Determination of N‐nitrosamines by automated dispersive liquid–liquid microextraction integrated with gas chromatography and mass spectrometry

Abstract

An automated dispersive liquid-liquid microextraction integrated with gas chromatography and mass spectrometric procedure was developed for the determination of three N-nitrosamines (N-nitroso-di-n-propylamine, N-nitrosopiperidine, and N-nitroso di-n-butylamine) in water samples. Response surface methodology was employed to optimize relevant extraction parameters including extraction time, dispersive solvent volume, water sample pH, sodium chloride concentration, and agitation (stirring) speed. The optimal dispersive liquid-liquid microextraction conditions were 28 min of extraction time, 33 μL of methanol as dispersive solvent, 722 rotations per minute of agitation speed, 23% w/v sodium chloride concentration, and pH of 10.5. Under these conditions, good linearity for the analytes in the range from 0.1 to 100 μg/L with coefficients of determination (r(2) ) from 0.988 to 0.998 were obtained. The limits of detection based on a signal-to-noise ratio of 3 were between 5.7 and 124 ng/L with corresponding relative standard deviations from 3.4 to 5.9% (n = 4). The relative recoveries of N-nitroso-di-n-propylamine, N-nitrosopiperidine, and N-nitroso di-n-butylamine from spiked groundwater and tap water samples at concentrations of 2 μg/L of each analyte (mean ± standard deviation, n = 3) were (93.9 ± 8.7), (90.6 ± 10.7), and (103.7 ± 8.0)%, respectively. The method was applied to determine the N-nitrosamines in water samples of different complexities, such as tap water, and groundwater, before and after treatment, in a local water treatment plant.

Process Optimization and Modeling of Phenol Adsorption onto Sludge-Based Activated Carbon Intercalated MgAlFe Ternary Layered Double Hydroxide Composite

“…Numerical optimization has been an indispensable tool for multivariate problems [ 34 , 56 ]. This is due to the intricacies associated with the identification of optimal operational points, which necessitated the simultaneous examination of all independent and dependent variables data.…”

Anion exchange polymeric sorbent coupled to high‐performance liquid chromatography with UV diode array detection for the determination of ten N‐nitrosamines in meat products: a validated approach

“…If compared with other procedures of sample purification, such as that reported by Amayreh et al . (), this method may result as more time‐consuming. However, automated SPE systems may be used for accelerating this step of the analytical procedure and improving, at the same time, its reproducibility.…”

Occurrence of erythromycin and its degradation products residues in honey. Validation of an analytical method

“…Optimization of the extraction solvent ensures both high recovery and adequate sediment volume for analyses. In general, the type of extraction solvent is one of the most influential factors on the extraction efficiency in DLLME‐based methodologies . In this study, four organic extraction solvents were tested: chlorobenzene (C 6 H 5 Cl, d 25 = 1.11 g/mL), dichloromethane (CH 2 Cl 2 , d 25 = 1.32 g/mL), chloroform (CHCl 3 , d 25 = 1.47 g/mL), and carbon tetrachloride (CCl 4 , d 25 = 1.58 g/mL).…”

“…A characteristic feature of DLLME‐based method is the formation of extraction solvent microdroplets that are dispersed in the aqueous phase. Therefore, a large surface area of contact between the two phases results in rapid mass transfer, thereby increasing extraction efficiency . The extraction time with vortex mixing has been proposed to increase interfacial tension of the extraction solvent and contribute to higher analyte recovery .…”

“…However, the maximum LOD is only 2 μg/mL and it cannot determine erythromycin at concentrations <2 μg/mL . Dispersive liquid–liquid microextraction (DLLME) is a very new sample pretreatment technique, which consists of a simple and rapid extraction and preconcentration of organic compounds from aqueous samples . In DLLME, the extraction solvent and dispersion solvent are rapidly injected into the aqueous solution.…”