Matching Calibration Research Articles

Interference from Soluble Iron on Mercury Determination in Water by Cold Vapor Atomic Absorption Spectrometry (CV-AAS) with Sodium Borohydride as Reductant.

This study demonstrated the signal enhancement interference from soluble iron (Fe) during mercury (Hg) determination in water by cold vapor atomic absorption spectrometry (CV-AAS) using sodium borohydride (NaBH4) as reductant. In the presence of 50 mg L-1 soluble Fe, Hg values will be overestimated by around 25%. The reason for the Hg signal enhancement is still unclear, but it is speculated to be attributable to the catalyst function for the equilibrium reduction reaction between Hg2+ and BH4- from the atomic Fe formed at the same time. Using the matrix matching calibration standards prepared in 50 mg L-1 Fe solution, the problem of Hg overestimation could be minimized. This study also indicated that stannous chloride (SnCl2), another common reductant for Hg analysis, does not suffer from the overestimation problem from soluble Fe in the presence of NaBH4.

A QuEChERS-HPLC-MS/MS Method with Matrix Matching Calibration Strategy for Determination of Imidacloprid and Its Metabolites in Procambarus clarkii (Crayfish) Tissues.

We developed a method for determination of imidacloprid and its metabolites 5-hydroxy imidacloprid, olefin imidacloprid, imidacloprid urea and 6-chloronicotinic acid in Procambarus clarkii (crayfish) tissues using quick, easy, cheap, effective, rugged, and safe (QuEChERS) and high-performance liquid chromatography-triple quadrupole mass spectrometry. Samples (plasma, cephalothorax, hepatopancrea, gill, intestine, and muscle) were extracted with acetonitrile containing 0.1% acetic acid and cleaned up using a neutral alumina column containing a primary secondary amine. The prepared samples were separated using reverse phase chromatography and scanned in the positive and negative ion multiple reaction-monitoring modes. Under the optimum experimental conditions, spiked recoveries for these compounds in P. clarkii samples ranged from 80.6 to 112.7% with relative standard deviations of 4.2 to 12.6%. The limits of detection were 0.02–0.5 μg·L−1, the limits of quantification were 0.05–2.0 μg·L−1 and the method of quantification was 0.05–2.0 μg·kg−1. The method is rapid, simple, sensitive and suitable for rapid determination and analysis of imidacloprid and its metabolites in P. clarkii tissues.

Lean fuel detection with nanosecond-gated laser-induced breakdown spectroscopy

Nanosecond-gated laser-induced breakdown spectroscopy (n-LIBS) has been used to quantify fuel mole fraction (ΧC2H4) in the cavity flameholder of a model high-speed combustor. The measurement locations selected, in the vicinity of the cavity shear layer, have low fuel concentrations. Previous n-LIBS measurements showed unexpectedly high values at these locations with expected low average fuel mole fraction (ΧC2H4) and intermittent fuel presence; thus, an effort was undertaken to understand potential sources of error with n-LIBS at low ΧC2H4. An improved direct spectrum matching (DSM) calibration matrix was thus constructed, focusing on low ΧC2H4 for both reacting and non-reacting conditions. Comparisons were made between n-LIBS measurements using two different laser systems for plasma generation, and the insensitivity of the signal to the specific laser was demonstrated for the first time. Uncertainty of the n-LIBS measurement technique at two different gas densities was analyzed through the processing of spectra acquired at known values of XC2H4. Measurements in the windtunnel, around the shear layer of the cavity flameholder, were conducted with a Mach-2 or Mach-3 freestream, and comparisons were made between n-LIBS results—using two DSM calibration matrices with different increments in XC2H4—and numerical results employing dynamic hybrid Reynolds-averaged Navier-Stokes and large-eddy simulation (DHRL). The high-resolution DSM matrix produced slightly lower XC2H4 than those from the coarse matrix, and comparisons with the simulation showed good agreement overall. For Mach-3 conditions, comparisons were made for both a non-reacting and a reacting cavity flameholder. Here, results showed a systematic difference between measured and simulated values of the mean XC2H4 within the shear layer but good (even excellent) agreement within the upper portion of the recirculation zone. For reacting condition, four reduced chemical kinetic models were implemented with the DHRL technique and compared to n-LIBS results. Overall, the four kinetic models produced a substantial range of results (e.g., temperatures and reaction progress), showing the importance of a validated diagnostic technique like n-LIBS for model testing.

