Effect of NaCl and HCl concentrations on primary pH measurement for the certification of standard materials

pH is an important parameter to control the production of food, medicine, petrochemical products and others. Thus, standard reference materials used to calibrate pH meters are necessary to guarantee reliability of the measurements. The Chemical Metrology Division (Dquim) of the National Metrology Institute of Brazil (Inmetro) has as one of its missions the certification of standard reference materials. In the case of pH, it will be done by the pH primary measurement system of Inmetro, in operation at Dquim since 2003. The buffer solution of nominal pH value equal to 6.865 will be the first to be certified. The study of some measurement parameters has already been accomplished, and will lead to the improvement of the primary pH measurement. In this paper, the effect of NaCl and HCl concentrations on the primary pH measurement is discussed, based on the results obtained by Inmetro in the regional comparison SIM 8.11P.

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Evaluation of sample homogeneity for geochemical standard reference materials used in microanalysis

Journal of Radioanalytical and Nuclear Chemistry ◽

10.1007/bf02055017 ◽

1987 ◽

Vol 110 (1) ◽

pp. 147-158 ◽

Cited By ~ 8

Author(s):

R. H. Filby ◽

S. Nguyen ◽

S. Campbell ◽

A. Bragg ◽

C. A. Grimm

Keyword(s):

Reference Materials ◽

Standard Reference Materials ◽

Materials Used ◽

Sample Homogeneity

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Preparation and Certification of Standard Reference Materials to be Used in the Determination of Retained Austenite in Steels

Advances in X-ray Analysis ◽

10.1154/s0376030800012398 ◽

1982 ◽

Vol 26 ◽

pp. 137-140

Author(s):

George E. Hicho ◽

Earl E. Eaton

Keyword(s):

Reference Materials ◽

Retained Austenite ◽

Solid Phase ◽

Standard Reference Materials ◽

Face Centered Cubic ◽

X Ray Diffraction ◽

X Ray ◽

Face Centered ◽

Materials Used ◽

Steel Hardening

In the steel hardening process, steel is heated to a temperature where a face-centered-cubic solid phase called austenite is formed. After a stabilization period, the steel is quenched into a medium which transforms the austenite into a metastable, body-centered-tetragonal solid phase called martensite. On occasion the austenite is not entirely transformed into martensite and some austenite remains. This untransformed (retained) austenite is sometimes detrimental to the finished product, and often there are requirements as to the amount of retained austenite permitted In the finished product.X-ray diffraction procedures (XRD) are normally used to determine the amount of retained austenite and this paper describes the preparation and characterization of the Standard Reference Materials used to calibrate x-ray diffraction units.

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Improving Topical Skin Delivery of Monocrotaline Via Liposome Gel-based Nanosystems

Current Drug Delivery ◽

10.2174/1567201816666191029125300 ◽

2019 ◽

Vol 16 (10) ◽

pp. 940-950 ◽

Cited By ~ 1

Author(s):

Jiandong Yu ◽

Zhi Chen ◽

Yan-zhi Yin ◽

Chaoyuan Tang ◽

Enying Hu ◽

...

Keyword(s):

Gradient Method ◽

Encapsulation Efficiency ◽

Ph Value ◽

Topical Administration ◽

Ph Gradient ◽

Stability Factor ◽

Buffer Solution ◽

Skin Delivery ◽

Skin Retention

Background: In this study, a liposomal gel based on a pH-gradient method was used to increase the skin-layer retention of monocrotaline (MCT) for topical administration. Methods: Using the Box-Behnken design, different formulations were designed to form liposome suspensions with optimal encapsulation efficiency (EE%) and stability factor (KE). In order to keep MCT in liposomes and accumulate in skin slowly and selectively, MCT liposome suspensions were engineered into gels. Results: A pH-gradient method was used to prepare liposome suspensions. The optimal formulation of liposome suspensions (encapsulation efficiency: 83.10 ± 0.21%) was as follows: MCT 12 mg, soybean phosphatidyl choline (sbPC) 200 mg, cholesterol (CH) 41 mg, vitamin E (VE) 5 mg, and citric acid buffer solution (CBS) 4.0 10 mL (pH 7.0). The final formulation of liposomal gels consisted of 32 mL liposome suspensions, 4.76 mL deionized water, 0.40 g Carbopol-940, 1.6 g glycerol, 0.04 g methylparaben, and a suitable amount of triethanolamine for pH value adjustment. The results of in vitro drug release showed that MCT in liposomal gels could be released in 12 h constantly in physiological saline as a Ritger-Peppas model. Compared with plain MCT in gel form, liposomal MCT in gel had higher skin retention in vitro. Conclusion: In this study, liposomal gels were formed for greater skin retention of MCT. It is potentially beneficial for reducing toxicities of MCT by topical administration with liposomal gel.

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From urban dust and marine sediment to Ginkgo biloba and human serum—a top ten list of Standard Reference Materials (SRMs)

Analytical and Bioanalytical Chemistry ◽

10.1007/s00216-021-03527-w ◽

2021 ◽

Author(s):

Stephen A. Wise

Keyword(s):

Human Serum ◽

Reference Materials ◽

Marine Sediment ◽

Ginkgo Biloba ◽

Standard Reference Materials ◽

Urban Dust

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Regression Analysis of Orthogonal, Cylindrical and Multivariable Color Parameters for Colorimetric Surface pH Measurement of Materials

Molecules ◽

10.3390/molecules26123682 ◽

2021 ◽

Vol 26 (12) ◽

pp. 3682

Author(s):

Katarína Vizárová ◽

Izabela Vajová ◽

Naďa Krivoňáková ◽

Radko Tiňo ◽

Zdenko Takáč ◽

...

Keyword(s):

Ph Value ◽

Critical Factor ◽

Ph Measurement ◽

Ph Indicator ◽

Water Quality Control ◽

Quality Management Systems ◽

Surface Ph ◽

Regression Parameters ◽

Ph Detection

The surface pH is a critical factor in the quality and longevity of materials and products. Traditional fast colorimetric pH detection-based tests such as water quality control or pregnancy tests, when results are determined by the naked eye, cannot provide quantitative values. Using standard pH papers, paper-printed comparison charts, or colorimetric microfluidic paper-based analytical devices is not suitable for such technological applications and quality management systems (QMSs) where the particular tested material should contain a suitable indicator in situ, in its structure, either before or after the process, the technology or the apparatus that are being tested. This paper describes a method based on the combination of impregnation of a tested material with a pH indicator in situ, its exposure to a process of technology whose impact on pH value is to be tested, colorimetric pH measurement, and approximation of pH value using derived pH characteristic parameters (pH-CPs) based on CIE orthogonal and cylindrical color variables. The hypotheses were experimentally verified using the methyl red pH indicator, impregnating the acid lignin-containing paper, and preparing a calibration sample set with pH in the range 4 to 12 using controlled alkalization. Based on the performed measurements and statistical evaluation, it can be concluded that the best pH-CPs with the highest regression parameters for pH are √∆E, ln (a),√∆H (ab), a/L, h/b and ln (b/a). The experimental results show that the presented method allows a good estimation of pH detection of the material surfaces.

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