Colorimetric Test Research Articles

Validation of a rapid test to dose SO<sub>2</sub> in vinegar

<abstract> <p>Sulfur dioxide is generally used in wine and vinegar production. It is employed to decrease the bacteria' growth, improve the wines' aroma (since it supports the extraction of polyphenols during maceration), protect the wines from chemical oxidation and the musts from chemical and enzymatic oxidation (blocking free radicals and oxidase enzymes such as tyrosinase and laccase). The composition and storage conditions (i.e., pH, temperature, and alcohol levels) affect oenological results. In various countries, competent authorities have imposed legal limits since it can have toxic effects on humans. It is crucial to dose SO<sub>2</sub> levels to allow vinegar production and compliance with legal limits. The iodometric titration named "Ripper test" is the legal method used to dose it in vinegar. In this work, an automatized colorimetric test was validated using the international guidelines ISO/IEC (2017) to allow its use instead of the Ripper test. The test reliability was verified on white, red, and balsamic vinegar with low or high SO<sub>2</sub> content. The automatized test showed linearity, precision, and reproducibility similar to the Ripper test, but the accuracy parameter was not respected for the vinegar with a low concentration of SO<sub>2</sub>. Therefore, the automatized colorimetric test can be helpful to dose SO<sub>2</sub> in vinegar with high concentrations of SO<sub>2</sub>.</p> </abstract>

In vitro evaluation of methanol extracts of edible fungi Pleurotus ostreatus and Lentinula edodes against Rhyssomatus nigerrimus Fahraeus.

The study aimed to evaluate the insecticidal activity of extracts of edible mushrooms Pleurotus ostreatus and Lentinula edodes against Rhyssomatus nigerrimus. Methanol:water extracts (70:30) of P. ostreatus and L. edodes were made and evaluated in two in vitro tests (exposure and immersion toxic effect) against R. nigerrimus. Subsequently, the toxicity test of the extracts against Artemia salina was evaluated. These extracts were subjected to colorimetric tests and gas chromatography-mass spectrometry. The results showed a mortality effect against R. nigerrimus of 50% for the P. ostreatus 2 extracts at a concentration of 20% in the immersion test. Likewise, in the toxic effect test, 90% mortality was observed after five days of exposure to a concentration of 10%. On the other hand, for the toxicity test, the extract that showed the values with the highest mortality against A. salina was P. ostreatus, starting with 80% mortality at 100μg/mL. The functional groups present in the extracts were saponins, coumarins, and alkaloids. Furthermore, the presence of more than 7 compounds in the mushroom extracts evaluated is reported. This study demonstrates the insecticidal activity of P. ostreatus and L. edodes fungal extracts and indicates the importance of using different in vitro tests to elucidate the mechanism of action for future studies.

Computational study of the interaction of the psychoactive amphetamine with 1,2-indanedione and 1,8-diazafluoren-9-one as fingerprinting reagents.

In this study, we used computational methods to investigate the interaction of amphetamine (AMP) with 1,2-indanedione (IND) and 1,8-diazafluoren-9-one (DFO) so as to understand whether AMP can be detected in latent fingerprints using either of these reagents. The results show that the binding energies of AMP with IND and DFO were enhanced by the presence of amino acid from -9.29 to -12.35 kcal mol-1 and -7.98 to -10.65 kcal mol-1, respectively. The physical origins of these interactions could be better understood by symmetry-adapted perturbation theory. The excited state properties of the binding structures with IND demonstrate distinguishable absorption peaks in the UV-vis spectra but zero fluorescence. Furthermore, the UV-vis spectra of the possible reaction products between AMP and the reagents reveal absorption peaks in the visible spectrum. Therefore, we could predict that reaction of AMP with IND would be observable by a reddish colour while with DFO, a colour change to violet is expected. To conclude, the reagents IND and DFO may be used to detect AMP by UV-vis spectroscopy and if their reactions are allowed, the reagents may then act as a potentially rapid, affordable and easy colorimetric test for AMP in latent fingerprints without destruction of the fingerprint sample.

