William L. Budde

Investigation of enhanced ion abundances from a carrier process in high-performance liquid chromatography particle beam mass spectrometry

Enhancements in ion abundances in high-performance liquid chromatography (HPLC) particle beam (PB) mass spectrometry were observed during coelution or when certain substances (e.g., ammonium acetate) were added to the mobile phase during a reverse-phase gradient elution HPLC separation. These enhancements were observed with two commercial PB interfaces and a variety of compounds generally not amenable to separation by gas chromatography. The enhancements are attributed to both improved chromatographic efficiency and a PB carrier process.

Determination of chlorinated acid herbicides and related compounds in water by capillary electrophoresis-electrospray negative ion mass spectrometry

Capillary electrophoresis electrospray negative ion mass spectrometry was investigated for the determination of chlorinated acid herbicides and several phenols in water. Sixteen analytes were separated as their anions in less than 40 min with a buffer consisting of 5 mM ammonium acetate in isopropanol-water (40:60, v/v) at pH 10. A sample stacking technique was used to provide lower detection limits and a fortified drinking water sample was made pH 10 and analyzed without further processing. Quantitative analyses with an internal standard gave recoveries in the 91-124% range and replicate measurements of a calibration standard gave relative standard deviations in the range of 3-10%.

Mass transport and calibration in liquid chromatography particle beam mass spectrometry.

Differences in the designs of two liquid chromatography particle beam mass spectrometry systems result in differences in the transport of ammonium acetate and differences in ion abundance-enhancing carrier effects. The effect of mobile phase composition, especially the proportion of water in the mobile phase, on transport efficiency is described. Instrument detection limits for 12 compounds with two different interface designs are presented. The calibrations are generally nonlinear explained in terms of mass transport effects and supported by experiments with isotopically labeled species that coelute with the native species. Summary results of a small multilaboratory study are presented. Calibration with isotopitally labeled internal standards is recommended for real-world environmental samples.

Capillary electrophoresis-electrospray mass spectra of the herbicides paraquat and diquat

The positive ion electrospray mass spectra of the quaternary ammonium salt herbicides paraquat and diquat are examined by on-line separation with capillary electrophoresis (CE) and by direct infusion of the analytes. The analytes are separated by CE in 7–10 min at pH 3.9 in 50% methanol-water by using several different separation buffer electrolytes. The capillary electrophoresis-electrospray ionization (CE-ES) mass spectra of paraquat and diquat consist primarily of doubly charged molecular ions, singly charged molecular ions, and singly charged deprotonated ions. The direct infusion spectra consist primarily of doubly charged molecular ions and singly charged deprotonated ions. The relative abundances of the doubly charged and deprotonated ions depend strongly on the presence or absence of ammonium ion in the CE separation buffer or the direct infusion solution. A deprotonation mechanism is proposed in which the free base ammonia is the deprotonating agent in the desolvating charged droplets or in the gas phase. The analytical potential of the CE-ES electrospray approach for environmental analyses is evaluated in terms of the precision of replicate injections, linear concentration range, and estimated detection limit.

Multilaboratory study of automated determinations of polychlorinated biphenyls and chlorinated pesticides in water, soil, and sediment by gas chromatography/mass spectrometry.

Polychlorinated biphenyls (PCBs) and chlorinated pesticides were determined in two water, three soil, and two sediment samples by six laboratories that used uniform calibration solutions and analytical procedures. Target analytes were identified and measured with special software operating on minicomputers that controlled mass spectrometer operation. PCBs were determined by level of chlorination, not as Aroclor formulations. All samples, except one soil sample, were fortified with pesticides. Water Bamples were fortified with PCBs (mixtures of Aroclorb), but solid samples were known to be environmentally contaminated with PCBs. Results obtained with four combinations of extraction and analyte enrichment procedures (cleanup) for solid samples were compared, but no combination could be selected as best for all five samples. Several factors affecting data quality were identified.

The mass spectrometer as a substance-selective detector in chromatography

Abstract The computerized mass spectrometer has several modes of data acquisition when applied as a detector in chromatographis systems. These and several modes of data reduction are defined with examples from the field of environmental measurements of organic pollutants. The overall advantages and disadvantages of the various techniques are discussed.

Development of an immunoassay for chlorinated dioxins based on a monoclonal antibody and an enzyme linked immunosorbent assay (ELISA)

Abstract A set of monoclonal antibodies to dioxin have been developed. These form the bases for a competition enzyme-linked immunosorbent assay capable of detecting 0.5 ng of 2,3,7,8-tetrachlorodibenzodioxin.

Negative ion electrospray of bromo- and chloroacetic acids and an evaluation of exact mass measurements with a bench-top time-of-flight mass spectrometer

The negative ion electrospray mass spectra of six bromo- and chloroacetic acids were measured using two different electrospray interfaces and single quadrupole and bench-top time-of-flight mass spectrometers. With each acid at 50 μg/mL in aqueous methanol at pH 10, the anions observed included deprotonated molecules, adducts, and fragment ions. With each acid at 100 ng/mL in aqueous acetonitrile at pH 10, mainly deprotonated molecules are observed. The exactm/z measuring capability of the time-of-flight mass spectrometer was evaluated to assess the potential for the determination of the individual acids in mixtures without an on-line separation. Mean measurement errors were nearly always less than ± 9 ppm and the majority were less than ± 5 ppm. Potential interferences by substances having similar exact masses and the ability to form anions in aqueous solutions were evaluated. The estimated detection limits of the five regulated haloacetic acids in drinking water, without a sample preconcentration step, are in the range of 24–86 ng/mL, which is within about a factor of 10 of the levels required for routine monitoring of the acids. Actual drinking water samples were not analyzed pending the development of slightly more sensitive techniques and quantitative analytical procedures.

