Identification Of Contaminant Research Articles

Evaluation of Groundwater Quality Through Identification of Potential Contaminant

Groundwater, is crucial for human consumption and industrial purposes, demands continuous monitoring to assess quality standards. This study conducts a comprehensive evaluation of groundwater quality to assess its overall condition and identify potential contaminants. The research predicts the presence and levels of contaminants such as heavy metals, organic pollutants, and microbial agents using hydrogeological studies, chemical analysis, and statistical modelling. A covariance analysis identified places with low water quality. Analysis shows most samples satisfy drinking water requirements. A consolidated map illustrates a significant expanse suitable for domestic and drinking purposes, particularly in terms of drinking water quality. However, water quality in 2467.09 sq. km is deemed unacceptable. Further analysis, including correlation, ANOVA, and t-tests such as One Sample Test, Bayesian Statistics, and Power Analysis, identifies 836.87 sq. km under the category of maximum permissible water quality and 9.19 sq. km as highly desirable for drinking and domestic use.

Investigation of a failed DNA assay leads to identification of an unexpected contaminant in a commonly used chromatography buffer.

For mammalian cell-derived recombinant biotherapeutics, controlling host cell DNA levels below a threshold is a regulatory requirement to ensure patient safety. DNA removal during drug substance manufacture is accomplished by a series of chromatography-based purification steps and a qPCR-based analytical method is most used to measure DNA content in the purified drug substance to enable material disposition. While the qPCR approach is mature and its application to DNA measurement is widespread in the industry, it is susceptible to trace levels of process-related contaminants that are carried forward. In this study, we observed failures in spike recovery studies that are an integral component of the qPCR-based DNA testing, suggesting the presence of an inhibitory compound in the sample matrix. We generated hypotheses around the origin of the inhibitory compound and generated multiple sample matrices and deployed a suite of analytical techniques including Raman and NMR spectroscopy to determine the origin and identity of the inhibitory compound. The caustic wash step and depth filter extractables were ruled out as root causes after extensive experimentation and DNA testing. Subsequently, 2-(N-morpholino)ethanesulfonic acid (MES), a buffer used in the chromatography unit operations, was identified as the source of the contaminant. A 500-fold concentration followed by Raman and NMR spectroscopy analysis revealed the identity of the inhibitory compound as polyvinyl sulfone (PVS), an impurity that originates in the MES manufacturing process. We have implemented PVS concentration controls for incoming MES raw material, and our work highlights the need for rigor in raw material qualification and control.

Successful Identification of a Neoplastic Tissue Contaminant in Surgical Pathology

Abstract Tissue contamination, where extraneous tissue becomes embedded into the paraffin block or fixed onto the slide, is a relatively common quality issue in surgical pathology and can occur at any step between specimen collection by the clinician and slide coverslipping. We report a case of tissue contamination within a paraffin block and describe our subsequent investigation, which was successful in identifying the source of contamination.

Quantification of sodium contaminant on steel surfaces using pulse CO2 laser-induced breakdown spectroscopy

Corrosion is one of the main reasons for in-core accidents in liquid sodium-cooled fast reactors, especially accidents due to fuel cladding pipe damage. It is urgently required to investigate what kind of compound is produced as a corrosion product after the interaction between stainless steel and sodium in fast breeder reactors (FBR). In this work, the identification and quantification of sodium contaminant on steel surfaces has been conducted using laser-induced breakdown spectroscopy utilizing the specific characteristics of a pulse transversely excited atmospheric CO 2 laser. Experimentally, a pulse TEA CO 2 laser (Shibuya, 10.64 μm, 200 ns) was directed and bombarded onto the sodium contaminant deposited on the surface of stainless steel. An excellent emission spectrum of sodium from the contaminant was obtained without any disturbance from analytical lines from the steel itself. A quantification of sodium contaminant on the steel surface has been successfully made by a linear calibration curve obtained from steel containing various concentrations of sodium. The limit of detection of sodium on the metal surface was estimated to be 0.5 mg/kg. Also, a comparative sodium analysis study was qualitatively made by using LIBS utilizing a pulse Nd:YAG laser. The results demonstrate that the present technique of TEA CO 2 LIBS is far superior to the case of Nd:YAG LIBS, as proven by an excellent emission spectrum of sodium with optimum intensity, and low noise and background emission.