Quantification of pollen viability in Lantana camara by digital holographic microscopy.

Pollen grains represent the male gametes of seed plants and their viability is critical for sexual reproduction in the plant life cycle. Palynology and viability studies have traditionally been used to address a range of botanical, ecological and geological questions, but recent work has revealed the importance of pollen viability in invasion biology as well. Here, we report an efficient visual method for assessing the viability of pollen using digital holographic microscopy (DHM). Imaging data reveal that quantitative phase information provided by the technique can be correlated with viability as indicated by the outcome of the colorimetric test. We successfully test this method on pollen grains of Lantana camara, a well-known alien invasive plant in the tropical world. Our results show that pollen viability may be assessed accurately without the usual staining procedure and suggest potential applications of the DHM methodology to a number of emerging areas in plant science.

Spectrophotometric Analysis of Nitrite in Gunshot Recentness Examinations from Non Toxic Ammunitions: Expanding the Frontiers of Forensic Chemistry

Nitrite ions consist on an important chemical clue related to gunshot examination, concerning to estimation of the time since discharge. Current forensic laboratory methods for nitrite analysis in gunshot residues are well established for investigating conventional ammunition residues. However, the use of these methods to analyze the so-called ecological or “non-toxic” ammunition has been less studied. Here, we have developed a spectrophotometric flow injection analysis method to test nitrite in samples of “non-toxic” ammunition residues. The ammunition used in these experiments was the NTA (non-toxic ammunition) model, .38 caliber, We also investigated the kinetics of nitrite decomposition for this type of ammunition over time. Sulfanilic acid and 1-naphthylethylenediamine in acetic acid were used as colorimetric reagents. The linear dependence of the spectrophotometric signal on the nitrite concentration was as follows: A = 2.07 x 104 µmol-1 L [NO2-] + 6.78 x 10-3 with a correlation coefficient (r) of 0.9994. The standard deviation (SD) of the analytical curve was 3.17 x 10-3 resulting in a limit of detection (LOD) = 0.46 µmol L-1 and a limit of quantification (LOQ) = 1.56 µmol L-1. The proposed instrumental method was more sensitive than conventional colorimetric tests and permitted the detection window to be extended to 32 days while ensuring the safety and reliability required for forensic analysis, in comparison to 7-10 days usually proposed for conventional ammunition. Therefore, the proposed method can be safely employed in forensic laboratories for routine analysis of nitrite ions in GSR samples from ecological or “non-toxic” ammunition.

Evaluation of Total Polyphenol and Flavonoid Contents of Fresh and Dried Pepper (<i>Piper nigrum</i>) from the Ivory Coast

The growing interest in the potential biological activity of polyphenols and flavonoids has highlighted necessity to assess their content in fresh and dried pepper from Ivory Coast. The total polyphenol content was determined using the Folin-Ciocalteu test and the total flavonoid content was also measured spectrophotometrically using the aluminum chloride colorimetric test. The results obtained indicate the total polyphenol levels of fresh and dried peppers are higher in the samples collected in Danane (0.8 ± 0.05 mg GAE/100g) and in Azaguie (0.4 ± 0.08 mg GAE/100g). The lowest concentrations were obtained with fresh and dried pepper samples collected in N’douci (0.22 ± 0.02 mg GAE/100g) and in PK 103 (0.22 ± 0.02 mg GAE/100g). The highest content of total flavonoids was revealed in the locality of PK 103 (1.85 ± 0.62 mg EC/100g) followed by the locality of Maféré (1.37 ± 0.25 mg EC/100g) respectively for black pepper and green pepper. Then, the lowest flavonoid contents were obtained in the dried pepper of Lopou (0.57 ± 0.03 mg EC/100g) and the fresh pepper of PK 103 (0.47 ± 0.03 mg EC/100g). The results obtained highlight the importance of these black spices as promising sources of phenolic compounds and could be used in pharmaceutical treatments and in food.

