Chase Scientific Glass, Inc.

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Frequently Asked Questions

Product Information

What is KG-33 Glass?
KG-33 is a borosilicate glass with a low coefficient of expansion and a very high resistance to chemical attack. It meets the requirements for Type 1 Class A glass of ASTM E438, "Glass in Laboratory Apparatus". The alkali content is low and it is made without elements of the calcium, magnesium and zinc group of heavy metals. The combined total of arsenic and antimony oxides is less than 0.005%.
What is N-51A Glass?
N51-A is a borosilicate glass possessing the best all-around chemical durability of available commercial glasses. Due to a comparatively low coefficient of expansion, N-51A also possesses good resistance to heat shock. N-51A meets the requirements for Type 1 Class B glass of ASTM E438.
What are the differences between K-33 and N-51A glass?
K-33 glass is much harder, due to its composition, and must be scored in order to cut. N51-A glass can be cut 51 expansion with a flame. As a result, 33 expansion glass won’t shatter in heat like 51 expansion will. Hence most laboratories use vials made from 33 expansion glass for that reason. Vials made with 33 expansion glass are more durable and are preferred for anything used around heat.
What is the difference between Class A and Class B Glassware?
Volumetric glassware that is permanently marked Class "A" is guaranteed to comply with volumetric tolerances prescribed in ASTM E694, and latest revisions. It is also supplied with a serialized certificate of precision. Volumetric glassware that is permanently marked Class "B" has a tolerance that is twice as large as Class "A".
What are the differences between soda lime and borosilicate glass?
Borosilicate glass is typically composed of 70% silica and at least 5% boric oxide, as well as sodium oxide, potassium oxide, and calcium oxide. It has a low thermal expansion coefficient and high chemical resistance, making it ideal for use in the medical and pharmaceutical industries. Borosilicate glass conforms to USP, Type I and ASTM Type I, Class B).

Soda lime glass is the most common commercial glass (90% of total production), and also the least expensive. Soda-lime glass is not very resistant to high temperatures, sudden thermal changes, or corrosive chemicals.
What are the properties of amber glass?
Amber glass is a Type I, Class A borosilicate glass with softening and working point temperatures lower than clear glass and a refractive index slightly higher than clear borosilicate glass.
Why is amber glass sometimes preferred over clear glass?
Amber glass blocks all radiation from 350 to 200 nanometers. UV radiation in the 10-200 nanometer range is called short wavelength UV and is absorbed by the air. The UVC range is 200-280 nanometers and refers to shorter UV wavelengths. They are often used for germ killing purposes. The UVB range is 280-315 nanometers and is the Ultraviolet zone that causes sunburn. The UVA range is 315-400 nanometers. Tanning spas operate in the 315 to 345 nanometer range. As you can see, not all UV radiation is blocked by the amber glass, but a large portion of it is.
Is the amber color a coating or is it in the glass itself? If it is a coating, is it on both sides of the glass?
Amber is a color, not a coating.
Does laboratory glassware contain arsenic, and if so, at what levels?
Arsenic oxide is used to eliminate the green color in glass caused by iron impurities and to minimize bubbles. It appears as the compound arsenic oxide and may be present in small amounts. The level of arsenic oxide complies with the ASTM E-438 specification for Glass in Laboratory Apparatus (.0005% for Type 1 Class A glass, and .1% for Type 1 Class B), which also meets the code for the US and European Pharmacopeias. Furthermore, glass suppliers who use arsenic oxide as a refining agent conduct an autoclave test which simulates shelf life to verify that arsenic will not leach out into samples over time. Typically, 15 minutes in the autoclave represents 2 years of shelf life. Chase glass is certified to meet the ASTM specification for glass in laboratory apparatus.
What is condensation in finished glass?
This phenomenon, also known as weathering or fogging, is created in Type 1 glass when heat causes water-soluble alkali salts to vaporize. Some of these salts condense on the cooler portions of the inner surface, leaving a white or gray film that looks like smoke. During transit and storage, the glass surface is exposed to moisture, which may cause the salt film to dissolves and form crystals. This phenomenon is normal and does not indicate a contaminate condition. The salt may be completely removed by rinsing with water.

As flint/soda lime glass is exposed to the atmosphere, a complex reaction occurs on the surface between the alkali on the glass and gases in the air. These reactions are commonly known as weathering. Weathering is a normal condition and the quantity and appearance vary depending upon the amount of time, humidity and temperature of storage. Keeping the glass under a constant low humidity is the most effective method to slow weathering as it keeps the surface dry. Periodic rotation of stock (first in/first out) is also effective as it minimizes the amount of exposure.

All types of glass weather, but some are more resistant than others. Borosilicate glass types, which we have included for you to sample, are the most resistant and are well suited for general use in chemistry, blood banks, hematology and all areas of the laboratory. In addition, they are more durable than the flint/soda lime glass.
What is heparinization and why is it used for blood collection tubes?
Heparin, an anticoagulant, is used in blood collection tubes to reduce the risk of a clot forming in blood in a tube after being collected in preparation for performing some kind of blood test.
How are laboratory consumables sterilized?
Most single use devices are terminally sterilized by ethylene oxide gas, or gamma radiation, or electron beam radiation. The sterilization process must be present on the pre-sterilized product. By means of the cGMP medical device regulations, FDA has established some of the requirements for an acceptable sterility assurance program. More specific guidelines for validation of the sterilization processes are developed and published by AAMI in conjunction with ISO.

