scholarly journals Analytical Strategies for the Determination of Arsenic in Rice

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Bruno E. S. Costa ◽  
Luciana M. Coelho ◽  
Cleide S. T. Araújo ◽  
Helen C. Rezende ◽  
Nívia M. M. Coelho
Keyword(s):  
Inorganic Arsenic ◽  
Sample Pretreatment ◽  
Fertilizer Application ◽  
Low Concentrations ◽  
The Matrix ◽  
Analytical Strategies ◽  
Recent Developments ◽  
Route Of Exposure ◽  
High Concentrations

Arsenic is an element of concern given its toxicological significance, even at low concentrations. Food is a potential route of exposure to inorganic arsenic and in this regard arsenic in rice is associated with soil contamination, fertilizer application, and the use of arsenic-containing irrigation water. Therefore, there is a need to investigate the regional rice crops with a view to future discussions on the need for possible regulatory measures. Several studies have reported high concentrations of arsenic in rice grown in soils irrigated with contaminated water; however, procedures used, including sample pretreatment and preconcentration steps, have to be followed to ensure sensitivity, accuracy, and reproducibility. Arsenic is a difficult element to measure in complex matrices, such as foods, because the matrix must be destroyed at an elevated temperature without the loss of the analyte or contamination. This review summarizes the major methods for the determination of arsenic in rice samples. The main purpose of this review is to provide an update on the recent literature concerning the strategies for the determination of arsenic and to critically discuss their advantages and weaknesses. These difficulties are described along with recent developments aimed at overcoming these potential issues.

scholarly journals The Double Face of Ketamine—The Possibility of Its Identification in Blood and Beverages

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 813
Author(s):  
Magdalena Świądro ◽  
Paweł Stelmaszczyk ◽  
Irena Lenart ◽  
Renata Wietecha-Posłuszny
Keyword(s):  
Date Rape ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Heroin Addiction ◽  
Assisted Extraction ◽  
Low Concentrations ◽  
High Concentrations ◽  
Rosé Wine ◽  
Tof Ms

The purpose of this study was to develop and validate a high-sensitivity methodology for identifying one of the most used drugs—ketamine. Ketamine is used medicinally to treat depression, alcoholism, and heroin addiction. Moreover, ketamine is the main ingredient used in so-called “date-rape” pills (DRP). This study presents a novel methodology for the simultaneous determination of ketamine based on the Dried Blood Spot (DBS) method, in combination with capillary electrophoresis coupled with a mass spectrometer (CE-TOF-MS). Then, 6-mm circles were punched out from DBS collected on Whatman DMPK-C paper and extracted using microwave-assisted extraction (MAE). The assay was linear in the range of 25–300 ng/mL. Values of limits of detection (LOD = 6.0 ng/mL) and quantification (LOQ = 19.8 ng/mL) were determined based on the signal to noise ratio. Intra-day precision at each determined concentration level was in the range of 6.1–11.1%, and inter-day between 7.9–13.1%. The obtained precision was under 15.0% (for medium and high concentrations) and lower than 20.0% (for low concentrations), which are in accordance with acceptance criteria. Therefore, the DBS/MAE/CE-TOF-MS method was successfully checked for analysis of ketamine in matrices other than blood, i.e., rose wine and orange juice. Moreover, it is possible to identify ketamine in the presence of flunitrazepam, which is the other most popular ingredient used in DRP. Based on this information, the selectivity of the proposed methodology for identifying ketamine in the presence of other components of rape pills was checked.

Manometric and Electrode-Probe Determination of CO2 in Fish Flesh

1982 ◽  
Vol 45 (10) ◽  
pp. 932-934 ◽  
Author(s):  
JIM W. CONRAD ◽  
GLENN C. ROBERTS ◽  
HAROLD J. BARNETT
Keyword(s):  
Mean Difference ◽  
Fish Products ◽  
Probe Technique ◽  
Fish Flesh ◽  
Ion Probe ◽  
Low Concentrations ◽  
Manometric Method ◽  
High Concentrations ◽  
Manometric Technique

A rapid electrometric method for determining endogenous and added CO2 in fish products was studied using an Orion CO2 probe and Orion ionalyzer model #801. Analytical results were compared to those using the standard Warburg manometric technique. Comparisons showed a ± 20.8% mean difference for low concentrations of CO2 (<350 ppm) and a ± 10.7% mean difference for high concentrations of CO2 (>800 ppm). The probe technique was found to be easier to use and required less time for operating and cleanup procedures than the manometric method. Based on recovery studies, the specific ion probe was more accurate at all levels of CO2 evaluated than the manometric device.

