Comprehensive two-dimensional GC (GCxGC) qMS analysis of tetrachloronaphthalenes in Halowax formulations

Atmospheric pressure ionization for gas chromatography-high resolution mass spectrometry determination of polychlorinated naphthalenes in marine sediments

In this work, the performance of the atmospheric pressure chemical ionization (APCI) and photoionization (APPI) was assessed to develop a new selective and sensitive gas chromatography-high resolution mass spectrometry (GC-HRMS) method for the determination of polychlorinated naphthalenes (PCNs) in sediment samples. The capability of both APCI and APPI sources for the ionization of PCNs was investigated, showing the formation of the molecular ion and the [M‒Cl+O]^‒ ion in positive and negative ion modes, respectively. Positive ion APCI provided high responses using high corona ion current, while the use of high vapour pressure dopant-solvents, such as toluene in positive mode and diethyl ether in the negative mode, was required to achieve high ionization efficiencies in APPI. The performance of the two API sources in the PCN determination by GC-HRMS were compared and the best results were achieved using the GC-APPI(+)-HRMS (Orbitrap) system. The GC-APPI(+)-HRMS (Orbitrap) method was applied to the characterization of Halowax mixtures and the analysis of marine sediments collected near to the coastal area of Barcelona (NE, Spain), demonstrating a great detection capability with low method limits of detection (0.2-1.6 pg g^-1 dry weight), good precision (RSD <15%) and trueness (relative error <13%). Total PCN concentrations ranged from 0.35 to 5.0 ng g^-1 dry weight and the presence of related compounds, such as polychlorinated biphenyls (PCBs), was also detected by combining positive and negative ion modes, providing complementary information to better monitor of all PCN congener groups. The results presented here show the feasibility of the GC-APPI-HRMS method for the suitable determination of PCNs.

Polychlorinated naphthalenes (PCNs) in food and humans

Polychlorinated naphthalenes (PCNs) are legacy contaminants that are listed by the Stockholm convention, initially for reduction of inadvertent production and ultimately, for elimination. They originate through releases from older electrical equipment, inadvertent contamination in industrial chemicals and from combustion processes such as incineration. Recent advances in measurement techniques have allowed a greater characterisation of PCN occurrence, yielding more specific data including individual PCN congener concentrations. Emerging data on food shows widespread occurrence in most commonly consumed foods from different parts of the world. Concurrently, toxicological studies have also allowed a greater insight into the potencies of some congeners, a number of which are known to elicit potent, aryl hydrocarbon receptor (AhR) mediated responses, often referred to as dioxin-like toxicity. The dietary pathway is widely recognised as the most likely route to non-occupational human exposure. This paper reviews some of the more recent findings on PCN occurrence in food, biota, and human tissues, and discusses the use of relative potencies to express PCN toxicity in foods.

Comprehensive 2-dimensional gas chromatography fast quadrupole mass spectrometry (GC × GC-qMS) for urinary steroid profiling: mass spectral characteristics with chemical ionization

Comprehensive 2-dimensional gas chromatography (GC × GC), coupled to either a time of flight mass spectrometry (TOF-MS) or a fast scanning quadrupole MS (qMS) has greatly increased the peak capacity and separation space compared to conventional GC-MS. However, commercial GC × GC-TOFMS systems are not equipped with chemical ionization (CI) and do not provide dominant molecular ions or enable single ion monitoring for maximal sensitivity. A GC × GC-qMS in mass scanning mode was investigated with electron ionization (EI) and positive CI (PCI), using CH(4) and NH(3) as reagent gases. Compared to EI, PCI-NH(3) produced more abundant molecular ions and high mass, structure-specific ions for steroid acetates. Chromatography in two dimensions was optimized with a mixture of 12 endogenous and 3 standard acetylated steroids (SM15-AC) relevant to doping control. Eleven endogenous target steroid acetates were identified in normal urine based on their two retention times, and EI and PCI-NH(3) mass spectra; nine of these endogenous target steroid acetates were identified in congenital adrenal hyperplasia (CAH) patients. The difference between the urinary steroids profiles of normal individuals and those from CAH patients can easily be visually distinguished by their GC × GC-qMS chromatograms. We focus here on the comparison and interpretation of the various mass spectra of the targeted endogenous steroids. PCI-NH(3) mass spectra were most useful for unambiguous molecular weight determination and for establishing the number of -OH by the losses of one or more acetate groups. We conclude that PCI-NH(3) with GC × GC-qMS provides improved peak capacity and pseudomolecular ions with structural specificity.

