Quality Control Methodology Research Articles

Taguchi-Based Six Sigma Defect Reduction of Green Sand Casting Process: An Industrial Case Study

In recent years, Six Sigma has become one of the most popular quality control methodologies, enabling many companies to make measurable increases in quality and decreases in variation and defects. This article applies the concept of Six Sigma define-measure-analyze-improve-control (DMAIC) methods to a metal casting industry to systematically identify and solve the major problems faced by the company that uses the green sand casting process. DMAIC phases are used to decrease the defect rate from 31% (baseline) to 4%. A casting industry case study was demonstrated step by step, systematically using Six Sigma in this article.

The role of dissolution testing in quality control

Semisolid systems (creams, gels etc.) for dermal application get more and more importance in pharmaceutical and cosmetic industry. However the number of methodologies for their physico-chemical characterization have been increasing; development of methods for the measurement of the active agent’s release onto the skin surface is still a challenging task. Beside measuring the amount of the active agent reaching the skin; dissolution testing (also called release testing) can be also a good indicator of product composition changes, therefore it can be used as quality control methodology. The purpose of this study was to investigate the in vitro drug release of active agents from hydrogels, organogels, o/w and w/o creams, emulgels and w/o/w multiple emulsions for dermal use by means of the vertical diffusion cell methodology, for quality control purposes.

A Narrative Review of the Laboratory Information System and Its Role in Antimicrobial Resistance Surveillance in South Africa

A laboratory information system (LIS) established in a microbiology department has the potential to play an important role in the quality of microbiology data such as culture of blood, urine, stool, pus swab samples etc. Such data could be effectively utilised to measure the burden of antimicrobial resistance among patients presented to various hospitals and clinics with an episode of an infectious illness of bacterial origin. A variety of clinical and epidemiological investigations are conducted using culture data and the presence of an electronic system such as LIS enhances such investigations and improves the reliability of measures of antimicrobial resistance owing to improved data quality as well as completeness of data gathered as opposed to paper based system. Therefore to improve surveillance of antimicrobial resistance in South Africa, there is a need to reinforce the functionality of the LIS in both public and private microbiology laboratories as this will help to improve internal quality control methodologies.

Application of clinical assay quality control (QC) to multivariate proteomics data: A workflow exemplified by 2-DE QC

Proteomics technologies can be effective for the discovery and assay of protein forms altered with disease. However, few examples of successful biomarker discovery yet exist. Critical to addressing this is the widespread implementation of appropriate QC (quality control) methodology. Such QC should combine the rigour of clinical laboratory assays with a suitable treatment of the complexity of the proteome by targeting separate assignable causes of variation. We demonstrate an approach, metric and example workflow for users to develop such targeted QC rules systematically and objectively, using a publicly available plasma DIGE data set. Hierarchical clustering analysis of standard channels is first used to discover correlated groups of features corresponding to specific assignable sources of technical variation. These effects are then quantified using a statistical distance metric, and followed on control charts. This allows measurement of process drift and the detection of runs that outlie for any given effect. A known technical issue on originally rejected gels was detected validating this approach, and relevant novel effects were also detected and classified effectively. Our approach was effective for 2-DE QC. Whilst we demonstrated this in a retrospective DIGE experiment, the principles would apply to ongoing QC and other proteomic technologies. This work asserts that properly carried out QC is essential to proteomics discovery experiments. Its significance is that it provides one possible novel framework for applying such methods, with a particular consideration of how to handle the complexity of the proteome. It not only focusses on 2DE-based methodology but also demonstrates general principles. A combination of results and discussion based upon a publicly available data set is used to illustrate the approach and allows a structured discussion of factors that experimenters may wish to bear in mind in other situations. The demonstration is on retrospective data only for reasons of scope, but the principles applied are also important for ongoing QC, and this work serves as a step towards a later demonstration of that application. This article is part of a Special Issue entitled: Standardization and Quality Control in Proteomics.

