Estimated Method Detection Limit Research Articles

Determination of fentanyl and acetylfentanyl in soil in their intact form and orthogonal corroboration of their presence by EI-GC-MS using chloroformate chemistry

In the field of forensic chemistry, methods for identifying and characterizing illicit drugs remain of great interest to government and law enforcement entities. To this end, the unambiguous identification of a drug in the environment (e.g., soil) prompts further investigation into the possibility of a clandestine point of production for such drug. In this report, a method for the analysis of the two common synthetic opioids fentanyl and acetylfentanyl in a soil matrix when present separately at 1 and 10 μg/g by electron ionization gas chromatography-mass spectrometry (EI-GC-MS) is presented. The method involves the initial extraction of the intact opioids followed by their reaction with 2,2,2-trichloroethoxycarbonyl chloride (Troc-Cl) to predictably generate Troc-modified norfentanyl, Troc-noracetylfentanyl and 2-phenylethyl chloride products that can be used to retrospectively corroborate the identity of the opioid by EI-GC-MS. Estimated method detection limits (MDLs) for the Troc-norfentanyl and Troc-noracetylfentanyl species were 15.4 and 13.6 ng/mL respectively from the soil matrix extracts employed (Virginia type A soil) while the calculated method’s LOQ values were 45.7 and 40.4 ng/mL respectively. The protocol presented herein describes for the first time the analysis of these highly toxic and common synthetic opioids in a soil matrix as well as their retrospective confirmation by analyzing the products arising from their reaction with Troc-Cl by EI-GC-MS.

Hyoscyamine and Scopolamine in Honey by HILIC–ESI-MS/MS

A simple but effective method was developed for the ultra-trace determination of two tropane alkaloid residues, hyoscyamine and scopolamine, in honey. Honey samples were dissolved in a concentrated aqueous solution of sodium acetate from which the alkaloids were subsequently extracted using acetonitrile. The resulting extract was analyzed using HILIC–ESI-MS/MS without any additional extract cleanup or enrichment steps. Enhanced sensitivity associated with the combination of HILIC and ESI-MS/MS techniques permitted the quantitation of the two tropane alkaloids at concentrations as low as 0.01 µg kg−1. The use of isotopically labelled analogs permitted accuracies ranging from 86.9 to 106.1% for honey samples fortified at 0.02, 0.2 and 2 µg kg−1 with precisions ranging from 0.8 to 6.2%. The estimated method detection limits for hyoscyamine and scopolamine were 0.002 and 0.003 µg kg−1, respectively. Twenty-three samples of honey were analyzed and only two samples were found to contain residues of the tropane alkaloids at concentrations above the limit of quantitation of 0.01 µg kg−1. Hyoscyamine was detected at 0.012 µg kg−1 in two honey samples, one of which also contained 0.012 µg kg−1 of scopolamine.

Determination of ultra-trace level of 232Th in seawater by ICP-SFMS after matrix separation and preconcentration

This article describes the development and validation of an analytical procedure for the matrix separation, preconcentration and determination of sub-ng kg−1 levels 232Th in a small volume (20 mL) of seawater samples. The matrix separation and Th preconcentration was carried out using a commercially available ion-chelation system seaFAST-pico. The acidified to pH < 2 seawater samples were mixed on-line with the ammonium acetate buffer (pH of 6.0 ± 0.2) before loading on the column containing resin with iminodiacetic and ethylenediaminetriacetic functional groups. At this pH, 232Th was quantitatively retained on the resin, demonstrating a good affinity (selectivity) for Th in seawater matrix. The element retained on the resin was eluted using only 0.2 mL of 1.8 M HNO3 enabling to achieve high preconcentration factor. The pretreatment procedure, with two sample loading cycles (each one 10 mL), was accomplished in about 25 min. Determining 232Th mass fraction in seawater samples was based on isotope dilution inductively coupled plasma mass spectrometry (ID ICP-MS) method, which was considered as the most accurate calibration strategy for precise quantification of 232Th mass fraction in seawater samples. ISO/IEC17025 and Eurachem guidelines were followed to perform the validation of the developed in this study procedure. In the case of seawater samples with natural level of thorium the major contributions to the expanded uncertainty arose from the uncertainty associated with isotopic ratio measurements in the isotopically spiked sample, followed by the correction for procedural blank and the correction for mass discrimination effect. The estimated method detection limit for 232Th was 0.005 ng kg−1. The developed method was successfully applied to the determination of 232Th mass fraction in seawater reference samples: IAEA-443, SLEW-3, NASS-4, NASS-6, and CASS-5. Although 232Th is not certified in any of the seawater reference materials, a good agreement was obtained between the results in this study and data published elsewhere.