Effective medium for in vitro sprouting of the buds and multiplication of the plantlets, and identification of the fungal contaminant associated with the explants of Gnetum

Effective medium for in vitro sprouting of the buds and multiplication of the plantlets, and identification of the fungal contaminant associated with the explants of Gnetum

Effective medium for in vitro sprouting of the buds and multiplication of the plantlets, and identification of the fungal contaminant associated with the explants of Gnetum

Plant tissue culture requires the optimization of growth media. Gnetum, known locally in Cameroon as “Eru” is an indigenous gymnospermous vegetable with diverse medicinal, nutritional, cultural and socio-economic values. This resource is over-exploited and expected to neighboring countries, resulting to increased scarcity in the forest. Preliminary work on the in vitro culture of nodal cuttings was faced by the problem of fungal contamination. It was therefore necessary to isolate and identify the fungal contaminant, optimize the surface sterilization of field material and compose an appropriate medium for sprouting. Pure cultures of the fungus were obtained and grown on Potato Dextrose Agar (PDA) and Sabouraud Dextrose Agar (SDA). The identification was based on the appearance of the fungal growth on plates and also on the microscopic view. This was affected by the use of keys. Gnetum explants were disinfected with the various concentrations of disinfectants, preceded in some instances by pre-treatments, as well as incorporating fungicides in the culture medium. Two different culture media were employed: the Woody Plant Medium (WPM) and the Murashige and Skoog (MS) based establishment medium (Y-1). Gnetum was found to live in association with a complex of Microsporum species. The level of contamination of cultures was reduced from 100% to 40% when pre-treated before disinfection and even lower to 10% by incorporating fungicides in the medium. Sprouting was observed in WPM. This study provides baseline information on the in vitro propagation of Gnetum and thus opens up avenues for more research to be carried out in this field.

Rapid and sensitive detection of ochratoxin A using antibody-conjugated gold nanoparticles based on Localized Surface Plasmon Resonance

The regulation of tolerable levels of ochratoxin A in food for human and animal consumption has been defined in some countries. To meet these levels, simpler, more efficient, and faster analytical methods are being developed to facilitate the identification of this dangerous contaminant in food. Here, we combined gold nanoparticles (AuNPs) with anti-ochratoxin A (OTA) IgG to detect elementary levels of OTA based on Localized Surface Plasmon Resonance. AuNPs were prepared with trisodium citrate and characterized by UV–visible spectroscopy, X-ray, dynamic light scattering, and transmission electron microscopy. The conjugation of AuNPs to IgG anti-OTA was confirmed by bathochromic shift (UV–vis) and RAMAN spectroscopy. The sensitivity of the nanosensor was investigated by measuring LSPR band λmax shifts. Our results suggest this assay is highly sensitive, with a lower detection limit of about 0.001 pg mL−1. The LSPR nanosensor reduced detection limits by roughly 10 times compared to other methods. We demonstrated that the approach investigated here is a rapid and sensitive method for OTA detection.

A Rapid and Mild Sulfation Strategy Reveals Conformational Preferences in Therapeutically Relevant Sulfated Xylooligosaccharides.

Although sulfated xylooligosaccharides are promising therapeutic leads for a multitude of afflictions, the structural complexity and heterogeneity of commercially deployed forms (e. g. Pentosan polysulfate 1) complicates their path to further clinical development. We describe herein the synthesis of the largest homogeneous persulfated xylooligomers prepared to date, comprising up to eight xylose residues, as standards for biological studies. Near quantitative sulfation was accomplished using a remarkably mild and operationally simple protocol which avoids the need for high temperatures and a large excess of the sulfating reagent. Moreover, the sulfated xylooligomer standards so obtained enabled definitive identification of a pyridinium contaminant in a sample of a commercially prepared Pentosan drug and provided significant insights into the conformational preferences of the constituent persulfated monosaccharide residues. As the spatial distribution of sulfates is a key determinant of the binding of sulfated oligosaccharides to endogenous targets, these findings have broad implications for the advancement of Pentosan-based treatments.

Isolation and identification of Pantoea agglomerans from the inflated bag with dried hop pellets stored under a modified atmosphere.

