Stir-bar-sorptive extraction and liquid desorption combined with large-volume injection gas chromatography-mass spectrometry for ultra-trace analysis of musk compounds in environmental water matrices

Stir-bar-sorptive extraction with liquid desorption followed by large-volume injection and capillary gas chromatography coupled to mass spectrometry in selected ion monitoring acquisition mode (SBSE-LD/LVI-GC-MS (SIM)) has been developed to monitor ultra-traces of four musks (celestolide (ADBI), galaxolide (HHCB), tonalide (AHTN) and musk ketone (MK)) in environmental water matrices. Instrumental calibration (LVI-GC-MS(SIM)) and experimental conditions that could affect the SBSE-LD efficiency are discussed. Assays performed on 30-mL water samples spiked at 200 ng L-1 under optimized experimental conditions yielded recoveries ranging from 83.7+/- 8.1% (MK) to 107.6+/- 10.8% (HHCB). Furthermore, the experimental data were in very good agreement with predicted theoretical equilibria described by octanol-water partition coefficients (K-PDMS/W approximate to K-O/W). The methodology also showed excellent linear dynamic ranges for the four musks studied, with correlation coefficients higher than 0.9961, limits of detection and quantification between 12 and 19 ng L-1 and between 41 and 62 ng L-1, respectively, and suitable precision (< 20%). Application of this method for analysis of the musks in real water matrices such as tap, river, sea, and urban wastewater samples resulted in convenient selectivity, high sensitivity and accuracy using the standard addition methodology. The proposed method (SBSE-LD/LVI-GC-MS(SIM)) was shown to be feasible and sensitive, with a low-sample volume requirement, for determination of musk compounds in environmental water matrices at the ultra-trace level, overcoming several disadvantages presented by other sample-preparation techniques.