Differential Accumulation of Short-, Medium-, and Long-Chain Chlorinated Paraffin in Free-Range Laying Hens from an E-Waste Recycling Area.

Chlorinated paraffins (CPs) are environmental pollutants of emerging concern. Long-chain CPs (LCCPs) are considered of lesser concern than other CPs in food due to their lower accumulation in most organisms. However, LCCPs have been shown to accumulate preferentially in birds. We used ultrahigh-performance liquid chromatography combined with electrospray ionization Orbitrap mass spectrometry (UPLC-ESI-Orbitrap MS) to analyze CPs (C10-26Cl4-12) in tissues of free-range hens, their feed, and local soils. Feed was found to be the main source of CP intake. The CP carbon chain length had little impact on their absorption. C18-CPs were excreted in preference to C13-CPs by laying. The metabolic elimination rates of CPs (0.2 µg/mL) estimated using chicken liver microsomes were in the order C12Cl6 (91%) > C12Cl8 (57%) > C18Cl6 (12%) > C18Cl8 (6%). CPs with longer carbon chains accumulated preferentially in muscle and adipose tissues, and the accumulation of specific carbon chain lengths was related to the content and composition of different CPs in the intake source.

A simplified method for determination of short-, medium-, and long-chain chlorinated paraffins using tetramethyl ammonium chloride as mobile phase modifier.

The formation of halide adducts ion is an important pathway to improve the sensitivity of analytes in liquid chromatography (LC) combined with negative electrospray ionization (ESI) mass spectrometry (MS). Although adding modifier in mobile phase is generally the simplest way to form anions adducts, the formation of halide adducts ion requires a complex post-column addition strategy since traditional halide ionization enhancement reagents are incompatible with LC systems. To solve this problem, the volatile organochlorine salt tetramethyl ammonium chloride (TMAC) was therefore investigated as a potentially non-corrosive mobile phase modifier that was confirmed to be compatible with both LC and MS systems in this study. When short-chain, medium-chain, and long-chain chlorinated paraffins (CPs) were determinated simultaneously by ultra-high performance LC combined with ESI high resolution MS (UPLC-ESI-HRMS), all of them tended to ionize by forming [M+Cl]- ions and exhibited excellent sensitivity with the instrumental detection limits of 1-4 pg/µL. Meanwhile, their sensitivities towards CPs were less dependent on their Cl content with the total relative response factors of 0.8-3.5. The method's utility was demonstrated through determination of CPs in surface soil and chicken muscle samples. This was an effective and practical method to enhance the selectivity for [M + Cl]- ions and improve sensitivity towards CPs with various carbon lengths. Importantly, post-column addition was not required, and thus the analytical procedure was simplified. The method has also improved sensitivity towards some other organohalides and may be generally useful in the determination of challenging organic analytes.