Method Detection Level Research Articles

Analysis of Thorium (Th) and Uranium (U) in radioactive wastewater sample in accordance with American Public Health Association (APHA) 3125 method

The main issue with thorium (Th) and uranium (U) in radioactive wastewater is the potential of these elements to contaminate the water bodies. The unregulated radioactive wastewater release can affect the ecosystem and potentially harm aquatic life. Therefore, there is a need to establish the analysis of Th and U using standard method to obtain better sensitivity and good confidence in the final report. In this study, the determination of uranium and thorium was employed using the American Public Health Association (APHA) method 3125 standard method. The method performance and method detection level (MDL) samples for APHA 3125 were prepared in the deionized water and digested using hot block (APHA 3030E) and microwave digester (APHA 3030K). The quantification of 238U, 235U and 232Th in the method performance and MDL samples was performed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). From the results, the method performance samples for both digestion methods were in accordance with the APHA requirement. The MDL obtained from APHA 3030E for 232Th, 238U, and 235U were 5, 7, and 8 μg L−1 respectively. Meanwhile, the MDL obtained from the microwave digester for 232Th, 238U, and 235U, and were 2, 3, and 3 μg L−1 respectively. The APHA 3030K digestion technique gives lower and better detection limit compared to the APHA 3030E technique. Based on APHA 3030K MDL, 232Th was detected in the radioactive wastewater sample while 238U and 235U were less than MDL. Meanwhile, for APHA 3030E, all elements were below MDL. This study will enhance the detection of uranium and thorium in the radioactive wastewater sample towards better environmental monitoring programs at the national and global levels.

Pesticides in small volume plasma samples: Method development and application to smallmouth bass (Micropterus dolomieu) from the Chesapeake Bay watershed, USA

Nontarget organisms are exposed to pesticides following applications in agricultural and urban settings, potentially resulting in deleterious effects. Direct measurements of pesticides in biological tissues may aid in characterizing exposure, accumulation, and potential toxicity versus analyses in environmental media alone (e.g., water, soil, and air). Plasma represents a nonlethal sampling medium that can be used to assess recent exposures to contaminants. Herein, a method was developed to test the extraction of 210 pesticides and their transformation products in small volume plasma samples (100 μL). Plasma samples were protein precipitated with 0.5 % formic acid in acetonitrile added to the sample (ratio of 3.5:1). Pass-through solid phase extraction was used for sample matrix and lipid removal and samples were analyzed by liquid chromatography and gas chromatography with tandem mass spectrometry. Recoveries of 70.0–129.8 % were achieved for 182 pesticides and degradates across the low (25 ng mL−1), medium (100 ng mL−1), and high (250 ng mL−1) spike levels. Method detection levels ranged 0.4–13.0 ng mL−1. Following development, the method was applied to smallmouth bass (Micropterus dolomieu) plasma samples (n = 10) collected from adults in the Chesapeake Bay watershed. Individual plasma samples resulted in four to seven analytes detected with summed concentrations ranging 16.4–95.0 ng mL−1. Biological multiresidue pesticide methods help elucidate recent exposures of bioactive compounds to nontarget organisms.

Ethyl carbamate in retail market condiments and risk assessment of its dietary exposure for the Korean population

ABSTRACT Ethyl carbamate (EC), a potential human dietary carcinogen, is found in fermented foods including the fermented soybean-based condiments, the major part of the Korean diet. Therefore, it is expected that their EC contents might pose health risks. Herein, we collected 111 condiments and estimated their EC contents via gas chromatography-mass spectrometry. Further, dietary intake of EC was evaluated, and the risk levels were assessed via the margin of exposure (MOE) approach and excess cancer risk assessment. EC contents of the condiments ranged from not detectable to 39.47 μg/kg, and the daily EC exposure ranged from 1.4 to 2.0 ng/kg BW per day, depending on gender and age groups in Korea. Of the condiments, soy sauce was the largest contributor to EC exposure. MOE and excess cancer risks for the average consumer were 166,300 and 9.0 × 10−8, respectively, and those for the consumers in the 95th percentiles (P95) were 53,504 and 2.8 × 10−7, respectively, indicating that the risk of exposure to EC is of lower concern in average consumers than heavy consumers. However, the EC exposure from condiments was higher than that in other Asian countries. Abbreviations: EC: ethyl carbamate; GC-MS: gas chromatography-mass spectrometry; MOE: margin of exposure; MRL: maximum residue level; IDL: instrumental detection level; IQL: instrumental quantification level; MDL: method detection level; MQL: method quantification level; EDI: estimated daily intakes; BMDL10: benchmark dose lower confidence limit

Mercury Removal from Wastewater Using Cysteamine Functionalized Membranes.