Validation of QuEChERS method for the determination of some pesticide residues in two apple varieties

ABSTRACTThis study was undertaken to validate the “quick, easy, cheap, effective, rugged and safe” (QuEChERS) method using Golden Delicious and Starking Delicious apple matrices spiked at 0.1 maximum residue limit (MRL), 1.0 MRL and 10 MRL levels of the four pesticides (chlorpyrifos, dimethoate, indoxacarb and imidacloprid). For the extraction and cleanup, original QuEChERS method was followed, then the samples were subjected to liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) for chromatographic analyses. According to t test, matrix effect was not significant for chlorpyrifos in both sample matrices, but it was significant for dimethoate, indoxacarb and imidacloprid in both sample matrices. Thus, matrix-matched calibration (MC) was used to compensate matrix effect and quantifications were carried out by using MC. The overall recovery of the method was 90.15% with a relative standard deviation of 13.27% (n = 330). Estimated method detection limit of analytes blew the MRLs. Some other parameters of the method validation, such as recovery, precision, accuracy and linearity were found to be within the required ranges.

Orthogonal zirconium diol/C18 liquid chromatography–tandem mass spectrometry analysis of poly and perfluoroalkyl substances in landfill leachate

Leachates coming from landfills contain a myriad of compounds of potential environmental and human health concern, including per- and polyfluorinated alkyl substances (PFASs). Micro liquid-liquid extraction was combined with a 900μl large volume injection (LVI) for the analysis of 70 PFASs in landfill leachate by orthogonal LC-MS/MS. The LVI approach introduced 7 times more extract than conventional injection approaches. Two zirconium-modified diol guard columns effectively retained PFASs from the organic leachate extract and an analytical C18 column was used for separation. Method accuracy and precision for PFASs with analytical grade reference materials ranged from 81–120% and 5.5–33%, respectively. Estimated method detection limits in the low to sub-ng/L. Seven landfill leachates were analyzed by the optimized analytical method for the purposes of method demonstration. Leachates were characterized by a wide variety of PFASs, reporting on 36 previously-unanalyzed PFASs in leachate. Perfluoroalkyl carboxylates were the most abundant class detected while phosphorous-containing PFASs, present in all leachates, were at low concentrations. The 3-perfluoropentyl propanoate (5:3 FTCA) was the most concentrated analyte in most samples and constitutes a previously unreported but significant component of landfill leachate.

Determination of polychlorinated biphenyls in soil and sediment by selective pressurized liquid extraction with immunochemical detection

A selective pressurized liquid extraction (SPLE) method was developed for a streamlined sample preparation/cleanup to determine Aroclors and coplanar polychlorinated biphenyls (PCBs) in soil and sediment. The SPLE was coupled with an enzyme-linked immunosorbent assay (ELISA) for an effective analytical approach for environmental monitoring. Sediment or soil samples were extracted with alumina, 10% AgNO3 in silica, and sulfuric acid impregnated silica with dichloromethane at 100°C and 2000psi. The SPLE offered simultaneous extraction and cleanup of the PCBs and Aroclors, eliminating the need for a post-extraction cleanup prior to ELISA. Two different ELISA methods: (1) an Aroclor ELISA and (2) a coplanar PCB ELISA were evaluated. The Aroclor ELISA utilized a polyclonal antibody (Ab) with Aroclor 1254 as the calibrant and the coplanar PCB ELISA kit used a rabbit coplanar PCB Ab with PCB-126 as the calibrant. Recoveries of Aroclor 1254 in two reference soil samples were 92±2% and 106±5% by off-line coupling of SPLE with ELISA. The average recovery of Aroclor 1254 in spiked soil and sediment samples was 92±17%. Quantitative recoveries of coplanar PCBs (107–117%) in spiked samples were obtained with the combined SPLE–ELISA. The estimated method detection limit was 10ngg−1for Aroclor 1254 and 125pgg−1 for PCB-126. Estimated sample throughput for the SPLE–ELISA was about twice that of the stepwise extraction/cleanup needed for gas chromatography (GC) or GC/mass spectrometry (MS) detection. ELISA-derived uncorrected and corrected Aroclor 1254 levels correlated well (r=0.9973 and 0.9996) with the total Aroclor concentrations as measured by GC for samples from five different contaminated sites. ELISA-derived PCB-126 concentrations were higher than the sums of the 12 coplanar PCBs generated by GC/MS with a positive correlation (r=0.9441). Results indicate that the SPLE–ELISA approach can be used for quantitative or qualitative analysis of PCBs in soil and sediments. To our knowledge, this is the first report of an SPLE–ELISA approach not requiring a post-extraction cleanup step for detecting Aroclors and coplanar PCBs in soil and sediment.