Data Fusion for Food Authentication. Combining near and Mid Infrared to Trace the Origin of Extra Virgin Olive Oils

Introduction I n recent years, food authentication and food traceability have emerged as issues of primary and common concern for both consumers and producers. Because of this, the number of researchers who tackle these problems by combining chemometrics coupled with a fingerprinting technique continues to increase. This kind of approach, indeed, has the undeniable advantage of allowing, in many cases, the use of rapid and relatively inexpensive analytical techniques that can, nonetheless, lead to reliable and accurate results. Among these analytical methods, an important role is played by the spectroscopic techniques and in particular in the infrared wavelength ranges. These are often chosen as the ideal analytical methods for the development of food quality control methodologies because of their inherent characteristics of non-destructivity, speed and cheapness of analysis, as well as not needing any sample pre-treatment. However, food quality control, in particular when traceability and authentication are concerned, is a complex problem for the chemist, and sometimes the acquisition of a single fingerprinting signal and the subsequent construction of a chemometric classification model is not enough to develop a methodology reliable enough for the intended purpose. In such cases, it is often possible to rely on the possibility of acquiring more than one single signal for each sample, and then to use the combined information from the two (or more) techniques to develop the final chemometric model. In this way, it is possible, sometimes, to benefit from the specific advantages and characteristics of the different techniques to create a more reliable and stable final model, in particular whenever there is complementarity between the information provided by the techniques employed. In these cases, however, the problem of how to combine the different information coming from the various analytical methods, namely the data fusion issue, is of major importance for the accuracy and reliability of the final results of the proposed methodology. In this context, the use of near infrared (NIR) and mid infrared (MIR) spectroscopy to solve authentication or traceability issues has already been described by many researchers, showing the great potential that both these techniques have in the field of food quality control analysis. Moreover, the peculiar characteristics of NIR and MIR, being different from one another, make them perfectly adaptable to being used together. Due to its greater molecular selectivity, the use of MIR spectroscopy often provides easier spectral interpretation than NIR, and it can sometimes be more related to some compound that is typical of the investigated food. NIR spectroscopy is more useful for its peculiarity of giving an overall fingerprint of the entire sample and it is commonly applied for the analysis of foods with excellent results. In this work, the problem of the traceability of extra virgin olive oils coming from the PDO Sabina (Italy), already tackled by the same authors by means of MIR and NIR spectroscopy separately, is handled by means of different strategies of data fusion, in order to improve the results obtained from the two techniques and to demonstrate the synergistic effect of coupling information obtained from the two wavelength regions.

Virtual Labs Project: A Paradigm Shift in Internet-Based Remote Experimentation

The lack of good and up-to-date lab experiments form a major impediment in the domain of engineering education. Often, the lab experiments are outdated. The Virtual Labs project addresses the issue of lack of good lab facilities, as well as trained teachers, by making remote experimentation possible. The pedagogy is student-centric. The Virtual Labs project has also developed a novel methodology for field trials, outreach, and quality control. Virtual Labs also provide tremendous cost advantage. The Virtual Labs project is a wonderful example of an open educational resource developed by a multiinstitution multidiscipline project team. Over 100000 students are currently using the online labs under the Virtual Labs project. Many of these labs are being accessed outside the regular lab hours.

Analysing the 100 year sea level record of Leixões, Portugal

► The long-term historic sea level data from Leixões (Portugal) has been recovered. ► Estimated mean sea level trend is not in line with global MSL rise predictions. ► Observed sea levels are influenced by prevailing weather systems and local atmospheric pressure. ► Caution is needed using a single tide gauge as representative of regional sea level. A new data set from the tide gauge at Leixões (North–West Portugal) has recently been transferred from its paper format into a digital time series of hourly sea level values. By measuring sea level variations since 1890, this tide gauge station is one of the few in the world with over 100 yr of digitised hourly records and the longest for the South West of Europe and Iberian Peninsula. This paper presents the procedures adopted to recover the Leixões sea level data from paper chart records as well as the data quality control and data editing methodologies. The mean rate of sea level change between 1906 and 2008 is −0.70 ± 0.27 mm yr −1 , which does not agree with the global mean sea level rise of 1–2 mm yr −1 . No evidence for vertical land movement was found and Global Isostatic Adjustment influence on sea level, at this location, can be neglected. It is likely that prevailing weather systems in the North Atlantic, especially in the winter, and local atmospheric pressure, influence sea levels at Leixões. A further contribution is found from tides and surges. The evolution of the port cannot be ignored when trying to understand sea level change.

