Determination Of Triclosan Research Articles

Copper-zinc nanoparticle-decorated nitrogen-doped carbon composite for electrochemical determination of triclosan.

Anew sensor based on copper-zinc bimetal embedded and nitrogen-doped carbon-based composites (CuZn@NC) was prepared for triclosan (TCS) detection by pyrolyzing the precursor of Cu-Zn binuclear metal-organic framework (MOF). The performance for detecting TCS was evaluated using linear scanning voltammetry (LSV) and differential pulse voltammetry (DPV), and the proton and electron numbers during TCS oxidation have been proved to be one-to-one. The results indicated that CuZn@NC can present a satisfactory analysis performance for TCS detection. Under the optimized conditions, the linear response range was 0.2-600 µM and the detection limit was 47.9nM. The sensor presented good stability (signal current dropped only 2.5% after 21days) and good anti-interference of inorganic salts and small molecular organic acids. The good recovery (97.5-104.1%) for detecting spiked TCS in commercial products (toothpaste and hand sanitizer) suggested its potential for routine determinationof TCS in real samples.

Comparative Evaluation of Triclosan in Selected Anti-bacterial Soaps

Background of the topic: Triclosan is a widely used antimicrobial agent in personal care products. Triclosan is readily absorbed into the skin and present in the human tissues and fluids. But the triclosan showed many side effects including carcinoma. Therefore the determination of triclosan in various personal health care products by simplest analytical methods is very much significant. Purpose of the study: The present study was aimed to do the comparative evaluation of triclosan in selected soaps and the evaluation was carried out by using ultraviolet spectroscopy. Methods: Comparative evaluation of the selected four anti-bacterial soaps were carried out and the percentage of triclosan was determined by calibration curve method. The analytical technique used was ultra-violet spectroscopy by using the solvent ethanol. The Linearity was tested using the standard triclosan in the range of 300 µg/ml - 1500 µg/ml. The validation methods such as ruggedness, repeatability, intermediate precision, linearity were done for all the four selected samples. Accurately weighed soap samples and dissolved in 3 ml of water. Transferred this solution into a separating funnel and extracted with chloroform. Organic layer was separated out and pipette out 1 ml of this organic layer and diluted to 10 ml with ethanol. The absorbance of the sample solution was measured at 307 nm. Results: Comparative evaluation of the selected anti bacterial soaps and triclosan content was estimated by UV-spectroscopy. The λmax was found to be 307nm. The method was found to be linear within 300 µg/ml - 1500 µg/ml. The percentage of triclosan present in selected four samples A, B, C and D were 0.28±0.8772, 0.24±0.9878, 0.32±1.123 and 0.73±0.9932 respectively. Conclusions: The percentage of triclosan in sample A sample B were within the limit and sample C and sample D slightly higher than that of the safe limit. The method used for the estimation of triclosan was UV spectroscopy method which was validated using ICH guidelines.

Disposable electrochemical sensor based on carbon black and ternary oxide (SiO2/TiO2/Nb2O5) for determination of triclosan in mouthwash and water samples

Disposable electrochemical sensor based on carbon black and ternary oxide (SiO2/TiO2/Nb2O5) for determination of triclosan in mouthwash and water samples

Temperature-controlled air-assisted liquid–liquid microextraction based on the solidification of floating deep eutectic solvents for the determination of triclosan and alkylphenols in water samples via HPLC

A novel and green microextraction technique, temperature-controlled air-assisted liquid–liquid microextraction based on the solidification of floating deep eutectic solvents (DESs), was developed and applied for the extraction of triclosan and alkylphenols in different environmental waters. Hydrophobic DESs composed of menthol and myristic acid with melting points slightly higher than room temperature (25 ± 2 °C) were prepared and used as extraction solvent. First, the solid DES was transformed into liquid DES while the aqueous sample was heated in a water bath. Then, fine droplets were formed by withdrawing and injecting the mixture of aqueous sample and DES with a 1 mL pipette several times. After extraction, the solidified DES phase was obtained in an ice water bath. And then the analyses were performed by HPLC-UV. The microextraction parameters were investigated by the Plackett-Burman design and central composite design. The analytical parameters of this method were investigated and good linear ranges (0.5/1.0–400 μg/L, R2 ≥ 0.9950), limits of detection (0.1–0.5 μg/L) and precision (≤5.9 %) were obtained. This method was successfully applied for the determination of triclosan and alkylphenols from five water samples with satisfactory recoveries (80.0–104.3 %). Subsequently, the green profile of the method was assessed by analytical Eco-Scale and Complementary Green Analytical Procedure Index. This method has the advantages of simplicity, rapidity, low cost, high sensitivity and green, which expands the application of solid solvents in liquid–liquid microextraction and has a wide application prospect.