This study demonstrates a three-step process consisting of primary pre-filtration followed by ultrafiltration (UF) and adsorption with thiol-functionalized microfiltration membranes (thiol membranes) to effectively remove mercury sulfide nanoparticles (HgS NPs) and dissolved mercury (Hg2+) from wastewater. Thiol membranes were synthesized by incorporating either cysteine (Cys) or cysteamine (CysM) precursors onto polyacrylic acid (PAA)-functionalized polyvinylidene fluoride membranes. Carbodiimide chemistry was used to cross-link thiol (−SH) groups on membranes for metal adsorption. The thiol membranes and intermediates of the synthesis were tested for permeability and long-term mercury removal using synthetic waters and industrial wastewater spiked with HgS NPs and a Hg2+ salt. Results show that treatment of the spiked wastewater with a UF membrane removed HgS NPs to below the method detection level (<2 ppb) for up to 12.5 h of operation. Flux reductions that occurred during the experiment were reversible by washing with water, suggesting negligible permanent fouling. Dissolved Hg2+ species were removed to non-detection levels by passing the UF-treated wastewater through a CysM thiol membrane. The adsorption efficiency in this long-term study (>20 h) was approximately 97%. Addition of Ca2+ cations reduced the adsorption efficiencies to 82% for the CysM membrane and to 40% for the Cys membrane. The inferior performance of Cys membranes may be explained by the presence of a carboxyl (−COOH) functional group in Cys, which may interfere in the adsorption process in the presence of multiple cations because of multication absorption. CysM membranes may therefore be more effective for treatment of wastewater than Cys membranes. Focused ion beam characterization of a CysM membrane cross section demonstrates that the adsorption of heavy metals is not limited to the membrane surface but takes place across the entire pore length. Experimental results for adsorptions of selected heavy metals on thiol membranes over a wide range of operating conditions could be predicted with modeling. These results show promising potential industrial applications of thiol-functionalized membranes.

VOC characteristics and source apportionment at a PAMS site near an industrial complex in central Taiwan

Hourly data of volatile organic compounds (VOCs) were collected for three consecutive years from photochemical assessment monitoring stations (PAMS) in Taixi, Taiwan. Analysis of the VOC data allows for apportionment of the anthropogenic sources of VOCs. The VOC concentrations and characteristics were analyzed for temporal variations over a three-year period 2014 to 2016. Out of 54 VOCs detected, 21 VOC compounds from 55 to 99% were below the method detection level; others ranged from 100% occurrence (ethane) to 56–61% for trimethylbenzene. In order to have meaningful statistical results, this paper only used results from 33 VOCs where they were detected at least 65% of the time. This was a requirement to be able to determine statistical parameters such as means and standard deviations. The highest VOC average concentrations observed for three consecutive years, in order, for the period were toluene (3.7–4.3 μg m−3), then propane (2.5–2.6 μg m−3), ethane (2.2–2.5 μg m−3), ethylene (1.1–1.5 μg m−3) and propylene (0.8–1.1 μg m−3). A positive matrix factorization (PMF) receptor model was used to evaluate VOC sources in the area. Six factors were identified by PMF analysis, including solvent use, vehicle exhaust, diesel exhaust, petrochemical, refinery and aged air mass. The conditional probability function indicates that the VOCs in six factors were emitted from their source locations via different wind directions. The contribution of the northwest industrial complex to the PAMS data is linked to the VOCs observed. Actually, seasonal wind directions having only north and north-northwest directions played an important role.

Use of a versatile, easy, and rapid atmospheric monitor (VERAM) passive samplers for pesticide determination in continental waters.

