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National Institutes of Health (U.S.). Biomedical E.

Annual report: National Institutes of Health. Division of Research Services. Biomedical Engineering and Instrumentation Branch (Volume 1980) online

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of the QUISTOR to mass spectrometric analysis of drugs and other compounds of
biological interest.



79



SMITHSONIAN SCIENCE INFORMATION EXCHANGE
PROJECT NUMBER (Do HOT use this space)



U.S. DEPARTMENT OF
HEALTH, EDUCATION, AND WELFARE
PUBLIC HEALTH SERVICE
NOTICE OF
INTRAMURAL RESEARCH PROJECT



PROJECT NUMBER



701 RS 10075-01 BEI



PERIOO COVERED



Q c tober 1, 1979 to September 30. 1980



TITLE OF PROJECT (80 characters or less)

Development of a new method for resolving power measurement



NAMES, LABORATORY AND INSTITUTE AFFILIATIONS, AND TITLES OF PRINCIPAL INVESTIGATORS AND ALL OTHER
PROFESSIONAL PERSONNEL ENGAGED ON THE PROJECT



PI:

OTHER:



L. Kelner
D. Rosenthal



Visiting Associate
Senior Chemist



BEIB DRS
CLSG RTI



COOPERATING UNITS (if any)

Chemistry and Life Sciences Group, Research Triangle Institute



LAB/BRANCH ,.,_-..

lomedical Engineering and Instrumentation



;t ion
Microanalysis Group



W.^ ^T^t'lresda, Maryland 20205



TOTAL MANYEARS:



1.0



PROFESSIONAL:



1.0



CHECK APPROPRIATE BOX(ES)
(J (a) HUMAN SUBJECTS

(J (al) MINORS Q (a2) INTERVIEWS



O (b) HUMAN TISSUES



G (,= ) NEITHER



SUMMARY OF WORK (200 words or less - underline keywords)

Decachlorobiphenyl and decabromobiphenyl have been analyzed under positive and
negative ion chemical ionization and positive ion electron impact conditions for the
purpose of using these compounds as references to evaluate the resolving power of
mass spectrometers in a wide mass range (M/Z 100-1000). Molecular clusters and
some fragments have been detected with different types of mass spectrometers:
magnetic sector as well as quadrupoles, including A.E.I. MS-9, LKB-9000, LKB-
2091, Finnigan 3200 and Finnigan 4000. The criteria to determine the resolving
power have been found based on the measurement of the minima of two adjacent
peaks of the molecular cluster of DCB or DBB. Molecular clusters for DCB and
DBB were determined theoretically by plotting the individual ions which constitute
each profile at the desired resolution using a standard Gaussian distribution of
intensities, and then summing the individual ions with the weighting factors derived
from the theoretical statistical isotope distribution ratios of carbon, chlorine, and
bromine. By comparing the theoretical values of minima vs. resolution with the
experimentally found values of minima between the same two adjacent peaks, the
resolving power of a given mass spectrometer can be determined. The method

"pHS-6040
(Rev. 10-76) ^v



80

Z01 RS 10075-01 BE1

developed here and the reference compounds DCB and DBB will be recommended
to manufacturers and users of mass spectrometers as an easy and accurate way to
estimate the resolving power of their instruments both for instrument acceptance
and as a routine check-out.

Objectives : To develop a method to measure the resolving power of various types
of low resolution mass spectrometers which will be easier, faster and require less
effort than the conventional methods.

Methods Employed: Theoretical values of ion abundances for molecular clusters of
decachlorobiphenyl and decabromobiphenyl will be used to determine the resolving
power of mass spectrometers by comparing them with the experimental values of
minima between two adjacent peaks in the molecular cluster.

Major Findings : The calibration curves MIN=f(R) have been found for molecular
clusters of DCB(M/Z 498) and DBB(M/Z 9'+4). The comparison between the
theoretically derived MIN values and the experimental data show good agreement
between observed and calculated values in the resolution range of 150-500 for DCB
and 300-900 for DBB. Thus the two compounds cover the useful range of a low
resolution mass spectrometer, i.e., 150-900. It also has been found that DBB may
be used as a sensitivity test reference for quadrupole mass spectrometers in a high
mass range (600-1000). It can be done by comparing intensities of the peaks
centered at M/Z 944 and M/Z 784. Their ratio should be about 0.5.

