High Spatial Resolution Laser Desorption/Ionization Mass Spectrometry Imaging of Organic Layers in an Organic Light-Emitting Diode.

To improve the durability of organic materials in electronic devices, an analytical method that can obtain information about the molecular structure directly from specific areas on a device is desired. For this purpose, laser desorption/ionization mass spectrometry imaging (LDI-MSI) is one of the most promising methods. The high spatial resolution stigmatic LDI-MSI with MULTUM-IMG2 in the direct analysis of organic light-emitting diodes was shown to obtain a detailed mass image of organic material in the degraded area after air exposure. The mass image was observed to have a noticeably improved spatial resolution over typical X-ray photoelectron spectroscopy, generally used technique in analysis of electronic devices. A prospective m/z was successfully deduced from the high spatial resolution MSI data. Additionally, mass resolution and accuracy using a spiral-orbit TOF mass spectrometer, SpiralTOF, were also investigated. The monoisotopic mass for the main component, N,N'-di-1-naphthalenyl-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (m/z 588), was measured with a mass resolution of approximately 80,000 and a mass error of about 5 mDa using an external calibrant. This high mass resolution and accuracy data successfully deduced a possible elemental composition of partially remained material in the degraded area, C36H24, which was determined as anthracene, 9-[1,1'-biphenyl]-4-yl-10-(2-naphthalenyl) by combining structural information with high-energy CID data. The high spatial resolution of 1 µm in LDI-MSI along with high mass resolution and accuracy could be useful in obtaining molecular structure information directly from specific areas on a device, and is expected to contribute to the evolution of electrical device durability.

Separation of complex mixtures of fluorobenzoic acids by capillary electrophoresis.

Fluorobenzoic acids are important intermediates in the synthesis of antibacterial drugs. Conditions for the separation of mixtures of twenty-five acids by CE have been optimized. A set of conditions with phosphate buffer (pH 3.1), successive multiple ionic-polymer layer (SMIL) coating capillary, and negative separation voltage provided a short time separation based on the difference in the acidic dissociation constant (pK(a)) of the sample acids. Addition of ACN to the separation solution improved the selectivity resulting in a broader distribution of migration times of the samples. The addition of tetradecyltrimethylammonium chloride below the CMC was also effective in changing the migration pattern of fluorobenzoic acids. Furthermore, practical utility was demonstrated through quantitative studies on the optimized condition including the durability of the SMIL coating.

A method for the low-level (ng/g) determination of perfluorooctanoate in carpet by LC-MS-MS using matrix extracted standards.

Fluorotelomer-based acrylic polymers are applied to the surface of carpet to impart oil, stain, and water repellence properties. Concerns that fluorotelomer-based polymers are a possible source of "low level" exposure to humans, coupled with their widespread use have prompted the need to develop a method to detect and measure perfluorooctanoate (PFO) in carpet. A liquid chromatography tandem mass spectrometry method for the determination of PFO in carpet using a dual labeled 13C-perfluoroctanoic acid (13C-PFOA) internal standard is successfully developed and validated. Levels of PFO are determined using a gradient, reversed-phase high-performance liquid chromatography (HPLC) method with acetic acid acidified water-methanol, separated on a 50 mm Phenomenex Synergi Polar RP column. Ions monitored are 413 (parent) and 369 (daughter) for PFO and 415 (parent) and 370 (daughter) for dual labeled 13C-PFOA internal standard. Accuracy and precision over three days for 5 to 900 ng/g PFO in carpet ranged from 2.4% to 7.6% and 3.7% to 14.1%, respectively. Overall extraction efficiency for samples (n=30) fortified with 13C-PFOA at 20 ng/g and perfluorooctanoic acid (PFOA) at 5, 50, and 500 ng/g is 98.9%+/-8.1%. Specificity of the method was evaluated with two different carpet samples.

Analysis of perfluorocarboxylic acids in air.

Perfluorocarboxylic acids have been used in limited but important applications, such as in the production of fluoroelastomers and as components of fire-fighting foams. A method for the measurement of perfluorocarboxylic acids of different chain lengths in air is presented. Chain lengths tested included those having 8, 9, 10, 11, and 13 carbon atoms. Occupational Safety and Health Administration (OSHA) Versatile Sampler airtubes with glass fiber filter, XAD-4 resin, and polyurethane foam were fortified with analyte at levels corresponding to 0.1, 0.5, 1.0, and 2.0 times the level representing a 0.01 mg/m3 analyte air concentration sampled for 8-hour period with an airflow rate of 1 L/min. Airtube sections were extracted with acetone. Analysis of analyte in airtube fraction extracts was by HPLC/MS using ammonium acetate in water and methanol mobile phase and single ion monitoring for quantification. The lower limit of quantification for the HPLC/MS was set at 0.0001 mg/m3 for each analyte. Total recoveries of analytes within National Institute for Occupational Safety and Health (NIOSH) guidelines of +/- 25% of the true value were obtained at three different atmospheric conditions: ambient, cool/dry, and warm/humid conditions. The maximum loading with acceptable recovery of each analyte was 9600 ng (48000 ng total) for the ambient and warm/humid conditions. The maximum loading with acceptable recovery was 4800 ng (24000 ng total) for the cool/dry condition. The ammonium salt of the eight-carbon perfluorocarboxylic acid, ammonium perfluorooctanoate, was similar to the parent acid in behavior at the ambient condition. Hydrohexadecafluorononanoic acid was tested as a possible surrogate standard for the method, and it was found unsuitable for use because of variable recoveries. Stability studies were completed, and the perfluorocarboxylic acid analytes were stable in airtube samplers for up to 14 days at either ambient or refrigerated condition.

