Storage Induced Artifacts

Question 1

Freeze-Thaw cycle

Answer 1

May impact stability of a drug
Decrease in concentration

Question 2

Photo Degradation

Answer 2

Light may induce decomposition w/ decreased in []
phenothazin

Question 3

Solvent Artifacts

Answer 3

Screen blood and other specimens for volatile substances
Dx acute toxicity
Vacutainers are routinely used for blood collection
Some contain significant amounts of VOCs
Toluene,o,m,p xylenes, ethylbenzene
Sources
Butyl rubber stoppers
Serum separator tube gels
Compounds introduced during manufacturing process

Question 4

Ethylbenzene and Xylene from Sarstedt Monovette Serum gel Blood collection tubes Case

Answer 4

nvestigation of a delayed death in MVA
Hx suggestive of possible solvent abuse
Testing of admission blood serum
Sarstadt Monovette Serum Gel tube
Ethylbenzene 17.6mg/L
M and p-xylene 10.9mg/L and o-xylene 9.7mg/l (coelute)
Red Flag: Lab experience finding of xylenes very rare
Questioned the source of volatiles
Huffing vs interference/artifact

Question 5

Ethylbenzene and Xylene from Sarstedt Monovette Serum gel Blood collection tubes Case

Answer 5

Confirmed use of ethylbenzene and xylene in manufacture of gel
Tubes filled with volatile free blood
Stand at room temperature for 24 hrs
Centrifuged and blood was sampled
Blood [] increase in all cases up to 96 hrs
Slight increase 96-120 hours in some
Significant difference in conc. Correlated with exp. Date suggestive of out-gassing

Question 6

Volatile Contamination due to collection tube
Dyne et al Case study

Answer 6

2 workmen using toluene-containing glue in an enclosed space were found unconscious
Admission plasma toluene concentrations were 6.6 and 3.3
Serum toluene concentration at 48 hrs were 11.2 and 19.2mg/L respectively
Sarstedt serum gel collection tubes
Contamination suspected as an explanation of rise in toluene concentration while in hospital care

Question 7

Dyne Research

Answer 7

Obtained a number of Sarstedt Monovette serum gel tubes
Added volatile free blood to each and incubated at room temp for up to 101 hrs
Samples were collected over the incubation time and tested
Contaimination noted in each tube
Toluene, 1-butanol, ethylbenzene, m/p xylene, oxylene
Concentratioons increased over time

Question 8

Contamination from blood sample containers

Answer 8

NPD gas chromatography eliminated many common interference encountered w/FID or MS
Phthalate plasticizers
Methylated fatty acids
Numerous authors using GC-NPD systems reported interference from plasticizer tributoxyethyl phosphate
Found in Vacutainers
Another contaminant Found in natural rubber seals N-isopropyl N- phenyl-p-phenylenediamine

Question 9

Vacutainer Effect exp. date

Answer 9

loose vacuum air in and air out containmination

Question 10

Vactutainer Effect most important

Answer 10

absorption adherence to rubber stopper losing concentration of particular drug

Question 11

Vacutainer Effect-ON THE TEST Jennison el al

Answer 11

Monitoring amitriptyline and nortriptyline in psychiatric patients noted sampling and storage conditions adversely affected the quantitation of these analytes
Decreases averaging 10% were found when various vacutainer tubes were refrigerated on their side for 24 hours
Evaluated effects of collection tubes
Samples were drawn with a glass syringe and various brands of vacutainer tubes
Some tubes decreased drug levels by 5 – 15%
Samples incubated @ 37 C for 2.5 hours in contact with a vacutainer stopper
Decreases averaging 44% and 41% for amitriptyline and nortriptyline, respectively

Question 12

Vacutainer effect Zetin

Answer 12

studied the effects of different sample-handling techniques on antidepressant drug concentrations
Whole blood placed into BD Vacutainer without stopper and covered with parafilm, with varying time from collection to centrifugation to plasma separation
Whole blood placed into BD vacutainer with green top [heparin]
Whole blood placed into the plastic syringe, then into a vacutainer
Decrease due to stopper

