Higher Limit Of Quantification Research Articles

Prevalence and emergence of steroidal and non-steroidal anabolic agents in the Australian community measured through wastewater analysis

Develop and validate a method for the detection of performance- and image-enhancing drugs (PIEDs) in wastewater. Investigate prevalence of steroidal and non-steroidal anabolic agents in around 45% of the Australian population during Census week in August 2021. Explore changes and patterns in use over a 13-year period (2009–2021) and emergence of non-steroidal anabolic agents, e.g., selective androgen receptor modulators (SARMs), within one Australian wastewater treatment plant (WWTP) catchment. Performance- and image-enhancing drugs include, inter alia, steroidal (anabolic-androgenic steroids) and non-steroidal anabolic agents [e.g., SARMs, peroxisome proliferator-activated receptor delta (PPAR-δ) agonists, growth hormone secretagogues]. Despite known serious negative health side effects, these substances are misused by athletes and non-athletes to boost physical performance as well as appearance. Due to their misuse, often at concentrations significantly higher than for medical purposes, easy access through the internet, and lack of quality controls, PIED use has become a public health problem. The extent of this issue is difficult to quantify and is currently monitored through the combination of multiple data sources such as surveys, seizures, and anti-doping. To fully understand the prevalence of these substances, especially among the general population, a broader monitoring tool is needed to complement current sources of data. In the past two decades, wastewater-based epidemiology has been developed to investigate exposure to, use, and prevalence of chemicals within entire populations and has potential to be a useful additional tool for PIED monitoring. A solid-phase extraction (SPE) liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the detection and quantification of around 50 anabolic agents and metabolites in wastewater. This method was applied to wastewater samples collected in August 2021 from 51 WWTPs across Australia, covering roughly 11.6 million people. This method was also used for temporal analysis of anabolic agents in wastewater from one catchment collected from 2009 to 2021. Limits of quantification (LOQs) were, with few exceptions, in the low ng/L with steroids and their metabolites generally having higher LOQs than the non-steroidal anabolic agents. Spatial wastewater analysis showed the use of multiple types of PIEDs within the Australian population in August 2021. Results of temporal samples indicated no clear trends for detected steroidal anabolic agents. However, they showed that the first non-steroidal anabolic agent was detected as early as 2011, with others following in later years. After their first detection, all non-steroidal anabolic agent concentrations increased almost linearly until 2021, often with a peak in concentration in 2018. LOQs are suitable for the detection of trace amounts of PIEDs in wastewater, especially for SARMs and other non-steroidal anabolic agents. As the method is semi-quantitative, concentrations only give an indication of anabolic agent levels, however, these estimates are likely conservative. The analysis of wastewater across 51 Australian WWTPs revealed widespread use of multiple types of steroidal and non-steroidal anabolic agents. The steady increase of concentrations of non-steroidal anabolic agents in the temporal wastewater samples demonstrates the growing popularity of these substances within the general community. A suitable SPE LC-MS/MS method was developed for the analysis of steroidal and non-steroidal anabolic agents in wastewater influent and was successfully applied to spatial and temporal wastewater samples. Many non-steroidal anabolic agents were detected in wastewater for the first time. Spatial analysis showed the prevalence of anabolic agents and temporal analysis revealed the first detections and subsequent emergence of non-steroidal anabolic agents within an Australian WWTP catchment. Results demonstrated that wastewater analysis is a useful complementary tool to further our understanding of PIED use within the general population and that wastewater data may be useful to public health and PIED researchers.

A MIP-based low-cost electrochemical sensor for 2-furaldehyde detection in beverages

There is an increasing interest in determining the concentration of furanic compounds naturally formed in food aqueous matrices, by in situ, fast and low-cost methods. A sensor presenting such characteristics is here proposed, and characterized. It is based on a molecularly imprinted polymer (MIP) as a receptor with electrochemical transduction on a screen printed cell (SPC). The molecularly imprinted polymer has been developed for a particular furanic derivative, 2-furaldehyde (2-FAL). The detection bases on the reduction of 2-FAL selectively adsorbed on the polymer layer in contact with the working electrode. The polymer layer is simply formed by in situ polymerization, directly over the SPC and it was characterized by IR, SEM and electrochemical methods. Even if based on an easy and fast preparation procedure, the layer sufficiently adheres to the cell surface giving a reusable sensor. Square wave voltammetry (SWV) was applied as the signal acquisition method. The sensor performance in aqueous solution (NaCl 0.1 M) was tested, obtaining that the dose-response curve is fitted by the Langmuir adsorption isotherm. The sensitivity, and so the limit of detection, were noticeably improved by a chemometric approach based on the Design of experiment method. (optimized conditions: Estep = 0.03 V, Epulse = 0.066 V, f = 31 s−1). In water solution at pH around neutrality the dynamic range was from about 50 μM to 20 mM. Similar results were obtained for a white wine containing 12% ethanol, which has been considered as a typical example of beverage possibly containing furhaldehydes. The higher limit of quantification can be modulated by the amount of MIP deposited, while the lower detection limit by the conditions of the electrochemical measurement.

