Biomedical subjects

Shane S Que Hee

Publications and source records attributed to Shane S Que Hee.

11 recordsLinked to original sources

PubMed2006

Permeation of a straight oil metalworking fluid through a disposable and a chemically protective nitrile glove.

The aim of the present study was to quantify the permeation parameters of a complex water-insoluble straight oil metalworking fluid (MWF) of low volatility through nitrile gloves. The permeation through a chemically protective and a disposable glove was investigated using the American Society for Testing and Materials (ASTM) F739-99a method with hexane as the collection medium. Analysis of collection side samples involved gas chromatography-mass spectrometry (GC-MS) and gravimetry. The detection breakthrough time for the chemically protective glove was >10 h. For the disposable glove, the detection breakthrough time was 0.7+/-0.3 h, the lag time was 1.6+/-0.1 h, the diffusion coefficient was (3.7+/-0.3)x10(-9) cm2/min, and the steady state permeation rate was 3.5+/-2.2 microg/cm2/min. The disposable nitrile glove can be worn for about 30 min for incidental contact with straight oil MWFs without known carcinogens. The chemically protective nitrile glove should be worn otherwise. The chromatogram for the permeate differed from that of the original MWF, resulting from the faster permeation of lower molecular weight congeners. The combination of chromatography and gravimetry allowed quantifying the permeation parameters of complex water-insoluble non-volatile mixtures.

Gas Chromatography-Mass Spectrometry↗

PubMed2006

Permeation of Comite through protective gloves.

The goal of the study was to assess how protective disposable (Safeskin) and chemical protective (Sol-Vex) nitrile gloves were against Comite emulsifiable concentrate formulation containing propargite (PROP) as active pesticidal ingredient, because there were no explicit recommendations for the gloves that should be worn for hand protection. The glove material was exposed in ASTM-type I-PTC-600 permeation cells at 30.0+/-0.5 degrees C, and gas chromatography-mass spectrometry used for PROP analysis. Aqueous solutions of Comite at 40.4 mg/mL permeated both Safeskin and Sol-Vex nitrile by 8h. Safeskin showed a mean PROP mass permeated of 176+/-27 microg after 8h compared with a mean mass permeated for Sol-Vex of 3.17+/-4.08 microg. Thus, Sol-Vex was about 56 times more protective than Safeskin for an 8-h exposure. However, the kinetics of the permeation revealed that Safeskin can be worn for at least 200 min before disposal. When undiluted Comite challenged both types of nitrile, much faster permeation was observed. Safeskin gloves showed two steady state periods. The first had lag times (t(l)) values of about 1h, although normalized breakthrough times (t(b)) were < 10 min. The second steady state rate (P(s)) was on average four times the rate of the first period, and the second steady state period t(l) was about three times as long as that of the first steady state period, and about the same t(l) as for the aqueous solution. Sol-Vex gloves exposed continuously to undiluted Comite permeated above the normalized breakthrough threshold beyond 2.7h. A risk assessment revealed that the PROP skin permeation rate of 7.1 ng cm(-2)h(-1) was much slower than the first steady state Safeskin glove P(s) of 62,000 ng cm(-2)h(-1). Infrared analysis showed that the glove surfaces were not degraded by the Comite challenge. The chemically protective Sol-Vex gloves protected adequately against undiluted formulation for about 2.7h, whereas they provided protection for nearly 8h when the formulation was diluted with water to the highest concentration for field application. In contrast, the disposable Safeskin gloves did not protect at all for the undiluted formulation, but did for 200 min when the formulation was diluted with water to the highest concentration for spraying.

Chromatography, Gas↗

PubMed2005

Gas chromatography-mass spectrometry analysis of di-n-octyl disulfide in a straight oil metalworking fluid: application of differential permeation and Box-Cox transformation.

