阅读说明：本技术 一种检测血清中5-羟色胺和褪黑素浓度的方法 (Method for detecting concentration of 5-hydroxytryptamine and melatonin in serum ) 是由 成晓亮 尚红 韩晓旭 戴锦娜 李美娟 张伟 于 2021-06-11 设计创作，主要内容包括：本发明提供一种检测血清中5-羟色胺和褪黑素浓度的方法,在血清样品的预处理过程中采用碳酸钠溶液作为pH调节剂,甲基叔丁基醚作为萃取液,可以增强5-羟色胺的萃取效率,并筛选出最佳的流动相、梯度和色谱柱等色谱条件,可以一次性对血清中5-羟色胺和褪黑素同时进行检测,灵敏度高、特异性强、准确且前处理过程简单,5.5分钟之内完成血清中5-羟色胺和褪黑素的分离和检测,准确度与精密度基本满足要求,可用于临床上血清中5-羟色胺和褪黑素的定量分析,为临床上5-羟色胺和褪黑素浓度监测提供简单快速的检测方法。(The invention provides a method for detecting the concentration of 5-hydroxytryptamine and melatonin in serum, which adopts sodium carbonate solution as a pH regulator and methyl tert-butyl ether as an extraction liquid in the pretreatment process of a serum sample, can enhance the extraction efficiency of the 5-hydroxytryptamine, screens out optimal chromatographic conditions such as a mobile phase, a gradient, a chromatographic column and the like, can simultaneously detect the 5-hydroxytryptamine and the melatonin in the serum at one time, has high sensitivity, strong specificity and simple pretreatment process, completes the separation and detection of the 5-hydroxytryptamine and the melatonin in the serum within 5.5 minutes, basically meets the requirements on accuracy and precision, can be used for the quantitative analysis of the 5-hydroxytryptamine and the melatonin in the serum clinically, and provides a simple and rapid detection method for the concentration monitoring of the 5-hydroxytryptamine and the melatonin in the clinically.)

1. A method for detecting the concentration of 5-hydroxytryptamine and melatonin in blood serum is characterized in that,

the internal standard substances corresponding to the 5-hydroxytryptamine and the melatonin are respectively as follows: 5-hydroxytryptamine-d 4 and melatonin-d 4;

detecting 5-hydroxytryptamine and melatonin in pretreated serum by adopting an ultra-high performance liquid chromatography tandem mass spectrometry technology, separating a substance to be detected from a serum matrix by utilizing the ultra-high performance liquid chromatography, establishing a calibration curve by utilizing a mass spectrometry isotope internal standard quantitative method and taking the concentration ratio of a standard substance to an internal standard substance as an X axis and the peak area ratio of the standard substance to the internal standard substance as a Y axis, and calculating the content of the 5-hydroxytryptamine and the melatonin, wherein the specific chromatographic conditions are as follows:

(1) ultra-high performance liquid chromatography conditions:

mobile phase A: 0.01 to 0.2 percent of formic acid-1 to 5mM ammonium acetate aqueous solution; mobile phase B: methanol;

the type of the chromatographic column: waters BEH C18;

a mixed mobile phase A and a mixed mobile phase B are adopted for gradient elution, and the initial ratio of the mobile phase A to the mobile phase B is 85-100: 25-0; the gradient elution procedure was as follows: in 0-1.5 minutes, the volume ratio of the mobile phase A to the mobile phase B is gradually changed from the initial ratio to 2:98 at a constant speed; the volume ratio of the mobile phase A to the mobile phase B is kept constant at 2:98 within 1.5-3.5 minutes; in 3.5-5.5 minutes, the volume ratio of the mobile phase A to the mobile phase B is gradually changed from 2:98 to the initial ratio at a constant speed; each sample was collected for 5.5 minutes;

(2) mass spectrum conditions:

in an electrospray ionization positive ion detection mode, a mass spectrum scanning mode of multi-reaction monitoring is adopted, and the capillary voltage is 0.5kV (ESI +); the ion source temperature is 150 ℃; the desolventizing temperature is 400 ℃; the desolventizing gas flow rate is 800L/hr; the air flow rate of the taper hole is 150L/hr; each target and its corresponding isotope internal standard were monitored simultaneously.