The versatile, easy, and rapid atmospheric monitor (VERAM), a passive sampler device widely used for air monitoring, was evaluated as passive sampler for the determination of 23 pesticides in water. Gas chromatography with mass spectrometry detection was employed for determination of pesticides after microwave-assisted-extraction and specific clean-up of deployed samplers. The proposed methodology reached method detection levels from 2 to 10ng pesticide per sampler. Sampling rate (Rs) was determined for every pesticide from an uptake isotherm study performed at three different concentration levels (50, 125, and 250ngL-1). The obtained RS values ranged from 0.06 to 0.76L d-1. The obtained limits of detection for a 24-h passive sampling were from 4 to 50ngL-1. The effect of water parameters, such as temperature, pH, and ionic strength, were evaluated for their effect on pesticides retention using VERAMs. Pesticide RS values were independent of the water composition and increased on increasing temperature. Finally, the VERAM uptake was compared with that obtained using classic semipermeable membrane devices (SPMDs). This study is the first precedent for the use of VERAMs as passive samplers for the adsorption and concentration of pesticides in water and it confirms the satisfactory analytical figures of merit of VERAM as passive sampler of water. Graphical Abstract Scheme of water sampling of pesticides using versatile, easy, and rapid atmospheric monitor (VERAM) passive samplers.

The Atmosphere can be a Source of Certain Water Soluble Volatile Organic Compounds in Urban Streams

AbstractSurface water and air volatile organic compound (VOC) data from 10 U.S. Geological Survey monitoring sites were used to evaluate the potential for direct transport of VOCs from the atmosphere to urban streams. Analytical results of 87 VOC compounds were screened by evaluating the occurrence and detection levels in both water and air, and equilibrium concentrations in water (Cws) based on the measured air concentrations. Four compounds (acetone, methyl tertiary butyl ether, toluene, and m‐ &amp; p‐xylene) were detected in more than 20% of water samples, in more than 10% of air samples, and more than 10% of detections in air were greater than long‐term method detection levels (LTMDL) in water. Benzene was detected in more than 20% of water samples and in more than 10% of air samples. Two percent of benzene detections in air were greater than one‐half the LTMDL in water. Six compounds (chloroform, p‐isopropyltoluene, methylene chloride, perchloroethene, 1,1,1‐trichloroethane, and trichloroethene) were detected in more than 20% of water samples and in more than 10% of air samples. Five VOCs, toluene, m‐ &amp; p‐xylene, methyl tert‐butyl ether (MTBE), acetone, and benzene were identified as having sufficiently high concentrations in the atmosphere to be a source to urban streams. MTBE, acetone, and benzene exhibited behavior that was consistent with equilibrium concentrations in the atmosphere.

Comparison of behaviour and fate of tetrabromobisphenol A (TBBPA) in membrane bioreactors and conventional activated sludge process

Research was completed on the behaviour and fate of tetrabromobisphenol A (TBBPA) in pilot-scale membrane bioreactors and conventional activated sludge (CAS) process at the City of Guelph Wastewater Treatment Plant. Emphasis was on the physicochemical processes, biological transformation and sorption kinetics. Measurement of TBBPA at the environmental level can be challenging, so the main focus of this paper was the development of an analytical method for the nano-level determination of TBBPA. The approach used was gas chromatography-negative ion chemical ionization-mass spectrometry in select ion monitoring mode. For the wastewater matrix studied, the developed method had a low method detection level (MDL) of 2.4 ng/L. The matrix effects for influent and activated sludge mixed liquor were determined to be 36.5 ± 5.9% (n = 10) and 79.2 ± 4.5% (n = 10), respectively. Preliminary results show that the CAS system demonstrates better performance for TBBPA removal, with removal at 83%. This was corroborated by the batch experiments that showed that the synergistic effects of biodegradation and biosorption potentially provide more removal of the TBBPA through the activated sludge process.