A simple and effective determination of methyl red in wastewater samples by UV–Vis spectrophotometer with matrix matching calibration strategy after vortex assisted deep eutectic solvent based liquid phase extraction and evaluation of green profile

In this study, a green, simple and sensitive vortex assisted deep eutectic solvent based liquid phase extraction (VA-DES-LPE) method was developed to preconcentrate methyl red from wastewater samples before its determination by UV–Vis spectrophotometry. Deep eutectic solvent (DES) was employed as the extractant for the isolation and preconcentration of methyl red from aqueous solution. Important parameters having effect on the extraction efficiency were investigated and optimized carefully using the “one-factor-at-a-time” approach. Under the determined optimum conditions, limit of detection (LOD) and limit of quantification (LOQ) values were determined as 2.3 and 7.5 µg/L, respectively. The preconcentration factor was calculated as 35 folds with respect to the developed method. Linearity of the presented method was determined in the range of 8.0–1000 µg/L. The developed method was successfully applied for the determination of methyl red in wastewater samples, and satisfactory percent recoveries (≈100%) were obtained for different spike concentrations.

Photochemical Vapor Generation Based Accurate Determination of Cadmium in Wastewater Using Novel Photoreactor and Gas-Liquid Separators Using Flame Atomic Absorption Spectrometry with Matrix Matching Calibration

Cadmium is widely applied in various industrial areas and poses serious problems to human health such as cancer. Many analytical methods are used to determine this toxic element at trace levels, and new methods such as photochemical vapor generation (PVG) offer a different perspective. In this study, a photochemical vapor generation-based method was developed and combined with flame atomic absorption spectrometry (FAAS) for the determination of cadmium in wastewater. To achieve this goal, low molecular weight organic acid type and concentration, ultraviolet (UV) irradiation period and gas-liquid separator design parameters that directly affect the analytical performance of the method were optimized. Under the optimum conditions, the limits of detection and quantification were 0.19 and 0.65 mg/L, respectively. In spike experiments carried out with wastewater samples, the recovery values were between 96 and 110%, showing high accuracy. Low values for the relative standard deviation also indicated good precision for replicate measurements.

Determination of copper in traditional coffee pot water samples by flame atomic absorption spectrometry and matrix matching calibration strategy after switchable solvent based liquid-phase microextraction.

Traditional copper coffee pots are widely used in these modern times and daily consumption of coffee brewed in overused/old pots increases the risk of copper ingestion. This study employed a green switchable solvent-based liquid-phase microextraction (SS-LPME) method to isolate and preconcentrate copper from water boiled in coffee pots. Copper was determined by a flame atomic absorption spectrometry (FAAS) system coupled with a slotted quartz tube (SQT). 1,5-Diphenylcarbazone was added to aqueous samples to form a complex with copper before the extraction step. Box-Behnken experimental design was applied to select optimum conditions of the extraction method that were used to validate the analytical method. The limits of quantification and detection of the optimized SS-LPME-SQT-FAAS method were determined as 9.1 and 2.7μg/L, respectively. Water samples boiled in traditional coffee pots were spiked at different concentrations and analyzed to ascertain the method's accuracy and applicability to real samples. Satisfactory recovery results obtained in the range of 92-107% established good accuracy, and percent relative standard deviations lower than 8.0% also proved high precision.

