compounds, which were obtained in separate runs.…”

“…In a previous article [6] we presented a two‐component model that can be used to estimate quantitation errors that occur when measuring LABs in the presence of TABs using gas chromatography–mass spectrometry (GC–MS). Our approach was based on the difference in the relative abundances of two major ion fragments of individual LAB and TAB compounds.…”

Alquilbenzeno sulfonato linear: uma abordagem ambiental e analítica

“…A alumina nem sempre retém todos os interferentes, tais como os alquilbenzenos não lineares que são os precursores dos tensoativos ABSs e podem co-eluir na separação cromatográfica com o LAB. A discriminação de ambos precursores dos tensoativos pode ser possível através da análise dos seus espectros de massas, pois os fragmentos mais intensos dos LABs são 91, 105 e 133 (m/z) e dos ABSs são 91 e 119 (m/z) 95 .…”