Multiresidue Method for GC-MS Amenable Multiclass Pesticides in Pineapple Fruit

A simple, rapid QuEChERS method is reported for simultaneous analysis of 86 multiclass pesticides in pineapple fruit. Based on a comparative recovery by three methods, the one involving ethyl acetate extractant and dSPE clean up with 50 mg PSA and 150 mg anhydrous sodium sulphate was found more appropriate and further validated following SANTE guidelines. The coeffiicient of determination (R2) value of all the pesticides ranged between 0.97–0.99. Limit of quantification (LOQ) of most of the compounds was10 ng g−1. Bifenox, bitertanol, carfentrazone ethyl, chlorfenvinphos, flusilazole, haloxyfop methyl, methamidophos, methyl paraxon, paclobutrazole and pyraclostrobin showed a higher LOQ of 50 ng g−1. Average recovery ranged within 70–120 per cent at 10, 50 and 100 ng g−1 fortification levels with RSDr, RSDwR below 20 per cent; Horwitz ratio between 0.5–2 at LOQ proved that this method is sufficiently accurate, repeatable and reproducible and therefore can be effectively utilized for pesticide residue analysis in pineapple fruits.

Comparison of green sample preparation techniques in the analysis of pyrethrins and pyrethroids in baby food by liquid chromatography–tandem mass spectrometry

A new selective and sensitive liquid chromatography triple quadrupole mass spectrometry method was developed for simultaneous analysis of natural pyrethrins and synthetic pyrethroids residues in baby food. In this study, two sample preparation methods based on ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) and salting-out assisted liquid–liquid extraction (SALLE) were optimized, and then, compared regarding the performance criteria. Appropriate linearity in solvent and matrix-based calibrations, and suitable recoveries (75–120%) and precision (RSD values≤16%) were achieved for selected analytes by any of the sample preparation procedures. Both methods provided the analytical selectivity required for the monitoring of the insecticides in fruit-, cereal- and milk-based baby foods. SALLE, recognized by cost-effectiveness, and simple and fast execution, provided a lower enrichment factor, consequently, higher limits of quantification (LOQs) were obtained. Some of them too high to meet the strict legislation regarding baby food. Nonetheless, the combination of ultrasound and DLLME also resulted in a high sample throughput and environmental-friendly method, whose LOQs were lower than the default maximum residue limit (MRL) of 10μgkg−1 set by European Community for baby foods. In the commercial baby foods analyzed, cyhalothrin and etofenprox were detected in different samples, demonstrating the suitability of proposed method for baby food control.

Simultaneous analysis of bisphenol A based compounds and other monomers leaching from resin-based dental materials by UHPLC-MS/MS.

Resin-based dental materials have raised debates concerning their safety and biocompatibility, resulting in a growing necessity of profound knowledge on the quantity of released compounds into the oral cavity. In this context, the aim of this study was to develop a comprehensive and reliable procedure based on liquid chromatography with mass spectrometry for the simultaneous analysis of various leached compounds (including bisphenol A based compounds) in samples from in vitro experiments. Different experiments were performed to determine the optimal analytical parameters, comprising mass spectrometry parameters, chromatographic separation conditions, and sample preparation. Four internal standards were used as follows: deuterated diethyl phthalate and bisphenol A (commercially available), and deuterated analogues of triethylene glycol dimethacrylate and urethane dimethacrylate (custom-made). The optimized method was validated for linearity of the calibration curves and the associated correlation coefficient, lower limit of quantification, higher limit of quantification, and intra- and interassay accuracy and precision. Additionally, the developed liquid chromatography with tandem mass spectrometry method was applied to the analysis of leaching compounds from four resin-based dental materials. The results indicated that this method is suitable for the analysis of different target compounds leaching from dental materials. This method might serve as a valuable basis for quick and accurate quantification of leached compounds from resin-based dental materials in biological samples.