2. The method of claim 1,

the initial ratio of the mobile phase A to the mobile phase B is 90-95: 10-5; the mobile phase A is 0.1-0.15% formic acid-1.5-2.5 mM ammonium acetate aqueous solution; the flow rate is 0.2-0.4 ml/min; the column temperature is 30-50 ℃; the injection volume is 1-10 mu L.

3. The method of claim 2,

the initial ratio of mobile phase a to mobile phase B is 90: 10; the mobile phase A is 0.1% formic acid-2 mM ammonium acetate aqueous solution; the flow rate is 0.3 ml/min; the column temperature was 40 ℃; the injection volume was 5. mu.L.

4. The method of claim 1, wherein the serum is human or animal serum.

5. The method of claim 1,

the pretreated serum was prepared as follows: adding the internal standard working solution, the pH regulator and the extraction liquid into the serum for extraction, oscillating, carrying out centrifugal treatment, taking supernatant, drying by nitrogen flow, mixing with redissolved solution, carrying out centrifugal treatment again, taking the supernatant for sample injection; wherein the pH regulator is 0.1-0.5M sodium carbonate solution, preferably 0.15-0.25M sodium carbonate solution, and more preferably 0.2M sodium carbonate solution; the extract is methyl tert-butyl ether; the complex solution is 10-80% methanol water solution, preferably 50% methanol water solution.

6. The method of claim 5,

the pretreated serum was prepared as follows: putting 200 mul of serum into a 1.5ml centrifuge tube, adding 20 mul of internal standard working solution, 20 mul of 0.2M sodium carbonate solution and 900 mul of methyl tert-butyl ether, oscillating for 3-10 min, and centrifuging for 4-10 min under the conditions of 12000-15000 r/min and 4-20 ℃; and then, drying 850 mu l of supernatant through nitrogen flow, mixing the supernatant with 80 mu l of 50% methanol aqueous solution, oscillating for 1-5 min, centrifuging for 1-5 min under the conditions of 12000-15000 r/min and 4-20 ℃, and taking the supernatant for sample injection.

7. The method according to claim 5 or 6,

the internal standard working solution is prepared according to the following method:

preparing the following internal standard mother liquor by using a methanol aqueous solution: 5-hydroxytryptamine-d 41 mg/ml, melatonin-d 40.01mg/ml;

respectively transferring each internal standard mother solution: 5-hydroxytryptamine-d 410 μ l, melatonin-d 44 μ l; then adding the mixture into 986 mu l of methanol water solution to obtain 1ml of mixed internal standard solution;

and adding 10uL of the mixed internal standard solution into 0.99ml of pure methanol to obtain the internal standard working solution.

8. The method of claim 7,

the standard is prepared according to the following method:

5-hydroxytryptamine and melatonin are prepared into standard mother liquor with the following concentrations: 1mg/ml of 5-hydroxytryptamine and 0.01mg/ml of melatonin;

respectively transferring mother liquor of each standard product: 20 mul of 5-hydroxytryptamine and 2 mul of melatonin; then adding the mixture into 978 mu l of methanol water solution to obtain 1ml of mixed standard stock solution;

preparing the mixed standard stock solution into a calibrator solution with seven different concentration points by using a blank serum matrix, wherein the seven concentration points of the calibrator solution are as follows:

seven concentration points of 5-hydroxytryptamine are as follows: 1ng/ml, 2.5ng/ml, 5ng/ml, 25ng/ml, 50ng/ml, 250ng/ml, 500 ng/ml;

the seven concentration points of melatonin are in order: 0.001ng/ml, 0.0025ng/ml, 0.005ng/ml, 0.025ng/ml, 0.05ng/ml, 0.25ng/ml, 0.5 ng/ml.

9. The method according to claim 7 or 8, wherein the aqueous methanol solution is 10% to 80% aqueous methanol solution, preferably the aqueous methanol solution is 50% aqueous methanol solution.

10. The method according to claim 8, wherein the serum blank matrix is 5% to 15% aqueous methanol, preferably 10% aqueous methanol.

Technical Field

The invention belongs to the technical field of blood detection, and particularly relates to a method for detecting concentrations of 5-Hydroxytryptamine (5-HT) and Melatonin (MLT) in serum.