In-situ formation of hydrophobic deep eutectic solvent for the enrichment and quantitative determination of triclosan in personal care products and environmental water samples

Green techniques for sample pretreatment and quantitative analysis are important for environmental concerns. In this work, a new liquid–liquid microextraction strategy is developed by in-situ formation of hydrophobic deep eutectic solvents (DESs) where a contaminant (such as triclosan) serves as a hydrogen bond acceptor and a hydrophobic compound (such as 2,2,4-trimethyl-1,3-pentanediol) acts as a hydrogen bond donor. This strategy, along with high performance liquid chromatography, is used to establish the method for enrichment and quantitative determination of trace triclosan from real samples. For this purpose, the factors affecting the extraction and determination were investigated by using single-factor test. The result showed that the optimal extraction condition was, extraction temperature 45 °C, the amount of extractant 150 mg, the pH of solution 5.9, the volume of diluent (methanol) 100 µL, the concentration of salt (NaCl), 1.00 mol/L. Under the optimum conditions, the linear range of the proposed method was 1.7–1000 µg/L with the linear correlation coefficient (R2) of 0.9991. The detection limit and quantitation limit were 0.5 and 1.7 µg/L, respectively. Finally, this method was used to determinate triclosan content in the leach solution of personal care products and environmental water samples, including facial cleanser, soap, toothpaste, hand sanitizer, tap water, surface water, rainwater, lake water, and wastewater of sewage treatment plant. The extraction recovery of triclosan was between 76 %−115 %, and the relative standard deviation was less than 7.36 %. These results indicate that the proposed method was effective and practical for the enrichment and quantitative determination of trace triclosan in personal care products and environmental water samples.

Smartphone-based colorimetric determination of triclosan in aqueous samples after ultrasound assisted-dispersive liquid–liquid microextraction under optimized response surface method conditions

In the present study, a simple and low cost methodology based on ultrasonic assisted-dispersive liquid–liquid microextraction (UA-DLLME) followed by smartphone-based colorimetric measurement was introduced for the separation and determination of Triclosan (TCS) from contaminated waters. This method is based on the formation of an azo compound from the alkaline reaction of TCS with a diazonium ion, resulting from the reaction of sodium nitrite and p-sulfanilic acid in an acidic medium. The orange-brown color product was extracted into a low volume of organic phase by UA-DLLME method and RGB values were recorded with free Android app Color Grab. The effective parameters in this procedure, namely solution pH, p-sulfanilic acid and nitrite concentration, reaction time and volume of the extraction solvent were investigated and optimized by response surface methodology (RSM) based on a Box-Behnken design (BBD) model. Under optimum conditions, the calibration graph was linear in the range of 3.0 and 200 μg L-1 of TCS. The limit of detection (LOD) and limit of quantification (LOQ) were 0.8 and 2.7 μg L-1, respectively. The proposed method was successfullyused for the analyses of triclosan in several water and wastewater samples and satisfactory results were obtained.

A molecularly imprinted electrochemical sensor based on cationic intercalated two-dimensional titanium carbide nanosheets for sensitive and selective detection of triclosan in food samples

An advanced molecularly imprinted electrochemical sensor (MIECS) based on two-dimensional materials MXene was developed for determination of triclosan (TCS) in food samples for the first time. Two-dimensional titanium carbide (Ti3C2Tx) were introduced to improve electrochemical response of the MIECS. K+ ions were spontaneously inserted into Ti3C2Tx nanosheets to form K+-Ti3C2Tx by soaking in alkali solution, thus improving the sensitivity of the sensor. Molecularly imprinted polymers (MIP) were prepared by electropolymerization of para aminobenzoic acid (p-ABA), which can specifically recognize TCS. Under optimal conditions, the linear relationship between the current intensity and TCS concentration was obtained from 10 nmol L−1 to 50 μmol L−1 with a low detection limit of 1.18 nmol L−1. The proposed MIECS showed good repeatability for detecting TCS at a concentration of 500 nmol L−1 solution by preparing five parallel modified electrodes, with a relative standard deviation (RSD) of 3.42%. At the spiked concentration levels of 0.05, 0.1, 0.5 mg L−1/mg kg−1, the recoveries range of TCS in peach juice, onions and fish samples were 86.38%–95.52%. The proposed MIECS combining the advantages of Ti3C2Tx and MIP exhibited good sensitivity and selectivity, providing strategy of utilizing MXenes in the construction of electrochemical sensing platform and holding great promise in the field of food safety.

