Method For Measurement Of pH Research Articles

PH Sensor Through a Self-Assembled Multifunctional Layer With Clitoria Ternatea Based on Long-Period Fiber Gratings

In this study, Clitoria ternatea was used to provide a quantifiable method for pH measurement. The researchers proposed a new pH measurement method that involves the use of a KrF excimer laser to perform laser-assisted etching of the crown structure of long-period fiber gratings. Processing of the front surface of the optical fibers through grating resulted in periodically structured optical fibers with a sensor diameter of 55 μm and a period of 660 μm; these structured optical fibers were encapsulated using glass slides. On the front surface of the optical fibers, functional group modification of the fiber surface was conducted and a nanogold coating was applied using the self-assembly method. Additionally, Clitoria ternatea was bonded to the surface of the optical fibers for the measurement of refractive index. In the pH sensing experiment, the average loss sensitivity detected by the sensors with no nanogold self-assembled coating was 0.0635 dB/pH. By contrast, the average resonant wavelength sensitivity of the sensors with a nanogold self-assembled coating under localized surface plasmon resonance was increased to 0.173 nm/pH. Compared with the sensors with no nanogold self-assembled coating, the sensors with this coating had a wavelength drift sensitivity enhanced by a factor of 37.

Combination of Ozone-Zeolite Filter to Reduce COD and Ammonia content in household waste

Domestic waste standard parameters according to PermenLH No. 68 Years. 2016 determined one of them based on the pH, COD and Ammonia values. Most household wastewater has these values, so a purification process is required before the wastewater returns to groundwater. One of the treatments carried out is in the form of ozone technology which can decompose organic and inorganic pollutants and kill microorganisms in the waste. The purpose of this study was to determine the quality of household wastewater resulting from ozone bubble treatment combined with zeolite filters. To support the research, we used the pH, COD and Ammonia measurement methods from the treated samples. The method used is in the form of ozone treatment and zeolite filters in wastewater with a variable length of treatment time. From the research results, it can be seen that the combination of ozone and zeolite filter has an effect on decreasing the concentration of COD and ammonia in wastewater.

Establishment of Traceability Chain For pH Measurement in Indonesia

As a consequence of the globalization of trade and industries, the presence of an accurate and traceable measurement has become very important for quality assurance of a product or service in the market, including pH measurement. pH measurement is a basic analysis used in a wide variety of applications, such as agriculture, wastewater treatment, industrial processes, research and development, and environmental monitoring. The reliable and comparable results of pH measurement are advantaged as one of the parameters for quality control that will affect the decision making. The Electrochemistry Laboratory under Deputy of National Measurement Standard – National Standardization Agency of Indonesia (SNSU–BSN) has a main duty to ensure the reliability, comparability, and traceability of pH measurements in Indonesia, as a commitment in building chemical metrology infrastructure. In this article, all the activities related to the establishment of traceability chain for pH measurement in Indonesia are comprehensively discussed. As of currently, the Electrochemistry Laboratory has successfully developed the secondary method for pH measurement using differential potentiometric cell, production of certified reference material (CRM) for buffer solution (oxalate, phthalate, phosphate, and borate buffer), dissemination by proficiency testing (PT) schemes for pH measurement, participation in the key comparison (KC) of APMP.QM-K91 for phthalate buffer, and claim submission for the Calibration Measurement Capabilities (CMCs) of phthalate buffer (pH 3.97-4.03) with expanded uncertainty 0.004.

Electropolymerization of Azure A and pH Sensing Using Poly(azure A)-modified Electrodes.

A modified electrode was developed by immobilizing poly(azure A) (pAA) onto the surface of a glassy carbon electrode via the electropolymerization of azure A (AA). The pAA immobilized on the electrode exhibited redox response during cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The redox reaction obeyed the Nernst equation because of the involvement of H+ ions. In addition, the peak potential was shifted according to the solution pH. The shifts of the oxidation peak potential could be more easily observed using DPV than when using CV, indicating that the developed electrode could be useful as a pH sensor. This pH measurement method can be successfully applied in the pH range of 1 to 10 and can be successfully repeated more than 50 times.

