Presence Of Concomitants Research Articles

Predictors of communication attitude in preschool-age children who stutter

PurposeAlthough preschool-age children who stutter report more negative attitudes toward communication than their typically fluent peers, few investigations have explored factors that may contribute to the differences observed in communication attitude. The purpose of the present study was to explore whether behavioral characteristics of stuttering severity (frequency, duration, physical concomitants) and time since onset of stuttering predict communication attitude in preschool-age children. MethodFifty-nine preschool-aged children who stutter completed two speaking samples and the KiddyCAT, a self-report assessment of communication attitude. Speech samples were analyzed for stuttering frequency (measured by percentage of stuttered syllables), duration, and presence of physical concomitants. Linear regression models were used to assess if these behavioral measures of stuttering and time since onset of stuttering predicted self-reported communication attitude. ResultsResults indicate stuttering behavioral measures and time since onset do not predict KiddyCAT scores of preschool-age children who stutter. ConclusionsPreliminary data suggest children who have presented with stuttering for a longer period of time are no more likely to report a negative communication attitude than children who have a shorter time since onset. Additionally, in contrast to school-age children who stutter, but similar to adults and adolescents who stutter, communication attitude is not linearly related to stuttering severity in preschool-age children.

Nickel determination in oily sludge leachates using isotope dilution inductively coupled plasma mass spectrometry following photochemical vapor generation: A feasibility study

The feasibility of photochemical vapor generation for the production of volatile Ni species was evaluated and applied to the analysis of acetic acid leachates obtained from oily sludge samples. Sludge samples originating from a petrochemical plant were submitted to extraction using standardized procedures with solutions adjusted to pH 2.88 or 4.93, with acetic acid. The leachate solutions were subsequently treated with a mixture of acetic and formic acid and exposed to UV radiation from a Hg discharge lamp; the irradiated solution was pumped to a gas-liquid separator and the volatile species were transported by a stream of argon for detection using inductively coupled plasma mass spectrometry. Experimental variables, including the nature and concentration of low molecular weight acids, irradiation interval, carrier gas flow rate and the effect of concomitant species on the efficiency of photochemical production of volatile Ni species were systematically evaluated. Oxygenated anions, particularly nitrate, were found to suppress the analytical signal, whereas the effect of cationic species depended on the nature of the cation. Lead was found to induce substantial signal suppression even at ppb levels. Considering the significant influence of concomitant species on the overall efficacy of the photochemical process, isotope dilution calibration was adopted as a strategy to overcome non-spectral interferences. Under optimized conditions, relative standard deviations better than 8.5% were achieved, along with detection limits better than 40 μg L−1. The accuracy was statistically attested upon comparison of the results to those obtained from the analysis of leachates using sample introduction via pneumatic nebulization. The proposed photochemical vapor generation setup was proven efficient to carry out the determination of Ni in the leachates, although the technique is highly sensitive to the presence of concomitants.

Automated Single-Phase Liquid-Liquid Extraction for Determination of Cr(VI) Using Graphite Furnace Atomic Absorption Spectrophotometry without Wet Digestion of Samples

This paper proposes a method to perform rapid and sensitive graphite furnace atomic absorption spectrometry (GFAAS) determination of Cr(VI) in vinegar samples without wet digestion. Taking into account low levels of Cr(VI) and the presence of several concomitants in the sample matrix, the proposed method uses single-phase liquid-liquid extraction (SPLLE). The method is automated, employing a flow-batch analyzer (FBA) which uses a mixing chamber designed to emulate a separation funnel promoting the formation/break of the single-phase solution, reaction and extraction. The Cr(VI) extraction procedure was performed by proportioned mixing of the vinegar sample (aqueous phase), amyl alcohol (organic phase), and ethanol (consolute) to form a single-phase solution. The chelating reagent sodium diethyldithiocarbamate (DDTC) dissolved in the consolute reacts rapidly with Cr(VI), in the single phase to produce a stable Cr-DDTC complex. The single-phase break step is performed by adding an excess of Britton-Robinson buffer, and then the organic phase enriched with Cr(VI) was analyzed by GFAAS. Factors such as extraction steps, single-phase composition, pH, chelating agent concentration, and flow-batch parameters were optimized. The FBA-SPLLE-GFAAS was evaluated in vinegar samples showing satisfactory analytical features in terms of limit of quantification (0.86 μg L −1 ), precision (RSD <12 %), characteristic mass (m0 = 0.32 pg), high sampling rate (26 h −1 ), and accuracy (recovery rate = 82–108 %). The proposed method requires one-step extraction and is eco-friendly since it consumes low amounts of non-toxic chemicals and generates little waste (about 700 μL per determination).