In-Situ Formation of Hydrophobic Deep Eutectic Solvent for the Enrichment and Quantitative Determination of Triclosan in Personal Care Products from Environmental Samples

In-Situ Formation of Hydrophobic Deep Eutectic Solvent for the Enrichment and Quantitative Determination of Triclosan in Personal Care Products from Environmental Samples

Electrochemical Determination of Triclosan Using ZIF-11/Activated Carbon Derived from the Rice Husk Modified Electrode

In the present paper, the composite of zeolite imidazolate framework-11 (ZIF-11) and activated carbon derived from rice husks (RHAC) was synthesized. The obtained materials were characterized by XRD, SEM, EDX-mapping, and nitrogen adsorption/desorption isotherms. The final composite ZIF-11/RHAC exhibits an even dispersion of ZIF-11 particles on activated carbon matrix. Herein, an electrochemical sensor based on a ZIF-11/RHAC was developed for a rapid determination of triclosan (TCS). It was found that the oxidation of TCS is irreversible and involves the transfer of one electron. The linear range for TCS detection in the optimized experimental conditions was found to be 0.1-8 μM with the limit of detection of 0.076 μM. Finally, the proposed method was successfully employed to detect TCS in different personal care product samples with high accuracy, which was confirmed by a good agreement between these results and those obtained using high-performance liquid chromatography (HPLC).

Assessment of direct analysis in real time accurate mass spectrometry for the determination of triclosan in complex matrices

In this work, the applicability of direct analysis in real time coupled to accurate mass spectrometry (DART-MS) to the quantitative determination of triclosan (TCS) in samples with increasing complexity, from personal care products to extracts from sewage, is investigated. In the first term, DART-MS spectra of TCS as free phenol and as derivatized species are characterized; thereafter, the effects of several instrumental variables in the detectability of TCS (i.e., temperature, solvent, and compound holder) are discussed. Under final selected conditions, TCS was determined from its [M-H]− ions, without need of derivatization, attaining an instrumental limit of quantification of 5 ng mL−1, with a linear response range up to 1000 ng mL−1. Complex matrices, such as solid-phase extracts obtained from environmental water samples, moderately inhibited the ionization efficiency of TCS, with signal attenuation percentages in the range of 6 to 57%, depending on the sample type and on the concentration factor provided by the SPE procedure. The accuracy of results obtained by DART-MS was evaluated using liquid chromatography (LC) with MS detection; in both cases, a time-of-flight (TOF) MS instrument was employed for the selective determination of the [M−H]− ions of TCS (m/z values 286.9439 and 288.9410) using a mass window of 20 ppm. DART-MS did not only provide enough sensitivity to detect the presence of TCS in environmental samples (raw and treated wastewater as well as freeze-dried sludge), but also measured concentrations matched those determined by LC-ESI-TOF-MS, with only slightly higher standard deviations. During analysis of personal care products, containing much higher concentrations of TCS in a less complex matrix, both techniques were equivalent in terms of accuracy and precision.Graphical abstract

Simultaneous determination of triclosan, triclocarban, triclocarban metabolites and byproducts in urine and serum by ultra-high-performance liquid chromatography/electrospray ionization tandem mass spectrometry.