Investigation of the effect of a dc glow discharge on the performance of a particle beam liquid chromatography/mass spectrometry interface

A low voltage (180-V) dc glow discharge device was inserted just below the pneumatic nebulizer in a particle beam interface of a high performance liquid chromatography/mass spectrometry system. The discharge in a helium atmosphere increased the signal produced by 12 test compounds by factors of about 2–6. The increases in signal were probably produced by an increase in the efficiency of solute transmission through the interface. The signal increases caused by the glow discharge were compared to somewhat larger increases caused by 0.01-M ammonium acetate in the mobile phase. The combination of glow discharge and ammonium acetate provided no meaningful advantage over the individual techniques. The mechanism of improved transport efficiency is not proven, but the neutralization of charged particles is a viable hypothesis.

Ron Hites: Gas Chromatography/Mass Spectrometry Pioneer and the Great Detector Debate

R Hites did his dissertation research at the Massachusetts Institute of Technology during the late 1960s. He and his mentor Klaus Biemann invented the data acquisition algorithm that is widely used to this day in computer-controlled gas chromatography/mass spectrometry (GC/MS) (Hites R. A.; Biemann, K. Anal. Chem. 1968, 40, 1217−1221). This algorithm, called continuous measurement of spectra, is also used in all other forms of combined chromatography/MS including the very popular liquid chromatography (LC)/ electrospray/MS, and various forms of chromatography combined with tandem mass spectrometry. However, as is often the case with new ideas, computercontrolled GC/MS was slow to gain acceptance during the 1970s even with the introduction of half-a-dozen or so commercial instrument systems. The GC/MS technology did receive an important boost by the U.S. Environmental Protection Agency (USEPA), which was created by an executive order by President Nixon in December of 1970. After an evaluation of available commercial systems in early 1971, the USEPA initially ordered six Finnigan model 1015 systems for several research and development laboratories and a few regional monitoring laboratories. However, the prognosis for widespread use of GC/MS in the USEPA was not very good as it was explained to me during a job interview in the spring of 1971 in Cincinnati, Ohio. I was interviewing for a position to lead a small GC/MS research group, and the laboratory director noted that GC/MS was not expected to be widely employed for analyses of environmental samples in the newly formed federal agency. A small number of GC/MS instruments in the hands of a few capable investigators would serve mainly as back-ups to the GC methods that used conventional GC detectors, principally the electron capture, flame ionization, flame photometric, and a few others. I thought to myself, as I agreed to accept the job, I wonder how that will work out. Ron Hites and his associates contributed mightily during the 1970s−1980s to the development and acceptance of GC/MS. They demonstrated repeatedly and convincingly how GC/MS could be used to efficiently identify new organic pollutants in many types of environmental samples. Ron and his colleagues also determined the extent of contamination at various waste sites including the infamous Love Canal chemical manufacturing waste site near Niagara Falls, NY. Ron showed that GC/MS gave superior results that were way beyond what could be obtained using conventional GC with standard detectors. His list of significant publications in this area is long and impressive. A major breakthrough for GC/MS occurred during the middle 1970s, although it required another 10 years to finally settle the issue. The USEPA was sued by several environmental interest groups for failing to implement certain provisions of the 1972 Federal Water Pollution Control Act Amendments. An agreement to settle the law suits, known as a consent decree, was approved in federal court in 1976. Under the consent decree the USEPA agreed to develop regulations to control the discharge of toxic organic and other substances into rivers and other bodies of water. A list of 129 priority pollutants was prepared as part of the settlement. Considerable USEPA resources were subsequently devoted to the identification and measurement of these substances by GC/MS and other techniques in a variety of industrial wastewater discharges. Ron Hites’ leadership publications were a significant factor in the selection of GC/MS by the USEPA for most of this large-scale project. However, this project was not without controversy and debate over the relative merits of GC/MS and GC with conventional detectors (see for example Kagel, R. O.; Stehl, R. H.; Crummett, W. B. Anal. Chem. 1979, 51, 223A). Some investigators experienced in organic environmental analyses, especially those who measured chlorinated hydrocarbon pesticide residues, were staunch supporters of GC with standard detectors for regulatory analyses. Their opinions were that GC/MS was too complex and costly, insufficient trained personnel and laboratory capacity existed, and the nation could not afford this approach. They also contended that GC/MS was not as sensitive as standard GC detectors for some important chlorinated compounds. The counter arguments were that GC/MS was far more reliable for compound identification, and far more versatile than standard GC detectors. It was argued that GC/MS was not as costly as it would first appear, and that instrument companies and commercial laboratories would provide the needed capacity if the market developed. Importantly, commercial GC/MS instrument systems were being improved rapidly with much more reliable and lower noise components, and far more capable minicomputers and software. A strong endorsement of GC/MS, but nevertheless a compromise, was published in the Federal Register of December 3, 1979. The USEPA proposed Guidelines Establishing Test Procedures for the Analysis of Pollutants under the Clean Water