Isolation and Characterization of Flavonoid Naringenin and Evaluation of Cytotoxic and Biological Efficacy of Water Lilly (Nymphaea mexicana Zucc.).

Despite its limited exploration, Nymphaea mexicana Zucc. can be beneficial if pharmacology, isolation, and biological evaluation are given attention. It is an aquatic species that belongs to the family Nymphaeaceae. The thrust area of the work was the extraction, isolation, and biological evaluation of different extracts of the N. mexicana Zucc. plant. The primary goal of this research was to assess the antimicrobial, antioxidant, and anticancer activities of the extracts and to isolate the target naringenin compound. Comparative FT IR analysis of different extracts of this plant revealed the presence of functional groups of plant secondary metabolites, including polyphenols, flavonoids, terpenoids, esters, amines, glycosides, alkanes, alkaloids, fatty acids, and alcohols. Moderate free radical scavenging potential has been achieved for the various extracts via reducing power and DPPH assays. While cytotoxic activity was evaluated by colorimetric and lactate dehydrogenase cell viability tests on potent cancer cell lines. Lung adenocarcinoma epithelial cells (A-549), and breast cells (MC-7) were treated with MeOH extract. The antimicrobial activity against bacterial strains was evaluated using Gram-positive and -negative cultures, where maximum and minimum inhibition zones were recorded for different strains, including 1.6-25.6 μg/mL for Streptococcus aureus, using the agar well diffusion method. In addition, the anti-inflammatory activity of different extracts of N. mexicana Zucc. was evaluated in a nitrite radical scavenging assay with high concentrations of secondary metabolites, which are important against human pathogens and other diseases.

Albumin-Functionalized Iron Oxide Nanoparticles for Theranostics: Engineering and Long-Term In Situ Imaging.

Magnetic nanosystems (MNSs) consisting of magnetic iron oxide nanoparticles (IONPs) coated by human serum albumin (HSA), commonly used as a component of hybrid nanosystems for theranostics, were engineered and characterized. The HSA coating was obtained by means of adsorption and free radical modification of the protein molecules on the surface of IONPs exhibiting peroxidase-like activity. The generation of hydroxyl radicals in the reaction of IONPs with hydrogen peroxide was proven by the spin trap technique. The methods of dynamic light scattering (DLS) and electron magnetic resonance (EMR) were applied to confirm the stability of the coatings formed on the surface of the IONPs. The synthesized MNSs (d ~35 nm by DLS) were intraarterially administered in tumors implanted to rats in the dose range from 20 to 60 μg per animal and studied in vivo as a contrasting agent for computed tomography. The long-term (within 14 days of the experiment) presence of the MNSs in the tumor vascular bed was detected without immediate or delayed adverse reactions and significant systemic toxic effects during the observation period. The peroxidase-like activity of MNSs was proven by the colorimetric test with o-phenylenediamine (OPD) as a substrate. The potential of the synthesized MNSs to be used for theranostics, particularly, in oncology, was discussed.

Antimicrobial and Antibiofilm Effect of 4,4'-Dihydroxy-azobenzene against Clinically Resistant Staphylococci.

