Practical Limit Of Quantification Research Articles

Salting-out assisted liquid–liquid extraction combined with LC–MS/MS for the simultaneous determination of seven organic UV filters in environmental water samples: method development and application

Organic UV filters (OUVFs), the active ingredient in sunscreens, are of environmental concern due to reported ecotoxicological effects in aquatic biota. Determining the environmental concentrations of these chemicals is essential for understanding their fate and potential environmental risk. Salting‐out assisted liquid–liquid extraction (SALLE) coupled with liquid-chromatography tandem mass spectrometry (LC–MS/MS) was developed for simultaneous extraction, separation, and quantification of seven OUVFs (2,4-dihydroxybenzophenone, 2,2′,4,4′-tetrahydroxybenzophenone, 4-methylbenzylidene camphor, butyl-methoxy-dibenzoyl methane, octocrylene, octyl methoxycinnamate, and oxybenzone). Method detection limits (MDLs) ranged from 11 to 45 ng/L and practical quantification limits (PQLs) from 33 to 135 ng/L. Method trueness, evaluated in terms of recovery, was 69–127%. Inter-day and intra-day variability was < 6% RSD. The coefficients of determination were > 0.97. The method was applied to river and seawater samples collected at 19 sites in and near Port Phillip Bay, Australia, and temporal variation in OUVF concentrations was studied at two sites. Concentrations of OUVF were detected at 10 sites; concentrations of individual OUVFs were 51–7968 ng/L, and the maximum total OUVF concentration detected at a site was 8431 ng/L. Recreational activity and water residence time at the site contributed to OUVF’s environmental presence and persistence. The benefits of the SALLE-LC–MS/MS method include its simple operation, good selectivity, precision over a wide linear range, and that obtained extracts can be directly injected into the LC–MS/MS, overall making it an attractive method for the determination of these OUVFs in environmental water matrices. To our knowledge, this is the first report of the occurrence of OUVFs in Port Phillip Bay, Australia.

Toward the Detection Limit of Electrochemistry: Studying Anodic Processes with a Fluorogenic Reporting Reaction.

Recently, shot noise has been shown to be an inherent part of all charge-transfer processes, leading to a practical limit of quantification of 2100 electrons (≈0.34 fC) [ Curr. Opin. Electrochem. 2020, 22, 170-177]. Attainable limits of quantification are made much larger by greater background currents and insufficient instrumentation, which restricts progress in sensing and single-entity applications. This limitation can be overcome by converting electrochemical charges into photons, which can be detected with much greater sensitivity, even down to a single-photon level. In this work, we demonstrate the use of fluorescence, induced through a closed bipolar setup, to monitor charge-transfer processes below the detection limit of electrochemical workstations. During this process, the oxidation of ferrocenemethanol (FcMeOH) in one cell is used to concurrently drive the oxidation of Amplex Red (AR), a fluorogenic redox molecule, in another cell. The spectroelectrochemistry of AR is investigated and new insights on the commonplace practice of using deprotonated glucose to limit AR photooxidation are presented. The closed bipolar setup is used to produce fluorescence signals corresponding to the steady-state voltammetry of FcMeOH on a microelectrode. Chronopotentiometry is then used to show a linear relationship between the charge passed through FcMeOH oxidation and the integrated AR fluorescence signal. The sensitivity of the measurements obtained at different timescales varies between 2200 and 500 electrons per detected photon. The electrochemical detection limit is approached using a diluted FcMeOH solution in which no faradaic current signal is observed. Nevertheless, a fluorescence signal corresponding to FcMeOH oxidation is still seen, and the detection of charges down to 300 fC is demonstrated.

Rapid determination of malondialdehyde in serum samples using a porphyrin-functionalized magnetic graphene oxide electrochemical sensor

An electrochemical sensor based on a screen-printed carbon electrode (SPCE) modified with porphyrin-functionalized magnetic graphene oxide (TCPP-MGO) was developed for the sensitive and selective determination of malondialdehyde (MDA), an important biomarker of oxidative damage, in serum samples. The coupling of TCPP with MGO allows the exploitation of the magnetic properties of the material for separation, preconcentration, and manipulation of analyte, which is selectively captured onto the TCPP-MGO surface. The electron-transfer capability in the SPCE was improved through derivatization of MDA with diaminonaphthalene (DAN) (MDA-DAN). TCPP-MGO-SPCEs have been employed to monitor the differential pulse voltammetry (DVP) levels of the whole material, which is related to the amount of the captured analyte. Under optimum conditions, the nanocomposite-based sensing system has proved to be suitable for the monitoring of MDA, presenting a wide linear range (0.01–100 µM) with a correlation coefficient of 0.9996. The practical limit of quantification (P-LOQ) of the analyte was 0.010 µM, and the relative standard deviation (RSD) was 6.87% for 30 µM MDA concentration. Finally, the developed electrochemical sensor has demonstrated to be adequate for bioanalytical applications, presenting an excellent analytical performance for the routine monitoring of MDA in serum samples.Graphical abstract