Stability studies of pH reference materials under repeated use conditions by the primary measurement method

This work presents the results from stability studies for a series of pH-certified reference materials submitted to repeated use conditions (repeated sampling) to meet the requirements from the latest versions of ISO 17034 and ISO Guide 35. The study was applied to reference materials with nominal pH values of 1.68, 4.00, 6.86, 9.18, and 10.01, which were submitted to a repeated use simulation under controlled conditions to reproduce their routine use in analytical laboratories. The materials were analyzed once a month by the primary pH measurement method to check for deviations, trends, or significant variations in the results, using linear regression and normalized error statistical tests. The results indicated that the pH variations found for the materials with pH values of 1.68, 4.00, and 6.86 could be considered normal or statistically insignificant, not affecting their certified values for the time studied. For the materials with pH values of 9.18 and 10.01, the pH variations found were statistically significant and even higher than those from the stability monitoring (bottles not submitted to the repeated use simulation), making it possible to estimate a new associated uncertainty source to the certified value and increase the reliability in the use of these materials. Graphical abstract.

Aerosol Acidity Sensing via Polymer Degradation.

The acidity of atmospheric aerosols is a critical property that affects the chemistry and composition of the atmosphere. Many key multiphase chemical reactions are pH-dependent, impacting processes like secondary organic aerosol formation, and need to be understood at a single particle level due to differences in particle-to-particle composition that impact both climate and health. However, the analytical challenge of measuring aerosol acidity in individual particles has limited pH measurements for fine (<2.5 μm) and coarse (2.5-10 μm) particles. This has led to a reliance on indirect methods or thermodynamic modeling, which focus on average, not individual, particle pH. Thus, new approaches are needed to probe single particle pH. In this study, a novel method for pH measurement was explored using degradation of a pH-sensitive polymer, poly(ε-caprolactone), to determine the acidity of individual submicron particles. Submicron particles of known pH (0 or 6) were deposited on a polymer film (21-25 nm thick) and allowed to react. Particles were then rinsed off, and the degradation of the polymer was characterized using atomic force microscopy and Raman microspectroscopy. After degradation, holes in the PCL films exposed to pH 0 were observed, and the loss of the carbonyl stretch was monitored at 1723 cm-1. As particle size decreased, polymer degradation increased, indicating an increase in aerosol acidity at smaller particle diameters. This study describes a new approach to determine individual particle acidity and is a step toward addressing a key measurement gap related to our understanding of atmospheric aerosol impacts on climate and health.

PH-Sensing Strips Based on Biologically Synthesized Ly-MgO Nanoparticles.

MgO nanoparticles (NPs) are widely used in diverse areas ranging from catalysis to sensing. Besides this, there is a lack of information regarding their toxicity on fauna and flora. The venture of this work is to evaluate the toxicity behavior and pH-sensing performance of l-lysine-modified MgO (Ly-MgO) NPs synthesized by the green approach using the clove (Syzygium aromaticum) bud extract. The detailed investigations revealed that concentration plays an important role toward in vitro toxicity of Ly-MgO NPs. The Ly-MgO NPs showed 105% biocompatibility toward Vigna radiata (green gram) seeds at 100 ppm concentration. Zero inhibition on microbial growth was observed toward two bacterial strains. Further, pH-sensing strips based on these Ly-MgO nanostructures were developed to test pH-sensing performance at pH values ranging from 2.0 to 13.0. The repeatability as well as recyclability of the prepared pH strips was also analyzed. Nanobased pH paper strips based on Ly-MgO NPs provide a simple, reliable, nontoxic, and affordable method for pH measurements.

Development and validation of secondary method for pH measurement of buffer solutions

This paper presents the development of a secondary pH measurement standard and the design of the most critical part of the measurement standard - the secondary cell. The parameters affecting the measurement accuracy are discussed. The validation of the method together with a full uncertainty budget is described. The intended use of the secondary pH measurement standard by the Bulgarian Institute of Metrology (BIM) is also presented.

