I found an interesting link on the Quickscreen tests. (This is the one I bought at Walgreens)

Hope it is not considered spamming.

I find it interesting that Ibuprofen is not on their list of compounds that will not interfere with test results..... think I will try another brand of test since I take massive amounts of Ibuprofen.

Marijuana Test Kit, Information on Passing Drug Test

QUICKSCREENâ?˘ 10 Minute Urine Test for THC (Marijuana)

LIMITATIONS OF THE TEST
1. This product is designed to be used for the detection of Cannabinoids in urine only.
2. Although the QUICKSCREENâ?˘ 10 Minute Urine Test Strip is very accurate in detecting the urine Cannabinoids level, there is a possibility of false results due to the presence of interfering substances in the urine.
3. Adulterants, such as bleach or other strong oxidizing agents, when added to urine specimens, may produce erroneous test results regardless of analysis method used. If adulteration is suspected, obtain another urine specimen.

PERFORMANCE CHARACTERISTICS
SENSITIVITY: The QUICKSCREENâ?˘ 10 Minute Test Strip has been designed for the detection of Cannabinoids in urine at the detection sensitivity of 50 ng/ml which is suggested for the immunoassay method. In house testing on a total of 249 samples by both GC/MS and the QUICKSCREENâ?˘ 10 Minute Urine Test Strip yield a sensitivity of 1.00.

SPECIFICITY: The QUICKSCREENâ?˘ Ten Minute Urine Test Strip can specifically detect 11-nor-D-9-tetrahydrocannabinol-9-carboxylic acid at levels of 50 ng/ml (0.1 Fg/ml) or higher. The in house data yields a specificity of 1.00.

ACCURACY: Based on the In House evaluation for 249 individual patient urines the QUICKSCREENâ?˘ 10 Minute Urine Test Strip had an accuracy of 100%.

Table 1 - Compounds that Give a Positive Reaction

Compound

Level of Positive Reaction
11-nor-D8-THC-9-COOH
50 ng/ml.
11-nor-D9-THC-9-COOH
50 ng/ml.
D8-THC
1Fg/ml
D9-THC
4Fg/ml
Cannabinol
10Fg/ml
11-hydroxy-D9-THC
10Fg/ml

Table 2 - Compounds that will not interfere with test results at concentrations up to 100Fg.ml (Unless Noted)
Acetaminophen
Hydromorphone
4-Acetamidophenol
Acetylsalicylic acid
Amikacin
Ampicillin
d,1-Amphetamine
Ketamine
Amitriptyline
Arterenol
Aspartame
Atropine sulfate
Benzoic add
Benzoyl ecgonine
Caffeine
Camphor
Chloroquine
Chlorpheniramine
Chlorpromazine HCI
Cocaine Hydrochloride
Cocaine
Cimetidine
Cortisone
Deoxyepinophrine
Dextromethorphan
Diazepam
Digitoxin
Digoxin
Ecgonine Hydrochloride
Ecgonine Methyl Ester
Ephedrine
Epinephrine
Gentisic acid
Glucose
Guaiacol
Glyceryl ether
Histamine
Hydrochlorothiazide
Hydrocodone
Homatropine
Imipramine
Isoproterenol
Lidocaine
d-Methamphetamine
Meperidine
Methadone
Methaqualone
Methlpehnidate
Morphine glucuronide
Morphine sulfate
Morphine
Naloxone
Neomycin
Niacinamide
Oxazepam
Perphenazine
Penicillin G
Phencyclidine
Phenobarbital
Phenyletylamine-
Phenylpropanolamine
Promethazine
Pseudoephedrine
Rantidine
Salycycic acid
Secobarbital r
Tetracycline
Tetrahydrozoline
Theophylline
Thioridazine
Trifluoperazine
Tryptophan