The validation of the GEWEX SRB surface shortwave flux data products using BSRN measurements: A systematic quality control, production and application approach

The NASA/GEWEX Surface Radiation Budget (SRB) project has produced a 24.5-year continuous record of global shortwave and longwave radiation fluxes at TOA and the Earth's surface from satellite measurements. The time span of the data is from July 1983 to December 2007, and the spatial resolution is 1° latitude×1° longitude. The inputs of the latest version (Release 3.0) include the GEOS Version 4.0.3 meteorological information and cloud properties derived from ISCCP DX data. The SRB products are available on 3-hourly, 3-hourly-monthly, daily and monthly time scales. To assess the quality of the product, we extensively validated the SRB data against 5969 site-months of ground-based measurements from 52 Baseline Surface Radiation Network (BSRN) stations. This paper describes first the characteristics of the BSRN data and the GEWEX SRB data, the methodology for quality control and processing of the shortwave BSRN data, and then the systematic SRB-BSRN comparisons. It is found that, except for occasional extreme outliers as seen in scatter plots, the satellite-based surface radiation data generally agree very well with BSRN measurements. Specifically, the bias/RMS for the daily and monthly mean shortwave fluxes are, respectively, -3.6/35.5 and -5.2/23.3W°m−2 under all-sky conditions.

A Real-Time and Offline Quality Control Methodology for SeaSonde High-Frequency Radar Currents

Abstract A near-real-time and offline quality control methodology for SeaSonde systems is proposed. It is applied on radial current maps and is based on the determination of the signal-to-noise ratio (SNR) values of the Doppler lines that contribute to the hourly radial current at each range-bearing (R, θ) pair, under the assumption that SNR is a proxy for radar data quality. The retrieval of the sequence of Doppler lines is performed through a minimization procedure that takes advantage of the statistical descriptors output in the short-term radial maps. The separation of the contributing Doppler velocities into valid observations and anomalous velocities is based on their spectral quality factor and on a range-dependent noise threshold derived from statistics (average and standard deviation) of the signal amplitudes in the tails of the Doppler spectra. The final product of the quality control procedure is a radial current map, in which Doppler velocities are weighted by their SNR values and their spectral quality factors, and averaged to produce an output that is fully compatible with the proprietary software. This procedure is fast, despite the fact that a large number of combinations might be required during the retrieval of the Doppler lines, and effective, because it removes both evident spikes as well as Doppler velocities that are not clearly identified as anomalous velocities. In principle, this approach can be used to fill gaps in the radar coverage without the need for interpolation in time or space, proved that the Doppler velocities satisfy predetermined SNR constraints.

Characterisation and authentication of A. senegal and A. seyal exudates by infrared spectroscopy and chemometrics

The authentication of Acacia gums samples requires usually the use of sophisticated and time consuming analytical techniques. There is a need for fast and simple analytical techniques for the objective of a quality control methodology. Commercial Acacia senegal and Acacia seyal gums present characteristic MIR spectra. Principal Component Analysis of the infrared spectra of gum exudates of trees allow to distinguish Acacia gums from another gum exudates (Combretum, Ghatti, Karaya, Tragacanth). Moreover, gums of A. senegal and A. seyal separate them and from other Acacia species (Acacia dealbata, Acacia karoo, Acacia nilotica, Acacia sieberiana). Chemometric treatments of A. senegal and A. seyal MIR spectra were assessed for the quantification of moisture content in Acacia gums, for the classification into the two species and for the adulteration detection and quantification. Results were quite satisfactory, the moisture content was estimated at 3.1%, adulteration was detected at 3.4% and quantified at 5.6%. The discrimination of the two species is done without any ambiguity.