scholarly journals Potentiometric Determination of Chlorate Impurities in Hypochlorite Solutions

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Dmitry V. Girenko ◽  
Al’ona A. Gyrenko ◽  
Nikolai V. Nikolenko
Keyword(s):  
Sodium Hypochlorite ◽  
Sodium Sulfite ◽  
Systematic Errors ◽  
Expanded Uncertainty ◽  
Iodide Ions ◽  
Low Concentrations ◽  
Sophisticated Equipment ◽  
The Matrix ◽  
Fold Excess

The method of iodometric determination of chlorates impurities in sodium hypochlorite solutions for medical and veterinary purposes was developed. This method does not require sophisticated equipment and can be implemented directly where the solutions are used. The method is based on the different rates of interaction of ClO- and ClO3- with iodide ions depending on the acidity of the medium. We have shown that blank titration is advisable to improve the accuracy of the determination of low concentrations of chlorates in the matrix of hypochlorite which is present in excess since in this case possible systematic errors due to the presence of oxidizing impurities in the reagents are prevented. To quantify the low concentrations of chlorates, we proposed to remove 85-95% of hypochlorite ions by means of reducing their excess with sodium sulfite at pH 10.5. The solution of sodium sulfite does not require standardization before each analysis in the proposed procedure. The possibility of quantitative determination of chlorate impurities in the range of 2-50 mg/L in the presence of 50-500–fold excess of sodium hypochlorite with an error of 5% has been proved. The expanded uncertainty of chlorate determination did not exceed 0.6 mg/L.

scholarly journals Effect of arsenosugar ingestion on urinary arsenic speciation

1998 ◽  
Vol 44 (3) ◽  
pp. 539-550 ◽  
Author(s):  
Mingsheng Ma ◽  
X Chris Le
Keyword(s):  
Arsenic Speciation ◽  
Inorganic Arsenic ◽  
Sample Pretreatment ◽  
Arsenic Species ◽  
Urine Samples ◽  
Standard Reference Materials ◽  
Dimethylarsinic Acid ◽  
Urinary Arsenic ◽  
Biomarkers Of Exposure

Abstract We developed and evaluated a method for the determination of μg/L concentrations of individual arsenic species in urine samples. We have mainly studied arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMAA), and dimethylarsinic acid (DMAA) because these are the most commonly used biomarkers of exposure by the general population to inorganic arsenic and because of concerns over these arsenic species on their toxicity and carcinogenicity. We have also detected five unidentified urinary arsenic species resulting from the metabolism of arsenosugars. We combined ion pair liquid chromatography with on-line hydride generation and subsequent atomic fluorescence detection (HPLC/HGAFS). Detection limits, determined as three times the standard deviation of the baseline noise, are 0.8, 1.2, 0.7, and 1.0 μ/L arsenic for arsenite, arsenate, MMAA, and DMAA, respectively. These correspond to 16, 24, 14, and 20 pg of arsenic, respectively, for a 20-μL sample injected for analysis. The excellent detection limit enabled us to determine trace concentrations of arsenic species in urine samples from healthy subjects who did not have excess exposure to arsenic. There was no need for any sample pretreatment step. We used Standard Reference Materials, containing both normal and increased concentrations of arsenic, to validate the method. Interlaboratory studies with independent techniques also confirmed the results obtained with the HPLC/HGAFS method. We demonstrated an application of the method to the determination of arsenic species in urine samples after the ingestion of seaweed by four volunteers. We observed substantial increases of DMAA concentrations in the samples collected from the volunteers after the consumption of seaweed. The increase of urinary DMAA concentration is due to the metabolism of arsenosugars that are present in the seaweed. Our results suggest that the commonly used biomarkers of exposure to inorganic arsenic, based on the measurement of arsenite, arsenate, MMAA, and DMAA, are not reliable when arsenosugars are ingested from the diet.

Inorganic polysulfides’ quantitation by methyl iodide derivatization: dimethylpolysulfide formation potential

2004 ◽  
Vol 49 (9) ◽  
pp. 179-184 ◽  
Author(s):  
A. Goifman ◽  
D. Ryzkov ◽  
J. Gun ◽  
A. Kamyshny ◽  
A.D. Modestov ◽  
...  
Keyword(s):  
Methyl Iodide ◽  
Direct Determination ◽  
Solubility Limit ◽  
Environmental Significance ◽  
Valuable Alternative ◽  
Natural Systems ◽  
Low Concentrations ◽  
Inorganic Polysulfides ◽  
High Concentrations