The spread of antibiotic resistance among human and animal pathogens is one of the more significant public health concerns. Moreover, the restrictions on the use of particular antibiotics can limit the options for the treatment of infections in veterinary clinical practice. In this context, searching for alternative antimicrobial substances is crucial nowadays. In this study, 4,4'-dihydroxy-azobenzene (DHAB) was tested for its potential in vitro as an antimicrobial agent against two relevant human and animal pathogens, namely Staphylococcus aureus and Staphylococcus pseudintermedius. The values of minimal inhibitory concentration (MIC) were 64 and 32 mg/L respectively, and they comparable to other azo compounds of probed antimicrobial activity. In addition, the minimal bactericidal concentrations (MCB) were 256 and 64 mg/L. The mechanism by which DHAB produces toxicity in staphylococci has been investigated. DHAB caused membrane damage as revealed by the increase in thiobarbituric acid reactive substances (TBARS) such as malondialdehyde. Furthermore, differential induction of the enzymes peroxidases and superoxide dismutase in S. aureus and S. pseudintermedius suggested their prevalent role in ROS-scavenging due to the oxidative burst induced by this compound in either species. In addition, this substance was able to inhibit the formation of biofilms by both bacteria as observed by colorimetric tests and scanning electron microscopy. In order to assess the relevance of DHAB against clinical strains of MRSA, 10 clinical isolates resistant to either methicillin or daptomycin were assayed; 80% of them gave values of CMI and CMB similar to those of the control S. aureus strain. Finally, cutaneous plasters containing a composite formed by an agar base supplemented with DHAB were designed. These plasters were able to inhibit in vitro the growth of S. aureus and S. pseudintermedius, particularly the later, and this suggests that this substance could be a promising candidate as an alternative to antibiotics in the treatment of animal skin infections, as it has been proven that the toxicity of this substance is very low particularly at a dermal level.

Colorimetric Detection of SARS-CoV-2 Using Plasmonic Biosensors and Smartphones.

Low-cost, instrument-free colorimetric tests were developed to detect SARS-CoV-2 using plasmonic biosensors with Au nanoparticles functionalized with polyclonal antibodies (f-AuNPs). Intense color changes were noted with the naked eye owing to plasmon coupling when f-AuNPs form clusters on the virus, with high sensitivity and a detection limit of 0.28 PFU mL-1 (PFU stands for plaque-forming units) in human saliva. Plasmon coupling was corroborated with computer simulations using the finite-difference time-domain (FDTD) method. The strategies based on preparing plasmonic biosensors with f-AuNPs are robust to permit SARS-CoV-2 detection via dynamic light scattering and UV-vis spectroscopy without interference from other viruses, such as influenza and dengue viruses. The diagnosis was made with a smartphone app after processing the images collected from the smartphone camera, measuring the concentration of SARS-CoV-2. Both image processing and machine learning algorithms were found to provide COVID-19 diagnosis with 100% accuracy for saliva samples. In subsidiary experiments, we observed that the biosensor could be used to detect the virus in river waters without pretreatment. With fast responses and requiring small sample amounts (only 20 μL), these colorimetric tests can be deployed in any location within the point-of-care diagnosis paradigm for epidemiological control.

Concentration measurement of coloured solution using optofluidic approach

In analytical process, measurement of concentration of solution based on colorimetric sensing is normally performed using commercial devices such as colorimeter and spectrophotometer. This approach has several disadvantages such as involving a large volume of reagent and analyte during testing and measurement, unextendible and expensive. Such problem can be solved by replicating its function using a simple optofluidic device with capability of carrying out colorimetric testing with low volume of analyte and reagent. Other benefits of optofluidic devices platforms includes ability to be expanded for automated sensing and mixing for various analytical based reaction. The measurement device works based on the absorbance of absorbance of light, which is related to Beer-Lambert law principles with LED and photodiode as its main optical components. The samples were prepared for concentration ranges between 0.2 to 2.0 M for testing. As a result, it is observed that these concentrations produce a linear voltage calibration curve with correlation coefficient, R2 equal to 0.9944. By using the obtained calibration curve, the final absorbance calculation gives an acceptable linear absorbance concentration with R2 equal to 0.9751 for the tested samples. As a conclusion, these microfluidic platforms not only have a good measurement performance, but also have advantages in terms of its portability and have potential to be implemented for real time application.