Background

5-hydroxytryptamine and melatonin are important indoleamine neurotransmitters in human bodies, have various biological activities of regulating biological rhythm, emotion, cognition, removing free radicals, promoting inflammation signal conduction and the like, and have important influence on bone metabolism. Melatonin is a metabolite of 5-hydroxytryptamine and can be converted into melatonin via 5-hydroxytryptamine N-acetyltransferase and 5-hydroxytryptamine N-acetylmethoxytransferase. In recent years, domestic and foreign researches discover that 5-hydroxytryptamine participates in the processes of bone formation and bone resorption, including the osteogenesis promoting effect of central 5-hydroxytryptamine and the negative regulation effect of peripheral 5-hydroxytryptamine on bone formation; meanwhile, the melatonin also has the functions of promoting the proliferation and differentiation of osteoblasts and expressing an osteodifferentiation marker, can inhibit the differentiation of osteoclasts by promoting the secretion of OPG and eliminating osteoclast free radicals, plays an important role in maintaining the dynamic balance of bone metabolism, and provides a new target and direction for bone metabolism diseases such as osteoporosis and the like. The ultra-high performance liquid chromatography tandem mass spectrometry technology is utilized to simultaneously detect the concentrations of 5-hydroxytryptamine and melatonin in serum, changes of the bone mass and the bone structure of a human body can be reflected by circulating the levels of the 5-hydroxytryptamine and the melatonin, the method is used for evaluating the osteoporosis conditions of the old, postmenopausal women, type 2 diabetes patients and other people, and scientific basis is provided for clinical diagnosis and treatment.

Chinese patent (application number: 201610220614.X) of Beijing Lockey clinical laboratory Co., Ltd in 2016 discloses a method and a kit for detecting melatonin in saliva by using high performance liquid chromatography tandem mass spectrometry, which provides a method for detecting melatonin in saliva by using high performance liquid chromatography tandem mass spectrometry, wherein the method has the advantages of single detection component, simple matrix, simple pretreatment condition if only melatonin is detected, high extract toxicity, long nitrogen blowing time and unsuitability for pretreatment of serum samples, 5-hydroxytryptamine and melatonin cannot be simultaneously detected even if the chromatographic condition and the pretreatment method in the patent are adopted, and the method has no great reference value for clinical detection of melatonin in serum. Another patent (application No. 201910058794.X) discloses a method for simultaneously detecting the content of multiple biogenic amines in soy sauce by HPLC, wherein although an object to be detected contains 5-hydroxytryptamine, a sample to be detected is not a biological sample, a matrix is simple, and a derivatization method is adopted for pretreatment, so that the method is very complicated.

Since 5-hydroxytryptamine and melatonin belong to alkaline and neutral substances respectively and are difficult to detect together, at present, the simultaneous detection of 5-hydroxytryptamine and melatonin in serum is not reported, and people such as Chau RM (Chau RM, Panel BA. determination of serotonin, memorandum and vitamins in gastrointestinal tract use high-performance electrochemical detection. biomeded chromatograph.2009, 23(2): 175-81) and the like adopt an electrochemical analysis technology to detect 5-hydroxytryptamine and melatonin together, the sensitivity is low (the detection limit of melatonin is 70ng/ml), the clinical detection requirement cannot be met, the analysis time is long (30min), and the clinical application is not beneficial.

Disclosure of Invention

The invention aims to provide a method for detecting the concentrations of 5-hydroxytryptamine and melatonin in serum on the basis of the prior art.

The technical scheme of the invention is as follows:

a method for detecting the concentration of 5-hydroxytryptamine and melatonin in serum,

wherein, the internal standard substances corresponding to the 5-hydroxytryptamine and the melatonin are respectively as follows: 5-hydroxytryptamine-d 4(5-HT-d4), melatonin-d 4(MLT-d 4);

after a serum sample is pretreated, oscillating and centrifuging, taking a supernatant for sample injection, detecting 5-hydroxytryptamine and melatonin in pretreated serum by adopting an ultra-high performance liquid chromatography tandem mass spectrometry technology, separating a substance to be detected from a serum matrix by using the ultra-high performance liquid chromatography, establishing a calibration curve by using a mass spectrum isotope internal standard quantitative method, taking the concentration ratio of a standard substance and an internal standard substance as an X axis and the peak area ratio of the standard substance and the internal standard substance as a Y axis, and calculating the content of the 5-hydroxytryptamine and the melatonin, wherein the specific chromatographic conditions are as follows:

(1) ultra-high performance liquid chromatography conditions:

mobile phase A: 0.01 to 0.2 percent of formic acid-1 to 5mM ammonium acetate aqueous solution; mobile phase B: methanol;

the type of the chromatographic column: waters BEH C18 (2.1X 100mm,1.7 μm);

a mixed mobile phase A and a mixed mobile phase B are adopted for gradient elution, and the initial ratio of the mobile phase A to the mobile phase B is 85-100: 25-0; the gradient elution procedure was as follows: in 0-1.5 minutes, the volume ratio of the mobile phase A to the mobile phase B is gradually changed from the initial ratio to 2:98 at a constant speed; the volume ratio of the mobile phase A to the mobile phase B is kept constant at 2:98 within 1.5-3.5 minutes; in 3.5-5.5 minutes, the volume ratio of the mobile phase A to the mobile phase B is gradually changed from 2:98 to the initial ratio at a constant speed; each sample was collected for 5.5 minutes;

(2) mass spectrum conditions:

in an electrospray ionization positive ion detection mode, a mass spectrum scanning mode of multi-reaction monitoring is adopted, and the capillary voltage is 0.5kV (ESI +); the ion source temperature is 150 ℃; the desolventizing temperature is 400 ℃; the desolventizing gas flow rate is 800L/hr; the air flow rate of the taper hole is 150L/hr; each target and its corresponding isotope internal standard were monitored simultaneously.

In order to improve the chromatographic separation selectivity, it may be considered to adjust the polarity of the mobile phase. The invention adds formic acid and ammonium acetate into the mobile phase A, can effectively improve the ionization efficiency of the target compound, has higher sensitivity for detecting the 5-hydroxytryptamine and the melatonin in the serum by adopting an LC-MS/MS method compared with the prior art under the coordination of other conditions, has simple pretreatment process, low cost, high sensitivity and strong specificity, and completes the separation and detection of the 5-hydroxytryptamine and the melatonin within 5.5 minutes. In a preferred embodiment, the mobile phase A is 0.1% -0.15% formic acid-1.5-2.5 mM ammonium acetate aqueous solution, and preferably 0.1% formic acid-2 mM ammonium acetate aqueous solution without affecting the effect of the invention.

In chromatography, the choice of the chromatographic column is important and the requirements for the chromatographic column: high column efficiency, good selectivity, high analysis speed and the like. The invention adopts methanol and 0.01-0.2% formic acid-1-5 mM ammonium acetate aqueous solution as mobile phase, the type of chromatographic column is Waters BEH C18(2.1 multiplied by 100mM,1.7 mu m), endogenous substances do not interfere the measurement of the sample under the coordination of other conditions, the sensitivity is high, the specificity is strong, and the accuracy and the precision basically meet the requirements.

When the internal standard method is adopted, the selection of the internal standard substance is very important work. The ideal internal standard should be capable of being added to the sample in an accurate, known amount, and have substantially the same or as consistent as possible physicochemical properties, chromatographic behavior, and response characteristics as the sample being analyzed; under chromatographic conditions, the internal standard must be sufficiently separated from the components of the sample. The method adopts the deuterated isotope as the internal standard, the internal standard and the substance to be measured have the same chemical properties and matrix effect, and the reproducibility and accuracy of the method for measuring the 5-hydroxytryptamine and the melatonin in the serum are better.

In a preferable scheme, the initial ratio of the mobile phase A to the mobile phase B is 90-95: 10-5. Further preferably, the initial ratio of mobile phase a to mobile phase B is 90: 10.

In a preferred embodiment, the flow rate is 0.2-0.4 ml/min, preferably 0.3 ml/min.

Further, the column temperature is 30-50 ℃, and preferably 40 ℃.

In one embodiment, the sample volume is 1-10. mu.L, e.g., 1. mu.L, 5. mu.L, or 10. mu.L.