Triclosan (TCS) and triclocarban (TCC) are ubiquitous antimicrobial agents incorporated in consumer and personal care products. Due to their human health risks, it is essential to develop a sensitive and accurate analytical method to simultaneously quantify TCS, TCC, as well as their metabolites and byproducts in urine and serum samples. The quantitative parameters of TCS, TCC, TCC metabolites and byproducts (2'-OH-TCC, 3'-OH-TCC, 6-OH-TCC, DHC, DCC, NCC) were optimized by using ultra-high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (UHPLC/ESI-MS/MS). Enzymatic hydrolysis of the samples was optimized based on enzyme dosage and incubation time. The efficiencies of solid-phase extraction (SPE) and liquid-liquid extraction (LLE) were compared. The effectiveness of the established method was evaluated, and method application was validated using real urine and serum samples. The conjugates were sufficiently hydrolyzed under 500 U/mL β-glucuronidase and 80 U/mL sulfatase at 37°C for 4h. Compared with the LLE method, SPE achieved higher extraction efficiency in both urine and serum samples. The optimized SPE-UHPLC/ESI-MS/MS method showed low limits of detection (LODs) in the range 0.001-0.3ng/mL and good linearity (R2 > 0.99) at 0.01-150 ng/mL in both matrices. Excellent recoveries of 82.0%-120.7% (urine) and 76.7%-113.9% (serum) were obtained with low relative standard deviation (RSD, <7.6%) for inter-day and intra-day injections. This method was applicable to quantify target compounds in multiple biological urine and serum samples. Notably, TCS and TCC were detected with average concentrations of 8.37 and 10.46 ng/mL, respectively, in 15 Chinese female urine samples, with the simultaneous detection of TCC metabolites and byproducts. A reliable method was established to simultaneously determine TCS, TCC, TCC metabolites and byproducts in urine and serum samples by using UHPLC/ESI-MS/MS. This sensitive methodology provides the basis for the evaluation of TCS and TCC exposure at the metabolic level.

Determination of Three Endocrine Disruptors in Water Samples by Ultrasound-Assisted Salt-Induced Liquid-Liquid Microextraction (UA-SI-LLME) and High-Performance Liquid Chromatography – Diode Array Detection (HPLC-DAD)

Endocrine-disrupting compounds are routinely detected in environmental water. In this study, a simple and rapid sample preparation method based on ultrasound-assisted salt-induced liquid-liquid microextraction (UA-SI-LLME) followed by high performance liquid chromatography – diode array detection (HPLC-DAD) was developed for the determination of triclosan, triclocarban and methyl-triclosan in water. Parameters that affect the extraction efficiency – such as type and mass of salt, type and volume of extraction solvent, extraction time, sample pH and sample volume – were studied. Under the optimized conditions, the method demonstrated linearity from 0.18 to 1000 µg L−1 with coefficients of determination R2 ≥ 0.9899, limits of detection from 0.05 to 0.2 µg L−1, and good recoveries (> 70%) with relative standard deviations < 10%. The method was applied for the determination of triclosan, triclocarban, and methyl-triclosan in swimming pool, lake, and wastewater. The greenness of the method was quantified using the Analytical Eco-Scale Index.

Electrode modified with nitrogen-doped graphene quantum dots supported in chitosan for triclocarban monitoring

Triclocarban is an antimicrobial agent frequently used in personal care products with potential activity for endocrine disrupting, and hence its monitoring is particularly important. A sensitive analytical tool was developed for electroanalysis of triclocarban by modifying a glassy carbon substrate with nitrogen-doped graphene quantum dots immobilized in chitosan. Electron microscopy results showed that the synthesized quantum dots had a diameter of 4.5 nm. The doping with nitrogen in the graphene matrix was confirmed by spectroscopic techniques. Electrochemical techniques showed excellent triclocarban oxidation current responses provided by the modified electrode compared to the bare electrode. The calibration plot for triclocarban was constructed in 0.1 mol L−1 phosphate buffer (pH 7.0):ethanol (95:5 v/v) in the range of 0.05 to 8.0 μmol L−1 with limits of detection and quantification of 17.0 and 57.0 nmol L−1, respectively. The modified electrode was effectively implemented in the quantification of triclocarban in personal care products with recoveries data in the range of 90 to 109%. Furthermore, the modified electrode was applied in the simultaneous determination of triclosan (+0.60 V) and triclocarban (+0.95 V) with limits of detection of 14.0 and 21.0 nmol L−1, respectively. The application was carried out in surface water samples with excellent accuracy indicated by recovery data in the range of 93 to 110%.