Method of alkalization and monitoring of urinary pH for prevention of recurrent uric acid urolithiasis: a systematic review.

Uric acid (UA) urolithiasis comprises around 5-10% of all stones and can frequently recur. Due to the fact that UA stones form in acidic urine with a pH <5.5, these patients require special attention compared to other stone patients. The international guidelines suggest treatment and metaphylaxis by urinary alkalization. The objective of this review is to critically asses the available evidence concerning the method and efficacy of this treatment modality. A systematic review on the methods of metaphylactic therapy using oral alkalization of UA urolithiasis was conducted by two authors. Evidence was sought using a predefined search strategy in seven different databases. The provided evidence was critically evaluated using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Cochrane collaboration tool for assessing the risk of bias. Twelve manuscripts were included of which one was a randomised trial. They focussed on ways to alkalize urine and its effect on stone recurrence. Because of their methodology and heterogeneity, the evidence is presented in a narrative review. There were differences in medication used for alkalizing urine, ways of monitoring urine pH and evaluating its efficacy. The reported outcomes also differed between studies. There is currently a lack of clear evidence for the method of alkalization of urine and the method of pH measurement. Besides this, for an established treatment modality, there is lack of long term results for the alkalization therapy. In conclusion, urine alkalization is an established treatment modality for the metaphylaxis of UA urolithiasis despite the lack of evidence from high quality studies on the methods of alkalization and its treatment efficacy. The studies published on this topic are scarce and contain notable risks of bias which should be kept in mind when interpreting the stated results.

In Situ Measurement of Local pH at Working Electrodes in Neutral pH Solutions by the Rotating Ring‐Disk Electrode Technique

AbstractWhen electrochemical reactions that generate/consume protons or hydroxide ions take place, the local pH in the vicinity of an electrode becomes considerably different from the bulk pH. However, measuring the local pH is very difficult, and the idea of using a rotating ring‐disk electrode (RRDE) is not applicable to solutions with neutral pH. Herein, we extend the theory of local pH measurement using a RRDE and make it applicable to solutions with a wide pH range. This extended theory is corroborated by measurements of hydrogen oxidation/evolution reactions in solutions with near‐neutral pH. In addition, the local pH change in a highly concentrated solution is also measured, and the results show that this local pH measurement method can be used regardless of the solution concentration.

Investigation of interactions in the cenospheres-water system

Methods of chemical analysis, conductometric titration and pH measurement were used to study chemical composition and acid-base properties of cenospheres’ surface. It has been established, that at the interaction of cenospheres and water anions of silicon acid, hydrocarbonates, cations of calcium, iron and aluminium are transferred to the solution. Recommendations were made regarding the use of cenospheres as a recyclable material for the production of aluminium and in coagulative water purification.

The hydrolysis constants of copper (I) (Cu+) and copper (II) (Cu2+) in aqueous solution as a function of pH using a combination of pH measurement and biospectroscopic methods and techniques

The hydrolysis constants of copper (I) (Cu+) and copper (II) (Cu2+) in aqueous solution as a function of pH using a combination of pH measurement and biospectroscopic methods and techniques

High-resolution optical pH imaging of concrete exposed to chemically corrosive environments

Major types of chemical concrete degradation such as carbonation, leaching and acid attacks are strongly associated with decreasing internal, surface and/or external pH. Thus, a precise pH determination is crucial for the assessment regarding the degree of corrosion and corresponding development of prevention strategies. Conventional pH measurement methods for concrete, such as pH visualization via color change of phenolphthalein indicator, pH analyses of extracted pore solutions and surface pH characterizations using flat surface electrodes have proven to hold significant limitations and inadequacies. This contribution presents the application of sensor foils based on luminescent, pH sensitive dyes for quantification and imaging of the spatial distribution of surface pH of concrete within a pH range between 9.35 and 12.35. For this purpose, an imaging technique called time-domain dual lifetime referencing (t-DLR) was used. High-resolution pH images of concrete samples exposed to carbonation and biogenic acid corrosion were successfully recorded and consequently compared to the state-of-the-art methods for pH assessment on concrete-based construction materials.

