 Contact us at:
Numegalab@aol.com
or by phone at:
(858)793-6057
|
NMR Services:
INSTRUMENTS:
Bruker AMX-500 II and Bruker
DMX-500
METHOD:
Proton NMR:
About 2-10 mg of sample is dissolved
in 0.6 ml of NMR Solvent. Sample solution in NMR tube is loaded into
probe inside the magnet. Deuterium signal is locked and the magnetic
field is adjusted to homogeneity. Pulse sequences and parameters are
optimized. Enough number of scans (usually > 64) are used to obtain
good signals. Chemical shift is calibrated with solvents, DMSO =2.50,
CDCL3 = 7.26, MeOD= 3.31, etc. If sample solution has no deuterium
lock signal, we use an insert with deuterium signal or we acquire
signals under no-lock conditions.
C-13 (125.7 MHz) P-31 (202 MHz) NMR:
A higher concentration of 20-50 mg/0.6
ml is required for good S/N ratio. 85% of phosphoric acid (0 ppm) is
externally used for P-31 calibration. DMSO (39.51 ppm) is used
externally for C-13 chemical shift calibration in D2O.
F-19 NMR:
INSTRUMENT:
AMX-400
FREQUENCY:
376.48 MHz
D1:
1 sec. if not specified
NS:
512
PULSE WIDTH:
5 us
PULSE ANGLE:
30 degree
CALIBRATON:
CFCL3 = 0 ppm, C6F6= -163 ppm
Special pulse Sequences:
Solvent presaturation, DEPT135, APT,
and quantitative sequences are available.
Other Nuclei:
Frequency
Standard Pulse Sequence
Si-29 (186.6) TMS
deptq or inept
V-51 (131.5) VOCl3 zg
B-10 (53.73) B10H14
B-11 (160.44) Boric Acid
N-15 (50.68) DMF
deptq
Sn-119 (178.21) TMT zg,
deptq
1-D NOE, and 2-D NMR:
COSY, NOESY, TOCSY, HMQC, HMBC are
performed with standard parameters if not specified.
DATA:
Data are stored in the computer system
at least for two weeks. Older data files are permanently stored on CD.
Data are available to you via e-mail.
REPORT:
Full
spectrum (10 to -.5 ppm H-1, or 200 to 0 ppm C-13), and expansions with
integration and peak-picking are sent to you within 24 hours for routine
analysis.
Mass Spec Services
INSTRUMENT:
Perkin Elmer PE-SCIEX API-150.
Detection range = 30 – 3000 amu.
METHOD:
1 ug of sample was dissolved in 1 ml of
suitable solvent. The sample solution was injected into electrospray ion
source chamber under high positive or negative potential. Positive and
negative ions traveling through detective zone under very high vacuum
are recorded.
Electrospray developed in 1980 is a mild
ionization technique which is useful for novolatile and unstable
materials. Normally the parent ions are dominated signals. Positive mode
usually detects M+H+,
M+Na+,
M+K+,
and negative mode detects M-H-,
and M+Cl-.
ACCURACY:
0.1%.
REPORT:
We can fax, mail, or e-mail both
positive and negative spectra to you. We normally scan 300-500 amu with
molecular ion near the center of the spectrum.
CHNS ANALYSIS
INSTRUMENT:
Perkin Elmer PE2400-Series II, CHNS/O
analyzer.
METHOD:
About 2mg of sample is weighed
accurately with a microbalance. The sample is introduced into the
combustion chamber and burned at high temperature >900 F under pure
oxygen. The resulting gas mixture and helium carrier gas pass through
various reductive and catalytic zones to convert the gas mixture into CO2,
H2O,
N2,
and SO2.
Signals of thermal conductivities of those gases separated by gas
chromatography are used to quantity CHNS.
PRECISON & ACCURACY:
Several blank and calibration runs are
performed to establish reproducibility and stability of the instrument.
Precision and accuracy = 0.3% for each element. Duplicated runs are
recommended.
REPORT:
Sample ID, C%, H%, N%, & S% listed. We
can fax, mail, and/or e-mail your results.
|
