Procedure

Preparation of solution to be injected into gas chromatograph:
Put 2.0ml serum, 1.5ml of pH10.5 borate buffer, and 0.50ml of PBCA dissolved in chloroform into a 15-ml glass-stoppered centrifuge tube pipet.
Vortex the contents for 3.5min. Centrifuge the tube for 5min at 2500rpm. Discard the aqueous layer. Using a 10 microliter syringe, inject 4microliters of the organic layer into the gas chromatograph.

Figure 3 shows a typical chromatogram of a sample containing PBCA, methaqualone and serum.

Figure 4 illustrates the chromatogram of sample containing only serum. This shows that the serum is pure and is free of interferences.

Figure 5 is a chromatogram of a sample containing methaqualone, from a patient using the authors' method.

Calibration Graph: Ratio of peak area methaqualone/peak area of PBCA( y-axis) against conc. of methaqualone v/v (x axis)

This calibration graph is plotted from results of the methaqualone standards of 5,10,20,30,40 mg/liter concentrations prepared previously.

Patient's sample of unknown concentration of methaqualone is put into the GC using the author's method. Peak area of methaqualone/peak area of PBCA(Internal standard) of sample is obtained. Concentration of methaqualone in patient is determined by using the calibration graph of standards.