Data quality in water analysis: validation of combustion-infrared and combustion-chemiluminescence methods for the simultaneous determination of Total Organic Carbon (TOC) and Total Nitrogen (TN)

Total Organic Carbon (TOC) and Total Nitrogen (TN) were simultaneously determined in water samples, applying the high-temperature (720°C) catalytic combustion (Pt/Al2O3) oxidation method. The detection of TOC and TN was performed using an infrared or a chemiluminescence detector, respectively. Following current law legislations as well as the need to provide accurate and repeatable results, a systematic work has been successfully undertaken for the accreditation according to EN ISO 17025/99. Method characteristics (r ange of measurement, calibration, method detection level, repeatability, reproducibility, precision, accuracy) and measurement uncertainties were determined, while participation in proficiency testing schemes was also implemented. The above methods were tested for the study of water purification from organic pollutants. To this end, organic dyes have been used as model organic pollutants and anionic hydrogels have been used as sorbents. With respect to the colorimetric techniques, TOC-TN characterization is proved to be a reliable tool with significantly lower detection limits of the organic load.

Quality Control for Federal Clean Water Act and Safe Drinking Water Act Regulatory Compliance

QC sample results are required in order to have confidence in the results from analytical tests. Some of the AOAC water methods include specific QC procedures, frequencies, and acceptance criteria. These are considered to be the minimum controls needed to perform the method successfully. Some regulatory programs, such as those in 40 CFR Part 136.7, require additional QC or have alternative acceptance limits. Essential QC measures include method calibration, reagent standardization, assessment of each analyst's capabilities, analysis of blind check samples, determination of the method's sensitivity (method detection level or quantification limit), and daily evaluation of bias, precision, and the presence of laboratory contamination or other analytical interference. The details of these procedures, their performance frequency, and expected ranges of results are set out in this manuscript. The specific regulatory requirements of 40 CFR Part 136.7 for the Clean Water Act, the laboratory certification requirements of 40 CFR Part 141 for the Safe Drinking Water Act, and the ISO 17025 accreditation requirements under The NELAC Institute are listed.

Laser diode thermal desorption mass spectrometry for the analysis of quinolone antibiotic residues in aquacultured seafood

Veterinary drug residue analysis of meat and seafood products is an important part of national regulatory agency food safety programs to ensure that consumers are not exposed to potentially dangerous substances. Complex tissue matrices often require lengthy extraction and analysis procedures to identify improper animal drug treatment. Direct and rapid analysis mass spectrometry techniques have the potential to increase regulatory sample analysis speed by eliminating liquid chromatographic separation. Flumequine, oxolinic acid, and nalidixic acid were extracted from catfish, shrimp, and salmon using acidified acetonitrile. Extracts were concentrated, dried onto metal sample wells, then rapidly desorbed (6 s) with an infrared diode laser for analysis by laser diode thermal desorption atmospheric pressure chemical ionization with tandem mass spectrometry (LDTD-MS/MS). Analysis was conducted in selected reaction monitoring mode using piromidic acid as internal standard. Six-point calibration curves for each compound in extracted matrix were linear with r(2) correlation greater than 0.99. The method was validated by analyzing 23 negative samples and 116 fortified samples at concentrations of 10, 20, 50, 100, and 600 ng/g. Average recoveries of fortified samples were greater than 77% with method detection levels ranging from 2 to 7 /g. Three product ion transitions were acquired per analyte to identify each residue. A rapid method for quinolone analysis in fish muscle was developed using LDTD-MS/MS. The total analysis time was less than 30 s per sample; quinolone residues were detected below 10 ng/g and in most cases residue identity was confirmed. This represents the first application of LDTD to tissue extract analysis. Published 2012. This article is a US Government work and is in the public domain in the USA.

Analysis of trenbolone acetate metabolites and melengestrol in environmental matrices using gas chromatography–tandem mass spectrometry