Isolation, characterization and identification of possible microbial contaminant(s) in the inflated foil bag containing hop pellets packed and stored in a modified atmosphere. Package gas of the inflated foil bag containing hop pellets was analysed by gas chromatography. Compared with the reference modified atmosphere, containing about 16vol.% of CO2 , the inflated bag atmosphere contained 53vol.% CO2 , suggesting possible microbial contamination. Therefore, several standard and mineral media, with added hop pellets or hop infusion, were used for cultivation at different temperatures under an anaerobic atmosphere. Cultivation in mineral medium with hop pellets yielded a bacterial isolate that was identified by MALDI-TOF mass spectrometry and verified by partial 16S rRNA gene analysis as Pantoea agglomerans, a known plant epiphyte. A novel strain of P. agglomerans (designed as DBM 3696) was found to be suspicious of causing inflation of the foil bag containing dried hop pellets packed in modified atmosphere. This study suggests that P. agglomerans, probably hop epiphyte, could cause sporadic inflation of bags with hop pellets packed in modified atmosphere causing logistical problems during bags transport.

Chemometric non-targeted analysis for detection of soybean meal adulteration by near infrared spectroscopy

In this study a quick and efficient routine procedure for food fraud detection by multiple adulterants is presented. Non-targeted analysis employs the Near Infrared (NIR) spectroscopy measurements and one-class classification modeling as the chemometric data processing. The approach is illustrated by the analysis of a large collection of NIR spectra of soybean meal. The clean and contaminated samples are studied. The main advantage of the proposed approach is that it is not aimed at identification and quantification of a specific contaminant. The procedure is designed in such a way that it detects any deviations from the clean samples. The non-targeted analysis has its own limit of detection (LoD). In the study we have presented an approach for LoD assessment. This issue is of great importance for practical applications. The proposed approach can be applied for other types of feed and food products.

Detection and Identification of Microbial Contaminant in Bakery Products in Yogyakarta City, Indonesia

Bread has been chosen as an alternative food because of its availability. In Indonesia, consumption of breads is increased due to the change of diet pattern into packed and ready-made meals. Therefore, it is important to raise the awareness of bakery products quality. The purpose of this study was to detect and identify the microbial contaminant in bakery products in Yogyakarta City, Indonesia. Bacterial colonies from expired bakery products were isolated into pure isolate then confirmed by API Staph and Polymerase Chain Reaction (PCR) method. The results showed there were five kinds of gram-positive bacteria. Isolated bacteria identified by API were Bacillus cereus (52.8%), Bacillus subtilis (97.7%), Staphylococcus aureus (97.7%), Staphylococcus epidermidis (97,9%) and Staphylococcus saprophyticus (72,2% and 61,8%).

Detection and Identification of Microbial Contaminant in Bakery Products in Yogyakarta City, Indonesia

Bread has been chosen as an alternative food because of its availability. In Indonesia, consumptionof breads is increased due to the change of diet pattern into packed and ready-made meals. Therefore, it isimportant to raise the awareness of bakery products quality. The purpose of this study was to detect andidentify the microbial contaminant in bakery products in Yogyakarta City, Indonesia. Bacterial coloniesfrom expired bakery products were isolated into pure isolate then confirmed by API Staph and PolymeraseChain Reaction (PCR) method. The results showed there were five kinds of gram-positive bacteria. Isolatedbacteria identified by API were Bacillus cereus (52.8%), Bacillus subtilis (97.7%), Staphylococcus aureus (97.7%),Staphylococcus epidermidis (97,9%) and Staphylococcus saprophyticus (72,2% and 61,8%).

The Temporal Degradation of Illicit Contaminants in Latent Fingermarks Using Fourier Transform Infrared Spectroscopic Imaging

