Although several per- and polyfluoroalkyl substances (PFAS) have been banned and classified as substances of very high concern by the European Chemicals Agency, similar chemicals remain widely used ...compounds to date. Even though more than 4700 PFASs may occur in the environment, only 40–50 compounds are routinely determined in targeted analysis by ESI-MS using isotopically labeled standards. Nontargeted analysis using high resolution (HR) molecular mass spectrometry suffers from a lack of data mining algorithms for identification and often low ionization efficiency of the compounds. An additional problem for quantification is the potential lack of suitable species specific standards. Here, we demonstrate the usefulness of a hard ionization source (ICP-MS/MS) as a fluorine-specific detector in combination with ESI-MS for the identification of fluorine containing compounds. Simultaneous hyphenation of HPLC-ICP-MS/MS with HR-ESI-MS is applied to evaluate biodegradation products of organofluorine compounds by sewage sludge. The data are analyzed in a nontarget approach using MZmine. Due to the fluorine-specific detection by ICP-MS/MS, more than 5000 peaks (features) of the ESI-MS were reduced to 15 features. Of these, one was identified as a PFAS degradation compound of fluorotelomer alcohol (8:2 FTOH) without using targeted analysis. The feasibility of the detection of organofluorine metabolites using a fluorine-specific detection was demonstrated using a model compound and can thus be applied to new experiments and unknown organofluorine containing samples in the future.
Six varieties of rice were exposed to low and high levels of arsenic in the same soil. Their individual responses of expressing phytochelatins have been correlated to inorganic arsenic uptake, ...transport, and accumulation in the rice grain.
Approaches for the unambiguous identification of lipophilic arsenic species in Saccharina latissima (sugar kelp) have been studied. Parallel use of high resolution ICPMS and electrospray ionization ...(ESI)-MS after separation revealed that Saccharina latissima contained three distinct classes of lipophilic As-species, a family of arsenic containing phospholipids (AsPL), all including As in the form of As–sugar–PO4, As-containing hydrocarbons (AsHC), and As-containing polyunsaturated fatty acids (AsFA). For detailed identification, the use of phospholipases, in particular phospholipase A2, was essential to define the fatty acid composition (determination of regioisomers) of the lipids without purification of the sample, while fragmentation of the molecules by MS2 measurements alone did not supply this information. Some of the identified AsPL contained unsaturated fatty acids (C16:1, C18:1 to C18:3), but saturated fatty acids dominated the AsPL. The fatty acid bound to the position 2″ was predominantly C16:0. Complete lipid hydrolysis showed that this alga did not contain arsenic containing fatty acids (AsFA) bound to complex lipids. Our investigations indicate that in addition to RP-HPLC-ICPMS/ESI-MS a range of different derivatization methods should be used for the comprehensive identification of unknown lipid-soluble arsenic compounds.
Paired grain, shoot, and soil of 173 individual sample sets of commercially farmed temperate rice, wheat, and barley were surveyed to investigate variation in the assimilation and translocation of ...arsenic (As). Rice samples were obtained from the Carmargue (France), Doñana (Spain), Cadiz (Spain), California, and Arkansas. Wheat and barley were collected from Cornwall and Devon (England) and the east coast of Scotland. Transfer of As from soil to grain was an order of magnitude greater in rice than for wheat and barley, despite lower rates of shoot-to-grain transfer. Rice grain As levels over 0.60 μg g-1 d. wt were found in rice grown in paddy soil of around only 10 μg g-1 As, showing that As in paddy soils is problematic with respect to grain As levels. This is due to the high shoot/soil ratio of ∼0.8 for rice compared to 0.2 and 0.1 for barley and wheat, respectively. The differences in these transfer ratios are probably due to differences in As speciation and dynamics in anaerobic rice soils compared to aerobic soils for barley and wheat. In rice, the export of As from the shoot to the grain appears to be under tight physiological control as the grain/shoot ratio decreases by more than an order of magnitude (from ∼0.3 to 0.003 mg/kg) and as As levels in the shoots increase from 1 to 20 mg/kg. A down regulation of shoot-to-grain export may occur in wheat and barley, but it was not detected at the shoot As levels found in this survey. Some agricultural soils in southwestern England had levels in excess of 200 μg g-1 d. wt, although the grain levels for wheat and barley never breached 0.55 μg g-1 d. wt. These grain levels were achieved in rice in soils with an order of magnitude lower As. Thus the risk posed by As in the human food-chain needs to be considered in the context of anaerobic verses aerobic ecosystems.