Spectrophotometric measurement of the pH of soil extracts using a multiple indicator dye mixture

SummaryThis paper describes the development of a spectrophotometric method with an expanded pH range of 3–9 that uses a mixed indicator solution (equimolar bromophenol blue, bromocresol purple, m‐cresol purple and thymol blue). The method uses measurements of absorbance of the dye mixture at two wavelengths (434 and 585 nm), chosen to represent the average acid and base peak maxima of the individual dyes within the mixture. The ratio of absorbance at these two wavelengths was used to calculate pH based on measured dye properties (pKa, molar absorptivity) and fundamental equations derived from Beer's law. The mixed dye spectrophotometric pH measurement was tested using certified pH buffers (pH (NBS/NIST) 4.00, 6.86, 9.18) and was found to be accurate to within ± 0–0.06 pH units. Measurements made with the mixed dye showed good correlation against conventional soil pH measurement using a glass electrode (r = 0.99), and also an alkalinity titration (r = 0.99) through the pH range 3–9. The average standard deviation was 0.07 for spectrophotometric soil pH measurement (n = 30) using the dye mixture. The mixed dye technique expands the working range of spectrophotometric pH measurement methods in soils and other applications.HighlightsWe developed a novel spectrophotometric method for measuring soil pH using a mixed indicator dye. The method greatly extends the working soil pH range of previous single indicator dye approaches. The results were well correlated with glass electrode measurements between pH 3 and 9. The method provides new opportunities to study soil chemical processes affected by pH.

Leaf Eh and pH: A Novel Indicator of Plant Stress. Spatial, Temporal and Genotypic Variability in Rice (Oryza sativa L.)

A wealth of knowledge has been published in the last decade on redox regulations in plants. However, these works remained largely at cellular and organelle levels. Simple indicators of oxidative stress at the plant level are still missing. We developed a method for direct measurement of leaf Eh and pH, which revealed spatial, temporal, and genotypic variations in rice. Eh (redox potential) and Eh@pH7 (redox potential corrected to pH 7) of the last fully expanded leaf decreased after sunrise. Leaf Eh was high in the youngest leaf and in the oldest leaves, and minimum for the last fully expanded leaf. Leaf pH decreased from youngest to oldest leaves. The same gradients in Eh-pH were measured for various varieties, hydric conditions, and cropping seasons. Rice varieties differed in Eh, pH, and/or Eh@pH7. Leaf Eh increases and leaf pH decreases with plant age. These patterns and dynamics in leaf Eh-pH are in accordance with the pattern and dynamics of disease infections. Leaf Eh-pH can bring new insight on redox processes at plant level and is proposed as a novel indicator of plant stress/health. It could be used by agronomists, breeders, and pathologists to accelerate the development of crop cultivation methods leading to agroecological crop protection.

Progression of Gastric Acid Production in Preterm Neonates: Utilization of In-vitro Method.

Background: Limited studies are done regarding ability to produce gastric acid in preterm infants and most studies used in vivo method of assessing gastric pH.Objectives: To assess the feasibility of using an in vitro method of measuring gastric pH in babies ≤ 28 weeks gestational age (GA) and determine whether changes in gastric pH differ with gestational age, mode of delivery, and use of antenatal steroids.Design/Methods: Prospective study that enrolled extremely low birth weight (ELBW) babies. Gastric aspirate collected before feeding. In vitro testing of gastric aspirates for pH were done on days of life 1, 3, 5, 7, 14, and 28 by using pH electrode. The pH was measured on each sample in triplicate, mean calculated and used for data analysis. Stastical methods included descriptive statistics, t-tests and repeated measures ANOVA.Results: 29 subjects ≤ 28 weeks or birth weight ≤ 1,000 g were enrolled. No significant change was noted in pH measurements over time. Antenatal steroids and mode of delivery did not affect gastric acid pH.Conclusion: The in vitro method for gastric pH measurements is non-invasive and affords more frequent testing. It would be useful in studying various conditions that may affect gastric pH.