A gas chromatographic instrument for measurement of hydrogen cyanide in the lower atmosphere

Abstract. A gas-chromatographic (GC) instrument was developed for measuring hydrogen cyanide (HCN) in the lower atmosphere. The main features of the instrument are (1) a cryogen-free cooler for sample dehumidification and enrichment, (2) a porous polymer PLOT column for analyte separation, (3) a flame thermionic detector (FTD) for sensitive and selective detection, and (4) a dynamic dilution system for calibration. We deployed the instrument for a ∼4 month period from January–June, 2010 at the AIRMAP atmospheric monitoring station Thompson Farm 2 (THF2) in rural Durham, NH. A subset of measurements made during 3–31 March is presented here with a detailed description of the instrument features and performance characteristics. The temporal resolution of the measurements was ~20 min, with a 75 s sample capture time. The 1σ measurement precision was &lt;10% and the instrument response linearity was excellent on a calibration scale of 0.10–0.75 ppbv (±5%). The estimated method detection limit (MDL) and accuracy were 0.021 ppbv and 15%, respectively. From 3–31 March 2010, ambient HCN mixing ratios ranged from 0.15–1.0 ppbv (±15%), with a mean value of 0.36 ± 0.16 ppbv (1σ). The approximate mean background HCN mixing ratio of 0.20 ± 0.04 ppbv appeared to agree well with tropospheric column measurements reported previously. The GC-FTD HCN measurements were strongly correlated with acetonitrile (CH3CN) measured concurrently with a proton transfer-reaction mass spectrometer (PTR-MS), as anticipated given our understanding that the nitriles share a common primary biomass burning source to the global atmosphere. The nitriles were overall only weakly correlated with carbon monoxide (CO), which is reasonable considering the greater diversity of sources for CO. However, strong correlations with CO were observed on several nights under stable atmospheric conditions and suggest regional combustion-based sources for the nitriles. These results demonstrate that the GC-FTD instrument is capable of making long term, in-situ measurements of HCN in the lower atmosphere. To date, similar measurements have not been performed, yet they are critically needed to (1) better evaluate the regional scale distribution of HCN in the atmosphere and (2) discern the influence of biomass burning on surface air composition in remote regions.

Persistence of pyrazosulfuron in rice‐field and laboratory soil under Indian tropical conditions

Pyrazosulfuron ethyl, a new rice herbicide belonging to the sulfonylurea group, has recently been registered in India for weed control in rice crops. Many field experiments revealed the bioefficacy of this herbicide; however, no information is available on the persistence of this herbicide in paddy soil under Indian tropical conditions. Therefore, a field experiment was undertaken to investigate the fate of pyrazosulfuron ethyl in soil and water of rice fields. Persistence studies were also carried out under laboratory conditions in sterile and non-sterile soil to evaluate the microbial contribution to degradation. High-performance liquid chromatography (HPLC) of pyrazosulfuron ethyl gave a single sharp peak at 3.41 min. The instrument detection limit (IDL) for pyrazosulfuron ethyl by HPLC was 0.1 µg mL(-1) , with a sensitivity of 2 ng. The estimated method detection limit (EMDL) was 0.001 µg mL(-1) and 0.002 µg g(-1) for water and soil respectively. Two applications at an interval of 10 days gave good weed control. The herbicide residues dissipated faster in water than in soil. In the present study, with a field-soil pH of 8.2 and an organic matter content of 0.5%, the pyrazosulfuron ethyl residues dissipated with a half-life of 5.4 and 0.9 days in soil and water respectively. Dissipation followed first-order kinetics. Under laboratory conditions, degradation of pyrazosulfuron ethyl was faster in non-sterile soil (t(1/2) = 9.7 days) than in sterile soil (t(1/2) = 16.9 days). Pyrazosulfuron ethyl is a short-lived molecule, and it dissipated rapidly in field soil and water. The faster degradation of pyrazosulfuron in non-sterile soil than in sterile soil indicated microbial degradation of this herbicide.