An extensive data set of total arsenic analysis for 901 polished (white) grain samples, originating from 10 countries from 4 continents, was compiled. The samples represented the baseline (i.e., not ...specifically collected from arsenic contaminated areas), and all were for market sale in major conurbations. Median total arsenic contents of rice varied 7-fold, with Egypt (0.04 mg/kg) and India (0.07 mg/kg) having the lowest arsenic content while the U.S. (0.25 mg/kg) and France (0.28 mg/kg) had the highest content. Global distribution of total arsenic in rice was modeled by weighting each country’s arsenic distribution by that country’s contribution to global production. A subset of 63 samples from Bangladesh, China, India, Italy, and the U.S. was analyzed for arsenic species. The relationship between inorganic arsenic content versus total arsenic content significantly differed among countries, with Bangladesh and India having the steepest slope in linear regression, and the U.S. having the shallowest slope. Using country-specific rice consumption data, daily intake of inorganic arsenic was estimated and the associated internal cancer risk was calculated using the U.S. Environmental Protection Agency (EPA) cancer slope. Median excess internal cancer risks posed by inorganic arsenic ranged 30-fold for the 5 countries examined, being 0.7 per 10,000 for Italians to 22 per 10,000 for Bangladeshis, when a 60 kg person was considered.
Bacterial infection often results in the formation of tissue abscesses, which represent the primary site of interaction between invading bacteria and the innate immune system. We identify the host ...protein calprotectin as a neutrophil-dependent factor expressed inside Staphylococcus aureus abscesses. Neutrophil-derived calprotectin inhibited S. aureus growth through chelation of nutrient Mn²⁺ and Zn²⁺: an activity that results in reprogramming of the bacterial transcriptome. The abscesses of mice lacking calprotectin were enriched in metal, and staphylococcal proliferation was enhanced in these metal-rich abscesses. These results demonstrate that calprotectin is a critical factor in the innate immune response to infection and define metal chelation as a strategy for inhibiting microbial growth inside abscessed tissue.
Rice is more elevated in arsenic than all other grain crops tested to date, with whole grain (brown) rice having higher arsenic levels than polished (white). It is reported here that rice bran, both ...commercially purchased and specifically milled for this study, have levels of inorganic arsenic, a nonthreshold, class 1 carcinogen, reaching concentrations of ∼1 mg/kg dry weight, around 10−20 fold higher than concentrations found in bulk grain. Although pure rice bran is used as a health food supplement, perhaps of more concern is rice bran solubles, which are marketed as a superfood and as a supplement to malnourished children in international aid programs. Five rice bran solubles products were tested, sourced from the United States and Japan, and were found to have 0.61−1.9 mg/kg inorganic arsenic. Manufactures recommend ∼20 g servings of the rice bran solubles per day, which equates to a 0.012−0.038 mg intake of inorganic arsenic. There are no maximum concentration levels (MCLs) set for arsenic or its species in food stuffs. EU and U.S. water regulations, set at 0.01 mg/L total or inorganic arsenic, respectively, are based on the assumption that 1 L of water per day is consumed, i.e., 0.01 mg of arsenic/day. At the manufacturers recommended rice bran solubles consumption rate, inorganic arsenic intake exceeds 0.01 mg/day, remembering that rice bran solubles are targeted at malnourished children and that actual risk is based on mg kg−1 day−1 intake.
Measuring sub-ppm levels of fluorine (F) directly with a commercial ICPMS is not possible due to the high ionisation potential of F. Mixing of barium and fluorine solutions enabled a new approach in ...fluorine analysis through the formation of the polyatomic ion BaF + using ICPMS/MS. Different parameters such as reaction gas flow rate, sampling position, nebuliser and makeup gas flow rate, waiting and acquisition time as well as RF power were optimized in order to obtain the highest possible sensitivities for 138 Ba 19 F + , as these parameters were important for polyatomic ion formation, avoiding barium oxide and barium hydroxide ion interference and sensitive detection in MS/MS. A limit of detection (LOD) of 0.043 mg L −1 was achieved with a good recovery of fluoride spiked in deionised water. For fluorine speciation analysis, coupling of anion exchange chromatography online with ICPMS/MS allowed separation and fluorine specific detection of fluoride and fluoroacetate. The response was compound independent as expected for ICPMS. The LODs of fluoride and fluoroacetate were 0.022 mg L −1 and 0.11 mg L −1 , respectively. Both compounds were baseline separated and detected quantitatively, making this newly developed method a promising candidate for non-target fluorine speciation analysis in environmental samples.
Synchrotron-based X-ray fluorescence (S-XRF) was utilized to locate arsenic (As) in polished (white) and unpolished (brown) rice grains from the United States, China, and Bangladesh. In white rice As ...was generally dispersed throughout the grain, the bulk of which constitutes the endosperm. In brown rice As was found to be preferentially localized at the surface, in the region corresponding to the pericarp and aleurone layer. Copper, iron, manganese, and zinc localization followed that of arsenic in brown rice, while the location for cadmium and nickel was distinctly different, showing relatively even distribution throughout the endosperm. The localization of As in the outer grain of brown rice was confirmed by laser ablation ICP−MS. Arsenic speciation of all grains using spatially resolved X-ray absorption near edge structure (μ-XANES) and bulk extraction followed by anion exchange HPLC−ICP−MS revealed the presence of mainly inorganic As and dimethylarsinic acid (DMA). However, the two techniques indicated different proportions of inorganic:organic As species. A wider survey of whole grain speciation of white (n = 39) and brown (n = 45) rice samples from numerous sources (field collected, supermarket survey, and pot trials) showed that brown rice had a higher proportion of inorganic arsenic present than white rice. Furthermore, the percentage of DMA present in the grain increased along with total grain arsenic.
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