A validated square‐wave voltammetric method for simultaneous determination of two insecticide metabolites: 3,5,6‐trichloro‐2‐pyridinol and malathion diacid and their binding constants with human serum albumin

AbstractA proposed validated square‐wave voltammetric method and high‐performance liquid chromatography, as a comparative method, are applied to measure simultaneously two metabolites‐ of current use pesticides‐ namely 3,5,6‐trichloro‐2‐pyridinol and malathion dicarboxylic acid. Method validation and quality control parameters are studied. Method detection limits are found to be 0.043 and 0.061 μg/ml for 3,5,6‐trichloro‐2‐pyridinol and malathion dicarboxylic acid, respectively whereas the practical quantification limits are found to be 0.135 and 0.193 μg/ml (voltammetry), 0.05 and 0.1 μg/ml (high‐performance liquid chromatography) for 3,5,6‐trichloro‐2‐pyridinol and malathion dicarboxylic acid, respectively. The application of the proposed method for the analysis of water samples collected from different sources has been assessed. The interaction of these metabolites with human serum albumin was studied, a 1:1 association complex was formed and their binding constants were evaluated through the calculation to be 0.30 × 102/M for 3,5,6‐trichloro‐2‐pyridinol and 8.414 × 103/M for malathion dicarboxylic acid. The low value of the binding of 3,5,6‐trichloro‐2‐pyridinol metabolite indicates that this metabolite is more likely to be more toxic than the other metabolite.

SERS-Based Methodology for the Quantification of Ultratrace Graphene Oxide in Water Samples.

The extensive use of graphene materials in real-world applications has increased their potential release into the environment. To evaluate their possible health and ecological risks, there is a need for analytical methods that can quantify these materials at very low concentrations in environmental media such as water. In this work, a simple, reproducible, and sensitive method to detect graphene oxide (GO) in water samples using the surface-enhanced Raman spectroscopy (SERS) technique is presented. The Raman signal of graphene is enhanced when deposited on a substrate of gold nanoparticles (AuNPs), thus enabling its determination at low concentrations with no need for any preconcentration step. The practical limit of quantification achieved with the proposed method was 0.1 ng mL–1, which is lower than the predicted concentrations for graphene in effluent water reported to date. The optimized procedure has been successively applied to the determination of ultratraces of GO in water samples.

Shot noise sets the limit of quantification in electrochemical measurements

Abstract Detection of single molecules, particles, and rapid redox events is a challenge of electrochemical investigations and requires either an amplification strategy or significant averaging in order to boost the electrochemical current above the noise level. We consider the minimum number of electrons required to reach the limit of quantification in these electrochemical measurements. A survey of the literature indicates that the state-of-the-art limit in current detection for different types of measurements (e.g., voltammetry, single-molecule redox cycling, ion channel recordings of single molecules, metal nanoparticle collision, phase nucleation, etc.) is independent of the nature of the measurement and increases linearly with reciprocal response time, Δt-1, over ∼5 orders of magnitude (from ∼10 to ∼106 s-1). We demonstrate that the practical limit of quantification requires cumulative measurement of ∼2,100 electrons during Δt, and is determined by statistics of counting electrons, i.e., the shot noise in the current.

Linear calibrations in chromatography: The incorrect use of ordinary least squares for determinations at low levels, and the need to redefine the limit of quantification with this regression model.

Ordinary least squares is widely applied as the standard regression method for analytical calibrations, and it is usually accepted that this regression method can be used for quantification starting at the limit of quantification. However, it requires calibration being homoscedastic and this is not common. Different calibrations have been evaluated to assess whether ordinary least squares is adequate to quantify estimates at low levels. All calibrations evaluated were linear and heteroscedastic. Despite acceptable values for precision at limit of quantification levels were obtained, ordinary least squares fitting resulted in significant and unacceptable bias at low levels. When weighted least squares regression was applied, bias at low levels was solved and accurate estimates were obtained. With heteroscedastic calibrations, limit values determined by conventional methods are only appropriate if weighted least squares are used. A "practical limit of quantification" can be determined with ordinary least squares in heteroscedastic calibrations, which should be fixed at a minimum of 20 times the value calculated with conventional methods. Biases obtained above this "practical limit" were acceptable applying ordinary least squares and no significant differences were obtained between the estimates measured using weighted and ordinary least squares when analyzing real-world samples.