Carbon-, sulfur-, and phosphorus-based charge transfer reactions in inductively coupled plasma–atomic emission spectrometry

In this work, the influence of carbon-, sulfur-, and phosphorus-based charge transfer reactions on the emission signal of 34 elements (Ag, Al, As, Au, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Ga, Hg, I, In, Ir, K, Li, Mg, Mn, Na, Ni, P, Pb, Pd, Pt, S, Sb, Se, Sr, Te, and Zn) in axially viewed inductively coupled plasma–atomic emission spectrometry has been investigated. To this end, atomic and ionic emission signals for diluted glycerol, sulfuric acid, and phosphoric acid solutions were registered and results were compared to those obtained for a 1% w w−1 nitric acid solution. Experimental results show that the emission intensities of As, Se, and Te atomic lines are enhanced by charge transfer from carbon, sulfur, and phosphorus ions. Iodine and P atomic emission is enhanced by carbon- and sulfur-based charge transfer whereas the Hg atomic emission signal is enhanced only by carbon. Though signal enhancement due to charge transfer reactions is also expected for ionic emission lines of the above-mentioned elements, no experimental evidence has been found with the exception of Hg ionic lines operating carbon solutions. The effect of carbon, sulfur, and phosphorus charge transfer reactions on atomic emission depends on (i) wavelength characteristics. In general, signal enhancement is more pronounced for electronic transitions involving the highest upper energy levels; (ii) plasma experimental conditions. The use of robust conditions (i.e. high r.f. power and lower nebulizer gas flow rates) improves carbon, sulfur, and phosphorus ionization in the plasma and, hence, signal enhancement; and (iii) the presence of other concomitants (e.g. K or Ca). Easily ionizable elements reduce ionization in the plasma and consequently reduce signal enhancement due to charge transfer reactions.

Evaluation of the use of multiple lines for determination of metals in water by inductively coupled plasma optical emission spectrometry with axial viewing

Inductively coupled plasma optical emission spectrometers (ICP OES) allow fast simultaneous measurements of several spectral lines for multiple elements. The combination of signal intensities of two or more emission lines for each element may bring such advantages as improvement of the precision, the minimization of systematic errors caused by spectral interferences and matrix effects. In this work, signal intensities for several spectral lines were combined for the determination of Al, Cd, Co, Cr, Mn, Pb, and Zn in water. Afterwards, parameters for evaluation of the calibration model were calculated to select the combination of emission lines leading to the best accuracy (lowest values of PRESS– Predicted error sum of squares and RMSEP– Root means square error of prediction). Limits of detection (LOD) obtained using multiple lines were 7.1, 0.5, 4.4, 0.042, 3.3, 28 and 6.7 µg L − 1 ( n = 10) for Al, Cd, Co, Cr, Mn, Pb and Zn, respectively, in the presence of concomitants. On the other hand, the LOD established for the most intense emission line were 16, 0.7, 8.4, 0.074, 23, 26 and 9.6 µg L − 1 ( n = 10) for these same elements in the presence of concomitants. The accuracy of the developed procedure was demonstrated using water certified reference material. The use of multiple lines improved the sensitivity making feasible the determination of these analytes according to the target values required for the current environmental legislation for water samples and it was also demonstrated that measurements in multiple lines can also be employed as a tool to verify the accuracy of an analytical procedure in ICP OES.