Question 13

Serum Separator Tube

Answer 13

Vacutainer Serum-Separator tubes used to collect hospital blood samples
May be only antemortem blood available
Tubes gained widespread acceptance in the clinical arena

Question 14

Adv. of serum separator tubes

Answer 14

advantage of barrier gel, rapid separation of serum from cellular constitutes of blood and prevents hemolysis on prolonged storage
relevative density of the gel is intermediate to serum an coagulum
serum separated from coagulum after clotting and centrifugation

Question 15

Major disadv. serum separator tubes

Answer 15

reduction in drug concentration are seen due to slow absorption of drug into the serum separator gel.
Reduction is related to time and sample
Greater time and smaller volume

Question 16

What drugs are minimally effected by SST

Answer 16

Caffeine, primidone, NA-PA, procainamide (PA), APAP, ASA, Valporic acid

Question 17

What drugs are significantly effected by SST

Answer 17

Lidocaine, phenobarb, phenytoin, TCAs

Question 18

Other drugs effected by SST

Answer 18

MTD, Benzoylecgonine [personal exp]

Question 19

Parish and Alexander Phenytoin
Dont need to know just know that there was heavy loss at room temp

Answer 19

Blood collected in plain tubes were more stable than compared to SST
Absorption in tube
No degradation occurred in plain red-tubes or SST that were refrigerated
Loss was present in SST stored at room temperature and elevated temp after 24hrs collected
Mean loss at room temp and elevated 17 and 25%

Question 20

Dasgupta study
Just know last two lines

Answer 20

evaluated the stability of seven commonly monitored therapeutic drugs
Phenytoin, phenobarbital
Lidocaine, quinidine, carbamazepine
Theophylline and salicylate
Significant decreases were noted [5.9% to 64.5%] in all but theophylline and salicylate
Decrease was a function of time and sample volume
Decreases were due to the absorption of drugs into gel barrier

Question 21

Reduced serum tricylic levels were due to

Answer 21

Gel Separators

Question 22

Nyberg and Martensson

Answer 22

Evaluated the stability of TCAs [amitriptyline, imipramine, clomipramine and their monomethylated metabolites in venous blood
Compared to venoject red [plain tube] and serum separator gel tubes
Losses greater than 40% in serum separator tubes
Result in content with gel and caps of tubes

Question 23

Methadone

Answer 23

also had decrease in concentration

Question 24

Shepard and Bliumkin

Answer 24

After storage for 1 day, ~50% of the drugs or metb have significantly lower concentrations [up to 27% lower] as compared to the non-gel tubes
After storage for 3 months, ~75% of drugs or metb had significantly lower concentrations compared to the non-gel tubes
Fentanyl, carfentanil, ketamine, diphenhydramine, and several antidepressants most susceptible to adsorption
Stimulants (meth, amp), opiates (morphine), and semi-synthetic opioids (HYM, OxyC] were least susceptible to loss
Benzos moderate to significant loss was observed

Question 25

Trace Metals

Answer 25

Rodushkin and Odman assesses potential contamination risk associated with devices routinely used in hospitals and clinical laboratories for collection and storage of blood
Tubes,vials,gel separators,needles
Evaluated 70 different elements
Apparent [] of several elements Al,Ba,Th,rare earth elements were higher in all devices tested

Question 26

Citrate Tubes

Answer 26

GHB
Evidence of in vitro production
Storage condition and sample type
Immediate prep of serum
Whole blood frozen
Elevated GHB in Citrate buffered blood
Ante and post
Citrate tubes
Yellow top, yellow tubes,black top w/yellow ring, pink top
Source of GHB not fully
LeBeau

Question 27

plastic vs glass SST

Answer 27

No difference besides CO2 that was expected due to opening and losing gas