A major disadvantage of taking urine as sample for drug testing is that donors tend to disrupt the test if stern rules are not imposed. A commonly used technique is that donors tend to replace their urine samples with clear urine samples. Apart from this, another commonly used technique is to use devices to ease substitution of the urine contents. To oppose this technique, the temperature of the sample is checked. If the sample is greater than 100 degree Fahrenheit or colder than 90 degree Fahrenheit, then re-sample is taken under direct observation.
However, measuring the temperature cannot be taken as a fair indicator despite the fact that it controls substitution of urine sample or its dilution with clean water. This is so because donors can warm the sample by keeping it close to their body, like in the armpit or groin area. This is more common because lots of techniques are available over the internet. When it was found that people substituted urine samples with Mountain Dew® drink, then the tests became more stringent. They started measuring the specific gravity, pH and mineral content. Fake samples often didn’t contain urea, despite having sodium and creatinine. The fake urine samples found over the internet counteracted by adding urea, and later potassium to make the samples seem natural.
Many donors also consume a lot of water to avoid a positive result. They consume water to sufficiently dilute the urine so that the drug concentration is lowered beyond the cutoff range. Therefore, regulations were introduced to counter these measures by checking for the specific gravity and markers such as creatinine. The issue that hinders this process is that a lot of people normally consume a lot of water because of which, it is essential that cheaters and regular water consumers are sifted out. Therefore, laboratory people now need a chart to tally the report figures. When the creatinine level falls between 20 mg/dL to 2 mg/dL with the specific gravity showing >1.0010 and <1.0030, then that sample is said to be ‘Diluted’. However, this matter remains controversial and many times, people who are higher consumers of water are required to give a repeat sample test. Moreover, if creatinine is at < 2 mg/dL and specific gravity is > 1.0010 but < 1.0200, or if the specific gravity is ≤1.0010 and creatinine is ≥2 mg/dL, then such a sample is deemed as being ‘Invalid’. However, if the creatinine concentration is <2 mg/dL with the specific gravity between ≤1.0010 or ≥1.0200, then that sample is termed as “Substituted”.
If any sample has a pH between 3 and 4.5 or 9 and 11, then they are “Invalid”. This is so because some immunoassays gave unpredictable result in these extreme pH ranges. Also, even though lesser samples have pH range beyond 4.5 and 9.0, it has been known that while transportation of urine samples, pH tends to change. Therefore, samples which are tested clinically without any delay can be quite accurate as compared to those which are stored for quite long or reach the laboratory after many days of being kept.
Many donors tend to adultrate the drug test by changing the urine constituents. A lot of techniques are found on the internet which can be used to sabotage the test and affect immunoassays. Change in pH, salts and mineral concentration can be done. Moreover, a lot of products are found on the internet which tend to ‘foil’ the test. The chemicals – also known as adulterants, can fail the initial screening test. Others tend to break the drug into small constituents so that they cannot be detected in the immunoassays or the GC/MS. For instance, Nitrate can break carboxy-THC and Iodine can break morphine.
This sabotaging of urine sample by donor is less serious as compared to a positive test result. Only those who are illegally using drugs sabotage their samples! As the laboratories gain experience, they also become smarter and are able to test for the special materials that are used to sabotage the samples. However, the manufacturers of adulterated material tend to change their constituents regularly in order to bypass the strict screening of the laboratories. The process taken for laboratories to discover and screen newer adulterants is quite tedious, which is why, most laboratories only check for the presence of nitrates, as that procedure utilizes the equipment as of the initial immunoassay test. Though, testing for nitrates requires additional screening of a second urine aliquot which is generally confirmed by ion chromatography. However, employers do not tend to pay extra to confirm what material is being used and that is why, laboratories limit their set ups as clients do not pay much especially when they know that the adulterated material tends to change quite frequently.