Frequently Asked Questions


I just received a neat standard, and the vial is empty! What's going on?

The vial may look empty, but it isn't. Agilent 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.

How do I work with such a small quantity?

Agilent 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.

My class A pipet won't fit into the neck of the ampule.

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.

I see crystals in my ampule.

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.

My volatile analyses are inconsistent.

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.

My volatile analyses are inconsistent, part 2.

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.

My phenol or nitrosamine analyses are inconsistent.

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.

I'm having problems with my endrin and DDT recoveries.

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.

I just got a new lot of Aroclor, and its GC pattern doesn't match the old lot.

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.