Quantitative analysis for detection of cholesterol using colorimetric platform

For blood serum analysis in the human body, a miniaturized platform was designed in order to produce a useful, affordable, and simple-to-use healthcare system. The current effort intends to construct a platform that can perform all types of clinical blood serum analysis by applying colorimetric tests and detecting the absorbance of light that passes through the tested sample. The sample's cholesterol content was examined in order to assess and confirm the platform's use. For both known and unidentified samples, cholesterol detection was carried out throughout a linearity range of 1 mg/dL to 1000 mg/dL. The created colorimetric and optical platform has the benefits of being easily accessible, useful, affordable, resilient, requiring a small amount of reagent, and not requiring highly specialized labor. Due to the stability, usage of powerful processing units, and incorporation of cutting-edge electrical mechanisms, the quantitative analysis time was slashed to thirty seconds, enabling quick inspection and great throughput. Thus, the provided framework might be a great complement to the existing resource area as a general platform for every clinical analysis by just changing the reagents and wavelength filter

Facile Synthesis of Fe-Doped Hydroxyapatite Nanoparticles from Waste Coal Ash: Fabrication of a Portable Sensor for the Sensitive and Selective Colorimetric Detection of Hydrogen Sulfide.

In this work, a new strategy has been reported for the portable detection of H2S based on Fe-doped hydroxyapatite nanoparticles (Fe-HA) using a colorimetric paper test strip integrated with a smartphone platform. Fe-HA NPs were fabricated successfully via recycling waste coal ash. The obtained probe response toward H2S was through a distinct visual color change. The sensing mechanism is based on the displacement reaction, in which PO4 3- is replaced by S2-. The prepared test strip shows high selectivity, and the other compounds containing thiol and sulfur anion have a negligible effect on the detection of H2S. The designed scheme is applied for H2S detection in the concentration range of 0.5-130 ppm with a limit of detection of 70 ppb. Furthermore, such a disposable sensor was used as a practical system for monitoring H2S in actual water samples, suggesting the promising potential of this platform for suitable analysis of H2S in an aqueous environment.

Comparative Colour Gamut Analysis Of Piezoelectric Inkjet (PIJ) And Sheet-Fed Offset Prinitng Technologies

This paper presents a comprehensive comparative analysis of the colour gamut achieved by Piezoelectric Inkjet (PIJ) and Sheet-Fed Offset printing technologies. The colour gamut, a crucial aspect of print quality, is a measure of the range of colours a printing process can reproduce. Both PIJ and Sheet-Fed Offset printing are widely employed in various industries, including graphic arts and commercial printing. The research methodology involves the characterization of the colour gamut of PIJ and Sheet-Fed Offset printing through empirical experiments and spectral measurements. A diverse set of colour targets is used to assess the gamut volume, including standard colorimetric tests such as colour gamut volume measurements. The study also considers factors such as substrate type, ink formulations, and printing conditions to provide a comprehensive understanding of the gamut limitations and advantages of each technology. Results reveal the strengths and weaknesses of both printing methods in terms of colour reproduction, highlighting areas where one technology may outperform the other. Insights gained from this comparative analysis can inform decision-making processes for print industry professionals, helping them choose the most suitable printing technology based on specific project requirements and desired colour outcomes. Ultimately, this research contributes valuable knowledge to the ongoing discourse on print technology selection, aiding in the optimization of colour reproduction processes for diverse applications ranging from high-quality graphics to commercial printing.

Colorimetric Test Paper for H2O2 Determination Based on Peroxidase‐Like Activity of an AuFe/ZIF‐8‐Graphene Composite

AbstractHerein, we prepared a bisuppport‐based bimetallic nanoparticle composite AuFe/ZIF‐8‐graphene. It exhibited high peroxidase activity compared to those hybrids without graphene support, which demonstrated the regulatory effect of graphene on the catalytic activity. SEM, TEM, EDX, XRD, FT‐IR and XPS characterization showed that Au and Fe3O4 NPs were successfully immobilized on ZIF‐8‐rGO carriers. Kinetic analysis confirmed that the fabricated composites showed better Km and Vmax for H2O2 than HRP and some other reported peroxidase mimics. Under the optimal conditions, a sensing assay for H2O2 determination was constructed with a linear detection range of 0.01–2.5 mM and a detection limit of 0.63 μM. On this basis, a colorimetric test paper with its standard card was prepared for rapid visualization detection. It realized H2O2 detection in the range of 0.01‐500 mM and was further successfully applicated in the semi‐quantitative detection of H2O2 in actual spiked water samples. This achievement was expected to encourage the development of rapid visual detection for other pollutants in environmental and medical field.

