Choose the matrix that answers the court’s question.

Oral fluid (saliva) — very recent use
Window: typically up to 1–2 days.
Best for: immediate recent drug use checks.
Note: shorter window than urine; mainly used in workplace settings.

Urine — recent use (short window)
Window: typically ~3–4 days after last use ( cannabis and some benzodiazepines may persist longer ).
Best for: demonstrating recent abstention; unannounced series can monitor ongoing abstention.

Hair — pattern of use over months
Window: 3 cm scalp hair ≈ ~3 months; longer hair can be segmented (by prior agreement) to explore earlier periods.
Lag: allow up to ~1 week for new use to appear in hair.
Best for: retrospective assessment of drug use patterns.
Hair frequently treated (e.g., colouring) can still yield positives; discuss if harsh treatments are recent.

Nails — long-term, chronic use only
Window: ~6–12 months averaged exposure.
Sensitivity: not good for occasional or very recent use.
Practicalities: nail polish/false nails preclude sampling; nails must be long enough. Chemical treatments can reduce concentrations.

Alcohol testing
Breath / blood / urine: reflect acute or very recent alcohol status only.
PEth (finger-prick dried blood spot): ~28-day window; useful for claimed abstinence or recent drinking patterns.
Hair EtG (± FAEE): assesses abstinence or chronic excessive consumption over the hair growth period (commonly ~3 months with a 3 cm sample).

Combining matrices
Urine + Hair complements recent and historical use; particularly useful where cannabis is suspected.
Select multiple drug panels only if needed to answer the court’s question.

Service standards (what we do for every case)

• Chain-of-custody collection and secure transport.
• Analysis by ISO/IEC 17025-accredited laboratories.
• Expert interpretative report suitable for court bundles (except where noted below).
• Collections under ISO 9001-certified procedures.

Segmental hair analysis (when and how)

• Not routine; agree in advance.
• Scalp hair only; sequential segments analysed to explore earlier time periods.

Clinical alcohol tests (what to expect)

• LFT/CDT (blood) and urine EtG can indicate recent or longer-term alcohol issues, but they are clinical indicators rather than definitive measures of pattern over time.
• NIVHA issues an expert interpretative report for PEth only.
• For LFT/CDT or urine EtG, you will receive the laboratory report with general comments. If an expert opinion is required, we can arrange consultant medical interpretation on request (additional fee).
• For court questions on alcohol patterns/abstinence, PEth (~28-day window) and/or Hair EtG (± FAEE) are usually more informative.

Urine Testing
Urine testing for drugs of abuse has been routinely used in substance abuse testing programs for many years. Targeted compounds in urine are often drug metabolites, generated as a result of drugs being actively converted in the body into new compounds in order to promote their elimination.

In general, many drugs and their metabolites can be detected in urine for up to 3 or 4 days after use. There are some notable exceptions however - cannabis metabolite, for example, can potentially be detected for up to several weeks following heavy cannabis use. Alcohol and the main heroin metabolite (acetylmorphine) are usually eliminated within 12 hours.

Urine Collection
A sample of urine is collected using a sampling kit designed for this purpose. Although direct observation of the collection is not usually appropriate, measures are taken to minimise the potential for sample adulteration or substitution. The collection facility is suitably prepared prior to collection taking place - donors are asked to wash their hands before collection, access to water taps is controlled and the temperature of the collected sample is monitored. In addition to these measures, each sample is routinely analysed in the laboratory for adulteration/dilution markers before analysis begins.
Collection is carried out under full chain-of-custody conditions. Before the collected sample is labelled and sealed, it is divided into several portions, one of which is retained unopened in the laboratory in case of dispute.

Urine Analysis
A sample of the submitted urine is initially screened in the laboratory for a number of target drug groups. If screening analysis presumptively detects drugs at a concentration that exceeds pre-defined cutoffs, another portion of the sample is taken and processed for confirmatory analysis.
This confirmatory analysis is specifically directed towards individual members of the drug groups that were found to be non-negative at the screening stage. Confirmatory analysis is carried out using highly specific techniques capable of identifying individual drugs with absolute certainty and measuring their concentrations.