Studies demonstrate that exposure to steroid hormones in receiving waters can adversely impact reproduction of aquatic organisms. In particular, exogenous steroid hormones widely used as growth promoters in animal agriculture are of high concern, yet no gas chromatography–tandem mass spectrometry (GC/MS/MS) analytical methods for the detection of these compounds in complex environmental matrices is described in the literature. This study utilizes analytical methods based upon N-methyl-N-(trimethylsilyl)trifluoro-acetamide-iodine (MSTFA-I2) derivatization for the analysis of metabolites of trenbolone acetate (TBA), including 17α-trenbolone, 17β-trenbolone, and trendione, and melengestrol acetate in receiving waters and surface soils associated with animal agriculture. Results suggest method detection levels of 0.5–1ng/L for the trenbolone metabolites, while detection of melengestrol is qualitative only. Isotope dilution methods employing d3-17β-trenbolone were used to improve steroid quantification. Method recoveries in spiked samples collected from a variety of representative receiving waters generally ranged from 80–120% with consistent and low standard deviation (generally<10%) for replicate analysis. Analysis of a storm water runoff sample from a commercial confined animal feeding operation (CAFO) that used TBA implants detected 17β-trenbolone and trendione at concentrations of 31 and 52ng/L, respectively. Analysis of surface soils at a commercial CAFO using TBA implants detected 17α-trenbolone at concentrations between 4–6ng/g dry weight. Method development efforts suggested that the concentration of I2 in MSTFA, the removal of I2 from sample extracts after derivatization, and the use of Florisil clean-up to reduce organic matter matrix were vital aspects of steroid hormone quantification at low (<30ng/L) concentrations in complex environmental matrices.

Analysis of N-nitrosamines in water by isotope dilution gas chromatography–electron ionisation tandem mass spectrometry

A method has been developed for the determination of eight N-nitrosamines in drinking water and treated municipal effluent. The method uses solid phase extraction (SPE), gas chromatography (GC) and analysis by tandem mass spectrometry (MS-MS) with electron ionization (EI). The target compounds are N-nitrosodimethylamine (NDMA), N-nitrosomethyethylamine (NMEA), N-nitrosodiethylamine NDEA), N-nitrosodipropylamine (NDPA), N-nitrosodi-n-butylamine (NDBuA), N-nitrosodiphenylamine (NDPhA), N-nitrosopyrrolidine (NPyr), N-nitrosopiperidine (NPip), N-nitrosomorpholine (NMorph). The use of direct isotope analogues for isotope dilution analysis of all analytes ensures accurate quantification, accounting for analytical variabilities that may occur during sample processing, extraction and instrumental analysis. Method detection levels (MDLs) were determined to describe analyte concentrations sufficient to provide a signal with 99% certainty of detection. The established MDLs for all analytes were 0.4–4ngL−1 in a variety of aqueous matrices. Sample matrices were observed to have only a minor impact on MDLs and the method validation confirmed satisfactory method stability over intra-day and inter-day analyses of tap water and tertiary treated effluent samples.

Simultaneous determination of estrogenic and androgenic hormones in water by isotope dilution gas chromatography–tandem mass spectrometry

A rapid gas chromatography–tandem mass spectrometry (GC–MS/MS) analytical method was developed for the simultaneous analysis of 7 estrogenic hormones (17α-estradiol, 17β-estradiol, estrone, mestranol, 17α-ethynylestradiol, levonorgestrel, estriol) and 5 androgenic hormones (testosterone, androsterone, etiocholanolone, dihydrotestosterone, androstenedione) in aqueous matrices. This method is unique in its inclusion of all 12 of these estrogens and androgens and is of particular value due to its very short chromatographic run time of 15 min. The use of isotope dilution for all analytes ensures the accurate quantification, accounting for analytical variabilities that may be introduced during sample processing and instrumental analysis. Direct isotopically labelled analogues were used for 8 of the 12 hormones and satisfactory isotope standards were identified for the remaining 4 hormones. Method detection levels (MDLs) were determined to describe analyte concentrations sufficient to provide a signal with 99% certainty of detection. The established MDLs for most analytes were 1–5 ng L −1 in a variety of aqueous matrices. However, slightly higher MDLs were observed for etiocholanolone, androstenedione, testosterone, levonorgestrel and dihydrotestosterone in some aqueous matrices. Sample matrices were observed to have only a minor impact on MDLs and the method validation confirmed satisfactory method stability over intra-day and inter-day analyses of surface water and tertiary treated effluent samples.

