The influence of several variables on hair research

1. Experimental background

According to the "Specifications for the Detection of Hair Samples for Drug-related Persons", it is understood that the requirements for collecting hair samples are "When extracting hair samples, the staff should wear disposable gloves, use medical scissors or serrated scissors to close the scalp surface of the person to be extracted and cut the back of the head.

(If you cannot extract enough hair from the back of the head, you can choose the head part closest to this part) Hair less than 3 cm in length; hair longer than 3 cm should be cut 3 cm from the root end.

"At the same time" the extracted hair samples should be divided into two parts, A and B, each with a weight of no less than 50 mg."

According to the industry standards of the Ministry of Justice, the Ministry of Public Security and the local standards of the Ministry of Public Security related to hair drug testing, the grinding sample size ranges from 20-50 mg, and the follow-up tests are mostly combined with chromatography and mass spectrometry.

2. Experimental process

 A. The influence of grinding time on grinding effect (control frequency is 50Hz)

(1) Sample collection and instrument preparation

√ About 50mg of dui gouduigou 2-3cm hair sample;

√ Grinding tube;

√ High-throughput tissue grinder, SCIENTZ-48L;

(2) Experimental design and results

step:1) Take 50.0mg of hair with a length of 5mm-2cm and put it into the grinding tube;

       2) Add 6 3mm grinding steel balls and close the lid tightly (see Figure 1);

       3) Set the instrument frequency to 50HZ, normal temperature, and time to 360s, 720s.

Result:

1) After grinding for 360s, the hair is in short fragments, some of which are 2-5mm in length 

2) Continue to grind for 360s, the hair is powdery 

B. The influence of grinding power on grinding effect

(1) Sample collection and instrument preparation

√ About 50mg of 2-3cm hair sample;

√ Grinding tube;

√ High-throughput tissue grinder, SCIENTZ-48L;

(2) Experimental design and results

step:1) Take 50.0mg of hair with a length of 5mm-2cm and put it into the grinding tube;

       2) Add 6 3mm grinding steel balls and close the lid tightly (see Figure 4);

      3) Set the normal temperature of the instrument, 360s, and the frequency to choose 50Hz and 60HZ respectively.

Result:

1) After grinding for 360s at 60Hz frequency, the hair is in powder form (see Figure 5).

2) After grinding for 360s at 50Hz frequency, the hair is in the form of short fragments, some of which are 2-5mm in length (see Figure 6)

C. The impact of grinding sample size on grinding

(1) Sample collection and instrument preparation

About 100mg of 2-3cm hair sample;

Grinding tube;

High-throughput tissue grinder, scientz Bio-SCIENTZ-48L;

(2) Experimental design and results

step:

1) Take 25.0mg and 50.0mg of hair with a length of 5mm-2cm and put it into the grinding tube;

2) Add 6 3mm grinding steel balls and close the lid tightly (see Figure 7);

3) Set the instrument's normal temperature, 360s, and frequency to 60HZ respectively.

Result:

1) After a 25mg sample is ground for 240s at 60Hz frequency, the hair appears as short fragments.

2) After grinding a 25mg sample at 60Hz frequency for 360s, the hair is powdery

3) After grinding a 50mg sample at 60Hz frequency for 360s, the hair is powdery

3. Experimental conclusion

(1) Under the same power, the longer the grinding time, the shorter the hair fragments and the finer the particle size;

(2) At the same time, the higher the grinding frequency used, the shorter the hair segment and the finer the particle size;

(3) Under the same power and time, the amount of sample in the grinding tube (unsaturated state) has a small difference in the grinding effect;

(4) It is recommended to use a more robust and reliable grinding tube, which can further shorten the grinding time when the frequency is increased.