Fourier Transform Infrared (FTIR) spectroscopy has been shown to be a rapid, non-destructive analytical technique capable of detecting trace amounts of exogenous particulate in fresh latent fingermarks. Fingermarks identified at a crime scene however, are rarely fresh and are likely to have been deposited days or even weeks before forensic analysis, leaving them prone to decomposition. In this study latent fingermarks were contaminated with trace amounts of the improvised explosive precursor’s ammonium nitrate and sodium chlorate, and the addictive narcotic cocaine. The latent fingermarks where then aged in natural daylight conditions over a 30 day period and intermittently analysed using FTIR spectromicroscopy. Exogenous particulate was identified using spectroscopic imaging of each fingermark, and spectra obtained from the samples were compared to control spectra to confirm the identification of the contaminant. This study demonstrates that these contaminants are detectable within latent fingermarks up to at least 30 days after deposition, with only ammonium nitrate showing signs of decomposition, and that fingermark chemistry has a minimal effect on their molecular integrity. This information has broad implications for the law enforcement community as it suggests that the detection of exogenous particulate within latent fingermarks is possible long after a suspect has handled an illegal substance. This study also confirms the use of spectroscopic imaging to provide a chemical signature for these illicit compounds weeks after deposition, and an image of the fingermark ridge pattern that can then be used for identification purposes.

Identification of the primary peptide contaminant that inhibits fibrillation and toxicity in synthetic amyloid-β42.

Understanding the pathophysiology of Alzheimer disease has relied upon the use of amyloid peptides from a variety of sources, but most predominantly synthetic peptides produced using t-butyloxycarbonyl (Boc) or 9-fluorenylmethoxycarbonyl (Fmoc) chemistry. These synthetic methods can lead to minor impurities which can have profound effects on the biological activity of amyloid peptides. Here we used a combination of cytotoxicity assays, fibrillation assays and high resolution mass spectrometry (MS) to identify impurities in synthetic amyloid preparations that inhibit both cytotoxicity and aggregation. We identify the Aβ42Δ39 species as the major peptide contaminant responsible for limiting both cytotoxicity and fibrillation of the amyloid peptide. In addition, we demonstrate that the presence of this minor impurity inhibits the formation of a stable Aβ42 dimer observable by MS in very pure peptide samples. These results highlight the critical importance of purity and provenance of amyloid peptides in Alzheimer’s research in particular, and biological research in general.

Identification of Trichloroethene in Groundwater Using Trees

Several tonnes of useful chemicals are produced every year for use in households, agriculture production and industries. However, these chemicals move from their original production or application sites through the air, surface or groundwater or soils and are deposited in unintended places. The resultant contamination of these matrices and the subsequent effects on living organisms, have become a major concern for researchers and policy makers. This study aimed at using literature to briefly review the role of plants in identifying trichloroethene contamination in groundwater. It was found that plants, through direct contact with the soil and such processes as advective uptake, translocation, diffusion and particle deposition are able to incorporate most of these contaminants into their tissues and store them in leaves, branches and trunks. The entire process of removing TCE by this method has thus been found to be inexpensive, easy to undertake and has been shown to be environmentally friendly. It may therefore be an effective way for the identification and analysis of this contaminant.

Identification and separation of protein, contaminant and substrate peaks using gentle‐secondary ion mass spectrometry and the g‐ogram

Secondary ion mass spectrometry (SIMS) is an important technique for the characterization of proteins at surfaces. However, interpretation of the mass spectra is complicated owing to confusion with peaks from contaminants and the substrate which is further compounded by complex fragmentation mechanisms. We test a new development of the G-SIMS method called the g-ogram to separate out spectral components without a priori information about which peaks to include in the analysis and which peaks relate to each component. The effectiveness of the g-ogram method is investigated using a model system of lysozyme adsorbed onto a silicon wafer and indium tin oxide substrates. In the method, two SIMS spectra are acquired using Bi(+) and Mn(+) primary ions which create lower and higher fragmentation in the spectra, respectively. The g-ogram separates out components using a separation parameter that is related to the fragmentation energy. The g-ogram separates the spectrum of lysozyme adsorbed onto a silicon wafer into three components: (i) the substrate and PDMS contamination; (ii) a second, but unexpected, contaminant; and (iii) peaks from the protein amino acids. Similar results are achieved for the indium tin oxide substrate. In addition, evidence of fragments from plural amino acids with two candidate peaks at 140.12 Da and 185.08 Da is observed. The g-ogram method effectively separates out mass peaks relating to the substrate, contamination and protein without any a priori information or subjective decisions about which peaks to include in the analysis (so called 'peak picking'). This is a great help to analysts. We find two possible peaks from plural amino acids but no evidence of pluralities is found for peaks above 240 Da that are generated from when using Bi or Mn primary ions.