Ultrasound-Promoted Cold Vapor Generation in the Presence of Formic Acid for Determination of Mercury by Atomic Absorption Spectrometry

A new cold vapor technique within the context of green chemistry is described for determination of mercury in liquid samples following high-intensity ultrasonication. Volatile Hg evolved in a sonoreactor without the use of a chemical reducing agent is carried to a quartz cell kept at room temperature for measurement of the atomic absorption. The mechanism involved lies in the reduction of Hg(II) to Hg(0) by reducing gases formed upon sonication and subsequent volatilization of Hg(0) due to the degassing effect caused by the cavitation phenomenon. Addition of a low molecular weight organic acid such as formic acid favors the process, but vapor generation also occurs from Hg solutions in ultrapure water. The detection limit of Hg was 0.1 microg/L, and the repeatability, expressed as relative standard deviation, was 4.4% (peak height). Addition of small amounts of oxidizing substances such as the permanganate or dichromate anions completely suppressed the formation of Hg(0), which confirms the above mechanism. Effect of other factors such as ultrasound irradiation time, ultrasound amplitude, and the presence of concomitants are also investigated. Some complexing anions such as chloride favored the stabilization of Hg(II) in solution, hence causing an interference effect on the ultrasound-assisted reduction/volatilization process.

Subsyndromal depression in the elderly: underdiagnosed and undertreated

Major depressive illness is present in about 5.7% of US residents aged ≥65 years, whereas clinically significant nonmajor or “subsyndromal” depression affects approximately 15% of the ambulatory elderly. Risk of developing subsyndromal depression increases as elderly people get older. Because they have numerous distressing ailments, everyday life can be burdensome for many elderly persons. Almost one third of Americans aged 75 years or older rate their health as “fair to poor.” Yet, the physical discomforts experienced by so many elderly individuals are unlikely to generate a clinically significant depression unless other ingredients such as loneliness, impairment of mobility, loss of a spouse, a serious financial reverse, and—probably most important—genetic susceptibility are added to the psychophysiological mix. Because depression damages quality of life and is usually eminently treatable, it is essential that physicians and other health professionals be trained to recognize true depression and distinguish it from confounding conditions caused by medications, organic brain disease, or short-term grief reactions. In the medically ill elderly, depressive symptoms may be overlooked because of the assumption that they are a part of the concurrent medical illness. Diagnosis of depression in the elderly can be greatly assisted by use of age-specific screening instruments such as the Geriatric Depression Scale. Ultimately, brain imaging and biochemical and physiological measurements may prove useful in diagnosis. The presence of somatic concomitants of depression such as severe neck and low back pain should alert the clinician to the possibility of an underlying mood disorder. Suicide and suicide attempts occur all too frequently in the depressed elderly; therefore, screening for late-life depression is urgently required among the elderly in primary and residential health care settings.

Masking agents in the determination of selenium by hydride generation technique

The effects of several masking agents in the determination of selenium by hydride generation was studied using a continuous flow hydride generator coupled with atomic absorption spectrometry. A miniature argon hydrogen diffusion flame was employed as the atomizer. The effects of masking agents (KI, NaSCN, thiourea, l-cysteine, 1,1,3,3 tetramethyl-2-thiourea) were studied both in the absence and in the presence of selected interfering species (Cu, Ag, Au, Ni, Co, Pd, Pt and Fe) and using different addition strategies of the masking agents to the reaction system: in batch mode, either to sample or NaBH 4 reducing solution; in on-line mode, to the sample either before or after the HG step). The combined effect of some masking agents was also investigated. The addition mode of the masking agent to the reaction system could play a decisive role in the control of interfering processes both in the absence and in the presence of concomitants. The addition of NaSCN to the reducing solution of NaBH 4 produced a moderate catalytic effect, similar to the one obtained in the presence of KI, and improved the tolerance limits for Cu, Ni, Co and Pd. Linearity of calibration graphs was unaffected by the on-line addition of 1,1,3,3 tetramethyl-2-thiourea to sample solution, while under similar conditions thiourea produced dramatic curvature of calibration graphs. The combined use of KI (added to reducing solution) and 1,1,3,3 tetramethyl -2-thiourea (added on-line to the sample) exhibited masking properties comparable but not superior to those of thiourea, except for Pt and Pd for which good tolerance limits were achieved. In the absence of KI in the reductant solution the masking efficiency of 1,1,3,3 tetramethyl-2-thiourea was considerably lowered. The addition of some masking agents such as thiourea, l-cysteine and 1,1,3,3 tetramethyl thiourea on-line to reaction solution after the NaBH 4+KI reduction step, could be highly effective in the control of Cu and Ag interferences. The method was applied to determination of trace of selenium in pure copper standard reference materials.