A dual-readout paper-based analytical device for the simultaneous determination of hexavalent Cr and total Cr.

Apaper-based analytical device (PAD) is presentedwith colorimetric/electrochemical dual readouts for the simultaneous sensing of total chromium (Cr) and hexavalent chromium (Cr(VI)). This device consists of a homemade three-electrode system and a patterned paper chip, integrating multiple functions including electrochemical detection, fluid driving, online oxidation, and colorimetric detection. The fiberglass filter paper with ahydrophilic microchannel was used to achieve self-driving fluidics without external equipment. One end of the microchannel was integrated with a homemade three-electrode system to achieve sample loading and electrochemical detection. The middle region on the microchannel was modified with oxidizing reagents to perform online pretreatment, and the yield of Cr(III) oxidation can reach 97.9%, ensuring reliable colorimetric detection of total Cr at another end of the microchannel modified with chromogenic agents. With this device, the signals of Cr(VI) (the signal peak at 0.29V vs. Ag/AgCl) and total Cr can be obtained in one single injection. After optimization, the limit of detection (LOD) of Cr(VI) andtotal Cr were0.01mg L^-1 and 0.06mg L^-1 and the linear ranges were 0.05-3.0mg L^-1 and 0.2-3.0mg L^-1, respectively. Therelative standard deviations (RSD) of the electrochemical testing ofCr(VI) results were in a range 1.3%-8.7% (n = 3), and the RSD values of the colorimetric testing oftotal Cr were between 0.7-9.2% (n = 3). The device's reliability was demonstrated by performing the practical speciation of Cr in tap water, river water, and electroplating wastewater while the recoveries obtained using the present method were in the range 93.5-106%. Overall, the proposed device provides highapplication prospect in the on-site rapid Cr speciation.

Assessing Analytical Methods for the Rapid Detection of Lead Adulteration in the Global Spice Market.

Lead adulteration of spices, primarily via Pb chromate compounds, has been documented globally as a growing public health concern. Currently, Pb detection in spices relies primarily on expensive and time-consuming laboratory analyses. Advancing rapid Pb detection methods, inclusive of their accuracy and precision, would improve field assessments by food safety inspectors, stakeholders, and the public in the hope of reducing Pb exposure risks at its source. Here, we present two field procedures for Pb detection: portable X-ray fluorescence analysis (pXRF) and a simple colorimetric test. We assess their efficacy to detect Pb and its chemical form in seven spice types, including powders, spice-salt mixtures, and dried roots, compared to the proven laboratory technique, inductively coupled plasma mass spectrometry (ICP-MS). Lead concentrations measured using pXRF and ICP-MS were within 5% of each other for spice powders and 24% for dried roots. By pXRF, spice samples were analyzed within collection plastic bags without preparation, resulting in a detection limit of 2 mg Pb/kg for spice powders, which is comparable to national food standards. The colorimetric test utilized here targets hexavalent chromium, making the method selective to Pb chromate adulteration assuming that this is its dominant source in spices. Color development, and thus detection, was observed when Pb concentrations exceeded approximately 5-70 mg/kg in dried turmeric roots and 1000 mg/kg in spice powders; however, it was ineffective for the spice-salt mixture. We show that pXRF analysis and a colorimetric assay provide information that may improve field decisions about Pb adulteration in a range of spice types, helping to minimize Pb exposure.