Inorganic polysulfides are important intermediates in the formation of dimethylpolysulfides and possibly other volatile sulfur compounds of environmental significance. Currently, direct determination of these ions in the concentration range of natural systems is practically impossible, particularly under oxic conditions. Polysulfide quantification by derivatization with methyl iodide or d6-methyl iodide is emerging as a valuable alternative method for studies of polysulfide formation in natural systems. This manuscript presents detailed studies aimed at the evaluation of this method. We determined the conversion of the inorganic polysulfides to dimethylpolysulfides by methylation with methyl iodide. Close to 100 per cent of the molar concentration of polysulfide salts were converted to organic polysulfides for very low concentrations of dissolved polysulfide solutions, but only a small recovery was obtained for high concentrations of polysulfide precursors or when the solubility limit was exceeded. The recovery of polysulfides based on the calculated dissolved polysulfide concentration exceeds 1,000 per cent for very low dissolved concentrations of polysulfides. This unexpected dependence is attributed to continuous inorganic polysulfide formation from hydrogen sulfide and sulfur precipitate concurrent with, and in fact driven by, the methylation process.

scholarly journals Determination of Zinc-Based Additives in Lubricating Oils by Flow-Injection Analysis with Flame-AAS Detection Exploiting Injection with a Computer-Controlled Syringe

2005 ◽  
Vol 2005 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Gustavo Pignalosa ◽  
Moisés Knochen ◽  
Noel Cabrera
Keyword(s):  
Flow Injection ◽  
Computer Control ◽  
Injection System ◽  
Mean Values ◽  
Lubricating Oils ◽  
Low Concentrations ◽  
Flow Injection System ◽  
High Concentrations ◽  
Zinc Levels

A flow-injection system is proposed for the determination of metal-based additives in lubricating oils. The system, operating under computer control uses a motorised syringe for measuring and injecting the oil sample (200μL) in a kerosene stream, where it is dispersed by means of a packed mixing reactor and carried to an atomic absorption spectrometer which is used as detector. Zinc was used as model analyte. Two different systems were evaluated, one for low concentrations (range 0–10 ppm) and the second capable of providing higher dilution rates for high concentrations (range 0.02%–0.2% w/w). The sampling frequency was about 30 samples/h. Calibration curves fitted a second-degree regression model (r2= 0.996). Commercial samples with high and low zinc levels were analysed by the proposed method and the results were compared with those obtained with the standard ASTM method. Thettest for mean values showed no significant differences at the 95% confidence level. Precision (RSD%) was better than 5% (2% typical) for the high concentrations system. The carryover between successive injections was found to be negligible.

scholarly journals Association of polymorphism rs7903146 gene TCF7L2 with low concentrations of autoantibodies in latent autoimmune diabetes of adults (LADA)

2016 ◽  
Vol 19 (3) ◽  
pp. 199-203 ◽  
Author(s):  
Iuliia V. Silko ◽  
Tatiana V. Nikonova ◽  
Olga N. Ivanova ◽  
Svetlana M. Stepanova ◽  
Marina V. Shestakova ◽  
...  
Keyword(s):  
Odds Ratio ◽  
Autoimmune Diabetes ◽  
Polymorphic Marker ◽  
Healthy Individuals ◽  
Tcf7l2 Gene ◽  
Latent Autoimmune Diabetes ◽  
Low Concentrations ◽  
High Concentrations

Aim. To determine the frequencies of alleles and genotypes of polymorphic marker rs7903146 of the TCF7L2 gene in latent autoimmune diabetes in adults (LADA) and healthy individuals. The aims of the study were also to compare the distribution of alleles and genotypes and to explore the association with the development of LADA.Materials and methods. A total of 96 patients (46 females and 50 males) with LADA and 201 healthy individuals were examined. A quantitative determination of autoantibodies GADA, ICA, IA-2A and ZnT8 in the serum of LADA patients was performed. All patients underwent genotyping of rs7903146 of the TCF7L2 genes.Results. There was an increased frequency of the T allele and genotype T+ of marker rs7903146 of the TCF7L2 gene in patients with LADA with low concentrations of autoantibodies compared to a group of patients with high concentrations and with controls. We observed significant associations of the T allele and genotype T+ with LADA in patients with low concentrations of autoantibodies [p = 0.02; odds ratio (OR) = 1.85; 95% confidence interval (CI) = 1.10–3.13 and p = 0.04; OR = 2.14; 95% CI = 1.01–4.53 for the T allele and genotype T+, respectively).Conclusion. The results of the study suggest that LADA patients with low concentrations of autoantibodies have a genetically pre-determined similarity with patients with type 2 diabetes.

scholarly journals A proteinaceous organic matrix regulates carbonate mineral production in the marine teleost intestine