Determination of pyridaphenthion in soybean sprout samples by gas chromatography mass spectrometry with matrix matching calibration strategy after metal sieve linked double syringe based liquid-phase microextraction

A novel analytical strategy for the trace determination of pyridaphenthion pesticide was developed in this study. Gas chromatography-mass spectrometry (GC–MS) was used for the accurate, feasible and precise determination of this analyte. Liquid phase microextraction (LPME) was performed with a metal sieve linked double syringe (MSLDS) system, which eliminated the need for a disperser solvent. In order to increase extraction efficiency for the analyte, all variable parameters were optimized and the system analytical performance of the proposed method was determined. Limit of detection and quantification (LOD and LOQ) values of pyridaphenthion were found to be 0.8 and 2.7 µg L−1, respectively. Compared to GC–MS system’s analytical performance, the developed method provided approximately 273-folds improvement in the detection limit of the analyte. Applicability/accuracy of the developed analytical strategy was checked by recovery experiments carried out with soybean sprouts, and the results obtained were satisfactory.

Development of a multiclass method to quantify phthalates, pharmaceuticals, and personal care products in river water using ultra-high performance liquid chromatography coupled with quadrupole hybrid Orbitrap mass spectrometry.

The organic micropollutants such as phthalates, pharmaceuticals, and personal care products (PPPCPs) enter the surface water through various routes. The aim of this study is to develop a sensitive and efficient method to identify and quantify 26 PPPCPs found in river water with acceptable accuracy and precision using a liquid chromatograph hyphenated with quadrupole hybrid Orbitrap mass spectrometry (Q-Orbitrap-MS) in a single chromatographic run. The organic micropollutants were extracted from river water by solid-phase extraction (SPE) using hydrophilic-lipophilic balance sorbent and analyzed using an ultra-high performance liquid chromatograph (UHPLC) equipped with C18 stationary phase for chromatographic separation. The targeted mass experiments were conducted in a Q-Orbitrap-MS system in positive and negative electrospray ionization mode. The method was found to be linear in the concentration range of 1-125ng/L with coefficient of determination lying in the range of 0.995-0.999. The method achieved limit of quantification in the range of 0.41-1.72ng/L, and method recovery measured at three different concentrations was found to be in the range of 75-115%. Intra- and interday precision expressed as percent relative standard deviation was found to be<15%. Matrix effect was found to be in the range of 83.5-109.79%. The matrix match calibration was used for quantification of PPPCPs in river water sample. The method performance was evaluated by analyzing real samples collected from Ganga River, and the concentrations of 21 analytes were found to be in the range of 0.76-9.49ng/L for pharmaceuticals, 1.49-8.67ng/L for phthalates, and 0.9-7.58ng/L for personal care products. The present method was found to be precise, sensitive, and rapid to determine 26 PPPCPs including phthalates in river water samples using SPE-UHPLC-Q-Orbitrap-MS.

Determination of fipronil and bixafen pesticides residues using gas chromatography mass spectroscopy with matrix matching calibration strategy after binary dispersive liquid-liquid microextraction

The objective of this study was to determine bixafen and fipronil residues in domestic and industrial wastewater, soil and mint samples by binary dispersive liquid-liquid microextraction method (BDLLME) prior to gas chromatography-mass spectrometry (GC-MS). Extraction efficiency for the selected analytes was improved by optimizing the parameters such as solvent type, ratio and volume, dispersive solvent type/volume, mixing type and duration to increase overall analytical performance. Under the optimum chromatographic and extraction conditions, limits of detection values for bixafen and fipronil were determined as 7.3 and 6.1 µg L−1, respectively. Spiking experiments were performed for domestic and industrial wastewater, soil and mint samples to evaluate applicability and accuracy of the proposed method. Recovery results for the samples were calculated in the range of 89.4%–112.6% via matrix matching calibration strategy. It was determined that the detection power of GC-MS system was improved 7.8 times for bixafen and 119 times for fipronil over LOD comparisons of conventional GC-MS and B-DLLME-GC-MS systems.