Development and validation of a successful microbiological agar assay for determination of ceftriaxone sodium in powder for injectable solution.

Ceftriaxone sodium is a cephalosporin with broad-spectrum antimicrobial activity and belongs to the third generation of cephalosporins. Regarding the quality control of medicines, a validated microbiological assay for the determination of ceftriaxone sodium in powder for injectable solution has not been reported yet. This paper reports the development and validation of a simple, accurate and reproducible agar diffusion method to quantify ceftriaxone sodium in powder for injectable solution. The assay is based on the inhibitory effect of ceftriaxone sodium on the strain of Bacillus subtilis ATCC 9371 IAL 1027 used as test microorganism. The results were treated statistically by analysis of variance and were found to be linear (r = 0.999) in the selected range of 15.0–60.0 μg/mL, precise with a relative standard deviation (RSD) of repeatability intraday = 1.40%, accurate (100.46%) and robust with a RSD lower than 1.28%. The results demonstrated the validity of the proposed bioassay, which allows reliable ceftriaxone sodium quantitation in pharmaceutical samples and therefore can be used as a useful alternative methodology for the routine quality control of this medicine.

SU-E-T-205: MLC Predictive Maintenance Using Statistical Process Control Analysis.

MLC failure increases accelerator downtime and negatively affects the clinic treatment delivery schedule. This study investigates the use of Statistical Process Control (SPC), a modern quality control methodology, to retrospectively evaluate MLC performance data thereby predicting the impending failure of individual MLC leaves. SPC, a methodology which detects exceptional variability in a process, was used to analyze MLC leaf velocity data. A MLC velocity test is performed weekly on all leaves during morning QA. The leaves sweep 15 cm across the radiation field with the gantry pointing down. The leaf speed is analyzed from the generated dynalog file using quality assurance software. MLC leaf speeds in which a known motor failure occurred (8) and those in which no motor replacement was performed (11) were retrospectively evaluated for a 71 week period. SPC individual and moving range (I/MR) charts were used in the analysis. The I/MR chart limits were calculated using the first twenty weeks of data and set at 3 standard deviations from the mean. The MLCs in which a motor failure occurred followed two general trends: (a) no data indicating a change in leaf speed prior to failure (5 of 8) and (b) a series of data points exceeding the limit prior to motor failure (3 of 8). I/MR charts for a high percentage (8 of 11) of the non-replaced MLC motors indicated that only a single point exceeded the limit. These single point excesses were deemed false positives. SPC analysis using MLC performance data may be helpful in detecting a significant percentage of impending failures of MLC motors. The ability to detect MLC failure may depend on the method of failure (i.e. gradual or catastrophic). Further study is needed to determine if increasing the sampling frequency could increase reliability. Project was support by a grant from Varian Medical Systems, Inc.

Use of Recycled Sand Produced at Construction Sites in Bedding Mortars

AbstractThe aim of this paper is to present a proposal for the recycling of construction and demolition waste (CDW) at construction sites and the use of recycled sand in bedding mortar. Three samples of CDW were collected at construction sites from the city of Recife, Brazil and milled in a hammer mill. The following properties of the recycled sands were analyzed: water absorption, material finer than 75 μm, bulk density, fineness modulus, and the presence of contaminants. Mortars were produced with different amounts of cement and replaced the natural material by recycled aggregate in proportions of 50, 75 and 100%. These mortars were characterized for compressive strength, fresh mortar density, and consistence. Masonry prisms with three ceramic blocks were produced for analyzing the bending and shear strength. Several correlations between the properties of aggregates, mortar, and prisms were obtained, leading the authors to propose a recycling process, dosage, and quality control methodology for bedding ...

