Critical angle refractive index detector

• US 5,139,661 A
• Filed: 01/11/1991
• Issued: 08/18/1992
• Est. Priority Date: 01/11/1991
• Status: Expired due to Fees

• Current Assignee: Biotage
• Original Assignee: Biotage Incorporated (Biotage)
• Inventors: Kolbert, Jason H.
• Primary Examiner(s): Dawson, Robert A.
• Assistant Examiner(s): KIM, SUN U
• Application Number:
  US07/639,870
• Time in Patent Office: 585 Days
• Field of Search: 210/198.2, 210/656, 356/128, 356/129, 356/130, 356/131, 356/132, 356/133, 356/134, 356/135, 356/136, 356/137, 356/246, 422/70, 73/61.1 C, 73/82.9, 73/82.11, 436/161
• US Class Current: 210/198.2
• CPC Class Codes: G01N 21/43 by measuring critical angle

Abstract

A critical angle refractive index detector for production liquid chromatography systems with flow rates as low as 100 ml/min to 25 l/min or higher as the system requires and pressures up to 4000 psi. The detector includes a flow cell with a sensing chamber volume selected to provide maximum detector sensitivity and minimum pressure drop at the maximum flow rate of the system for accurate discernment of critical refractive index peaks of each constituent in the sample. Explosion protected controls for zero and span settings are located to the exterior of a purged safe enclosure containing the system.

Claims

1. A critical angle refractive index detector for a liquid chromatography system which is capable of carrying out a production chromatography process comprising, a full flow-through cell constructed to accommodate pressures of up to 4000 psi and a flow of from 100 ml/min to 25 l/min from a liquid chromatography column, a detector chamber in the flow cell, an inlet to the detecting chamber for admitting the liquid flow thereto, an opening in the flow cell providing optical access to the chamber, a sapphire window in said opening, a light source, means for collimating and focusing a light beam from said source through said window on an interface surface between the liquid and window, a light sensitive silicon wafer detector for receiving a reflected beam for analysis of the liquid by discerning critical peak response for each constituent, and the volume of the detecting chamber being selected as follows:

space="preserve" listing-type="equation">v.sub.cell =π

/4 d.sup.2 l,

where d is the diameter of the inlet to the detecting chamber and l is an a range of 1 to 4 centimeters determined experimentally to provide maximum detector sensitivity and a limited pressure drop on the order of 1-2% of a pressure rated at maximum flow rate through the chamber of said liquid chromatography system.

2. A critical angle refractive index detector according to claim 1 which further includes controls for zero and span of the liquid sample which are rated explosion protected and are mounted on the exterior of a purged safe enclosure containing the liquid chromatography system.