A passive sampling-based analytical strategy for the determination of volatile organic compounds in the air of working areas

An analytical methodology based on the use of a polyethylene layflat tube filled with activated carbon and Florisil (ACFL-VERAM) was employed for the passive sampling of volatile organic compounds (VOCs) in the air of working areas of packing industries. VOCs amount in the ACFL-VERAM sampler was directly determined through head-space-gas chromatography–mass spectrometry (HS-GC–MS) allowing a direct determination in only 20 min without the need of any previous treatment. Uptake parameters, like sampling rate ( R S) and sampler–air partition coefficient ( K SA), were determined for every studied VOC from adsorption isotherm data. Additionally, experimental equations have been proposed to predict R S and K SA from the octanol–air partition coefficients reported in the literature. The proposed methodology reaches method detection levels from 0.007 to 0.2 mg m −3 for the studied VOCs.

An enzyme-linked immunosorbent assay for the determination of dioxins in contaminated sediment and soil samples

A 96-microwell enzyme-linked immunosorbent assay (ELISA) method was evaluated to determine PCDDs/PCDFs in sediment and soil samples from an EPA Superfund site. Samples were prepared and analyzed by both the ELISA and a gas chromatography/high resolution mass spectrometry (GC/HRMS) method. Comparable method precision, accuracy, and detection level (8 ng kg −1) were achieved by the ELISA method with respect to GC/HRMS. However, the extraction and cleanup method developed for the ELISA requires refinement for the soil type that yielded a waxy residue after sample processing. Four types of statistical analyses (Pearson correlation coefficient, paired t-test, nonparametric tests, and McNemar’s test of association) were performed to determine whether the two methods produced statistically different results. The log-transformed ELISA-derived 2,3,7,8-tetrachlorodibenzo- p-dioxin values and log-transformed GC/HRMS-derived TEQ values were significantly correlated ( r = 0.79) at the 0.05 level. The median difference in values between ELISA and GC/HRMS was not significant at the 0.05 level. Low false negative and false positive rates (<10%) were observed for the ELISA when compared to the GC/HRMS at 1000 ng TEQ kg −1. The findings suggest that immunochemical technology could be a complementary monitoring tool for determining concentrations at the 1000 ng TEQ kg −1 action level for contaminated sediment and soil. The ELISA could also be used in an analytical triage approach to screen and rank samples prior to instrumental analysis.

Technical Note: Evaluation of HDPE Water Sample Bottles and PVC Sampler Tubing Used in Herbicide Dissipation Studies

The recovery of six herbicides (triclopyr, triclopyr ester, sulfometuron methyl, metsulfuron methyl, imazapyr, and hexazinone) was evaluated in two stream water samples, one from Weogufka Creek in the Alabama Piedmont and one from a stagnant stream in the Escambia Experimental Forest near Florida. Simulated field study conditions were used to evaluate collection, ambient (pre-retrieval) field storage, and freezer storage phases of stream water sampling. Method detection levels were developed for each herbicide in each water matrix. None of the herbicides degraded significantly in either stream water after 24 days at 22C to 25C or after 12 months of freezer storage below -15C. None of the herbicides tested appeared to leach from the automatic sampler tubing into subsequently collected samples. However, slight carryover of about 0.8% of the spiking level was observed in the first post-spike blanks collected for all herbicides. This appeared to be the result of physical adhesion of water droplets on tubing walls; no detectable carryover was observed in subsequent blanks. These results support the use of HDPE sample containers and flexible PVC automatic sampler tubing in environmental fate studies of herbicides.

Quantification of Six Phytoestrogens at the Nanogram per Liter Level in Aqueous Environmental Samples Using 13C3-Labeled Internal Standards

In light of the estrogenic potentials and the recent concentration levels found for six phytoestrogens in surface waters, detailed monitoring and assessment of potential input sources are required. An accurate, precise, and sensitive HPLC-MS/MS analytical method incorporating five (13)C 3-labeled internal standards for the quantification of these plant estrogens in various aqueous environmental samples is presented here for the first time. The compounds investigated included biochanin A, daidzein, equol, formononetin, genistein, and coumestrol. The use of [ (13)C 3]biochanin A, [ (13)C 3]daidzein, [ (13)C 3]equol, [ (13)C 3]formononetin, and [ (13)C 3]genistein ensured an accurate quantification of the target analytes unaffected by matrix effects and analyte losses. Absolute method recoveries for all analytes ranged from 63 to 105%, from 63 to 99%, and from 73 to 133%, relative recoveries from 90 to 132%, from 89 to 139%, and from 89 to 115%, method detection levels from 0.5 to 2.7 ng/L, from 0.5 to 2.6 ng/L, and from 0.4 to 11.0 ng/L, and precision from 1 to 19%, from 1 to 16%, and from 1 to 11% in drainage water, river water, and WWTP effluent, respectively. The validated analytical method was applied in investigating the emission of the phytoestrogens via drainage water from a pasture containing 43% red clover ( Trifolium pratense) and in monitoring their occurrence in Swiss surface waters. Isoflavone concentrations ranging from 4 to 157 ng/L and up to 22 ng/L were found in drainage and river water, respectively.

