Comparison of multiple API techniques for the simultaneous detection of microconstituents in water by on‐line SPE‐LC‐MS/MS

Abstract

This study described a fully automated method using on-line solid phase extraction of large volume injections coupled with high performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS) to simultaneously detect a group of recalcitrant microconstituents (pharmaceuticals and personal care products, steroid hormones and sterols) in aqueous matrices. Samples (1 mL to 20 mL) were loaded to the preconcentration column at 1 mL/min, and the column was washed with 1000 μL of 25% methanol in LC/MS water to remove polar and ionic interferences before LC-MS/MS analysis. Three different atmospheric pressure ionization (API) techniques, including photoionization (APPI) with four different dopants (acetone, anisole, chlorobenzene and toluene), heated electrospray ionization (HESI) and atmospheric pressure chemical ionization (APCI), were evaluated on the basis of method detection limits (MDLs) and recoveries from different aqueous matrixes. Results indicated that APPI with toluene as dopant was the most sensitive ionization method for the majority of the analytes. When using 5 mL of sample, MDLs for pharmaceuticals and personal care products, including carbamazepine, DEET, caffeine, naproxen, acetaminophen and primidone, were between 0.3 ng/L and 15 ng/L. MDLs of hormones, including testosterone, equilenin, progesterone, equilin, 17β-estradiol, 17α-ethynylestradiol, estrone, androsterone, mestranol and estriol, were between 1.2 ng/L and 37 ng/L. The combination of APPI with dopant allowed the detection of two difficult to ionize fecal related sterols, such as coprostan-3-ol and coprostan-3-one with MDLs of 5.4 ng/L and 11 ng/L, respectively. Calculated MDLs are more than adequate for analysis of wastewater using 1 to 5 mL sample size and for surface waters using up to 20 mL sample size.

Uptake and depuration of pharmaceuticals in reclaimed water by mosquito fish (Gambusia holbrooki): A worst‐case, multiple‐exposure scenario

“…The observed concentrations for trimethoprim, caffeine, sulfamethoxazole, diphenhydramine, diltiazem, carbamazepine, erythromycin, and fluoxetine in reclaimed water were higher than those in previous reports [8,9] in which reclaimed water was directly drawn from irrigational sprinklers. The mechanism for the loss in the reclaimed water drawn from sprinklers is unclear but is likely the result of different input sources.…”

Rapid analysis of trace organic compounds in water by automated online solid-phase extraction coupled to liquid chromatography–tandem mass spectrometry

“…The calculated MDL for most analytes was o5 ng/L with only four compounds (benzophenone, benzotriazole, bisphenol A, and norgestrel) being 4 10 ng/L. The MDLs in this study (Table 2) were comparable and in most cases lower than previously published literature while using lower sample volumes of 1.7 mL [33,42]. A further advantage of using low sample volume was that the mass of isotopically-labeled standard added to each sample was much lower when compared to other published methods.…”

“…However, most of these methods have focused on analysis of specific classes of TOrC such as pharmaceuticals [28][29][30], hormones [24,31] or pesticides [32] only. Other methods still require multiple injections for analysis of all analytes [33], large sample volumes [34], require derivitization [35], or are not completely automated which may reduce the reproducibility and/or increase time of analysis.…”

Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization

“…They are typically used for small (<1000 u) molecules that are not sufficiently polar for efficient ionization by electrospray ionization (ESI). However, APPI is generally perceived to be more efficient for low polarity compounds than APCI, as has been shown for polycyclic aromatic hydrocarbons (PAHs) [5], triterpenes [6], certain steroids [7], and pharmaceuticals [8].…”