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 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.

An optimized protocol for high precision measurement of Hg isotopic compositions in samples with low concentrations of Hg using MC-ICP-MS

2018 ◽  
Vol 33 (11) ◽  
pp. 1932-1940 ◽  
Author(s):  
Hongyan Geng ◽  
Runsheng Yin ◽  
Xiangdong Li
Keyword(s):  
High Precision ◽  
Precision Measurement ◽  
Direct Determination ◽  
Gas Flows ◽  
High Precision Measurement ◽  
Isotopic Compositions ◽  
Low Concentrations ◽  
Optimized Protocol ◽  
Icp Ms

Optimized gas flows achieved the direct determination of Hg isotopic compositions of 0.1 ng mL−1 solutions.

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 Trace Determination of Selected Heavy Metal Ions in Bleaching Creams in the Local Market of Saudi Arabia

2017 ◽  
Vol 14 (4) ◽  
pp. 1349-1354
Author(s):  
Faten M. Ali Zainy
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Saudi Arabia ◽  
Direct Determination ◽  
Optical Emission ◽  
Local Market ◽  
Icp Oes ◽  
Recovery Percentage ◽  
High Concentrations

ABSTRACT: Bleaching cream and cosmetics products of skin have risk of toxicity and deleterious effects to the human health because of their multiplicative contamination with heavy metals and uncertain mixing of different components. Thus, the present study reports a comprehensive study on the trace selected heavy metal (Hg, Cd, Ti, Bi, Pb, As and Tl) determination in 16 samples of bleaching creams and samples mixture of bleaching creams simultaneously to get a double activity (shiny and faster) on the skin from the local market of Saudi Arabia. Samples were digested with high pressure microwave technique followed by direct determination by inductive coupled plasma - optical emission spectrometer (ICP-OES). Hg, Bi, Ti and Pb levels on samples were found equal 5739.16, 7013.53, 21407.73, 456.70 µg/g, respectively whereas other elements (Cd, As and Tl) were found less than 28.99 ppm. One sample of the mixtures showed high concentrations of Hg (13338.50 µg/g,) and Bi (619.23 µg/g). Thus, creams and cream mixtures containing heavy metals above the permissible limit must be blind. The lower detection limits (LOD) were achieved at 2.5-50 µg/g concentration level, RSD was less than 14.72%, and recovery percentage for cosmetics were in the range of 88.52 -99.62%. The proposed method for sample digestion and ICP-OES measurements was fast, precise, convenient and provided good recovery of the tested elements.

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 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.

scholarly journals Evaluation of the P-solubilizing activity of soil microorganisms and its sensitivity to soluble phosphate

2011 ◽  
Vol 48 (No. 9) ◽  
pp. 397-400 ◽  
Author(s):  
O. Mikanová ◽  
J. Nováková
Keyword(s):  
Tricalcium Phosphate ◽  
Agricultural Soils ◽  
Potassium Phosphate ◽  
Direct Determination ◽  
Soluble Phosphate ◽  
Natural Ecosystems ◽  
High Concentrations ◽  
Filter Papers ◽  
Solubilizing Activity

Microbial solubilization of hardly soluble mineral phosphates in soil is an important process in natural ecosystems and in agricultural soils. Regulation of the P-solubilizing activity by the presence of soluble phosphates in medium was determined. For this reason we decided to test a&nbsp;number of soil bacteria showing a&nbsp;high P-solubilizing activity for its sensitivity to the presence of soluble dihydrogen potassium phosphate in medium. At these studies, the direct determination of the solubilized phosphate in medium was masked by the presence of relatively high concentrations of soluble phosphate added. Therefore, we have modified the method, determining the residual tricalcium phosphate. The effect of soluble phosphate in medium on the P-solubilizing activity of rhizosphere isolates and strains of Rhizobium were tested in liquid cultures with the addition of various concentrations of soluble KH<sub>2</sub>PO<sub>4</sub>. The medium was filtered after incubation and the remaining tricalcium phosphate was separated by filtration. Filter papers with the remaining tricalcium phosphate were hydrolysed with 2N H2SO4. Phosphorus was determined spectrophotometrically. The P-solubilizing activity was expressed as a&nbsp;difference between the tricalcium phosphate added and its remainder after the incubation. These results fully confirmed that there exist the strains, whose P-solubilizing activity is inhibited and other strains, whose P-solubilizing activity is not inhibited or is inhibited very little in the presence of soluble phosphate. The use of our adapted method was much more suitable for this type of experiments.

Effect of low fibrinogen concentrations on the rheology of human blood in vitro

1979 ◽  
Vol 236 (3) ◽  
pp. H447-H450
Author(s):  
W. Blattler ◽  
P. W. Straub ◽  
C. Jeanneret ◽  
G. S. Horak
Keyword(s):  
Human Blood ◽  
Cell Aggregation ◽  
Fibrinogen Concentration ◽  
Shear Rates ◽  
Red Blood Cell Aggregation ◽  
Low Concentrations ◽  
Normal Human ◽  
High Concentrations

The influence of low concentrations of fibrinogen on the rheology of normal human blood was investigated with an instrument that permitted simultaneous determination of viscosity and the state of red blood cell aggregation and deformation. Fibrinogen, in concentrations of 9-82 mg/100 ml, decreased blood viscosity at all shear rates below the value obtained with red blood cells suspended in serum. At concentrations above 116 mg/100 ml viscosity was increased. Aggregate formation increased progressively as the fibrinogen concentration increased, necessitating higher dispersing shear rates. The deformation and alignment of the red cells, occurring at a shear rate of 230 s-1, was facilitated by low concentrations. The effect of fibrinogen on low-shear viscosity is explained by the formation of different kinds of aggregates. At low concentrations, the aggregates consist of only few cells forming spherelike particles displaying hemodynamic properties better than those of the single discoid cells. At normal or high concentrations big rodlike aggregates occur and increase resistance to flow.

Determination of urinary norepinephrine and epinephrine by liquid chromatography with fluorescence detection and pre-column derivatization

1990 ◽  
Vol 36 (5) ◽  
pp. 732-736 ◽  
Author(s):  
P Moleman ◽  
J van Dijk
Keyword(s):  
Liquid Chromatography ◽  
Present Method ◽  
High Performance ◽  
Reversed Phase ◽  
Fluorescence Derivatization ◽  
Specificity And Sensitivity ◽  
Low Concentrations ◽  
High Concentrations ◽  
Phase Column

Abstract We assayed norepinephrine and epinephrine by utilizing solvent extraction, fluorescence derivatization, and "high-performance" liquid chromatography. A 100-microL aliquot of urine was extracted twice according to Smedes et al. (J Chromatogr 1982;231:25-39) and subsequently incubated with 1,2-diphenylethylenediamine. A 100-microL aliquot of the resulting mixture was injected into a reversed-phase column, and norepinephrine and epinephrine were detected fluorometrically. The within-day CV was 3.0-4.0% and the between-day CV 3.4-7.1% for normal and high concentrations of both analytes. At low concentrations (15-40 nmol/L) these CVs were 4.2-6.8% and 6.8-9.2%, respectively. The detection limit of the assay was less than 0.4 nmol/L for each analyte. We discuss the critical steps for extraction, derivatization, and chromatography. The present method combines the qualities of high precision, specificity, and sensitivity.

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