Parts-per-trillion LC-MS(Q) analysis of herbicides and transformation products in surface water

The goal of this study was to develop a robust method of analyzing surface water samples for S-triazine herbicides, chloroacetanilide herbicides, and their transformation products (TPs) using solid-phase extraction (SPE) followed by liquid chromatograph-mass spectrometry (LC-MS) with electrospray ionization (ESI) by in-source collision-induced dissociation (ISCID) capability of an orthogonal electrospray ionization probe on a single quadrupole LC-MS system. The method developed here met the goals of the study and yielded estimated method detection limits (EMDLs) averaging 0.3 ± 0.1 ng L−1 for S-triazines and their TPs and 0.7 ± 0.4 ng L−1 for chloroacetanilides and TPs. Spiked filtered river water yielded SPE recoveries ranging from 94.2 % ± 4.8 % for S-triazines and TPs after eliminating three compounds with less that 65 % recovery from analysis and 95.9 % ± 19 % for chloroacetanilides and their TPs. The method was field-tested with filtered water samples collected from four sites over a four-month period. Detectible values of S-triazines and TPs ranged from 0.3 to 1540 ng L−1 with a mean of 79.3 and a median of 19.4 ng L−1. Detectible values for chloroacetanilides and TPs ranged from 0.31 to 3780 ng L−1 with a mean of 252 and a median of 25.6 ng L−1. An additional goal was to determine if the method was useful for microbial degradation studies using native bacterial communities. The bacteria transformed atrazine (2-chloro-4-ethylamino-6-isopropylamino-S-triazine) solely into 2-hydroxy atrazine (2-hydroxy-4-ethylamino-6-isopropylamino-S-triazine) with concentrations of 78.4, 63.3 and 32.5 ng L−1 after 12 days of incubation compared with 6.3 and 7.1 ng L−1 for control dark and control sunlight respectively.

Measurement of ultra-trace beryllium in occupational hygiene samples by extraction and fluorescence detection

Beryllium is widely used in industry and commercial products for its unique properties; however, occupational exposure to beryllium particles can cause dermal sensitization and a potentially fatal lung ailment, chronic beryllium disease (CBD). Consequently, exposure limits for beryllium particles in air and action levels on surfaces have been established in efforts to minimize exposure risks for workers. In recent research, a molecular fluorescence method for the determination of trace beryllium in workplace samples, i.e., air filters and dust wipes, was evaluated and validated through intra- and inter-laboratory testing. The procedure entails extraction of sampled beryllium in dilute ammonium bifluoride (aqueous), followed by fluorescence measurement of the complex formed between beryllium and hydroxybenzoquinoline sulfonate (HBQS). The estimated method detection limit is 400-fold excess concentration compared to that of beryllium) are negligible or minimal. The procedure is effective for the dissolution and quantitative determination of beryllium extracted from refractory beryllium oxide particles, and was successfully modified for measuring beryllium content in large BeO particles and in soil samples. The method performance compares favorably with methods employing sample digestion in acid mixtures that include hydrofluoric acid, followed by inductively coupled plasma-mass spectrometry. ASTM International voluntary consensus standards and US National Institute for Occupational Safety and Health methods based on the methodology have been promulgated.

Multiple Spiking Species-Specific Isotope Dilution Analysis by Molecular Mass Spectrometry: Simultaneous Determination of Inorganic Mercury and Methylmercury in Fish Tissues

This work demonstrates, for the first time, the applicability of multiple spiking isotope dilution analysis to molecular mass spectrometry exemplified by the speciation analysis of mercury using GC(EI)MS instrumentation. A double spike isotope dilution approach using isotopically enriched mercury isotopes has been applied for the determination of inorganic mercury Hg(II) and methylmercury (MeHg) in fish reference materials. The method is based on the application of isotope pattern deconvolution for the simultaneous determination of degradation-corrected concentrations of methylmercury and inorganic mercury. Mass isotopomer distributions are employed instead of isotope ratios to calculate the corrected concentrations of the Hg species as well as the extent of species degradation reactions. The isotope pattern deconvolution equations developed here allow the calculation of the different molar fractions directly from the GC(EI)MS mass isotopomer distribution pattern and take into account possible impurities present in the spike solutions employed. The procedure has been successfully validated with the analysis of two different certified reference materials (BCR-464 and DOLT-4) and with the comparison of the results obtained by GC(ICP)MS. For the tuna fish matrix (BCR-464), no interconversion reactions were observed at the optimized conditions of open focused microwave extraction at 70 degrees C during 8 min. However, significant demethylation was found under the same conditions in the case of the certified dogfish liver DOLT-4. Methylation and demethylation factors were confirmed by GC(ICP)MS. Transformation reactions have been found to depend on the sample matrix and on the derivatization reagent employed. Thus, it is not possible to recommend optimum extraction conditions suitable for all types of matrices demonstrating the need to apply multiple spiking methodologies for the determination of MeHg and Hg(II) in biological samples. Double spike isotope dilution analysis methodologies using widespread GC(EI)MS instrumentation are proposed here for the routine analysis of inorganic mercury and methylmercury in fish samples. The estimated method detection limits were below 10 ng g(-1) for both mercury species. Precision was evaluated for the concentrations present in the certified reference materials (CRMs) which vary from 0.1 to 5 microg g(-1), achieving values of coefficients of variation ranging from 7% to 2%. The concentrations obtained in both CRMs analyzed were in excellent agreement with the certified values, demonstrating the accuracy of the method at these concentration levels.