When auditors come to your facility to discuss sterilization requirements, they usually want to see two things: 1) the original validation package that determined what type of sterilization is best and what dose is appropriate (for radiation), and 2) review of periodic dose audits for the same product. An initial validation study usually takes 6 to 8 weeks, and is done on the largest container size in a series of the same material. That qualifies all sizes of that material to accept the same dose.

For gamma radiation, which we use for most of our products, there are several AAMI/ISO methods available to sterilize a medical device. All of these methods use product bioburden enumeration and a bioburden organism resistance test, which is referred to as the verification dose resistance experiment. The most appropriate methodology is selected based on the projected production schedule and size.
1. AAMI/ISO 11137 Method 1 – For large and frequent production batches
2. AAMI/ISO 13409 – For small production batches
3. AAMI/ISO 15844 – For large but infrequent production batches
4. AAMI/ISO VDmax – a new validation method which I use which is cheaper, and requires less samples
Initial validation costs upwards of $5,000, and periodic quarterly dose audits (or however often you make a production run) cost around $1,500. A dose audit is a sterility test of samples which have been irradiated at a defined kGy level determined as part of an AAMI dose validation study. Sterilization and reporting is usually around $1,000. These costs have to be included in your pricing, unless you have already validated the container/bottle. Chase only offers two I-Chem sizes as sterilized 400 series level products, since we had to have the containers validated, using the largest size, and we have to do a quarterly dose audit in accordance with AAMI/ISO guidelines. That becomes part of the pricing structure. We only run those quarterly, so we do a dose audit each time we do a production run.

If you have a defined kGy level for your containers, then someone must have commissioned an initial validation study, which you should have a copy of at EPSP. If you sell more than once, however, then you need to do quarterly dose audits, based on that initial validation report.
What are some of the common laboratory uses for blood collection tubes?
Hundreds of blood tests are performed every day in today’s modern labs. In general, there are four main types of blood tests:
- Hematology tests
- Microbiology tests
- Biochemistry tests
- Serology tests
Hematology tests examine the blood to identify:
- The types and numbers of blood cells that are present (e.g., red blood cells, white blood cells and platelets)
- The appearance of the cells, especially their maturity
- The ability for the blood to form a blood clot and the speed at which clotting occurs
Biochemistry tests measure the amounts of normally occurring chemicals and biochemicals in the blood, both individually and in relation to other chemicals. These measurements are compared to normal ranges for that test and are used to determine whether blood biochemicals are in a proper and healthy balance. Biochemicals and other substances that may be studied include the following:
- Sodium
- Hormones
- Recreational drugs
- Cholesterol and other fats
- Blood gases
- Alcohol
- Vitamins and minerals
- Prescription drugs
Not only can biochemical tests precisely measure these substances, but they can also be used to indicate how well some organs and organ systems are functioning. For instance, the amount of blood sugar (glucose) in the bloodstream can help to diagnose or monitor diabetes, and indirectly reflect how much insulin is being produced by the pancreas.

Microbiology tests examine blood for the presence of infectious microscopic organisms such as the following:
- Smears, in which a small amount of blood is placed on a glass slide for examination under a microscope. Sometimes the blood smear is stained with special dyes before examination.
- Blood cultures, in which a small amount of blood is placed in a nutrient broth, incubated for days or weeks and then examined for growth of disease-causing bacteria.
Serology tests (tests done on blood serum) can detect the presence of antibodies that are produced by white blood cells to attack microscopic organisms. They are frequently used to detect viral diseases. Most hospital laboratories do not have the equipment or specially trained personnel necessary to isolate the viruses themselves, so serology tests are done instead to identify the infecting organism by studying the antibodies produced against it.
What are some of the potential effects of pipette sterilization?
Sterilization by means of irradiation may cause cross-linkage or scission of chemical bonds at the molecular level. The amount of scission or cross linkage is dependent upon chemical composition, morphology, and radiation absorption. These effects may increase or decrease over time. Although the effects of radiation on particular types of material may be predicted, they may also depend upon outside stresses placed in the product during manufacturing or storage after process, which can lead to brownish discoloration of the glass.

Therefore, qualification of materials/products at a dose at or above the maximum dose range followed by product functionality at several time frames through out predicted life span of the product is recommended. The results of this testing should be used to establish the maximum dose for routine processing.

Pipettes are sterilized at a 25.0-40.0 kGy range based on an AAMI dose validation study performed by our sterilization vendor. The bioburden test data and the dose calculation from that study determine the dose required.
What causes smoke rings in finished culture tubes?
Smoke rings, sometimes called boron haze, may occur when gases are trapped inside the tube during finishing. Sometimes, the smoky appearance is caused by condensation since borosilicate glass is thermal shocked with water.
What is involved in sterile processing by heat?
Sterilization is defined as the destruction or removal (by filtration) of all microorganisms and their spores. Sterilization is usually achieved via heat or radiation.

Sterilization by heat may be achieved by autoclaving, dry heat in hot air ovens, or boiling. Autoclaves can terminally sterilize products that can withstand a temperature of 121C for 30 minutes. There are two types of autoclaves: pressure cooker type and gravity displacement models with automatic air and condensate discharge.

Steam sterilization is a process of killing microorganisms through the application of moist heat (saturated steam) under pressure. Heat destroys the cell’s essential structures, including the cytoplasmic membrane. The rate of at which bacterial cells are destroyed depends on the temperature and time of heat exposure.