If the concentrations of confirmed drugs are above pre-defined cutoffs, a positive laboratory report is issued. If the drugs detected are consistent with medication declared at the time of collection, this is reflected in the laboratory report. If drugs resulting from prescribed medication are detected, the donor should be able to demonstrate legitimate prescription.
If either the screening or confirmatory results are such that drug concentrations lie below the defined cutoff values, no further work is undertaken and a negative laboratory report is issued.

Urine Cutoffs
Cutoff concentrations are used to distinguish those samples that are to be considered negative or positive. Such interpretative cutoffs are commonly used in the drug testing industry for workplace and substance abuse casework and cutoffs for many common drugs have been defined in industry guidelines (eg. European Workplace Drug Testing Society (ewdts.org)).
These cutoffs are usually applied in the laboratory and their application enables drug test results to be used to identify drug use with a high probability; passive or low level exposure is likely to result in a negative outcome.
Quantitative results are reported in such a way that allowance has been made for analytical variation.
Cutoffs may also be represented by the sensitivity of the analytical method and in these cases expert interpretation of the results is provided. This can occur for example where cutoffs for a particular drug have yet to be defined within the drug testing industry.

Urine - Scope of Analysis
The drugs included in the analytical panels include the majority of common drugs of abuse. Donors may be breathtested for alcohol at the time of collection. Special targeted analysis for unusual drugs is also available on request and may be appropriate in the testing for specific drugs or New Psychoactive Substances (NPS).

Urine - Alcohol Markers:
Urine testing for alcohol markers (EtG and EtS) can be useful in some circumstances. These compounds are minor metabolites of alcohol and can be detected in urine after alcohol has been eliminated. EtG can be detected in urine for up to about 24 hours, even after consumption of small quantities of alcohol; after excessive consumption the window of detection can be longer. EtG and EtS levels in urine cannot distinguish between a binge drinking event several days beforehand and minor alcohol intake a few hours before the sample was taken.

Hair Testing
Although a typical 3-cm proximal length of scalp hair represents drug use averaged over a 3-month retrospective time period approximately, time boundaries can be diffuse due to growth rate variation and incorporation from sweat and sebum. For this reason, sufficient time must be allowed to elapse for a period of abstinence to be reflected in hair drug concentrations.

Although scalp hair is preferable, hair taken from other sources (eg chest & body hair) can also be used. The time period covered by a sample of non-scalp hair generally represents a longer retrospective time period than a similar length of scalp hair and as hair samples from alternative sources are analysed in their entirety, analysis can represent a much longer retrospective detection period.
Note that neither underarm nor pubic hair is suitable for alcohol marker analysis.
Also, as underarm hair drug concentrations can be lower, hair from this source should only be selected if unavailable elsewhere. 

Hair Collection
A sample of hair (roughly the width of a pencil) is taken from the back of the crown of the head (posterior vertex). In subjects who have poor hair distribution, several smaller locks can be obtained and combined. The most common length of head hair analysed is 3 cm (proximal), even though a longer sample is often collected; a 3-cm length of scalp hair analysed represents a retrospective time period of 3 months, approximately.
Although shorter samples of hair can also be collected, representing shorter growth periods, it is advisable that at least 3-cm is available for analysis for alcohol markers.
Collection is carried out under full chain-of-custody conditions, usually in duplicate (one of the samples is reserved unopened in the laboratory in case of dispute).

Hair Analysis
In the laboratory, a sample of submitted hair is analysed for a range of target drugs & their metabolites.

The hair is washed in the laboratory using a procedure validated for this purpose to remove surface contamination prior to further analysis.. Analysis is carried out using highly specific techniques capable of identifying individual drugs with absolute certainty and measuring their concentrations.
As part of the protocol, the washings may also be analysed to help assess the potential influence of environmental drug exposure.
There can be some variation in the detail of the analytical strategy depending on the laboratory used and particular drugs targeted.

Hair Cutoffs
Cutoff concentrations are used to distinguish which samples are to be considered negative or positive. Such interpretative cutoffs are commonly used in the drug testing industry for workplace and substance abuse casework and cutoffs for many common drugs have been defined [eg. Guidelines of the Society of Hair Testing (soht.org) and European Workplace Drug Testing Society, (ewdts.org)].
These cutoffs can be applied in the laboratory and their application enables drug test results to be used to identify drug use with a high probability; low level, occasional or historic drug use is likely to result in a negative outcome.
Quantitative results can be reported in such a way that allowance will have been made for variation in analytical measurement.
The cutoffs used can also be represented by the analytical sensitivity of the method and in such circumstances expert interpretation of the results will be provided.