Effects of Matrix Elements on the Analyte Emission Signals in Inductively Coupled Plasma Optical Emission Spectrometry Using a Thermospray Sample Introduction System

Matrix effects due to Ca, K, Na, and P on analyte transport rate, line intensities, and plasma excitation conditions were studied using a fused silica capillary thermospray nebulizer. Several emission lines of Ba, Cd, Co, Cr, Cu, Mg, Mn, Ni, Pb, and Zn, differing in their excitation and ionization energies, were investigated. In general, the addition of matrix elements to the analyte solution resulted in a reduction of the analyte emission signal. The greatest reductions were observed for matrices containing calcium and for the analyte emission lines with higher sum of excitation and ionization energies. A decrease in the analyte transport rate was the highest for single potassium matrix and for binary matrices containing calcium. The excitation temperature was not significantly changed in the presence of Na, K, and P, but it was depressed for single and composite matrices containing Ca. It was shown that variations in the analyte emission intensities in the presence of concomitants could be attributed to changes in the plasma as well as to changes in the analyte transport efficiency.

Matrix interferences in the determination of trace elements in waste waters by inductively coupled plasma atomic emission spectrometry with ultrasonic nebulization

The use of inductively coupled plasma atomic emission spectrometry with ultrasonic nebulization (USN-ICP-AES) for determining Ag, Al, As, Ba, Bi, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, Sb, Sr, V and Zn in complex matrices of Ca, Na, K and P in waste waters is described. Generally, depressions in the analyte emission intensity occur in the presence of concomitants. Matrix interferences can be minimized by increasing the operating power and lowering the carrier gas flow rate. However, the enhancement of the signal-to-background ratios (SBRs) shows an opposite trend. Therefore, routine analyses were performed at a compromise power setting of 1,350 W, a carrier gas flow rate of 0.8 L min(-1) and an observation height of 14 mm above the load coil and using a matrix matched calibration procedure. Limits of detection (LODs) at chosen operating conditions were at microg L(-1) levels for most of the elements studied, including mercury when KBr is added to the analyte solution to enhance sensitivity. LODs were not significantly changed in the presence of matrix elements. Recoveries for the majority of added elements from spiked waste water samples are between 93 and 105% using a matrix matched calibration.

New organosilicon polymer for the extraction and luminescence analysis of uranyl in environmental samples

A new polymer for the extraction and luminescence analysis of uranyl in environmental samples is presented. High extraction efficiencies (above 90%) of uranyl concentrations as low as part-per-billion were obtained in water and acidic solutions. The presence of concomitants in water samples did not affect the extraction capability of the new material. The luminescence characteristics of the uranyl–polymer complex demonstrate the potential for the development of a uranium phosphorescence sensor.

Analytical Application of some Chemical Modifiers in Atomic Absorption Spectrometric Investigation and Determination of Mn(II) and Mn(VII)

The interfering effects of a range of cations, acids and organic compounds on the absorption signal of manganese(II) and manganese(VII) were studied in different media under diverse flame profile of different observation heights and fuel flow rates. The signal response of Mn(II) and Mn(VII) is slightly changed under different flame conditions, whereas it is markedly affected in the presence of concomitants. Several chemical modifiers were successfully applied for controlling such effects. Of these, boric acid, lanthanum chloride, strontium chloride, ammonium chloride and aluminium chloride were found to be effective as inorganic chemical modifiers in eliminating specific interferences on Mn(II) and Mn(VII) encountered from inorganic addenda. A combination of boric acid and strontium chloride, 500 ppm each, was able to overcome the potential effects of all inorganic interferences studied. Butylamine and piperidine were also used as excellent chemical modifiers organic reagents for controlling inorganic and organic interferences on manganese. The mechanism of the interfering effects and the releasing action is discussed which is based on masking the interferent(s) with the inorganic reagent(s) through the formation of refractory species, whereas the organic reagent(s) protect(s) the analyte by forming an easily dissociated complex in the flame. A procedure was described for precise determination of manganese in synthetic mixture and some manganese complexes.