Identification and removal of nitroxide spin label contaminant: Impact on PRE studies of α‐helical membrane proteins in detergent

NMR paramagnetic relaxation enhancement (PRE) provides long-range distance constraints (~15-25 Å) that can be critical to determining overall protein topology, especially where long-range NOE information is unavailable such as in the case of larger proteins that require deuteration. However, several challenges currently limit the use of NMR PRE for α-helical membrane proteins. One challenge is the nonspecific association of the nitroxide spin label to the protein-detergent complex that can result in spurious PRE derived distance restraints. The effect of the nitroxide spin label contaminant is evaluated and quantified and a robust method for the removal of the contaminant is provided to advance the application of PRE restraints to membrane protein NMR structure determination.

Contribution of compressional waves to the identification and quantification of a water contaminant

The generation of compressional waves in liquids can change the resonance frequency of a quartz crystal, although this factor has been ignored in most of the published works on piezoelectric quartz crystals operating in liquid media. In fact, oscillatory behaviour of the frequency of resonance is seldom reported, although we believe it is not rarely perceived by investigators with data acquisition systems. These compressional waves, that propagate normal to the quartz surface, can lead to systematic errors in analysis when the frequency of oscillation is the analytical signal. With this work we intended to show that compressional waves are not always an annoying phenomena and a source of problems but that they can be useful in chemical analysis. The work is focused on the analytical problem and intends to show the advantage of using the period of the signal fluctuation in chemical analysis. Series frequency and period of its fluctuation were both monitored in the presence of several organic pollutants in water: ethanol, acetone, tetrahydrofuran, tetrachloroethylene and chloroform. Quantification based solely on the series frequency faced some difficulties, as different compositions could give rise to the same signal. The additional information obtained by measuring the period of the signal fluctuation allowed to establish the concentration of the solution without ambiguities, and can also, in particular situations, allow to identify the pollutant. Besides, for waters contaminated with a known pollutant in low concentrations, when ambiguity in concentration range is not an issue, sometimes, higher sensitivity was obtained measuring the wave periodicity rather than the series frequency of oscillation.

Identification of an unknown extraneous contaminant in pharmaceutical product analysis

During the content uniformity test of a drug product (tablet formulation), an unknown peak was observed in the HPLC chromatograms. Upon further investigation, it was determined that the unknown peak was originated from an external source and, therefore, the drug product is free of this unknown peak. The next step was to identify the structure of this unknown peak in order to determine the source of this contaminant species. In this paper, we wish to present the strategy and the results of the experiments that led to the identification of this unknown peak. LC–PDA/UV and LC–MS n analyses were conducted to obtain the UV spectrum, molecular weight and MS n fragmentation pathways of the unknown peak. The MS analysis revealed certain structural features of the unknown species and a number of model compounds that contain such features were then examined for their UV absorbance profiles in an attempt to establish the functional group connectivity within the unknown species. A careful examination of these results in conjunction with the determination of the high-resolution molecular weight led to a short list of potential candidates for the unknown species, among which the most likely one was 1,3-diphenylguanidine. The identification of the unknown contaminant was confirmed by spiking experiments using the authentic compound. The potential source of this contaminant was also identified as derived from the safety filler of the pipette bulb used to prepare the sample solutions during the drug analysis.

Contamination of dry foods with trimethyldiphenylmethanes by migration from recycled paper and board packaging

Contamination of foods with trimethyldiphenylmethanes is reported and the origin is shown to be migration from food packaging materials of which the use of recycled carbonless copy paper was found to be the major source. This chemical is one of the solvents used in the carbonless copy paper and its presence in food and the environment has not been previously identified. In this paper we have pursued previous studies on diisopropylnaphthalenes and hydrogenated terphenyls contamination from packaging and now report the identification of this new food contaminant and present evidence of its source. Solid foods such as egg pasta, barley coffee and rice were analysed by GC/MS and a mean concentration of 18 µg/kg of trimethyldiphenylmethanes was found. Extracts from carbonless copy paper were analysed by proton NMR to characterize the trimethyldiphenylmethanes. Since trimethyldiphenylmethanes are found in solid food together with diisopropylnaphthalenes, and considering their similar chemical character, they may follow the same migration pathway as one another.