Measuring magnetosomal pH of the magnetotactic bacterium Magnetospirillum magneticum AMB-1 using pH-sensitive fluorescent proteins.

Magnetotactic bacteria synthesize uniform-sized and regularly shaped magnetic nanoparticles in their organelles termed magnetosomes. Homeostasis of the magnetosome lumen must be maintained for its role accomplishment. Here, we developed a method to estimate the pH of a single living cell of the magnetotactic bacterium Magnetospirillum magneticum AMB-1 using a pH-sensitive fluorescent protein E2GFP. Using the pH measurement, we estimated that the cytoplasmic pH was approximately 7.6 and periplasmic pH was approximately 7.2. Moreover, we estimated pH in the magnetosome lumen and cytoplasmic surface using fusion proteins of E2GFP and magnetosome-associated proteins. The pH in the magnetosome lumen increased during the exponential growth phase when magnetotactic bacteria actively synthesize magnetite crystals, whereas pH at the magnetosome surface was not affected by the growth stage. This live-cell pH measurement method will help for understanding magnetosome pH homeostasis to reveal molecular mechanisms of magnetite biomineralization in the bacterial organelle.

Evaluation of a Portable Urinary pH Meter and Reagent Strips.

To evaluate a portable electronic pH meter and to put its accuracy in perspective with reagent strips read by a layperson, a healthcare professional, and an electronic reading device. Based on a preanalysis on 20 patients, a sample size of 77 urine aliquots from healthy volunteers was necessary to obtain sufficient study power. Measurements of urinary pH were obtained by use of reagent strips, a portable pH meter and a laboratory pH meter (gold standard). Reagents strips were read by a professional experienced in interpreting strips, a layperson, and an electronic strip reader. The mean matched pair difference between measurement methods was analyzed by the paired t-test. The degree of correlation and agreement were evaluated by the Pearson's correlation coefficient and Bland-Altman plots, respectively. The mean matched pair difference between the gold standard and all other pH measurement methods was the smallest with the portable electronic pH meter (bias 0.01, 95% confidence interval [CI] -0.07 to 0.08; p = 0.89), followed by strips read by a professional (bias -0.09, 95% CI -0.21 to 0.02; p = 0.10), layperson (bias -0.17, 95% CI -0.31 to -0.04; p = 0.015), and electronic strip reader (bias -0.29, 95% CI -0.41 to -0.16; p < 0.001). The portable electronic pH meter achieved the highest Pearson's correlation coefficient and narrowest 95% limits of agreement, followed by strip interpretation by a professional, electronic strip reader, and layperson. To quantify the ability of pH measurement methods to correctly classify values within a predefined urinary pH target range, we performed classification tests for several stones. The portable electronic pH meter outperformed all other measurement methods for negative predictive values. Findings of this study support that the portable electronic pH meter is a reliable pH measuring device. It appears to be more accurate compared to reagent strips readings.

Accurate pH Sensing using Hyperpolarized 129Xe NMR Spectroscopy

In the search for powerful non-invasive methods for pH measurement, NMR usually suffers from biases, especially for heterogeneous samples or tissues. In this Communication, using the signals of hyperpolarized 129 Xe encapsulated in a pair of water-soluble cryptophanes, we show that a differential pH measurement can be achieved, free from most of these biases, by monitoring the difference between their chemical shifts.

PH MEASUREMENT IN ORTHOPEDIC DENTISTRY

Change value of saliva’s pH is a predisposing factor in the development of galvanic phenomena in the oral cavity in patients with dental prostheses, which contain a metal alloy. The displacement of the pH of the oral fluid to the values determining the acidic environment (closer to 6.0) indirectly indicates an increase in the galvanic properties of saliva and it can be a prerequisite for development of pathological conditions of oral mucosa. Therefore, method of pH measurement has an important diagnostic value in orthopedic dentistry. In this research Ph measurement of mixed saliva was carried out using electronic pH-meter and color test strips in patients with clasp dental prosthesis of titanium alloy. The measurements were conducted to determine the predisposition to development to galvanic phenomena in the oral cavity.