A method for the low-level (ng g(-1)) determination of perfluorooctanoate in paper and textile by liquid chromatography with tandem mass spectrometry.

The determination of perfluorooctanoate (PFO) in articles of commerce has become increasingly important to understand if treated products are a possible source of PFO. An LC-MS/MS method for the determination of PFO in paper and textile using a dual labeled 13C-PFOA internal standard was successfully developed and validated. Residues of PFO were determined using an isocratic, reversed-phase high-performance liquid chromatography (HPLC) method with an ammonium acetate/methanol buffer. Ions monitored were 413 (parent) and 369 (daughter) for PFO and 415 (parent) and 370 (daughter) for dual labeled 13C-PFOA internal standard. As a precaution against ubiquitous PFO that occasionally occurs in mobile phase or instrument components, two Hypercarb cartridges (4 mm) were placed before the HPLC injector. Any PFO that was captured by the cartridges was removed before each injection by flushing the system with 100% methanol prior to equilibration with the isocratic mobile phase. Overall recovery and standard deviation over a 3 day validation regimen for samples (n=54-55) fortified with PFOA at 5, 50, and 200 ng g(-1) were 114+/-4.9% for textile and 110+/-7.6% for paper. The results also established a limit of detection (LOD) of 1 ng g(-1) in textile and 2 ng g(-1) in paper based upon S/N of the 5.0 ng g(-1) fortification versus the untreated paper and textile.

Method for trace level analysis of C8, C9, C10, C11, and C13 perfluorocarbon carboxylic acids in water.

A method was developed for the trace level analysis of pentadecafluorooctanoic acid (C8), heptadecafluorononanoic acid (C9), nonadecafluorodecanoic acid (C10), heneicosafluoroundecanoic acid (C11) and pentacosafluorotridecanoic acid (C13) in water. Samples were concentrated by solid-phase extraction (SPE) before analysis by combined liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS). A surrogate standard, 9-hydrohexadecafluorononanoic acid (9H), was used to monitor recovery. The lower limit of quantitation (LLOQ) for C8, C9, C10, C11, and C13 was determined to be 25 ng/L in water. The specificity of the method was established by showing no significant interferences (<20% of the LLOQ standard) in control samples of well, stream, spring, tap, omnisolve, and type I water at the retention time of the target analytes. The linearity of the method was determined; the coefficients of determination for the five calibration curves generated were all >0.985. Good within-day and between-day accuracy and precision were demonstrated. Extracts and standards were shown to be stable after remaining at room temperature for approximately 24 h. Samples fortified with C8, C9, C10, and C11 were shown to be stable after remaining at room temperature for 14 days before extraction. Samples fortified with C13 were shown to be stable after remaining at room temperature for 7 days before extraction. Fortified samples, extracts, and standards demonstrated stability after being stored in a refrigerator for 14 days for all analytes. Long-term storage stability was demonstrated for methanolic stock solutions.

Dichloropentafluoropropanes as solvents for size exclusion chromatography.

We have found that HCFC225s (HCFC225ca: 3,3-dichloro-1,1,1,2,2-pentafluoropropane, HCFC225cb: 1,3-dichloro-1,1,2,2,3-pentafluoropropane) are superior mobile phases for size exclusion chromatography (SEC). As alternatives of CFC113, they have been shown to possess a number of excellent properties, such as low flammability, low viscosity, low cost, high purity, and environmental and operational friendliness. In addition, they have distinct advantages for the SEC measurement, because they solubilize some kinds of acrylate such as poly(methyl methacrylate) (PMMA) and commercial monodispersed PMMA can be used to prepare calibration curves necessary for the measurement of equivalent molecular weight of some polymers. Furthermore, we propose an HCFC225/1,1,1,3,3,3-hexafluoroisopropanol mixed solvent for use in the SEC of poly(ethylene terephthalate) (PET) and polyamides. Poly(2-(perfluorooctyl)ethyl acrylate), whose PMMA equivalent weight average molecular weight was 118,100 Da, was evaluated by a multi-angle laser light scattering (MALLS) detector to have an absolute molecular weight of 439,000 Da. The difference can be attributed to the molecular size of the polyfluorinated polymer compared to the non-fluorinated one. The possible application of this novel mobile phase system for molecular size and molecular weight characterization of perfluoropolyethers, PET, nylon 6 and nylon 6,6 are also discussed.