Polychlorinated naphthalenes in polar environments--a review

Polychlorinated naphthalenes (PCNs) consist of naphthalene substituted with 1-8 chlorines, yielding 75 possible congeners. They were formerly used in industry, occur at trace levels in commercial PCB mixtures, and have current sources in combustion processes. PCNs are widespread in arctic air with higher levels in the European Arctic. Concentrations were higher during the cold months in arctic Canada and Russia, but no seasonality was noted in subarctic Canada and Greenland. "Marker" congeners indicative of combustion were evident at some sites. Total toxic equivalents (TEQ) in air due to PCNs+dioxin-like PCBs were dominated by PCNs in arctic Canada and Russia, but not in subarctic Canada. Deposition of PCNs in snow was measured in northern Norway and Svalbard. Surveys of PCNs in the lower food web are limited to the northern Baltic Sea and lakes/rivers of northern Scandinavia. PCNs showed little or no biomagnification in lower food webs of the northern Baltic and discrimination among congeners suggested preferential metabolism. There are no reports of PCNs in fish and invertebrates from the Arctic Ocean, and only one from Antarctica. Total PCNs in marine mammals followed the order: harbour seal~pilot whale>or=polarbear>beluga>ringed seal~Weddell seal. Total PCNs in seabirds varied over 100-fold, with higher concentrations in glaucous gull eggs and plasma from Bear Island, and livers of northern fulmar from the eastern Canadian Arctic. Lower concentrations occurred in eggs of glaucous gull from Svalbard and black-backed gull from the Faroe Islands. PCNs accounted for <1% of total TEQ in ringed seal, Weddell seal, seabirds and polar bear, but up to 6-15% in beluga and pilot whale. TEQ due to PCNs were generally low in harbour seal, but up to 9% of total TEQ in some animals.

Dioxin-like compound compositional profiles of furnace bottom ashes from household combustion in Poland and their possible associations with contamination status of agricultural soil and pine needles

A compositional profile of PCDDs, PCDFs, non- and mono-ortho PCBs, and PCNs of several type furnace bottom ashes obtained after the heating muffle stove for domestic use combustion of hard coal, coke, wood, and solid domestic waste mixture have been examined as possible contributors to environmental diffusion with these compounds in Poland. The uppermost concentration of dioxin-like compounds with 2.0 ng TEQ kg(-1) dry weight found for wood ash was dominated by PCDDs and PCDFs, while for other types of ashes were in the range from 0.052 ng TEQ kg(-1) to 0.67 ng TEQ kg(-1) dry weight. The multivariate statistical analysis displayed some compositional similarity of PCDDs, PCDFs and PCNs between the ashes and environmental pine needle or agricultural soil matrices collected in Poland.

Multivariate analysis of identity of imported technical PCN formulation

Chloronaphthalenes form a class of compounds consisting of 8 CN homologue groups and altogether of 75 congeners, which used have been most extensively in 1930--1950. An investigation have been performed on the possible origin of unidentified by name technical chloronaphthalene formulation unlawfully imported recently from the United Kingdom to Japan. Principal component analysis (PCA) and Cluster Analysis of chloronaphthalene congener isomer-specific and homologue classes' compositional HRGC/HRMS data of imported CN formulation and of certain brands of technical CN formulation called Halowax (Halowax 1000, 1001 and 1031) enabled to identify that unnamed product is not Halowax 1001. A less accurate multivariate examination based on CN homologue classes patter did indicate on large similarity between unlawfully imported technical CN formulation and Halowax 1001 (manufactured by the Koppers Ind. Co., USA), while a more accurate based on CN congeners pattern differentiated them as to of various origin mixtures. Based on chlorine content of imported CN formulation (50-52%) and its no similarity to Halowax 1001 it seems reasonable to conclude that unnamed CN mixture examined could be a sample of stockpiled Seekay wax R93.