Method validation for direct determination of some trace and toxic elements in soft drinks by inductively coupled plasma mass spectrometry

ABSTRACT The consumption of soft drink beverages has increased in the last few years around the world and it is related to the diversity of brands and flavours available, increasing also the risk of ingestion of compounds considered non-beneficial to the health of consumers. In this study, fast, easy and simple method of analysis for direct determination of As, Pb, Cd, Sb, Hg, Cu, Zn, Fe, Al, Cr, Sn, Co, Mn and Ni in soft drink samples using quadrupole inductively coupled plasma mass spectrometry (Q-ICP–MS) was validated. The estimated detection limits, practical quantification limits, linearity (linear dynamic ranges and method linearity), accuracy (trueness and precision) and measurement uncertainty parameters were studied under optimised (Q-ICP–MS) conditions. The method showed that the estimated detection limits were varied between 0.02 and 2.403 µg/L, and the quantification limits were varied between 0.5 and 20 µg/L. The mean recoveries ± standard deviations at different spiking levels were varied between 75.03 ± 0.62% and 117.07 ± 2.83% and the coefficients of variation were varied between 0.49% and 9.79%. The method trueness was confirmed by using four different certified reference materials (soft drinks and treated water) purchased from FAPAS (Food Analysis Performance Assessment Scheme) and all obtained results were within satisfactory ranges and had acceptable recovery and Z-score values. The method precision, in terms of relative standard deviation, was below 4.88%. The method uncertainty expressed as expanded uncertainty of all validated elements was found to be ≤22.52%. The results obtained make the method suitable for accurate determination of validated elements in different kinds of soft drink samples at these low concentration values. Validated method was used for the determination of metallic contaminants in 40 commercial soft drink samples and the results were compared with the provisional guideline of the elements stated by Egyptian, WHO and European standards in drinking and potable bottled natural mineral water.

Analytical Method Validation and Determination of Iron and Phosphorus in Vegetable Oil by Inductively Coupled Plasma–Mass Spectrometry with Microwave Assisted Digestion

ABSTRACTInductively coupled plasma–mass spectrometric determination of iron and phosphorus in three vegetable oils (soybean, coconut, and sunflower) was validated for the intermediate precision, trueness, linearity, and quantitation limit. The overall precision (n = 5) for the analytes, which were above the method’s practical limit of quantification, were less than 2% relative standard deviation and the same as the laboratory control, NIST-SRM-1849a. Trueness was demonstrated with spike recoveries of the analytes in all vegetable oils at limit of quantification-level spiking. Although good linearity (regression coefficient greater than 0.9990) obtained, the recovery of phosphorus (156–189%) was high, possibly due to oil matrix enhancement, compared to the recovery of iron (91–106%). For soybean oil, sunflower oil, coconut oil, and medium chain triglycerides, the concentrations (mg/kg) of iron were in the range of 0.10–1.47, 0.09–1.51, 0.20–0.35, and 0.09–0.13, respectively. Similarly, phosphorus concentrations (mg/kg) were in the range of 0.77–124.56, 0.49–125.57, 0.52–9.72, and 0.85–11.90, respectively. The study achieved considerably low instrument-based practical limits of quantification for iron (0.005 mg/kg) and phosphorus (0.05 mg/kg), which are fivefold lower than the AOAC Official Method 2015.06. The high instrument sensitivity and selectivity of the method allow the determination of trace levels of iron and phosphorus in vegetable oils with good precision and trueness.