Development of an SPE/CE method for analyzing HAAs

A method to analyze haloacetic acids (HAAs) in drinking water was developed using a capillary electrophoresis (CE) ion analyzer for analyte separation and detection. The effects of background electrolyte (BGE) composition, sample injection approach, and on‐ and offcapillary preconcentration techniques on HAA peak resolution and method sensitivity were evaluated. The recommended BGE consists of 25 mM phosphate buffer at pH 5.7 with 1 mM tetradecyltrimethylammonium hydroxide as the electroosmotic flow modifier. Aqueous samples were preconcentrated using solid‐phase extraction (SPE) and then loaded onto an extended light path capillary (75‐μm inside diameter ÷ 56‐cm effective length) using pressure injection (50 mbar for 12 s). The estimated method detection limits were in the range of 1.5–3.5 μg/L. The SPE/CE method was used to analyze ambient and spiked water samples from a water distribution system, and results were in good agreement with those using US Environmental Protection Agency method 552.2. The main advantage of the SPE/CE method over the currently approved HAA analysis methods is that it does not require HAA derivatization, which involves potentially hazardous chemicals and conditions. Disadvantages of the SPE/CE method are that it does not offer a significant time savings (because of the need for off‐capillary sample preconcentration) and chlorodibromoacetic acid could not be quantified because of interference from a contaminant peak.

Validation of a liquid chromatography–mass spectrometry multi-residue method for the simultaneous determination of sulfonamides, tetracyclines, and pyrimethamine in milk

A multiresidue method suitable for confirmation and determination of six sulfonamides (SAs), three tetracyclines (TCs), and pyrimethamine (PYR) in cow milk was validated. Milk samples were extracted using copolymer Oasis HLB solid-phase extraction (SPE) and analyzed by liquid chromatography–electrospray mass spectrometry with positive ion mode. Estimated method detection limits (MDL) and method quantitation limits (MQL) ranged from 0.48 to 2.64 and 0.61 to 8.64 ng/mL, respectively. These values are far lower than the maximum residue limits (MRLs) established by several control authorities. Excellent linear dynamic range was observed from the method quantitation limits to 300 ng/mL with correlation coefficients better than 0.9900 for all compounds. The method was accurate with recoveries ranging from 72.01 to 97.39%. Good intra-precision and intermediate precision were obtained with RSD better than 11.08%. The method is fairly robust with sample pH being the only critical control point.

Trace Analysis of Semivolatile Organic Compounds in Large Volume Samples of Snow, Lake Water, and Groundwater

An analytical method was developed for the trace analysis of a wide range of semivolatile organic compounds (SOCs) in 50-L high-elevation snow and lake water samples. The method was validated for 75 SOCs from seven different chemical classes (polycyclic aromatic hydrocarbons, organochlorine pesticides, amides, triazines, polychlorinated biphenyls, thiocarbamates, and phosphorothioates) that covered a wide range of physical-chemical properties including 7 orders of magnitude of octanol-water partition coefficient (log K(ow) = 1.4-8.3). The SOCs were extracted using a hydrophobically and hydrophilically modified divinylbenzene solid-phase extraction device (modified Speedisk). The average analyte recovery from 50 L of reverse osmosis water, using the modified Speedisk, was 99% with an average relative standard deviation of 4.8%. Snow samples were collected from the field, melted, and extracted using the modified Speedisk and a poly(tetrafluoroethylene) remote sample adapter in the laboratory. Lake water was sampled, filtered, and extracted in situ using an Infiltrex 100 fitted with a 1-microm glass fiber filter to trap particulate matter and the modified Speedisk to trap dissolved SOCs. The extracts were analyzed by gas chromatographic mass spectrometry with electron impact ionization and electron capture negative ionization using isotope dilution and selective ion monitoring. Estimated method detection limits for snow and lake water ranged from 0.2 to 125 pg/L and 0.5-400 pg/L, respectively. U.S. historic and current-use pesticides were identified and quantified in snow and lake water samples collected from Rocky Mountain National Park, CO. The application of the analytical method to the analysis of SOCs in large-volume groundwater samples is also shown.