Sensitive and selective determination of triclosan using visual spectroscopy

Triclosan is a commonly used biocide effective against bacterial and fungal infections. However, its overuse in pharmaceutical and personal care products has resulted in its abundance in the natural environment. The detection of triclosan by visual spectroscopy can be carried out using the azo-coupling reaction of diazonium complexes. However, the reaction is also common to other phenolic compounds and aromatic amines, posing significant challenge. In this work, we investigate the azo-coupling reaction of triclosan and several commonly occurring analogous compounds to develop an improved spectroscopic method for the selective determination of triclosan without interference. We find that the azo-coupling reaction between the diazotized derivative and the phenolic compounds is highly dependent on the pH of the reaction media. At pH 7.2, the absorbance of the azo dye product of triclosan shows a peak at 452 nm which has minimal interference from other phenolic azo-dye products with the exception of naphthol. Naphthol shows an interference corresponding to 58% of the analytical signal of equimolar triclosan concentration. To overcome this, we develop an analytical model for the simultaneous determination of triclosan and naphthol from mixed solutions of the compounds. A linear calibration plot from 1.7 to 34 µM was obtained for both triclosan and naphthol with limit-of-detection (LOD) of 0.62 µM and 1.03 µM respectively. The developed protocol was tested for the analysis of water samples collected from various environmental sources spiked with different concentrations of triclosan and naphthol. The samples were enriched by solid-phase-extraction which allowed a 50-fold enhancement in detection of triclosan. The average relative recovery of triclosan in real samples was found to be 98.6% .

In-Situ Formation of Hydrophobic Deep Eutectic Solvent for the Determination of Triclosan in Personal Care Products Coupled with High Performance Liquid Chromatography

In-Situ Formation of Hydrophobic Deep Eutectic Solvent for the Determination of Triclosan in Personal Care Products Coupled with High Performance Liquid Chromatography

A sensitive voltammetric sensor based on silver nanoparticles/carbon nitride nanotubes@graphene quantum dots/a novel organic liquid: determination of triclosan in wastewater

A new sensor approach based on silver nanoparticles (AgNPs)/carbon nitride nanotubes (C3N4NTs)@graphene quantum dots (GQDs)/5-nitro-2-(3-hydroxy-4-methoxybenzylidenamino)-thiazole (ILs) was presented for triclosan (TCS) detection in wastewater samples. X-ray diffraction method, scanning electron microscope, electrochemical impedance spectroscopy, transmission electron microscope and cyclic voltammetry methods were used for all nanomaterials’ characterizations. The linearity range and the detection limit (LOD) were found as 1.0 × 10−11 to 1.0 × 10−8 M and 2.0 × 10−12 M, respectively. The nanocomposite-modified electrode was used for wastewater sample analysis in the presence of different agents.

Electrode modified with graphene quantum dots supported in chitosan for electrochemical methods and non-linear deconvolution of spectra for spectrometric methods: approaches for simultaneous determination of triclosan and methylparaben.

Two analytical methods were developed using electrochemical and spectrometric techniques for the simultaneous determination of endocrine disruptors triclosan and methylparaben in the monitoring of personal care products. For the electroanalytical analyses, a sensitive electrode based on graphene quantum dots supported in chitosan was employed. Under optimized conditions and a working potential of typically + 0.60V for triclosan and + 0.81V (vs. Ag/AgCl) for methylparaben, the calibration plots obtained by differential pulse voltammetry were linear in the range 0.10 to 10.0μmolL-1. The detection limits were 0.03 and 0.04μmolL-1 for triclosan and methylparaben, respectively. For the spectrometric method, UV/VIS spectrometry was used with a mathematical processing of non-linear deconvolution. This processing was used to solve the problem of overlapping absorption bands of triclosan (282nm) and methylparaben (257nm), which enabled simultaneous determination. The calibration plots by UV/VIS spectrometry were linear in the range1.0 to 14.0μmolL-1 with detection limits of 0.42 and 0.37μmolL-1, respectively, for triclosan and methylparaben. Similar results obtained from the calibration plots of individual analytes suggest that the methods can be applied for individual or simultaneous determination of these species. Both methods were employed in the analysis of five samples of personal care products: toothpaste, antiseptic soap, antiseptic deodorant, shampoo, and a bath kit (soap and shampoo). The statistical tests indicated that there were no significant differences regarding the accuracy and precision of the data provided by the two methods described herein. Graphical abstract Schematic representation for simultaneous determination of triclosan and methylparaben: electrochemical method employing an electrode modified with graphene quantum dots supported in chitosan and spectrometric method applying a non-linear deconvolution of spectrum.