Quality control methodology and implementation of X-radiation standards beams, mammography level, following the standard IEC 61267

This study presents the results of the establishment of a quality control program developed and applied for the X-ray system of the Calibration Laboratory of IPEN. The X-ray standard beams, mammography level, using molybdenum and aluminum as additional filtration were established after the application of this quality control and the spectrometry of these qualities was made. The reference ionization chamber has traceability to the PTB. The radiation qualities RQR-M, RQA-M, RQN-M and RQB-M, following the recommendations of the IEC 61267 and the IAEA TRS 457 were established.

Disturbance rejection for the control of batch end-product quality using latent variable models

The control of batch end-product quality is an important issue in many high value-added manufacturing industries, particularly specialty chemicals and pharmaceuticals. An attractive approach for controlling such systems is to apply partial least squares (PLS) models, which can utilize the low-dimensional latent variable (or score) space with the corresponding control optimization performed on these few latent variables. The manipulated variable trajectories (MVTs) can then be reconstructed from the optimized scores. The existing PLS-based batch end-product quality control methodology does not incorporate the disturbance model in its formulation. As a result, it is demonstrated in this paper that these control formulations can be incapable of adequate disturbance rejection. To reject disturbances adequately, it is necessary to utilize feedback information and re-compute optimal control sequences at multiple instants during a batch run. However, this can lead to erratic control action, resulting in the deterioration of batch end-product quality. To resolve this issue, a revised PLS-based batch end-product quality controller is proposed in this paper that explicitly accounts for disturbance induced plant-model mismatch by including a simple disturbance model. Furthermore, the proposed controller formulation adds hard constraints to incremental changes of the re-computed control sequences to avoid erratic behavior in the case of multiple control decision points. The ability of the proposed control scheme to reject disturbances and obtain desirable MVTs is demonstrated using a benchmark simulation of a fed-batch fermentation process.

Quantitative Evaluation of Acetaminophen in Oral Solutions by Dispersive Raman Spectroscopy for Quality Control

This work used dispersive Raman spectroscopy to evaluate acetaminophen in commercially available formulations as an analytical methodology for quality control in the pharmaceutical industry. Raman spectra were collected using a near-infrared dispersive Raman spectrometer (830 nm, 50 mW, 20 s exposure time) coupled to a fiber optic probe. Solutions of acetaminophen diluted in excipient (70 to 120% of the commercial concentration of 200 mg/mL) were used to develop a calibration model based on partial least squares (PLSs) applied to Raman spectra of solutions and, subsequently, obtain linearity, accuracy, precision (repeatability), and sensitivity of the method using the near-infrared spectroscopy (NIRS) as a gold standard method. This model was used to predict the acetaminophen concentration in commercial samples from different lots of acetaminophen formulations (200 mg/mL) with a PLS-prediction error of about 0.6%. Commercial medicines had PLS predicted concentrations errors below 2.5%, whereas NIRS had an error of about 3.7% compared to the label concentration. It has been demonstrated the applicability of Raman spectroscopy with fiber probe for quality control in pharmaceutical industry of commercial formulations.

Lipopolysaccharide challenge of the mammary gland in cows induces nitrosative stress that impairs milk oxidative stability

The aim of this work was to study the effects of mastitis induced by intramammary lipopolysaccharide (LPS) challenge on milk oxidative stability, as well as to understand the underlying biochemical processes that cause such changes. LPS challenge was associated with nitric oxide burst from the surrounding mammary epithelial cells and consequently induced nitrosative stress that was induced by the formation of NO2• from nitrite by lactoperoxidase. This response was associated with an ∼3-fold increased formation of hazardous compounds: nitrotyrosines, carbonyls and lipid peroxides. We sustained the involvement of xanthine oxidase as a major source of hydrogen peroxide. In consistent with previous findings, catalase has been shown to play a major role in modulating the nitrosative stress by oxidizing nitrite to nitrate. The current hygienic quality criteria cannot detect mixing of low-quality milk, such as milk with high somatic cells, and nitrite with high-quality milk. Thus, development of an improved quality control methodology may be important for the production of high-quality milk.