The aim of this study was to identify and quantify an unknown peak in the chromatogram of a very complex mixture, a straight oil metalworking fluid (MWF). The fraction that permeated through a thin nitrile polymer membrane had less mineral oil background than the original MWF did at the retention time of the unknown peak, thus facilitating identification by total ion current (TIC) gas chromatography-mass spectrometry (GC-MS). The peak proved to be di-n-octyl disulfide (DOD) through retention time and mass spectral comparisons. Quantitation of DOD was by extracted ion chromatogram analysis of the DOD molecular ion (mass-to-charge ratio (m/z) 290), and of the m/z 71 ion for the internal standard, n-triacontane. Linear models of the area ratio (y) of these two ions versus DOD concentration showed a systematic negative bias at low concentrations, a common occurrence in analysis. The linear model of y(0.8) (from Box-Cox power transformation) versus DOD concentration showed negligible bias from the lowest measured standard of 1.51 mg/L to the highest concentration tested at 75.5 mg/L. The intercept did not differ statistically from zero. The concentration of DOD in the MWF was then calculated to be 0.398+/-0.034% (w/w) by the internal standard method, and 0.387+/-0.036% (w/w) by the method of standard additions. These two results were not significantly different at p < or = 0.05. The Box-Cox transformation is therefore recommended when the data for standards are non-linear.

Alkanesulfonic Acids↗

PubMed2005

Permeation of Telone EC through protective gloves.

Telone is a potent fumigant that is based on the chlorinated unsaturated hydrocarbon, 1,3-dichloropropene (1,3-DCP). It is often applied without dilution and so poses severe inhalation and air pollution threats. Urinary metabolites of 1,3-DCP have been detected after Telone skin exposure, so that preventing dermal exposure is also important. The objective of the study was to assess if nitrile and multi-layer ("laminated") gloves provide adequate protection against Telone EC formulation. To accomplish this, disposable (Safeskin) and chemically resistant (Sol-Vex) nitrile and laminated (Barrier mark and Silver Shield) glove materials were challenged by Telone EC with hexane liquid collection in an ASTM-type I-PTC-600 permeation cell. Analyses of cis- and trans-1,3-DCP in the collection fluid at specified times were performed on a moderately polar capillary column by gas chromatography-electron capture detection. Telone EC caused microholes in both nitrile materials, though the chemically protective material was degraded slower than the disposable nitrile. The laminated gloves offered limited protection. Silver Shield protected best because 1.5-2.3 mg 1,3-DCP permeated by 8 h relative to 2.5-7.6 mg for Barrier, implying about 2.5 times more protection for 8 h. Even for Silver Shield, the extent of protection was inadequate as illustrated by a risk assessment of the skin exposure situation. The normalized breakthrough times for both types of laminated gloves varied between 27 and 60 min. It is recommended that Viton gloves still be worn for protection.

Allyl Compounds↗

PubMed2005

Comparison of UV, fluorescence, and electrochemical detectors for the analysis of formaldehyde-induced DNA adducts.

A high-performance liquid chromatography (HPLC) method for normal and formaldehyde-modified deoxynucleosides after hydrolysis of exposed and unexposed human placental DNA was compared with ultraviolet (UV), fluorescence (FL), and electrochemical (EC) detectors. The lower quantifiable limits (LQL) for UV detection at 254 nm were 10-22 pmol for N(6)-hydroxymethyldeoxyadenosine (N(6)-dA), N(2)-hydroxymethyldeoxyguanosine (N(2)-dG), and N(4)-hydroxymethyldeoxycytidine (N(4)-dC), with N(4)-dC having the highest LQL and the 2 purines the lowest LQL. Similarly, LQLs using FL (excitation: 264 nm; emission: 340 nm) were 14-30 pmol, with N(2)-dG having the lowest LQL and N(6)-dA the highest. The LQL for N(2)-dG by EC detection at +1.10 V was 27 pmol, over 50-fold greater sensitivity than for the other hydroxymethyl deoxynucleosides; deoxyguanosine was similarly detected more sensitively than the other normal deoxynucleosides. Percent relative standard deviations ranged between 6 and 13% for both intra- and interrun assays for all detectors. HPLC-UV allows all the deoxynucleosides to be detected without the flow cell washing and use of fresh solutions necessary for the more selective FL detection, the latter not having enzyme blank interferences. EC allows only deoxyguanosine and N(2)-dG to be detected at pmol levels with no blank interferences. HPLC-UV allowed more sensitive detection of N(2)-dG and N(6)-dA than the other techniques and is recommended. The UV, FL, and EC properties of the hydroxymethyl deoxynucleosides of dA, dG, and dC are reported for the first time.

Chromatography, High Pressure Liquid↗

PubMed2005

Analysis of captan on nitrile glove surfaces using a portable attenuated total reflection fourier transform infrared spectrometer.