Combination of an Efficient Photochemical Vapor Generation System and Flame Atomic Absorption Spectrophotometry for Trace Nickel Determination in Wastewater Samples

A photochemical vapor generation – atomic absorption spectrometry combination was applied for the determination of nickel. Optimizations of low molecular weight organic acid type, concentration of low molecular weight organic acid, ultraviolet irradiation period, mixing type and period, flow rate of carrier gas, and temperature of atomizer were conducted in order to maximize analytical signals. Under the optimum conditions, analytical performance of the photochemical vapor generation – atomic absorption spectrometry system was evaluated; the limits of detection and quantification were determined to be 3.5 and 11.6 µg/L, respectively. Spiking experiments were carried out in wastewater samples to investigate the applicability and accuracy of the developed method. Matrix matching calibration was used to calculate the recovery since negative matrix effects (approximately 45%) were observed on the analyte with external calibration. The recovery results for 40, 60 and 80 µg/L of spiked concentration were determined to be 106.2%, 101.4% and 99.0%, respectively, indicating the high accuracy of the developed method for the selected matrix.

CVD grown carbon nanofibers: an efficient DSPE sorbent for cleanup of multi-class pesticide residue in high fat and low water commodities by QuEChERS using GC-ECD.

An inexpensive, effective, and efficient dispersive solid-phase extraction (DSPE) sorbent was developed as an alternative totraditionally used sorbents (primary secondary amine and C18) for fatty matrices using theQuEChERS method. Catalytic chemical vapor deposition grown carbon nanofibers dispersed on activated carbon fibers (Ni-ACF/CNF) having aBET specific surface area of738 (m2/g) were for thefirst time evaluated as a DSPE material for sample cleanup before gas chromatographic analysis. Based on cleanup performance and recoveries, 10mg of Ni-ACF/CNF was found optimalfor the determination of twenty-seven multi-class pesticides in high fat and low water commodities/matrices (peanut, soybean, sesame, and flaxseed). The recoveries obtained for all analytes were in the range ~ 72 to ~ 117%, with relative standard deviation values ≤ 15%. The limits of detection and quantification values were 0.7-4.2ng/g and 2.3-13.9ng/g, respectively. The matrix match calibration curve was linear in the range 20-500ng/g with a correlation coefficient of ≥ 0.993. The results reveal thatthe Ni-ACF/CNF is a competent DSPE sorbent, similar to primary secondary amines and C18sorbent materials, for pesticide determination by QuEChERS methods in high fat and low water commodities. Graphical abstract.

Accurate, sensitive determination of omega-6 and omega-3 polyunsaturated fatty acids in human plasma, urine samples.

Quantitative determination of omega-6 and omega-3 polyunsaturated fatty acids in human plasma and urine with high accuracy and precision provides significant information to monitor the underlying etiology of several diseases. In this regard, liquid chromatography-mass spectrometry is a good choice owing to its great selectivity and sensitivity. Additionally, the hybrid quadrupole-time of flight-mass spectrometer systems provides easy identification of target compounds with superior mass measurements. In this study, an analytical method has been developed for simple, accurate and simultaneous determination of linoleic acid, arachidonic acid, docosahexaenoic acid and eicosapentaenoic acid in a short chromatographic analysis period. The developed method is suitable for the quantitative detection of these four compounds with detection limits ranging between 1.1-3.0 ng ml-1 and its applicability was assessed in human urine and plasma samples. As a result, acceptable accuracy (between 83 and 111%) and good precision (<6%) were obtained for target compounds using matrix matching calibration strategy.

Determination of Iron in Licorice Samples by Slotted Quartz Tube Flame Atomic Absorption Spectrometry (FAAS) with Matrix Matching Calibration Strategy after Complexation with Schiff Base Ligand-Based Dispersive Liquid–Liquid Microextraction

In this study, a slotted quartz tube flame atomic absorption spectrometry (FAAS) system has been developed for the determination of iron after dispersive liquid–liquid microextraction. The iron coordinate complex was formed by using a ligand synthesized from the reaction of o-phenylenediamine and 5-bromosalicylaldehyde. Using the optimum conditions, the relative standard deviation was found to be 1.7% calculated from the lowest concentration of calibration plot, and the limits of detection and quantification were found to be 5.3 and 17.4 µg L−1, respectively. Other figures of merit of the developed method were satisfactory and an approximate 48-fold enhancement in detection power was recorded compared to the conventional FAAS system. The developed method was applied to licorice samples to evaluate the accuracy and applicability to real samples. The recovery values were in the range from 88% to 106% with low standard deviations.

