Sample pad

Dry two fiberglass sample pads by placing them on the balance ring, dropping cover over pads, and closing analyzer door. 

The technology of the immunochromatographic test, also called lateral flow test or strip test, has been used for many years. However, its application to food safety, especially in mycotoxin testing is quite recent. The typical immunochromatographic test strip consists of a sample pad conjugate pad, membrane absorbent pad and adhesive backing. 

Fig. 1. The lateral flow strip structure (A) Schematic representation of the lateral flow strip. A lateral flow strip typically consists of four zones of a sample pad, a conjugate pad, a membrane containing the test and control lines, and an absorbent pad on a backing plate. (B) Lateral (toft and over (bottorft views of a lateral flow strip. The outmost layers of the ends of the strip are plastic cover films.

Fig. 5. Assembly of the lateral flow strip master card. (A) Components for the strip lamination 1, white cover film with arrows (sample end) 2, sample pad 3, conjugate pad 4, blotted membrane 5, absorbent pad 6, blue cover film (distal end) 7, adhesive backing plate. (B) The blotted membrane, conjugate, sample and absorbent pads are put in the correspondent places on the adhesive backing plate, sequentially as described in the text. (C) A master card. The sample and distal ends are covered with the white and blue films, respectively.

In addition, a sample pad, conjugate release pad, and wicking material are often utilized for LFAs however, we have found these to be unnecessary for the assays described in this chapter. 

Sample pad May contain dried buffer and is sample entrance into test... 

Place sample pad over the conjugation pad and align it with the left edge of the backing card. 

Figure 3. Schematic design of a lateral flow test (According to [69]) (a) sample pad (sample inlet and filtering), conjugate pad (reactive agents and detection molecules), incubation and detection zone with test and control lines (analyte detection and functionality test) and final absorbent pad (liquid actuation), (b) Start of assay by adding liquid sample, (c) Antibodies conjugated to colored nanoparticles bind the antigen, (d) Particles with antigens bind to test line (positive result), particles w/o antigens bind to the control line (proof of vahdity).

The lateral flow home pregnancy immunoassay shown schematically in the figure is a qualitative test for hcG. Urine is applied to the sample pad at the left end of a horizontal test strip made of nitrocellulose that serves as a wick. Liquid flows from left to right by capillary action. Liquid first encounters detection reagent on the conjugate pad. The reagent is called a conjugate because it consists of hcG monoclonal antibody... 

Ion mobility spectrometry (IMS, Section 5.5) is the most common instrument used in tiie field detection of explosives. At airports, IMS is utili2fid to screen devices such as portable computers a swiped sample obtained by wiping a sample pad over the case is inserted into the instrument, producing an alarm-noalarm response. IMS can also be used in a laboratory as part of a GQMS or IMS-MS system, but to date its forensic applications have been outside the laboratory. IMS is also used at border crossings and ports to detect smu led drugs. 

Figure 5.19 (a) Schematic of the paper-based Y or T sensor, an alternative to the existing microfluidic Y device. The interface between the two flnids remains constant as long as there is sufficient source fluid in the source pad and ample unfilled capacity in the absorbent pad to continue flow in the device, (b) Size-based separation in a paper H filter. (A) Image of a paper H filter with a mixture of blue-black BS A and tartrazine in the left sample pad and deionized (DI) H2O in the right. (B) Schematic of the extraction process. 

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