This study developed a method to produce uniform captan surface films on a disposable nitrile glove for quantitation with a portable attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrometer. A permeation test was performed using aqueous captan formulation. Uniform captan surface films were produced using solvent casting with 2-propanol and a 25 mm filter holder connected to a vacuum manifold to control solvent evaporation. The coefficient of variation of the reflectance at 1735 +/- 5 cm(-1) was minimized by selection of the optimum solvent volume, airflow rate, and evaporation time. At room temperature, the lower to upper quantifiable limits were 0.31-20.7 microg/cm2 (r = 0.9967; p < or = 0.05) for the outer glove surface and 0.55-17.5 microg/cm2 (r = 0.9409; p < or = 0.05) for the inner surface. Relative humidity and temperature did not affect the uncoated gloves at the wavelength of captan analysis. Glove screening using ATR-FTIR was necessary as a control for between-glove variation. Captan permeation, after 8 hours exposure to an aqueous concentration of 217 mg/mL of Captan 50-WP, was detected at 0.8 +/- 0.3 microg/cm2 on the inner glove surface. ATR-FTIR can detect captan permeation and can determine the protectiveness of this glove in the field.

Algorithms↗

PubMed2004

Formaldehyde-induced DNA adducts as biomarkers of in vitro human nasal epithelial cell exposure to formaldehyde.

Formaldehyde (FA) is a mutagen that, at high concentrations and long durations, has been reported to cause nasal cancer in rats and in some humans. The level of FA-induced modified DNA in nasal cells should serve as a biomarker of FA exposure and effect. In the present study, a high-performance liquid chromatography (HPLC)-ultraviolet (UV) method at 254 nm was developed and optimized to detect and quantify hydroxymethyldeoxynucleosides after the isolated DNA in exposed human nasal epithelial cells (HNEC) was enzymically digested. Normal and modified deoxynucleosides were successfully resolved from one another and from tissue and enzyme blank interferences. The viability of HNEC exposed to FA in solution for 24 h decreased, and there was a linear dose response between % nonviability and FA dose from 10 to 500 microg/mL. Amounts of 18.0 +/- 1.5 pmol N6-dA and 12.0 +/- 1.2 pmol N2-dG derivatives were determined in a 10 microL injection after 1.4 x 10(7) HNEC (106 microg DNA) were exposed to 500 microg/mL in solution. The respective tissue concentrations in pmol hydroxymethyldeoxynucleoside/mg DNA were 170 +/- 14 and 113 +/- 11. The lower quantifiable limits were about 97 and 88 pmol/mg DNA, respectively. Diffusive exposure of HNEC to air FA up to 100 ppm (v/v) for 24 h did not produce quantifiable hydroxymethylnucleosides. FA-modified deoxynucleosides may be useful biomarkers for FA exposure in biological monitoring samples taken by nasal lavage or brush biopsy.

Animals↗

PubMed2003

Permeation of captan through disposable nitrile glove.

The purpose of this study was to investigate the permeation of an aqueous emulsion of the pesticide, captan, as a wettable powder (48.9% captan) through a disposable nitrile glove material using an American Society for Testing and Materials (ASTM)-type I-PTC-600 permeation cell. The goal was to investigate the protective capability of the gloves against dermatitis. The analytical method was based on gas chromatography-mass spectrometry (GC-MS) and gas chromatography-electron capture detection (GC-ECD). The least quantifiable limit (LQL) was 6 ng for GC-ECD and 30 ng for GC-MS. Testing was conducted using the ASTM F739 closed-loop permeation method and a worst-case aqueous concentration 217 mg/ml of captan 50-WP. The average permeation rates were low, with 12+/-5 ng/(cm(2)min) after 2h, 50+/-25 ng/(cm(2)min) after 4h, and 77+/-58 ng/(cm(2)min) after 8h. The calculated diffusion coefficient was (1.28+/-0.10) x 10(-5)cm(2)/h. No significant swelling or shrinkage occurred at P</=0.05. Infrared (IR) reflectance analysis of pre- and post-exposure glove surfaces confirmed no outer or inner surface degradation. The disposable nitrile glove showed excellent resistance to a highly concentrated aqueous emulsion of captan. Because the ASTM normalized breakthrough detection time of 250 ng/cm(2) was <2h, these gloves should not be reused once worn, and decontamination is not advised. Protection is also advised for agricultural reentry field workers, because captan has been shown to persist on crops with a half-life greater than the current reentry intervals of 1-4 days.

