scholarly journals Simultaneous Determination of Droplet Size, pH Value and Concentration to Evaluate the Aging Behavior of Metalworking Fluids

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8299
Author(s):  
Patrick Wahrendorff ◽  
Mona Stefanakis ◽  
Julia C. Steinbach ◽  
Dominik Allnoch ◽  
Ralf Zuber ◽  
...  

Metalworking fluids (MWFs) are widely used to cool and lubricate metal workpieces during processing to reduce heat and friction. Extending a MWF’s service life is of importance from both economical and ecological points of view. Knowledge about the effects of processing conditions on the aging behavior and reliable analytical procedures are required to properly characterize the aging phenomena. While so far no quantitative estimations of ageing effects on MWFs have been described in the literature other than univariate ones based on single parameter measurements, in the present study we present a simple spectroscopy-based set-up for the simultaneous monitoring of three quality parameters of MWF and a mathematical model relating them to the most influential process factors relevant during use. For this purpose, the effects of MWF concentration, pH and nitrite concentration on the droplet size during aging were investigated by means of a response surface modelling approach. Systematically varied model MWF fluids were characterized using simultaneous measurements of absorption coefficients µa and effective scattering coefficients µ’s. Droplet size was determined via dynamic light scattering (DLS) measurements. Droplet size showed non-linear dependence on MWF concentration and pH, but the nitrite concentration had no significant effect. pH and MWF concentration showed a strong synergistic effect, which indicates that MWF aging is a rather complex process. The observed effects were similar for the DLS and the µ’s values, which shows the comparability of the methodologies. The correlations of the methods were R2c = 0.928 and R2P = 0.927, as calculated by a partial least squares regression (PLS-R) model. Furthermore, using µa, it was possible to generate a predictive PLS-R model for MWF concentration (R2c = 0.890, R2P = 0.924). Simultaneous determination of the pH based on the µ’s is possible with good accuracy (R²c = 0.803, R²P = 0.732). With prior knowledge of the MWF concentration using the µa-PLS-R model, the predictive capability of the µ’s-PLS-R model for pH was refined (10 wt%: R²c = 0.998, R²p = 0.997). This highlights the relevance of the combined measurement of µa and µ’s. Recognizing the synergistic nature of the effects of MWF concentration and pH on the droplet size is an important prerequisite for extending the service life of an MWF in the metalworking industry. The presented method can be applied as an in-process analytical tool that allows one to compensate for ageing effects during use of the MWF by taking appropriate corrective measures, such as pH correction or adjustment of concentration.

2017 ◽  
Vol 1 (1) ◽  
pp. 50-55
Author(s):  
Vitor Todeschini ◽  
Regiane Leite ◽  
Maximiliano Sangoi ◽  
Paulo Oliveira ◽  
Thiago Barth

A multicomponent ultraviolet (UV) spectrophotometric method was developed and validated for simultaneous determination of delapril (DEL) and indapamide (IND) in tablets employing the partial least squares regression (PLSR) approach. The PLSR method was developed by a multilevel factorial design using 25 synthetic mixtures of drugs and a significant predict model (p < 0.05) were obtained at 225 nm for DEL (r2 = 0.9992) and 243 nm for IND (r2 = 0.9997). Validation parameters such as the specificity, linearity, precision, accuracy and robustness were evaluated in accordance with the ICH requirements, giving satisfactory results within the acceptable range. The proposed PLSR method was successfully applied for simultaneous determination of DEL and IND in fixed dose combinations and can be used as simple alternative to separation techniques.


2019 ◽  
Vol 131 (16) ◽  
pp. 5310-5314 ◽  
Author(s):  
Weikang Wang ◽  
Fan Zhao ◽  
Mingzhi Li ◽  
Chuanping Zhang ◽  
Yuanhua Shao ◽  
...  

1995 ◽  
Vol 49 (6) ◽  
pp. 747-753 ◽  
Author(s):  
M. Blanco ◽  
J. Coello ◽  
H. Iturriaga ◽  
S. Maspoch ◽  
E. Bertran

A new method for the simultaneous determination of vulcanized rubber additives by Fourier transform infrared (FT-IR) spectrophotometry using partial least-squares regression (PLSR) for multivariate calibration was developed. The effect of various wavenumber ranges and the use of the absorbance and first-derivative spectral modes on performance were studied by applying the method to three different sample batches containing several additives in different proportions, all of which were resolved with satisfactory results.


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