Evaluation of the rotating disk sorptive extraction technique with polymeric sorbent for multiresidue determination of pesticides in water by ultra-high-performance liquid chromatography–tandem mass spectrometry

The use of pesticides has been associated with the increase of productivity of crops and control of vectors that cause diseases. However, excessive use of these compounds can cause human health and environmental problems, especially regarding to water resources. In this work, a method for multiresidue determination of 62 pesticides in surface water using the rotating disk sorptive extraction (RDSE) technique for sample preparation and ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC–MS/MS) for analysis was optimized and validated. The parameters time and rotational disk velocity for the extraction step, types and amounts of sorbents, sample pH, ionic strength, time and velocity of the rotating disk in the desorption step, as well different desorption solvents were evaluated. The best results were obtained using 50mL of sample, acidified at pH 2.0, and 2.5g of sodium chloride. The selected velocity of rotation in the extraction step was 1600rpm for 80min. Inside the disk cavity, a small amount (20mg) of the polymeric sorbent Oasis® HLB was used. The desorption step was performed immerging the disk in 3mL of methanol and rotating the disk at 1600rpm for 60min. Procedural calibration curves showed linearity between 0.05 or 0.1–2μgL−1, with r2>0.99 for all compounds. The method presented practical limit of quantification of 0.05 or 0.1μgL−1 and suitable accuracy and precision, with recoveries from 70.1 to 119.9% and RSD≤20% for the levels 0.05, 0.1, 0.5 and 2μgL−1. The validated method was applied to surface water samples from different river and residues of atrazine, azoxystrobin, clomazone, difenoconazole, epoxiconazole, propoxur, simazine and tebuconazole were found in the range of 0.06–0.35μgL−1. The results indicate that the proposed method is suitable for the determination of pesticide residues in surface water, allowing an easy and simultaneously preparation of several samples with low material consumption.

Determination of furfurals in Manuka honey using piston-cylinder liquid–liquid extraction and gas chromatography

A rapid analytical approach for the direct measurement of furfurals such as 2-furfural and 5-methyl-2-furfural at parts-per-billion level in Manuka honey is described. The approach employs a piston-cylinder based liquid–liquid extraction device using chloroform extraction solvent. This device substantially reduces extraction time by a factor of 120 times compared to solid phase micro-extraction and reduces solvent consumption by a factor of 25 times compared to liquid–liquid extraction with mechanical agitation. A recently commercialised capillary column offering a high degree of inertness permits separation and detection of the analytes at ultra-trace level without derivatisation. A three-port planar microfluidic device with a mid-point pressure is also incorporated to back-flush heavier compounds in the matrix to improve column longevity and overall system cleanliness. With this approach, analysis is conducted in less than 7min. Repeatability of retention times for all compounds is less than 0.1% (n=20). The compounds cited can be analysed over a range from 1ng/g to 10μg/g in honey with a 5ng/g limit of quantification (LOQ) and correlation coefficients of at least 0.999. Relative precision is less than 2.8% RSD (n=20) at 50ng/g level with analyte extraction efficiency of greater than 99% (n=3) over a range from 5ng/g to 10μg/g in the matrix described. The analytical system requires only minimal maintenance and is suitable for remote site deployment. Under the analytical conditions established and with a practical LOQ of 5ng/g, 100 samples can be analysed before septum/liner/o-ring replacements are needed. As a preventive measure, the pre-column can be replaced once every six months to maintain chromatographic fidelity.

Exploring alternative hapten tethering sites for high-affinity anti-picoxystrobin antibody generation

The relevance of the linker tethering site in haptens was investigated for antibody generation and immunoassay development. Three derivatives of the strobilurin fungicide picoxystrobin were synthesized with the same functionalized spacer arm located at three different positions. Protein conjugates of those haptens were employed as immunogens, and novel polyclonal antibodies were produced and characterized. All haptens afforded highly specific antibodies, but different affinities to the free analyte were observed among the obtained antisera. Next, competitive enzyme-linked immunosorbent assays were studied in several formats, and site heterology was confirmed as an effective strategy for detectability improvement. An indirect heterologous immunoassay was eventually selected and optimized, showing a limit of detection for picoxystrobin of 0.02 μg/L and a working range between 0.03 and 1.30 μg/L. Finally, the developed extraction and analytical procedures revealed a practical limit of quantification of 5 μg/kg for this fungicide in soybean sprouts, well below the maximum residue limits in the European Union.

A statistical approach for evaluation of PCR results to improve the practical limit of quantification (LOQ) of GMO analyses (SIMQUANT)