Captan↗

PubMed2003

Elements in fish of Malibu Creek and Malibu Lagoon near Los Angeles, California.

Our aim was to assess whether past discharges from a wastewater treatment plant increased metal pollutant loads in stream mobile species in a one-day baseline sampling study that included a coastal wetland. Mosquitofish (Gambusia affinis) of two sizes, black bullhead (Ameiurus melas), and crayfish (Pacifastacus leniusculus) were collected from Malibu Creek, and California killifish (Fundulus parvipinnis) of three sizes, as well as arroyo chub (Gila orcutti) were sampled from Malibu Lagoon near Los Angeles, California. Species from each locality were pooled by length, homogenized, digested by microwave wet ashing, and analyzed by simultaneous inductively coupled plasma atomic emission spectroscopy for 27 elements. Lagoon killifish 2.0-3.5 cm long contained levels of arsenic and lead above the levels for 95% of California fish, the EDL95. Black bullhead upstream of the discharge contained elevated levels of As, Cr and Se. Young mosquitofish <3 cm in length upstream of the discharge differed greatly in the order of abundance of their elements relative to larger mosquitofish and to other species collected. More sampling than this baseline study allowed was needed to determine if the wastewater treatment plant was a pollution source.

Animals↗

PubMed2003

Folpet permeation through nitrile gloves.

The aim of this study was to investigate whether two different brands of unsupported and unlined nitrile gloves protected against aqueous emulsions of a Folpet wettable powder (50% Folpet) using an ASTM type-I-PTC 600 permeation cell at 30.0 +/- 0.1 degrees C held in a shaking water bath. An analytical method to determine Folpet using the internal standard method was first developed based on gas chromatography-mass spectrometry (GC-MS), and gas chromatography-electron capture detection (GC-ECD). A novel pyrolysis GC-ECD technique that quantified the thermal degradation product phthalimide had pg sensitivity suitable to detect the trace amounts of Folpet that permeated. The on-column conversion was (68.0 +/- 9.5) percent at 170 degrees C over the folpet injected mass range of 3 to 148 pg. The challenge solution in the permeation cell was 1.4 mg/mL aqueous emulsion of Folpet wettable powder, and 2-propanol was the collection solvent. After evaporation of the collection solvent, the time weighted average rate of permeation of Folpet through SafeSkin nitrile (an exams type of glove) after 8 hours was (42.1 +/- 2.9) ng/cm(2)/min compared with (2.04 +/- 0.69) ng/cm(2)/min for the Sol-Vex nitrile (industrial chemical resistant), the latter being about 21 times more protective and also near the limits of detection. The respective values after 4 hours of exposure were (28.4 +/- 1.2) and (0.65 +/- 0.36) ng/cm(2)/min. Diagnostic reflectance infrared minima of both challenge and collection sides of the gloves showed small changes in wave number and intensity values after 8 hours of exposure, with Folpet being detected in dried spots on the challenge side. GC-ECD-based permeation and IR reflectance data indicated high chemical resistance of the Sol-Vex gloves to an aqueous emulsion of Folpet.

Chromatography, Gas↗

PubMed2002

Vapor/Solid chemisorption model for passive sampling of aldehydes.

The vapor-phase chemisorption isotherms of valeraldehyde (n-valeraldehyde; 1-pentanal) and acrolein (2-propenal) above the critical face velocity (7.5 cm/s) were investigated at 25 degrees C and 36 percent relative humidity (RH) for a passive air sampling pellet of 10 percent O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride (PFBHA) on Tenax TA solid sorbent (80/100 mesh). A dynamic air dilution system with syringe pumps generated the vapor concentrations and humidity for the exposure chamber. The O-oxime derivatives were desorbed with hexane for gas chromatographic analysis on a nonpolar capillary column and electron capture detection. The pellet capacity was about 30 micromoles. Adsorption of valeraldehyde was best fitted by a Langmuir or Brunauer-Emmett-Teller (BET) I model. That for acrolein was described best by a Dubinin-Radushkevich model. A microporosity model explained why all the classical isotherms described the chemisorption behavior. An activated extrinsic precursor was suggested to facilitate the addition reaction by production of a protonated intermediate formed by the transfer of a proton to the aldehyde from an activated reaction site consisting of at least 2 PFBHA molecules.

Adsorption↗