Hair - Scope of Analysis
The drugs included in each analytical panel have been defined and a detailed list of the drugs/metabolites targeted is included in the laboratory report. Short descriptors for the panels are provided in the tables below.
Although the standard panels include the majority of common drugs of abuse, special targeted analysis is also available for unusual drugs. This may be appropriate in the testing for specific drugs, anabolic steroids or for New Psychoactive Substances (NPS).
Details of unusual or specific requests should be discussed with NIVHA prior to collection being arranged.

Hair - Alcohol Markers
Although analysis for alcohol in hair is not possible, analysis for its minor metabolites can be used as an indication of excessive alcohol consumption. These metabolites are ethyl glucuronide (EtG) and FAEE’s (fatty acid ethyl esters) and their concentrations in hair can be used to support an assertion of chronic excessive alcohol consumption. They can also be used to help confirm self-declared abstinence.
EtG is the most useful metabolite used for this purpose although analysis for FAEE’s (at additional cost) can be a useful enhancement. Although EtG concentrations can be reduced by chemical treatment of the hair, FAEE concentrations can be elevated by the use of alcohol-containing hair-care products.

The evidential value of these compounds is maximised if analysis is carried out on scalp hair segments of between 3 and 6 cm in length. Body hair can also be used, but the interpretative value of the results will be associated with greater uncertainty; full interpretative support will be provided in hair alcohol cases. Pubic and underarm hair are not suitable for alcohol assessment.

Hair - Segmental Analysis
Although hair analysis results typically represent an average of drug intake during the entire growth period, segmental analysis can be useful in certain circumstances. With this technique, more detailed information on drug abuse profiles can be useful. If segmental analysis is considered, NIVHA can provide expert guidance on its application for a particular case.

Hair Drug (& Alcohol) Panels
For hair drugs analysis we offer 4 defined panels, covering many of the drugs of abuse encountered, and their metabolites. Most of the common drugs of abuse are covered in panel 1 and this can be expanded at extra cost to include additional drugs listed in panel 2. All of the drugs included in panels 1 and 2 have industry standard cut-offs already defined.

The drugs listed in panel 3 can be requested to further expand the scope of panels 1 & 2 or can be requested as a stand-alone panel. Currently the drugs listed in panel 3 do not have cut-offs defined, but interpretative guidance will be provided when appropriate.

Panel 4 contains a selection of unregulated benzodiazepine drugs. These non-pharmaceuticals are currently prevalent in crime casework in Northern Ireland and GB. This panel is likely to be of particular interest if ‘street’ benzodiazepine use is suspected. It can be selected as a stand-alone product (DP4) or in addition to DP1 or DP2 (common drugs of abuse and pharmaceutical benzodiazepines).

In addition to the standard panels, analysis for anabolic steroids, alcohol markers and New Psychoactive Substances is also offered.

Some minor variation in the details of drugs listed in the panels is possible; specific drugs analysed in each case is provided in individual laboratory reports.

Although hair testing is well established for retrospective drug abuse assessment over extended periods, there are some circumstances when nail clippings may be used as a suitable alternative.  These include unavailability of scalp and body hair, or if recent harsh chemical treatment of scalp hair could have potentially reduced drug concentrations to sub- cutoff levels.

Although many donors treat their hair (eg. colouring), positive outcomes in this cohort of casework (ie drugs detected) are still commonly encountered.

It should also be noted that nails can also be subjected to chemical treatment, and such treatment can reduce drug concentrations. 

Nail polish, false nails will preclude analysis. The nails must also be long enough for the sample to be taken.

Sensitivity

If nail clippings are used for drug use assessment, sensitivity of detection will be limited to chronic, long-term drug use averaged over a period of 6 to 12 months; less frequent use (or recent use) may not be picked up.  
 

Interpretation of Results  

Although the drug panels used for hair can also be used for nail clippings, hair cutoffs are not valid when interpreting drug concentrations found in nails; there is no current consensus which can be applied to nail clippings. 
Nail concentrations of the main alcohol marker (EtG) tend to be much higher than those in scalp hair.