A novel and rapid extraction protocol for sensitive and accurate determination of prochloraz in orange juice samples: Vortex-assisted spraying-based fine droplet formation liquid-phase microextraction before gas chromatography-mass spectrometry.

A novel, ecofriendly, and easy extraction and preconcentration method named as vortex-assisted spraying-based fine droplet formation liquid-phase microextraction was proposed for the determination of prochloraz at trace levels in orange juice samples by gas chromatography-mass spectrometry (GC-MS). In this novel system, extraction solvent is dispersed by the help of spraying apparatus instead of dispersive solvent. Various parameters of the method were carefully optimized to increase signal-to-noise ratio of the analyte. Under the optimum chromatographic and extraction conditions, limit of detection and limit of quantification were calculated as 3.2 and 10.8 μg/kg, respectively. Moreover, enhancement in quantification power for the GC-MS system was determined as 372 folds based on LOQ comparison. Relative recovery results for orange juice samples were found to be between 95.0-107.7% by utilizing matrix matching calibration. Furthermore, the developed method may be used to efficiently and simply extract other organic compounds for their determinations in several matrices.

Chitosan magnetic hydrogel based ligandless magnetic solid phase extraction for the accurate and sensitive determination of thallium by slotted-quartz tube flame atomic absorption spectrophotometry with matrix matching calibration strategy

In this study, a promising method was developed for the determination of thallium at trace levels by applying chitosan based magnetic solid phase extraction using slotted quartz tube atomic absorption spectrometry. Chitosan based magnetic hydrogels (CMH) were synthesized and used as solid phase extraction sorbents. The variable parameters required for the extraction method such as hydrogel amount, adsorption period and eluent volume were optimized, and under the optimized conditions, limits of detection and quantification values were recorded as 12 and 39 ng/mL, respectively. Real sample applications were performed to test the accuracy of the proposed method. For this purpose, recovery studies were carried out in two different spiking concentrations of thallium in lake water, well water and wastewater samples using the developed extraction/preconcentration method (chitosan magnetic hydrogel based ligandless magnetic solid phase extraction, CMH-LMSPE). The obtained percent recovery values of 87.2–113.2% confirmed the applicability of the method with high accuracy and precision.

Determination of trace manganese in soil samples by using eco-friendly switchable solvent based liquid phase microextraction-3 holes cut slotted quartz tube-flame atomic absorption spectrometry

This study presents a novel preconcentration and separation method for manganese determination using a green switchable solvent-based liquid-phase microextraction and slotted quartz tube-flame atomic absorption spectrometry (SS-LPME-SQT-FAAS). The switchable solvent was prepared from the mixture of N,N dimethylamine and ultrapure water, using dry carbon dioxide for protonation. A coordinate complex of manganese was formed with ((E)-2,4-dibromo-6-(((3-hydroxyphenyl)imino)methyl)phenol ligand synthesized in the lab. Parameters including pH, buffer volume, ligand concentration/volume, switchable solvent volume and sodium hydroxide concentration/volume were optimized to enhance complex formation and extraction efficiency. The limit of detection (LOD), limit of quantification (LOD) and enrichment factor were determined as 0.71 µg L−1, 2.4 µg L−1 and 101 folds, respectively. The applicability of the developed method was tested in soil samples using the matrix matching calibration method. The percent recovery results obtained (98–105%) established the method’s accuracy and applicability to real samples.

Reverse phase dispersive liquid–liquid microextraction coupled to slotted quartz tube flame atomic absorption spectrometry as a new analytical strategy for trace determination of cadmium in fish and olive oil samples

In the present study, trace level of cadmium was determined by a new, sensitive and simple analytical method called as reverse phase dispersive liquid–liquid microextraction (RP-DLLME) combined to slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) system. Microextraction parameters such as type and volume of disperser solvent, volume of extraction solvent, heating effect, initial sample volume, final volume, centrifugation period and type/period of mixing were optimized. FAAS and SQT-FAAS systems were also examined to get high signal to noise ratio. After optimizing all significant parameters, the limit of detection (LOD) and limit of quantification (LOQ) of the developed analytical strategy were calculated as 0.74 and 2.48 μg/kg, respectively. In order to determine the applicability and accuracy of the RP-DLLME-SQT-FAAS method, recovery studies were performed in fish oil syrup. Matrix matching calibration strategy was used to eliminate heavy matrix effects on analytical signals, and percent recovery results were found between 95.6 and 105.7 %.

