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A Word On Purities

REFERENCE

How Many 9's Do You Need? This site provides two types of specifications for a given gas: The "assay" or minimum purity of the gas The maximum individual values for each given impurity detect in the gas

Assay (minimum purity of the gas)

This first specification represents the total amount of impurities analytically detected within the gas expressed as a gravimetric percentage, i.e. - Nitrous Oxide Sigma 3 Grade is expressed as follows: Product Specification: Nitrous Oxide (N2O) Grade: Sigma 3 Minimum Purity: 99.9997% Maximum Impurities: 0.0003% Therefore, for this grade of Nitrous Oxide for a 99.997% purity there will be a maximum of 0.0003% of impurities or 3

parts per million (ppm). It's important to note that as additional impurities are analytically detected within the gas, the purity level of the gas gets "worse." In other words, as you look for more species within a given gas with the intent to produce a better product (where more impurities are classified) the minimum purity of this product will decrease, or the number of 9's will decrease. Therefore, even though a lesser purity number is present for this product to the market, the product itself represents a more desirable material as a better quantification of its composition is now available.

Maximum individual values for each given impurity detected in the gas

This second specification lists the maximum levels of the individual impurities that we have analyzed within the gas. In the case of Nitrous Oxide Sigma 3 Grade and continuing from above, these impurities are as follows: The levels of individual impurities listed in this specification represent the maximum amount to be found within the specific grade of gas. For example, no more than 2 ppm of nitrogen will be found in Sigma 3 Grade Nitrous Oxide. However, this does not mean that these impurities will always be present within this grade of gas. In other words, the first specification is limiting, saying that a maximum of 3 ppm of impurities will be found within this grade of gas.

Individual cylinder analysis, standard for high grades and available for all grades upon request, will reveal actual values for individual impurities. Conclusions:  • The minimum purity or "assay" specifies the maximum amount of impurities  • The individual value for each impurity is reported separately as a maximum  • Individual cylinder analysis specifies quantitatively "actual" impurities.

Grade	Purity	Maximum Individual Impurities (ppm)
		N2	O2	THC	CO2	H2O	CO	NH3	NO	NO2	Halogens
Sigma 3	99.9997%	2	0.4	0.1	0.5	1	0.1	1	0.5	0.5	0.5

To Our Customers

We constantly strive to exceed the high-purities demanded in the semiconductor industry. This web site contains a large offering of mixtures and high purity gases already in use by many semiconductor manufacturers. However, we can also develop and produce custom products to meet unique application requirements.

Tell us which impurities are relevant for a given process so we can apply specific analytical procedures and determine their presence in a given gas. Tell us which metal or chemical compounds you need to identify and control within a certain gas. Our goal is to partner with you to meet your needs. Contact us and begin the collaborative process.