Development of an innovative and “green” stir bar sorptive extraction–thermal desorption–gas chromatography–tandem mass spectrometry method for quantification of polycyclic aromatic hydrocarbons in marine biota

There is a growing awareness of the need to reduce the negative impact of chemical analyses on the environment and to develop new eco-friendly and sustainable analytical methods without compromising performance. In this study, we developed a “green” analytical method enabling the accurate and simultaneous routine analysis of 21 polycyclic aromatic hydrocarbons (PAHs) in reduced quantities (100mg and 1g wet weight (WW)) of marine biota samples (fish muscle, mussel and oyster tissues) using alkaline digestion combined with stir bar sorptive extraction–thermal desorption–gas chromatography–tandem mass spectrometry (SBSE–GC–MS/MS). The innovative method provides good selectivity and specificity for most compounds. In 1gWW samples, limits of quantification (LOQs) ranged from 1 to 10μg/kgWW in fish muscle and from 0.5 to 10μg/kgWW in mussel tissue. The method enables most analytes to be quantified below the restrictive limits established by the European Commission (2 and 10μg/kgWW in fish muscle and bivalve mollusc, respectively). Higher LOQs were obtained in 100mgWW samples ranging from 1 to 50μg/kgWW. Recovery and linearity were assessed for all analytes. The results were satisfactory for most compounds with recoveries ranging from 94% to 117% in 1gWW mussel samples at spike concentration of 10ng/gWW with standard deviation not exceeding 12%. However, results confirmed that the SBSE efficiency is affected by the complexity of biological matrices, especially for high molecular weight compounds in lipid-rich mussel tissue. Because of the matrix effects, matrix-matched calibrations were carried out. Validation was performed using the standard reference material 1974c with recovery ranging from 71% to 119% except for naphthalene, anthracene and benzo(e)pyrene that were therefore not validated. Overall, the developed method meets analytical validation criteria for most compounds. Thanks to the combination of alkaline digestion and SBSE, which greatly simplifies sample treatment and limits solvent use to ethanol, the developed method followed most green analytical chemistry principles.

Comparison of HPLC Methods for the Determination of Amino Sugars in Soil Hydrolysates

A study on the suitability of chromatographic techniques such as high performance anion exchange chromatography (HPAEC) with fluorescence detection (FL) and pulsed amperometric detection (PAD) and reversed phase (RP) chromatography for the determination of galactosamine, glucosamine, mannosamine, and muramic acid in soil hydrolysates was carried out. The reversed phase fluorescence method was rapid, provided good validation parameters, and employed relatively inexpensive instrumentation. The HPAEC methods had slightly higher limits of quantification, 0.6–5.0 µmol L−1 (HPAEC-FL) and 1.0–10.0 µmol L−1 (HPAEC-PAD), compared to the reversed phase fluorescence method (0.5–5.0 µmol L−1). Various sample pretreatment methods and chromatographic methods were investigated and the advantages and disadvantages of the HPLC methods are discussed.

Bioanalytical Method Development and Validation for Herbal Quercetin in Nano Formulation by RP-UFLC in Rabbit Plasma

A sensitive reverse phase ultra fast liquid chromatography (RP-UFLC) has been developed and validated for the quantification of Quercetin in nano formulation in rabbit plasma using solid phase extraction method (SPE). Best chromatographic resolution was achieved on a reverse phase Hibar®C18 (250×4.6 mm i.d., 5 μ) column with the mobile phase consisted of acetonitrile: pottasium dihydrogen ortho phosphate (pH 3.5) in the ratio of 65:35 (v/v) with a flow rate of 0.8 mL/min. The retention time for the drugs was found to be 8.6 min and 10.0 min for internal standard (fluticasone propionate). The analyte was detected by using a Photo-diode array (PDA) detector with LC solution software. Linearity was obtained in the concentration range of 10 to 400.0 ng/mL (r2= 0.989). Lower limit of quantification (LLOQ) was found to be 10 ng/mL. Middle limit of quantification (MQC) was found to be 200 ng/mL and higher limit of quantification (HQC) was found to be 380 ng/mL. The average recovery of the analyte was found to ranging from 95.91 to 98.59%. The developed method isapplicablefor estimation of Quercetin in nano-formulation, routine quality control analysis, pharmacokinetic and bioequivalence studies.

Solid phase microextraction of macrolide, trimethoprim, and sulfonamide antibiotics in wastewaters

In this work, we optimize a solid phase microextraction (SPME) method for the simultaneous collection of antibiotics (sulfonamides, macrolides, and trimethoprim) present in wastewaters. The performance of the SPME method is compared to a solid phase extraction (SPE) method. Analytes in both cases were quantified by high performance liquid chromatography–tandem mass spectrometry (HPLC–MS–MS) with electrospray ionization. The advantages offered by SPME in this application are: decreased sample volume requirements, ease of sample processing and extraction, decreased cost, and most importantly, elimination of electrospray matrix effects. Despite having higher limits of quantification (16–1380 ng/L in influent and 35–260 ng/L in effluent), nearly all of the compounds found to be present in Edmonton Gold Bar wastewater by SPE were measurable by SPME (i.e., sulfamethoxazole, trimethoprim, erythromycin, and clarithromycin), with values similar to those obtained using the former method. Limits of quantification for the SPE method for the measured compounds were 4.7–15 ng/L and 0.86–6.1 ng/L for influent and effluent, respectively.