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Kevin L. Schauer ◽  
Christophe M. R. LeMoine ◽  
Adrian Pelin ◽  
Nicolas Corradi ◽  
M. Danielle McDonald ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Organic Matrix ◽  
Magnesium Content ◽  
Inhibitory Effect ◽  
Marine Teleost ◽  
Low Concentrations ◽  
The Matrix ◽  
Mineral Production ◽  
High Concentrations

AbstractMarine teleost fish produce CaCO3in their intestine as part of their osmoregulatory strategy. This precipitation is critical for rehydration and survival of the largest vertebrate group on earth, yet the molecular mechanisms that regulate this reaction are unknown. Here, we isolate and characterize an organic matrix associated with the intestinal precipitates produced by Gulf toadfish (Opsanus beta). Toadfish precipitates were purified using two different methods, and the associated organic matrix was extracted. Greater than 150 proteins were identified in the isolated matrix by mass spectrometry and subsequent database searching using anO. betatranscriptomic sequence library produced here. Many of the identified proteins were enriched in the matrix compared to the intestinal fluid, and three showed no substantial homology to any previously characterized protein in the NCBI database. To test the functionality of the isolated matrix, a micro-modifiedin vitrocalcification assay was designed, which revealed that low concentrations of isolated matrix substantially promoted CaCO3production, where high concentrations showed an inhibitory effect. High concentrations of matrix also decreased the incorporation of magnesium into the forming mineral, potentially providing an explanation for the variability in magnesium content observed in precipitates produced by different fish species.

scholarly journals Simple determination of nonionic surfactants in highly-polluted aqueous samples

2011 ◽  
Vol 9 (6) ◽  
pp. 1150-1157 ◽  
Author(s):  
Marek Šváb ◽  
Martina Švábová ◽  
Petra Mečířová
Keyword(s):  
Humic Acids ◽  
Nonionic Surfactants ◽  
Sample Pretreatment ◽  
Objective Evaluation ◽  
Ionic Surfactants ◽  
Spectrometric Method ◽  
Aqueous Samples ◽  
Hydrocarbon Chains ◽  
High Concentrations

AbstractThis study examined the direct spectrometric method for determining non-ionic surfactants in highly-polluted samples (i.e., soil leachates) containing high concentrations of humic acids. Meso-tetra-(3,5-dibromo-4-hydrooxyphenyl)-porphyrin served as a coloration agent. The method was tested by use of two polyethoxylate/polypropoxylate — based non-ionic surfactants: Triton CF-21 containing aromatic groups in the structure and Novanik 1047A containing only linear hydrocarbon chains. The main goal was to quantify the influence of interfering species to the results. A test for coincidence of regression lines was employed for objective evaluation of the humic acid influence on the determination. It was observed that for linear surfactant Novanik 1047 A the method provides reliable result and thus, can serve for routine analyses. Regarding Triton CF-21, an interfering effect of humic acids was observed; however, after sufficient dilution of the samples, the method can be used as well. Finally, the method can be used for simple analyses of problematic samples without complicated sample-pretreatment.

scholarly journals Atomic Absorption Spectrometric Determination of Chromium, Copper, Lead, Mercury, and Zinc in Sediments Collected in Bayou d'Inde, Southwestern Louisiana

2002 ◽  
Vol 85 (1) ◽  
pp. 225-232 ◽  
Author(s):  
Carey Hardaway ◽  
Kermit Gauthreaux ◽  
Joseph Sneddon ◽  
James N Beck
Keyword(s):  
Trace Metals ◽  
Atomic Absorption ◽  
Sediment Cores ◽  
Sedimentation Rates ◽  
Low Concentrations ◽  
High Concentrations ◽  
Atomic Absorption Spectrometric ◽  
Copper Lead

Abstract The concentrations of the metals chromium (Cr), copper (Cu), lead (Pb), mercury (Hg), and zinc (Zn) were determined in sediment cores taken from Bayou d'Inde in southwestern Louisiana. Previous studies had reported elevated concentrations of these trace metals in sediments along this waterway. The current study, conducted more than a decade later, was designed to determine if these metals had migrated from the areas of highest concentrations. Concentrations as high as 400 mg/kg for Cr, 1100 mg/kg for Cu, 10 mg/kg for Hg, and 600 mg/kg for Pb and Zn were found. Areas of high concentrations of metals were isolated within a distance of about 1 km from the most highly contaminated areas in the bayou. Low concentrations of metals were found at the mouth of the bayou. Estimated sedimentation rates of 0.67–1.2 cm/yr were based on the burial of the sediments originally studied. The concentrations of the metals studied remained high and were also highly localized, both spatially and temporally.

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