Heroin detection in a droplet hosted in a 3D printed support at the miniaturized electrified liquid-liquid interface

Simple sensing protocols for the detection of illicit drugs are needed. Electrochemical sensing is especially attractive in this respect, as its cost together with the analytical accuracy aspires to replace still frequently used colorimetric tests. In this work, we have shown that the interfacial transfer of protonated heroin can be followed at the electrified water-1,2-dichloroethane interface. We have comprehensively studied the interfacial behavior of heroin alone and in the presence of its major and abundant cutting agents, caffeine and paracetamol. To maximally increase developed sensing protocol applicability we have designed and 3D printed a platform requiring only a few microliters of the aqueous and the organic phase. The proposed sensing platform was equipped with a cavity hosting a short section of Ag/AgCl electrode, up to 20 µL of the aqueous phase and the end of the micropipette tip being used as a casing of a fused silica capillary having 25 µm as the internal pore diameter. The volume of the organic phase was equal to around 5 µL and was present inside the micropipette tip. We have shown that under optimized conditions heroin can be detected in the presence of caffeine and paracetamol existing in a sample with 10,000 times excess over the analyte of interest. The calculated limit of detection equal to 1.3 µM, linear dynamic range spanning to at least 50 µM, good reproducibility, and very low volume of needed sample is fully in line with forensic demands.

Ninhydrin and isatin appended 2-Hydrazinobenzothiazole based simple Schiff bases for colorimetric selective detection of Cr3+ and Pb2+ ions

A simple and easily synthesizable chromogenic small molecules probe L4(2-(2-(benzo[d]thiazol-2-yl)hydrazono)-1H-indene-1,3(2H)-dione) and L5 (2-(2-(benzo[d]thiazol-2-yl)hydrazono)indolin-3-one) have been synthesized and characterized by various spectroscopy techniques such as FT-IR, NMR, and HRMS. The colorimetric naked eye detection of probe L4 showed a color change towards Cr3+ from orange color to pale yellow, whereas in case of L5 Pb2+ yellow to orange color was witnessed. The jobs plot analyses indicate the 1:1 binding stoichiometric for Cr3+ and 1:2 binding stoichiometric for Pb2+ ions with probes L4 and L5 respectively. The binding association constant (ka) values for L4 and L5 were found to be 6.651 × 10-5 M for Cr3+ and 6.493 × 10-5 M for Pb2+ ions. The limit of detection was found to be for Cr3+ (1.69 × 10−7 M) and Pb2+ (1.208 × 10−7 M) are far below than the limit set by the World Health Organization (WHO) for drinking water. Finally, the designed probes were applied for visible colorimetric test kits and real samples for rapid detection of Cr3+ and Pb2+ for all practical purposes, indicating their potential use in environmental samples.

Pb removal from water by three types of biofilters

IntroductionAs aquatic organisms are directly affected by water quality, the use and evaluation of biofilters aiming at the previous removal of Pb guarantee the adequate water physicochemical parameters to the maintenance of the organisms of interest. ObjectiveThis note aims to report the results of a water pre-treatment testing three types of biofilters (river gravel and two types of seashell-based media: self-collected and commercial) to evaluate their ability to absorb and consequently remove the Pb from water. M&MTemperature and salinity were measured using Hg thermometers and a refractometer, respectively. Commercial colorimetric test kits were used to monitor pH and the toxic ammonia concentration. The Pb determination was performed by using GF AAS analytical technique. ResultsAccording to results, biofilters can significantly remove concentrations of Pb from the water column. The evaluated biofilters kept the water physical-chemical parameters stable. Results support the use of these biofilters to treat water before any experiment. ConclusionThis report may subside future studies on the use of these biofilters in other activities, such as aquaculture and waste treatment, to maintain the physical-chemical water parameters well-controlled. Statement of NoveltyThe present study has tested in laboratory conditions, three types of biofilters (river gravel and two types of seashell-based media: self-collected and commercial) to evaluate their ability to absorb and consequently remove the Pb. This report may subside studies on the use of these biofilters in activities, such as aquaculture and waste treatment, to maintain the physical-chemical water parameters well-controlled, applying low-cost biomaterials.