Comparison of extraction of a β-blocker from plasma onto a molecularly imprinted polymer with liquid–liquid extraction and solid phase extraction methods

An optimised solid phase extraction (SPE) method developed for the extraction of a structural analogue of the β-blocking drug propranolol from plasma utilising a molecularly imprinted polymer (MIP) has been compared with methods based on conventional liquid–liquid extraction (LLE), and SPE using C18-bonded and immobilised phenyl boronic acid (PBA). All four methods could be used for the extraction of the analyte with acceptable accuracy and precision. The MIP-based method, unlike the other methods required a protein precipitation step prior to extraction to eliminate the effects of co-extracted protein. The best performance was seen with the LLE method followed by SPE on the C18 phase. The MIP-based method represented no advantage over the comparator methods for this analyte. Indeed the performance of the MIP-based method was marginally worse as leaching of low level template impurities prevented detection of the target analyte at low concentrations (5 ng mL −1). This relatively poorer performance was evident as worse accuracy at low concentrations with a consequent higher limit of quantification than the conventional methods.

Quantitative analysis of oxytetracycline and its impurities by LC-MS-MS

A liquid chromatographic-tandem mass spectrometric method using an Xterra MS C 18 chromatographic column ( 100 mm×2.1 mm i.d., 3.5 μm) that allows complete separation of oxytetracycline (OTC) and the impurities: 4-epi-oxytetracycline (EOTC), tetracycline (TC), 4-epi-tetracycline (ETC), 2-acetyl-2-decarboxamido-oxytetracycline (ADOTC), α-apo-oxytetracycline (α-AOTC) and β-apo-oxytetracycline (β-AOTC) was developed. Gradient elution was used and calibration curves were obtained using the scan mode selected reaction monitoring (SRM). Acceptable correlations were obtained for OTC, TC, EOTC and ADOTC whereas the correlations of α-AOTC and β-AOTC were less accurate resulting in higher limits of quantification (LOQ) and limits of detection (LOD) relative to the other compounds. The intraday and interday accuracy varied for all the compounds from 90 to 112% and the intraday and interday precision were lower than 7.1%. The method was applied for analysis of commercial available ointments containing OTC resulting in an acceptable quantification of OTC and the impurities in the drug preparations. The advantage of this method compared to the other separation methods is an empty separation window right after the large peak corresponding to OTC in the chromatogram, which facilitates an accurate determination of ADOTC and the other impurities.

Determination of fungicide residues in fruits and vegetables by liquid chromatography–atmospheric pressure chemical ionization mass spectrometry

A liquid chromatography (LC) method for the quantitative determination of five fungicide residues (dichloran, flutriafol, o-phenylphenol, prochloraz and tolclofos methyl) in oranges, lemons, bananas, peppers, chards and onions is described. The residues were extracted by matrix solid-phase dispersion (MSPD) using C 8. Quantitative analysis was performed by isocratic LC coupled to quadrupole mass spectrometer using atmospheric pressure chemical ionization in the negative ionization mode. The limit of quantification was 0.01 mg kg −1 for flutriafol, o-phenylphenol and dichloran, and 0.1 mg kg −1 for prochloraz and tolclofos methyl. The MSPD method is also suitable for LC–UV analysis but higher limits of quantification (between 1 and 5 mg kg −1) were obtained. Validation of the method was performed between 0.01 and 25 mg kg −1. Recoveries for fungicides ranged from 52.5 to 91.1% with relative standard deviations between 6.1 and 11.9%. The method was applied to the determination of residues in samples taken from agricultural cooperatives. The fungicides most often detected were o-phenylphenol and prochloraz.

A liquid chromatography-tandem mass spectrometry method for fluazifop residue analysis in crops.

An LC-MS-MS assay is described for fluazifop residue analysis in crops. The residues are extracted with acidified organic solvent, the esters and conjugates are hydrolysed with 6 M hydrochloric acid, then the extracts are cleaned-up by solid phase extraction using C2(EC) and Si cartridges in tandem. Quantitative analysis is performed by gradient liquid chromatography coupled to triple quadrupole mass spectrometer using atmospheric pressure chemical ionisation. All fluazifop-P-butyl, free fluazifop-P and any conjugates are quantified as fluazifop-P. The limit of quantification is 0.01-0.05 mg/kg depending on crop matrices. The clean-up method is also suitable for LC-UV analysis with a compromise in higher limit of quantification 0.05-0.2 mg/kg.