A Position-Independent Reflection-Only Method for Complex Permittivity and Permeability Determination with One Sample

AbstractThis paper presents a position-independent reflection-only method for determining complex permittivity and permeability of a sample. In this method, both the short and match calibration kits are used to measure the reflection coefficients. Only one sample positioned arbitrarily is measured using a one-port vector network analyzer (VNA), while the complex permittivity and permeability of the sample are determined simultaneously. Experimental results in X-band for the Acrylonitrile Butadiene Styrene plastic (ABS) are included to exhibit the validity of the proposed method. The results show that the complex permittivity and permeability determined by the proposed method have a good agreement with the parameters determined by the well-known Nicolson–Ross–Weir (NRW) method. In addition, a magnetic material is simulated to further validate the proposed method.

Determination of Trace Amounts of Gold in Electroplating Rinsing Bath by Slotted Quartz Tube Flame Atomic Absorption Spectrometry with Matrix Matching Calibration Strategy after Preconcentration with Vortex Assisted Dispersive Liquid–Liquid Microextraction

With the aim of mitigating the low sensitivity of the conventional flame atomic absorption spectrometer (FAAS) for gold determination, a dispersive liquid–liquid microextraction (DLLME) method was used to preconcentrate gold from the sample solution and a slotted quartz tube (SQT) was attached to the FAAS burner head to boost the residence time of the atoms in the flame. Three main optimization studies were performed to enhance the absorbance signal of gold by the FAAS system. The SQT-FAAS system was optimized based on the fuel and sample flow rates and the position of SQT on the burner head. Parameters including the pH and volume of buffer solution, volume of ligand solution, and mixing period were optimized for the efficient complexation of gold with diethyldithiocarbamate. The DLLME method was optimized based on the type and volume of dispersive and extraction solvents, type of ionic salt and mass of ionic salt. With the optimized values obtained, 1.7 and 5.6 µg/L were determined to be the method limit of detection (LOD) and limit of quantification (LOQ), respectively. The method applicability and accuracy in quantifying gold in a real sample matrix were determined by the use of spike recovery tests of electroplating rinse bath solution. Close to 100% recovery results were obtained using a matrix matching calibration method.

Determination of fenazaquin in irrigation canal water and soil samples by gas chromatography mass spectrometry

The urgent call for the control and regulation of pesticide usage arose from the adverse health effects associated with their excessive and wrong application mostly in the agricultural field. The uncontrolled use of pesticides has been proved to affect the environment because of their ability to accumulate in different environmental resources such as water and soil. Fenazaquin is one of the mostly used pesticides in the agricultural field known by its adverse health effects. In this study, the previously mentioned pesticide was analyzed in two different kind of environmental samples: irrigation canal water and soil samples using a highly accurate gas chromatography mass spectrometer (GCMS). In the first step of the study, the limit of qualification (LOD), limit of quantification (LOQ), and relative standard deviation (RSD) were determined and calculated to be 0.04 mg/L, 0.14 mg/L and 10.2%, respectively . In the following step, the samples were spiked at different concentrations using low volumes of high concentration stock solution, to ensure the real effects of the sample matrices were observed. All measurement were performed by applying the adequate temperature program of the sensitive analytical instrument GCMS. The results obtained using the classical recovery procedure was satisfactory but matrix matching calibration strategy was used to improve the percent recoveries to almost 100%. Thus, this study explains the possibility of fenazaquin determination in two different environmental samples using the classical recovery and matrix matching strategies. Irrigation canal water and soil samples are on a high contamination risk from the pesticides used in the agricultural field.