Simultaneous detection of a wide variety of commonly abused drugs in a urine screening program using thin-layer identification techniques

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A single-step extraction method and thin-layer identification techniques capable of testing a wide variety of drugs of abuse are presented. These techniques are well suited for large and/or small drug programs involved in urine testing because they provide substantial economic benefits and improve clinical functioning. The drugs are absorbed on a 6 × 6 cm piece of paper loaded with cation-exchange resin and then eluted from the paper at pH 10.1 using ammonium chloride—ammonia buffer. The simultaneous thin-layer detection of sedatives, hypnotics, narcotic analgesics, central nervous system stimulants and miscellaneous drugs is accomplished by spotting the solution of extracted residue on a 20 × 20 cm Gelman pre-coated silica gel glass microfiber sheet (ITLC Type SA). A two-stage solvent system is used in order to obtain a chromatogram with optimum separation of a wide range of drugs. This system can separate methadone and/or cocaine from propoxyphene, methaqualone, methylphenidate, pentazocine, pipradrol, Doxepin, chlorpromazine, phenazocine, naloxone, naltrexone, imipramine and trimeprazine; amphetamine from phenylpropanolamine and dimethyltryptamine; codeine from dextromethorphan; methamphetamine from dimethyltryptamine, etc. Different detection reagents are then applied in succession to different marked areas of the developed chromatogram. This elegant method of extraction and spraying has enabled us to detect morphine base at a sensitivity level of O.15 μg/ml, amphetamine sulfate at 1.0 μg/ml, methamphetamine hydrochloride at 0.5 μg/ml, phenmetrazine hydrochloride at 0.5 μg/ml, codeine phosphate at 0.5 μg/ml, methadone hydrochloride at 1.0 μg/ml, secobarbital at 0.36 μg/ml and phenobarbital at 0.5 μg/ml in urine. The minimum volume of urine needed to achieve these sensitivities is 20 ml. The cost of analysis per urine specimen using these techniques for concomitant screening of these drugs is less than US$ 1.