The predominant approach for quantification of genetically modified organisms (GMO) is the application of quantitative real-time PCR. However, for a large number of processed food and feed products, this approach is unsuitable, because they contain low amounts (mass) of amplifiable DNA. Here we present a novel approach, “Single molecule quantification” (SIMQUANT) for GMO quantification of samples with extremely low amounts of DNA. The approach is based on statistics and application of multiple qualitative parallel PCRs. Here the qualitative PCRs were done using real-time PCR setup, but this is not a requirement. The difference is that the quantitative real-time PCR requires that the target copy number exceeds the absolute limit of quantification (LOQabs) and provides quantity estimates by extrapolation from a linear regressional relationship between an observed cycle threshold (Ct) value and copy numbers, while with SIMQUANT the template DNA typically contains very few, e.g., one target copy per PCR volume and the quantity is estimated on the basis of observed ratio between positive and negative individual PCRs. The components of this analysis are the numbers of test samples, the size of each sample and the outcome in number and relative ratio of positive and negative test results. The approach results in a statistical estimate of the relative GM concentration based on the probability that one or more amplifiable GM template copies are present in discrete volumes. Thus, the approach is based on the ratio of discrete volumes without or with one or more PCR-amplifiable GM target copies. The approach described here can be used reliably with more than a 100-fold improvement of the practical LOQ (LOQpract) compared to real-time quantitative PCR based on standard curves.

Levels of polychlorinated biphenyls (PCBs) in transformer oils from Korea

Using Korean waste official method, polychlorinated biphenyls (PCBs) were analyzed from 33 transformer oils collected under National Institute of Environmental Research (NIER) in Republic of Korea (ROK) and their emission rate in Korea was estimated. Practical quantification limits analyzed by this method were in the ranges of 0.02 and 0.05 mg L −1, and recovery of samples was in the ranges of 77–97%. The analytical results showed that PCBs in the transformer oils were identified as Aroclor 1242, 1254 or 1260. Twenty-nine samples were determined to contain PCBs of >0.05 mg L −1 and among these samples, nine samples contained to have >2 mg kg −1 which is limit of Waste Control Act (WCA) with regard to PCBs in transformer oil from Korea. The concentrations of PCBs in transformer oils were between N.D. (not detected) and 48.33 mg kg −1. PCBs concentrations did not exceed 50 mg kg −1 which is generally accepted limit for the definition of waste in POPs Guideline of Basel Convention.

Analysis of major components of residual bacitracin and colistin in food samples by liquid chromatography tandem mass spectrometry

A selective and sensitive liquid chromatography tandem mass spectrometric (LC–MS/MS) method has been developed for simultaneous determination of residual bacitracin and colistin in bovine milk samples. Milk samples were deproteinized and extracted with a mixture of trichloroacetic/formic acid. After centrifugation, bacitracin and colistin in the extracts were separated on a reversed phase Alltima BDS C 18 column (250 mm × 2.1 mm, 5 μm) using a gradient elution programme of ammonium formate buffer (saturated ammonium formate:formic acid:acetonitrile:water, 1:5:50:950, v/v/v/v) and 0.1% formic acid in acetonitrile at 0.2 ml min −1. Using electrospray LC–MS/MS with time-scheduled multiple reaction monitoring (MRM), identification and quantification of the major components of the two polypeptides were performed based upon the intensities of mass fragments from the respective doubly charged precursor ions: bacitracin A at 712 → 199 amu and 712 → 227 amu, and colistin A at 586 → 101 amu, 586 → 202 amu and 586 → 241 amu, respectively, at the defined retention time windows and the matching of the specific tolerance of the relative abundance of the monitored ions. Polymyxin B, a polypeptide of colistin family, was employed as the internal standard. With an additional solid phase extraction procedure, the analytical method was applicable to the analysis of the two polypeptide antibiotics in animal's liver and tissue samples. The practical quantification limits of bacitracin A and colistin A were 100 and 50 μg kg −1; and mean intra-day ( n = 7) and inter-day ( n = 4) recoveries were in the range of 89.2–110% (R.S.D. < 10%), and 90.4–112% (R.S.D. < 13%) respectively in all matrices.

Protocol Development for Assessing Arsenic Background Concentrations in Florida Urban Soils

Knowledge of arsenic background concentrations in urban soils is important for making remediation decisions. The soil cleanup target level (SCTL) for arsenic in Florida lies within the range of arsenic background concentrations. The residential SCTL is also near the practical quantification limits using analytical procedures. Currently no standard protocols are available for determining arsenic background concentrations in urban soils, apart from site-specific cases. Therefore, a pilot study was conducted to develop and employ appropriate protocols to determine arsenic distribution in urban soils. This involved: site selection (e.g. size and sampling frame), sample collection (e.g. sampling technique), and statistical considerations (e.g. design). Factors such as ease of sample collection and maintaining anonymity of private properties were also considered as they influence the successful implementation of the study. Forty surface soil samples each were collected from five categories in three land use classes (residential-yard and right-of-way, commercial and public land-parks and public building), digested using EPA method 3051a and analysed using graphite furnace atomic absorption spectrometry. Experiences from the pilot study (e.g. complications during sample selection, digestion, data censoring etc.) were used in the development of the final protocol to be used in determining the distribution of arsenic in urban areas.