3D printed fluidic platform with in-situ covalently immobilized polymer monolithic column for automatic solid-phase extraction

In this work, 3D stereolithographic printing is proposed for the first time for the fabrication of fluidic devices aimed at in-situ covalent immobilization of polymer monolithic columns. Integration in advanced flow injection systems capitalized upon programmable flow was realized for fully automatic solid-phase extraction (SPE) and clean-up procedures as a ‘front-end’ to on-line liquid chromatography. The as-fabricated 3D-printed extraction column devices were designed to tolerate the pressure drop of forward-flow fluidic systems when handling large sample volumes as demonstrated by the determination of anti-microbial agents, plastic additives and monomers as models of emerging contaminants (4-hydroxybenzoic acid, methylparaben, phenylparaben, bisphenol A and triclosan). Decoration of the monolithic phase with gold nanoparticles (AuNPs) was proven most appropriate for the enrichment of phenolic-type target compounds. In particular, the absolute recoveries for the tested analytes ranged from 73 to 92% both in water and saliva samples. The 3D printed composite monolith showed remarkable analytical features in terms of loading capacity (2 mg g−1), breakthrough volume (10 mL), satisfactory batch-to-batch reproducibility (<9% RSD), and easy on-line coupling of the SPE device to HPLC systems. The fully automatic 3D-printed SPE-HPLC hyphenated system was also exploited for the on-line extraction, matrix clean-up and determination of triclosan in 200 μL of real saliva samples.

Application of carbon nanotubes and zwitterionic surfactant-modified acetylene black electrode for the determination of triclosan in household commodities

ABSTRACT A novel electrochemical sensor for the determination of triclosan (TCS) based on acetylene black (AB)/carbon nanotube (CNT)/cetyl sulphonyl betaine (SB16) was prepared. The composite AB/CNT/SB16 sensor was constructed using AB electrode with CNT and SB16 as sensitising materials. Sensor performance was evaluated by cyclic voltammetry, scanning electron microscopy and electrochemical impedance spectroscopy analyses. The linear equation was Ip(μA) = 19.16C TCS (μM) + 0.1319(R2 = 0.9823), and the linear range of the prepared method for the detection of TCS was from 0.01 μM to 2.0 μM with a detection limit of 6.18 nM. The sensor also displayed excellent selectivity, repeatability, and stability for TCS determination. Finally, the sensor was successfully used to detect TCS in real commodity samples, with a relative standard deviation from 0.56% to 2.32%, consistent with the results of high-performance liquid chromatography.

High performance liquid chromatographic determination of triclosan, triclocarban and methyl-triclosan in wastewater using mini-bar micro-solid phase extraction

An analytical method for the determination of the antibacterial agents (triclosan, triclocarban and methyl-triclosan) in wastewater is described. Attention was paid to sample pre-treatment where a new device, the mini-bar micro-solid phase extraction (mini-bar μ-SPE) was introduced. As in conventional micro-solid phase extraction (μ-SPE) device, sorbent (graphene, 20 mg) was introduced into a porous polypropylene (PP) bag (1.5 cm × 0.8 cm). It was next inserted into another slightly bigger PP bag (2.0 cm × 0.8 cm) together with a small metal rod (diameter, 1 mm; length, 1.5 cm). The open end of the outer bag was heat-sealed to secure the contents. After the extraction, the extracts were analysed by liquid chromatography on a pentafluorophenyl column (250 mm × 4.6 mm × 5 μm) with ultraviolet detection. Various experimental conditions influencing the mini-bar μ-SPE such as the effects of membrane type, preconditioning solvent, stirring speed, sorbent type and amount, sample volume and pH on the extraction were optimized. The desorption parameters (sonication time, solvent type and volume) were also studied. The method was validated, and calibration curves were linear with r2 > 0.99 over the range of 0.2–1000 μg L−1. The limits of detection were in the range 0.04–0.07 μg L−1. Recoveries were in the range between 80.8 and 103% for the target analytes. The relative standard deviation for inter- and intra -day precision was in the range of 3.6–27% for all analytes. The validated method was applied to the determination of the antibacterial agents in a campus wastewater treatment plant. Advantages of the mini- bar μ-SPE over the conventional μ-SPE are also highlighted.