Chemical modifiers for controlling interferences in the flame atomic absorption spectrometric determination of chromium(III) and chromium(VI) and their separation

The interfering effects of a range of organic and inorganic species on the atomic absorption signals of CrIII and CrVI were investigated. Such effects were eliminated by adding 20 mmol l–1 butylamine (BA) or N-cyanoacylacetaldehyde hydrazone (CyAH), as a chemical modifier, to both the sample and standard solutions. The role of BA was extended to separate CrIII from CrVI in admixture, with 100% recovery, using oleic acid as a surfactant at a pH of 5.5 ± 0.2. A mechanism for Cr atom population in the flame in the presence and absence of concomitants is suggested. Also, the role of BA or CyAH in eliminating interferences was investigated. The flotation mechanism is discussed. A simple, sensitive and rapid procedure for the separation and determination of CrIII from aqueous solutions was elaborated. The method was applied to the determination of CrIII in some complexes.

Determination of chloride at picogram levels by molecular fluorescence in a graphite furnace

Chloride was determined at nanogram levels by adding excess of indium to the sample introduced into a graphite furnace and measuring the laser induced molecular fluorescence of indium chloride. The diatomic molecules of indium chloride were excited by a pulsed dye laser at 267 nm and fluorescence was measured at 359 nm. The effects of various parameters including amount of indium added, furnace thermal conditions and presence of concomitants were also studied. A linear calibration in the range of 0.025-1.25 ng and a detection limit of 17 pg of chloride were obtained under optimum conditions. The analytical usefulness of the method was checked by determining the chloride content in National Institute of Standards and Technology, Standard Reference Materials 1571a and 1571b Orchard Leaves.

An internal standardization procedure for the determination of yttrium and the rare earth elements in geological materials by inductively coupled plasma-mass spectrometry

Determinate error (bias) has been observed while using an inductively coupled plasma mass spectrometry (ICP-MS) based method for the determination of yttrium and the rare earth elements (REE) in geological materials. This error is related to the matrix of the samples and is non-spectroscopic in origin. The magnitude of the error has been observed to be a linear function of analyte mass. An internal standardization procedure has been developed which uses ruthenium and rhenium as internal standard elements to establish a linear function relating the magnitude of the observed determinate error to the analyte mass. This function is then used to correct for the determinate error associated with the Y and REE analytical data. Using this procedure a long term precision of ±4% relative standard deviation is obtained. The accuracy of determinations is shown to be comparable to that obtained from isotope dilution mass spectrometry and instrumental neutron activation analysis. This level of performance is achieved for the routine determination of Y and the REE in geological materials by ICP-MS. The results of experiments on the effect of rf power, nebulizer gas flow, ion-optic settings and the presence of concomitants demonstrate the effectiveness of the correction procedure.

Behavioral conditioning and experimental motion-induced sickness

Adult male squirrel monkeys were the subjects of experiments conducted to determine whether or not repeated exposures to sickness-inducing horizontal rotation would result in behavioral conditioning of emetic responses. The development of conditioned food aversion and feeding suppression as a consequence of pre- and postrotation eating was quantified. It was concluded that neither instrumental conditioning nor classical conditioning were valid alternative hypotheses for the occurrence of repeated vomiting episodes over a period of ten daily exposures to motion. Conditioned aversion to fresh banana and feeding suppression developed gradually if rotation, which induced multiple bouts of vomiting, was sustained for 1- or 2-hour sessions. If spinning was terminated immediately after the first emetic response, no aversion or suppression emerged. The occurrence of food aversion, by itself, is questioned as a valid index of the presence of subjective concomitants of motion sickness in animals.

Mechanism of interference elimination by thiourea in electrochemical atomic absorption spectrometry

The mechanism of interference elimination by thiourea in electrothermal atomization is discussed. Activation energies of atomization were measured. The experimental values for bismuth, lead, copper and cadmium were not altered in the presence of concomitants, provided that thiourea was added before atomization. These elements from complexes with thiourea which are converted to sulphides during the charring stage. Atom formation occurs from the sulphides without compound formation between analyte and concomitants.