I just received a neat standard, and the vial is empty! What's going on?
How do I work with such a small quantity?
My class A pipet won't fit into the neck of the ampule.
I see crystals in my ampule.
My volatile analyses are inconsistent.
My volatile analyses are inconsistent, part 2.
My phenol or nitrosamine analyses are inconsistent.
I'm having problems with my endrin and DDT recoveries.
I just got a new lot of Aroclor, and its GC pattern doesn't
match the old lot.
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I just received a neat standard, and the vial is empty! What's going on?
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The vial may look empty, but it isn't. ULTRA sells its neat
standards in very small quantities, usually 100 milligrams or less. Thus, the
volume of the standard may be very small compared to the volume of the vial.
For example, 5 milligrams of a liquid PCB occupies about 4.2 microliters of
volume, making it very difficult to see in a 4 milliliter vial. Look for a tiny
drop lodged in the corner of the vial.
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| How do I work with such a small quantity?
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ULTRA uses strict weighing tolerances when packaging our neat
standards. The weight contained is never less than the nominal weight, nor is
it more than 1% greater than the nominal weight. Thus an assured weight can be
obtained from the vial by rinsing the contents of the vial into a volumetric
flask with an appropriate solvent.
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| My class A pipet won't fit into the neck of the ampule.
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Unfortunately, ampules tend to be narrower than pipets. We
recommend that a scrupulously clean, glass bodied syringe be used to transfer
to proper amount of solution from the ampule to your volumetric flask. We
generally overfill our ampules approximately 20% to ensure that you will be
able to transfer the proper amount of standard with no problems.
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| I see crystals in my ampule.
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Some solutions contain components that can crystallize during
refrigeration. Gently warming the ampule (at less than 40°C) and shaking is
usually sufficient to redissolve the material. If this is unsuccessful, an
ultrasonic bath may be used.
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| My volatile analyses are inconsistent.
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Ampules containing highly volatile components (such as gases)
should be chilled thoroughly prior to opening to ensure that the gases are in
the solution, and not in the headspace of the ampule.
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| My volatile analyses are inconsistent, part 2.
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The best diagnosis tool for this problem is a direct injection
of the standard onto the column, by-passing the purge & trap system. If the
direct injection greatly improves the response of the components, the problem
probably lies within the purge & trap system. If the direct injection does
not improve the chromatography, then the problem may lie in the column,
detector system, or with the standard.
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| My phenol or nitrosamine analyses are inconsistent.
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These compounds may react with active sites on the GC column.
Condition the column by injecting a concentrated solution of the analytes (2 to
5 times higher than the highest point of the calibration curve). This will
saturate the active sites, and yield more consistent results.
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| I'm having problems with my endrin and DDT recoveries.
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Endrin and DDT can break down in the GC injector port at
elevated temperatures. Poor recoveries of these analytes often indicate that
the injection port liner needs cleaning or replacement. The use of cool,
on-column injection can also alleviate this problem.
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| I just got a new lot of Aroclor, and its GC pattern doesn't
match the old lot.
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Chlordane, toxaphene, and the Aroclors are examples of
technical mixtures composed of many compounds. Due to variations in the
manufacturing process, the exact composition of these products varies from lot
to lot.
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