Determination of vegetable oils and fats adulterants in diesel oil by high performance liquid chromatography and multivariate methods

The current legislation requires the mandatory addition of biodiesel to all Brazilian road diesel oil A (pure diesel) marketed in the country and bans the addition of vegetable oils for this type of diesel. However, cases of irregular addition of vegetable oils directly to the diesel oil may occur, mainly due to the lower cost of these raw materials compared to the final product, biodiesel. In Brazil, the situation is even more critical once the country is one of the largest producers of oleaginous products in the world, especially soybean, and also it has an extensive road network dependent on diesel. Therefore, alternatives to control the quality of diesel have become increasingly necessary. This study proposes an analytical methodology for quality control of diesel with intention to identify and determine adulterations of oils and even fats of vegetable origin. This methodology is based on detection, identification and quantification of triacylglycerols on diesel (main constituents of vegetable oils and fats) by high performance liquid chromatography in reversed phase with UV detection at 205nm associated with multivariate methods. Six different types of oils and fats were studied (soybean, frying oil, corn, cotton, palm oil and babassu) and two methods were developed for data analysis. The first one, based on principal component analysis (PCA), nearest neighbor classification (KNN) and univariate regression, was used for samples adulterated with a single type of oil or fat. In the second method, partial least square regression (PLS) was used for the cases where the adulterants were mixtures of up to three types of oils or fats. In the first method, the techniques of PCA and KNN were correctly classified as 17 out of 18 validation samples on the type of oil or fat present. The concentrations estimated for adulterants showed good agreement with the reference values, with mean errors of prediction (RMSEP) ranging between 0.10 and 0.22% (v/v). The PLS method was efficient in the quantification of mixtures of up to three types of oils and fats, with RMSEP being obtained between 0.08 and 0.27% (v/v), mean precision between 0.07 and 0.32% (v/v) and minimum detectable concentration between 0.23 and 0.81% (v/v) depending on the type of oil or fat in the mixture determined.

MetaQC: objective quality control and inclusion/exclusion criteria for genomic meta-analysis

Genomic meta-analysis to combine relevant and homogeneous studies has been widely applied, but the quality control (QC) and objective inclusion/exclusion criteria have been largely overlooked. Currently, the inclusion/exclusion criteria mostly depend on ad-hoc expert opinion or naïve threshold by sample size or platform. There are pressing needs to develop a systematic QC methodology as the decision of study inclusion greatly impacts the final meta-analysis outcome. In this article, we propose six quantitative quality control measures, covering internal homogeneity of coexpression structure among studies, external consistency of coexpression pattern with pathway database, and accuracy and consistency of differentially expressed gene detection or enriched pathway identification. Each quality control index is defined as the minus log transformed P values from formal hypothesis testing. Principal component analysis biplots and a standardized mean rank are applied to assist visualization and decision. We applied the proposed method to 4 large-scale examples, combining 7 brain cancer, 9 prostate cancer, 8 idiopathic pulmonary fibrosis and 17 major depressive disorder studies, respectively. The identified problematic studies were further scrutinized for potential technical or biological causes of their lower quality to determine their exclusion from meta-analysis. The application and simulation results concluded a systematic quality assessment framework for genomic meta-analysis.

Quality Control Methodology and Their Application in Analysis on HPLC Fingerprint Spectra of Herbal Medicines

As traditional Chinese medicine (TCM) is gradually accepted by many countries, people pay much attention to the quality of herbal medicines. Because of the significant variation in active components in them, the quality control of herbal medicines is a very important issue. Nowadays, high-performance liquid chromatography (HPLC) fingerprint spectra (FPS) are widely used in identification and quality control of herbal medicines. This paper will analyze the methodology and their application in identifying and evaluating herbal medicines by means of HPLC FPS, which includes simple comparing, clustering, principal component analysis (PCA), and similarity analysis methods.