Development of an analytical technique and stability evaluation of 143 C3-C12 volatile organic compounds in Summa canisters by gas chromatography-mass spectrometry.

A technique using Summa canisters with cryogenic preconcentration and gas chromatographic-mass spectrometric (GC-MS) detection was developed to determine 143 C3-C12 volatile organic compounds (VOCs) including alkanes, alkenes, aromatics and halohydrocarbons in ambient and indoor air. The method detection limits and practical quantification limits were sensitive at 0.02 and 0.10 ppbv, respectively, and the method precision and accuracy were also satisfactory. The stability of C3-C12 VOC standards at ppbv levels under elevated pressure in canisters was assessed over various time intervals (from 1 week to 4 months after preparation) and most of the compounds were found to be acceptably stable with a mean recovery of 85.6 +/- 9.9% during the course of a 4-month study. However, a small fraction (approximately 6%) of the compounds, including two halohydrocarbons (bromotrichloromethane and benzyl chloride) and six alkenes (2-methylbuta-1,3-diene (isoprene), cis-4-methylpent-2-ene, cis-3-methylpent-2-ene, hept-1-ene, oct-1-ene and styrene) displayed relatively low recoveries in the range 34.6-67.9%. The loss of these compounds is most probably caused by their physical adherence to the active sites of the canister surface, chemical decomposition and/or reactions with other species. The results indicated that one must be cautious in attempting to measure these compounds owing to their instability in canisters. Overall, this analytical technique, which has been used for the determination of the VOCs under study in the toxic air pollutant monitoring network administered by the HKSAR Government, was amenable to the measurement of airborne VOCs collected both outside and inside a semi-confined car park in the present study.

Determination of amoxicillin in human serum and plasma by high-performance liquid chromatography and on-line postcolumn derivatisation

A highly selective, sensitive and fast HPLC method was developed for the determination of amoxicillin in human serum and plasma. After protein precipitation with perchloric acid, an aliquot of the supernatant was neutralized by mixing it with sodium acetate solution and injected into a C 18 HPLC column. Detection was done by a fluorescence detector after on-line postcolumn derivatisation with fluorescamine. The practical limit of quantification was 0.1 μg/ml using 0.3 ml of plasma. Linearity was given in the tested range of 0.1 to 15 μg/ml plasma. Inter-day precision (relative standard deviation) over 7 days for 0.42 μg/ml was ±7.27%; for 4.54 μg/ml, ±5.24% and for 13.18 μg/ml, ±5.25%. Stability over 50 days in serum and plasma occurs at −70°C but not at −20°C (−25 to −35% reduction). This method was used for thousands of human serum and plasma samples.

HRGC/HRMS analysis of hazardous waste incinerator scrubber water for PCDDs and PCDFs

A multi-laboratory study was conducted using the U.S. EPA HRGC/HRMS Method 8290 to establish realistic method detection and practical quantification limits for 2,3,7,8-substituted polychlorodibenzo-p-dioxins (PCDDs) and 2,3,7,8-substituted polychlorodibenzofurans (PCDFs) in hazardous waste incinerator scrubber water. The data were required by the U.S. Environmental Protection Agency to establish guidelines for the disposal of PCDD- and PCDF-contaminated scrubber water.

Determination of chloroacetyl chloride in air by high-performance liquid chromatography

An HPLC procedure has been developed for the determination of chloroacetyl chloride (CAC) in air. CAC is collected on Tenax-GC coated with 9-((N-methylamino)methyl)anthracene (MAMA) packed in glass tubes. The MAMA acts as an in situ derivatizing agent for CAC, and the resulting amide is solvent desorbed from the Tenax support and analyzed by HPLC with fluorescence detection. Standard vapor concentrations of CAC were generated in silanized glass for laboratory validation in the range of 5-2500 ppb CAC based on a 5-L air sample. The average recovery was 79% with a pooled relative standard deviation of 0.083. Up to 100 L of air was sampled and similar recoveries were obtained implying a practical limit of quantification 1 ppb. The limit of detection for the MAMA derivative of CAC, N-(9-anthracenylmethyl)-2-chloro-N-methylacetamide, under optimal conditions is less than 1 pg. 12 references, 1 figure, 2 tables.