Significance : A simple method to determine the resolving power of mass
spectrometers has been developed. The method can be used in all types of mass
spectrometers and with different ionization techniques (electron impact, chemical
ionization, positive or negative ions, etc.). The method will be beneficialy to all
mass spectrometry users and may improve the specifications of the instruments at
their acceptance.

Pr oposed Course : The experimental data for the measurement of the resolving
power on different types of mass spectrometers will be analyzed. The inlet system
to conveniently introduce DCB and DBB into the ion source region of the mass
spectrometers will be developed. The possible automation of the procedure with
the help of a dedicated computer system (MS/DS) will be evaluated.



81



SMITHSONIAN SCII
PROJECT NUMBER I



■JCE INFORMATION EXCHANGE
)o NOT use this space)



U.S. DEPARTMENT OF
HEALTH, EDUCATION, AND WELFARE
PUBLIC HEALTH SERVICE
NOTICE Of
INTRAMURAL RESEARCH PROJECT



PROJECT NUMBER



701 RS 10076-01 DEI



PERIOD COVERED

October 1, 1979 to September 30, 1980



TITLE OF PROJECT (80 characters or less)

Elemental Analysis of Microdroplets



NAMES, LABORATORY AND INSTITUTE AFFILIATIONS, AND TITLES OF PRINCIPAL INVESTIGATORS AND ALL OTHER
PROFESSIONAL PERSONNEL ENGAGEO ON THE PROJECT



PI:

OTHER:



A.F„ LeRoy
N. Roinel



Chief, Micro. Group
Chemist



BEIB DRS
CEN, France



COOPLHATING UNITS (if any)

Department of Biology, Centre d"Etudes Nucleaires, Saclay, France



LAB/BRANCH

Biomedical Engineering and Instrumentation

sect Ton

Microanalysis Group



institute and location

DRS, NIH, Bethesda, Maryland 20205
totaT 'manyearsT~



1.5



PROFESSIONAL:



1.5



OTHER:



CHECK APPROPRIATE BOX(ES)
TJ (a) HUMAN SUBJECTS

(J (al) MINORS ( a2 ) INTERVIEWS



□ (b) HUMAN TISSUES



D (fc) NE



SUMMARY OF WORK (200 words or less - underline keywords)

The principal instruments used in this project are the Cameca MBX 2-50 KeV
scanning el ectron be am m[crojp_rqbe and a Cameca MS-46 electron microprobe,
eachequipped with two wavelength disp ersive spectrometers. Quantitative e le-
mental analy sis in volumes of the order of 10 liter are possible using these
Instruments. The signal for some elements changes with time as a function of
beam current density, sample mass thickness and some other characteristics of the
samples. A systematic quantitative study of the variables that affect stability of
the signal has been undertaken to establish the ranges of values of these variables
that permit usable results to be obtained.



PHS-6040

(Rev. IO-76)



82

Z01 RS 10076-01 BEI

Objectives : To establish the ranges of instrument operating conditions that yield
stable signals for the elements analyzed with the MBX microprobe.

Methods Employed : Mathematical analysis of data obtained on representative
microdroplets to quantify dependence of element X-ray signal on operating
conditions as a function of time.

Significanc e: To provide a sound basis for quantitative analysis of microdroplets.

P roposed Course : To extend the number of variables included in the study to
include temperature of the sample analyzed and the sizes of crystals analyzed.

Publications :

Roinel, N.G. and LeRoy, A.F.: Variations in characteristic signals of the elements
during microprobe analysis of droplets: A review. Microbeam Analysis, 129-132,
1980.

LeRoy, Andre and Roinel, Nicole: Quantitative analysis of lyophilized solutions:
Loss of elements during the irradiation time as a function of sample current
density and mass thickness. Proceedings of the Seventh European Congress on
Electron Microscopy, The Hague, The Netherlands, August, 1980.



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Online LibraryNational Institutes of Health (U.S.). Biomedical EAnnual report: National Institutes of Health. Division of Research Services. Biomedical Engineering and Instrumentation Branch (Volume 1980) → online text (page 7 of 7)