Multi-pollutant concentration measurements around a concentrated swine production facility using open-path FTIR spectrometry

Open-path Fourier transform infrared (OP/FTIR) spectrometry was used to measure the concentrations of ammonia, methane, and other atmospheric gases around an integrated industrial swine production facility in eastern North Carolina. Several single-path measurements were made over an 8-day period from 11 to 22 January 1999. Nine different monitoring paths were configured to determine the concentration ranges of ammonia and methane throughout this facility, with an emphasis on isolating the emissions from the farrowing/nursery barns, the finishing barns, and the waste lagoon. A series of sequential measurements was made on 13 January 1999, to estimate the target gas concentrations downwind from each of these sources and at an upwind background site under similar meteorological conditions. The path-averaged concentration (mean±standard deviation) of ammonia during these measurements was below the estimated method detection limit of 0.003 ppm at the background site, 0.328±0.044 ppm between the farrowing/nursery and finishing barns, 2.063±0.140 ppm perpendicular to the airflow from the exhaust fans of the finishing barns, 0.488±0.110 ppm along the western berm of the lagoon, and 0.722±0.659 ppm along the eastern berm of the lagoon. The mean-path-averaged concentration of methane during this same time period was 1.89±0.03 ppm at the background site, 2.58±0.11 ppm between the farrowing/nursery and finishing barns, 2.70±0.05 ppm perpendicular to the airflow from the exhaust fans of the finishing barns, 2.27±0.06 ppm along the western berm of the lagoon, and 11.02±9.69 ppm along the eastern berm of the lagoon as the prevailing westerly winds died down. The concentration measurements made along different monitoring paths during this study indicate that the confinement barns can be a significant source of ammonia, while the lagoon is a major source of methane. Attempts to apply tracer-based dispersion modeling techniques to the single-path OP/FTIR data to estimate emission rates of ammonia and methane from the different sources present at this facility were met with limited success.

On-line deoxygenation in reductive (and oxidative) amperometric detection: environmental applications in the liquid chromatography of organic peroxides

Cyclic voltammetry was used qualitatively to characterize and determine the feasibility of the oxidation and reduction of selected organic peroxides and hydroperoxides at a glassy carbon electrode. Organic peroxides were determined using reversed-phase high-performance liquid chromatography with simultaneous reductive and oxidative amperometric detection in a thin-layer dual parallel–adjacent electrode configuration. An on-line deoxygenator allowed the removal of molecular oxygen from the mobile phase and this resulted in an extension of the negative potential range of the glassy carbon electrode by approximately 750 ± 50 mV vs. the Ag/AgCl reference electrode. Chromatographically assisted hydrodynamic voltammetric measurements, in the dual parallel–adjacent electrode configuration, provided confirmation of the feasibility of simultaneously monitoring two independent redox reactions, for a single analyte, and allows for both the qualitative and quantitative analysis of organic peroxides (and hydroperoxides). The reductive amperometric responses were, on average, 2–5 times greater, depending on the particular organic peroxide, than the corresponding oxidative amperometric responses. An empirically determined parameter was evaluated and developed, {[iOxiRed–1] or [iaic–1]}, from two independent electrode reactions, that allows the qualitative identification of organic peroxide analytes by comparison of samples with standard injections. Estimated method detection limits (MDLs) for butan-2-one (butan-2-one) peroxide (2-BP), tert-butyl hydroperoxide (t-BHP) and cumene hydroperoxide (CHP) in reductive amperometry are approximately 0.8, 0.4 and 5 ppb, respectively and the oxidative amperometric MDLs are about 3, 2.5 and 12 ppb, respectively. The reductive amperometric responses for 2-BP, t-BHP and CHP are linear over 4–5 orders of magnitude of concentration, extending from ca. 1 µg l–1 to ca. 100 mg l–1, and the corresponding correlation coefficients are of the order of 0.9997–0.99994.