Data quality in water analysis: validation of ion chromatographic method for the determination of routine ions in potable water

Ion chromatography provides a simple, fast, small sample volume demanding, and fit-for-purpose methodology for the concurrent determination of 10 ions (F −, Cl −, Br −, NO 3 −, PO 4 3−, SO 4 2−, Na +, K +, Ca 2+ and Mg 2+) in surface, ground and potable water samples. Current law legislations, as well as the need to constantly provide accurate and reliable results, enforce public sector laboratories to practice quality management system, according to the EN ISO 17025 standard. In this paper, the work that was undertaken for the accreditation of the above determinations at the chemical laboratory of EYDAP SA, is presented. The laboratory has developed two in-house methods, which are carried out simultaneously by a dual chromatographic system. The method for the analysis of anions is based on the 4110B APHA standard method and the one for the cations based on the ISO14911. Deviations from the standard procedure made a full method validation imperative, therefore, for all 10 ions, method characteristics were determined and assessed towards the fitness-for-purpose scope (range of measurement, calibration, method detection level, level of quantification, repeatability, reproducibility, precision, accuracy, peak resolution). Additionally, measurement uncertainty was determined and procedures for daily measurement quality control, assessment of individual analyst capability, measurement, sample and reagent traceability, and regular participation in proficiency testing schemes were implemented. Methodology and results for method validation, uncertainty quantification and quality control is presented in detail in the full paper.

Temperature-Dependent Chemical-Specific Emission Rates of Aromatics and Polyaromatic Hydrocarbons (PAHs) in Bitumen Fume

Chemical-specific emission rates for simple aromatic and polycyclic aromatic hydrocarbon compounds (PAHs) from bitumens during hot mix asphalt (HMA) production and placement activities were evaluated using a headspace gas chromatography method. Temperature-dependent headspace concentrations of the EPA listed aromatic and polycyclic aromatic compounds were measured in the laboratory using headspace gas chromatographs equipped with a variety of detectors. The methodology has previously been calibrated and verified by a program of simultaneous laboratory and field tests, and is accurate in identifying field inhalation exposure potential to individual compounds in asphalt fumes. The results indicated that chemical-specific emission rates of aromatic and PAHs are strongly linked to both the performance grade of the asphalt binder and the binder temperature. Individual chemical compounds were quantified for 22 paving grade bitumen sources from throughout the United States. Chemical-specific emission rates from each binder were measured at a series of temperatures spanning the range, typically used for application of HMA, and at temperatures well in excess of those used for HMA applications in the United States. Emissions of all detected compounds increased with elevating temperature. The amount and composition of PAHs were markedly influenced by changes in temperature. At binder temperatures at or below 190°C, only very small amounts of mostly 2- and 3-ringed PAHs were emitted. Concentrations of individual two-ringed PAHs ranged from 0.5 to 11 μ g/m 3 at 150°C and ranged from 2.0 to 100 μ g/m 3 at 190°C. Concentrations of 3-ringed PAHs were below method detection level of 0.1 μ g/m 3 and ranged from 0.1 to 120 μ g/m 3 at 190°C. Larger ring number PAHs were below detection at 150°C and less than 10 μg/m 3 for 4-ringed PAHs at 190°C. As binder temperature increased above the typical limit for HMA production and application, several PAHs with greater ring numbers (4-, 5-, and 6-ringed PAHs) and more potent toxicity equivalency factors (carcinogenic potential) were detected.