Method for detecting an unknown contaminant concentration in a substance

Abstract

A method for detecting contaminants in a solution by determining a change in resonant frequency (ΔF) and motional resistance (ΔR) of a crystal microbalance (CM) immunosensor is presented. The method includes measuring ΔF and determining ΔR of a CM immunosenor exposed to various samples including known concentrations and a sample including an unknown concentration of the contaminant. The unknown contaminant concentration may be determined according to ΔR of the samples with the known and unknown contaminant concentrations, or ΔF of the same. If ΔR of the CM immunosensor exposed to the samples with the known contaminant concentrations more accurately reflects the known contaminant concentrations than ΔF does, the unknown contaminant concentration may be determined according to ΔR of the samples with the known contaminant concentrations and the unknown contaminant concentration. Otherwise, the unknown contaminant concentration may be determined according to ΔF of the same.

1 . A method for determining an unknown contaminant concentration in a first sample, the method comprising: 
 determining a change in a first motional resistance of a crystal microbalance (CM) immunosensor exposed to the first sample (ΔR 1 );    measuring a change in a first resonant frequency of the CM immunosensor exposed to the first sample (ΔF 1 );    measuring a change in a second motional resistance of the CM immunosensor exposed to a plurality of second samples (ΔR 2 ), wherein the second samples include a plurality of known contaminant concentrations;    measuring a change in a second motional frequency of the CM immunosensor exposed to the plurality of second samples (ΔF 2 ); and    determining the unknown contaminant concentration according to ΔR 2  and ΔR, or ΔF 2  and ΔF 1 .    
   
   
       2 . The method of  claim 1 , wherein the crystal includes quartz.  
   
   
       3 . The method of  claim 1  further comprising creating the first sample from a substance.  
   
   
       4 . The method of  claim 1 , wherein the first sample is created from the substance and a plurality of immuno-beads.  
   
   
       5 . The method of  claim 1 , wherein the first sample is created from the substance and a plurality of immuno-magnetic beads.  
   
   
       6 . The method of  claim 1 , wherein the first sample is created from the substance and a plurality of immuno-magnetic microbeads.  
   
   
       7 . The method of  claim 1 , wherein the first sample is created from the substance and a plurality of immuno-magnetic nanobeads.  
   
   
       8 . The method of  claim 1 , wherein the ΔF 1  is measured and ΔR 1  is determined simultaneously.  
   
   
       9 . The method of  claim 1 , wherein the ΔF 2  is measured and ΔR 2  is determined simultaneously.  
   
   
       10 . The method of  claim 1 , wherein determining ΔR, and/or ΔR 2  includes measuring ΔR, and/or ΔR 2 .  
   
   
       11 . The method of  claim 1 , wherein determining ΔR, includes measuring a conductance (G f1 ) and a susceptance (B f1 ) of the CM immunosensor exposed to the first sample.  
   
   
       12 . The method of  claim 11 , wherein ΔF 1 , G f1 , and B f1  are measured approximately simultaneously.  
   
   
       13 . The method of  claim 11 , wherein ΔR, is determined as a function of G f1  and B f1 .  
   
   
       14 . The method of  claim 13 , wherein the function is a Butterworth-Van Dyke model.  
   
   
       15 . The method of  claim 1 , wherein measuring ΔR 2  includes measuring a conductance (G f2 ) and a susceptance (B f2 ) of the CM immunosensor exposed to the plurality of second samples.  
   
   
       16 . The method of  claim 15 , wherein ΔF 2 , G f2 , and B f2  are measured approximately simultaneously.  
   
   
       17 . The method of  claim 15 , wherein ΔR 2  is determined as a function of G f2  and B f2 .  
   
   
       18 . The method of  claim 17 , wherein the function is a Butterworth-Van Dyke model.  
   
   
       19 . The method of  claim 1 , wherein determining the unknown contaminant concentration according to ΔR 2  and ΔR, or ΔF 2  and ΔF, comprises determining whether ΔR 2  more accurately reflects the known contaminant concentrations than does ΔF 2 .  
   
   
       20 . The method of  claim 19 , wherein determining whether ΔR 2  more accurately reflects the known contaminant concentrations than does ΔF 2  includes determining whether ΔR 2  includes a greater proportionality to the known contamination concentrations than does ΔF 2 .  
   
   
       21 . The method of  claim 19 , wherein determining whether ΔR 2  more accurately reflects the known contaminant concentration than does ΔF 2  includes determining whether ΔR 2  provides a greater sensitivity than does ΔF 2 .  
   
   
       22 . The method of  claim 1 , wherein determining the unknown contaminant concentration according to ΔR 2  and ΔR, or ΔF 2  and ΔF, comprises comparing ΔR, to ΔR 2  if ΔR 2  more accurately reflects the known contamination concentrations.  
   
   
       23 . The method of  claim 1 , wherein determining the unknown contaminant concentration according to ΔR 2  and ΔR 1  or ΔF 2  and ΔF 1  comprises comparing ΔF 1  to ΔF 2  if ΔF 2  more accurately reflects the known contamination concentrations.