As there is no current cutoff consensus for alcohol intake assessment using nails, it is not recommended that EtG concentrations in nails are routinely used for this purpose (for hair, there is cutoff consensus for self-declared abstinence and chronic excessive alcohol use). If suitable hair is not available, blood PEth may be considered a useful alternative to nails.

Blood testing for alcohol markers can be a useful adjunct to hair and urine testing or as part of an ongoing monitoring regime. The results should not be used in isolation of other evidence.

The assessment of alcohol consumption is best carried out using several analytical tests and other factors.

Indirect alcohol markers include liver function tests, in particular gamma glutamyl Transferase (GGT), mean corpuscular volume (MCV) and Carbohydrate-deficient Transferrin (CDT). In general, these markers are enzymes or cell changes in response to acute or chronic alcohol consumption.

Direct alcohol markers are created when alcohol is metabolized or reacts with substances in the body. Phosphatidyl Ethanol (PEth) is a direct alcohol marker produced after alcohol exposure in cell membranes. It is reported to be independent of gender, age and liver disease, is relatively specific and has a detection window of up to several weeks after alcohol intake.
Although no international consensus exists at present for the interpretation of PEth concentrations in blood, its application potential is broader than for many other alcohol markers and can be useful in the overall assessment of alcohol use.

Blood Collection
Blood collections are carried out using a standardised evacuated blood collection system, supplied by the laboratory. The collected sample is dispatched to the laboratory for analysis. There is no provision for the collection of a ‘B’ sample for this type of testing. Sample integrity systems are typical of those used in clinical laboratories.

Blood Analysis
Blood samples are analysed by CPA/ISO accredited laboratories. Results are accompanied with general interpretative information such as reference ranges and may or may not include interpretive comments specific for a particular case.

- PEth analysis in liquid blood has now been replaced with PEth analysis using

Dried Blood Spots
This approach has significant advantages over venepuncture. 

A small volume of capillary blood is collected by a simple finger-prick. A tiny amount of the blood is transferred onto absorbent material using a specially designed capillary device. This ‘dry blood spot’ is then despatched to the laboratory for analysis.

This test is a modern, sensitive alternative to using venous blood and can detect alcohol use for up to several weeks after cessation. The test is fully accredited under international quality standard ISO-17025
Full chain-of-custody protection and expert interpretative reporting are both a feature of this service.

The PEth-DBS test can usefully complement hair EtG analysis, particularly in individuals with hair that has been subjected to harsh chemical treatment or if an assessment of recent alcohol use is required.

The following table provides a rough guide to the detection times expected after the last instance of use for a range of common drugs and alcohol. These approximations are dependent on a number of factors, including pattern of use, dose administered and detection cutoff concentrations (usually standardized for workplace testing).

Oral fluid - concentrations generally reflect blood concentrations after the first few hours following use. In general, drugs can be detected for a day or so in oral fluid with some exceptions.

Urine - drug metabolites are usually targeted in urine, and many drugs of abuse can be detected for up to 3 or 4 days after use. Cannabis and long-acting benzodiazepines such as diazepam have longer persistence potential, depending on how they are used.

Hair – because drugs are incorporated into growing hair, the analysis of a sample of hair can detect retrospective drug use for a much longer period than oral fluid or urine. For example, the analysis of a 3 cm proximal sample of scalp hair reflects drug or alcohol abuse history over a 3-month period approximately. The retrospective time period of drug detection is usually extended for non-scalp hair.

Nail - If nail clippings are used for drug use assessment, sensitivity of detection will be limited to chronic, long-term drug use averaged over a period of 6 to 12 months; less frequent use (or recent use) may not be picked up.

Blood- generally not used in these case types, although some clinical blood tests may be useful in monitoring alcohol use.

Alcohol Markers in Blood
PEth is a direct alcohol marker and can be detected in blood for up to several weeks after alcohol use, depending on original alcohol consumption levels.
Indirect clinical alcohol markers such as CDT, LFTs, MCV can also be useful in some cases. These markers reflect changes in response to alcohol consumption and may not be as sensitive to moderate consumption or episodic drinking.