In a preferred scheme, when the ultra-high performance liquid chromatography tandem mass spectrometry technology is adopted to detect 5-hydroxytryptamine and melatonin in pretreated serum, the specific chromatographic conditions are as follows:

(1) ultra-high performance liquid chromatography conditions:

mobile phase A: 0.1% formic acid-2 mM ammonium acetate in water; mobile phase B: methanol;

the type of the chromatographic column: waters BEH C18 (2.1X 100mm,1.7 μm);

adopting a mode of gradient elution by taking a mobile phase A and a mobile phase B as a mixed mobile phase, wherein the initial ratio of the mobile phase A to the mobile phase B is 90: 10; the gradient elution procedure was as follows: the volume ratio of the mobile phase A to the mobile phase B is gradually changed from 90:10 to 2:98 at a constant speed within 0-1.5 minutes; the volume ratio of the mobile phase A to the mobile phase B is kept constant at 2:98 within 1.5-3.5 minutes; the volume ratio of the mobile phase A to the mobile phase B is gradually changed from 2:98 to 90:10 at a constant speed within 3.5-5.5 minutes; each sample was collected for 5.5 minutes; the gradient elution mode is specifically shown in table 1; the flow rate was 0.3ml/min, the column temperature was 40 ℃ and the injection volume was 5. mu.L.

TABLE 1 mobile phase gradient elution parameters

Time (min)	Flow rate (ml/min)	％A	％B	Curve
					0.0	0.3	90	10	-
1.5	0.3	2	98	6
					3.5	0.3	2	98	6
5.5	0.3	90	10	1

(2) Mass spectrum conditions:

in an electrospray ionization positive ion detection mode, a mass spectrum scanning mode of multi-reaction monitoring is adopted, and the capillary voltage is 0.5kV (ESI +); the ion source temperature is 150 ℃; the desolventizing temperature is 400 ℃; the desolventizing gas flow rate is 800L/hr; the air flow rate of the taper hole is 150L/hr; the mass spectrum source parameters are shown in table 2, and the mass spectrum parameters of each target and the corresponding isotope internal standard thereof are monitored at the same time, and are shown in table 3.

TABLE 2 Mass Spectrometry Source parameters

TABLE 35 measurement of Mass Spectrometry parameters for serotonin and melatonin

The serum mentioned in the invention is human or animal serum.

The pretreated serum mentioned in the present invention is prepared as follows: adding the internal standard working solution, the pH regulator and the extraction liquid into the serum for extraction, oscillating, carrying out centrifugal treatment, taking supernatant, drying by nitrogen flow, mixing with redissolved solution, carrying out centrifugal treatment again, taking the supernatant for sample injection; among them, the pH adjuster is a 0.1M to 0.5M sodium carbonate solution, preferably a 0.15M to 0.25M sodium carbonate solution, and more preferably a 0.2M sodium carbonate solution. The extract was methyl tert-butyl ether. The composite solution is 10-80% methanol water solution, preferably 50% methanol water solution. The internal standard working solution is diluted by 100 times for the mixed internal standard solution.

Since 5-hydroxytryptamine and melatonin belong to alkaline and neutral substances respectively and are difficult to detect together, the simultaneous detection of 5-hydroxytryptamine and melatonin in serum is not reported at present. Based on the characteristics of the 5-hydroxytryptamine and the melatonin, the invention finds that the extraction efficiency of the 5-hydroxytryptamine can be enhanced by adopting the pH regulator (sodium carbonate solution) and the methyl tert-butyl ether as the extraction liquid in the pretreatment process of the serum sample, the aim of detecting the serum sample and the melatonin is fulfilled, and the extraction method is simple, the pretreatment is rapid, and the clinical popularization and use are easy. When a specific pH regulator is selected, when a similar alkaline solution, such as a sodium hydroxide solution and a potassium hydroxide solution, is used as the pH regulator, and a similar extraction solution, such as n-hexane, ethyl acetate or a mixture of the two is used as the extraction solution to extract the serum sample, the extraction efficiency of 5-hydroxytryptamine is low, 5-hydroxytryptamine cannot be extracted well, and the quantitative analysis of 5-hydroxytryptamine in the serum sample cannot be satisfied.

In a preferred embodiment, the pretreated serum of the present invention is prepared as follows: putting 200 mul of serum into a 1.5ml centrifuge tube, adding 20 mul of internal standard working solution, 20 mul of 0.2M sodium carbonate solution and 900 mul of methyl tert-butyl ether, oscillating for 3-10 min, and centrifuging for 4-10 min under the conditions of 12000-15000 r/min and 4-20 ℃; and then, drying 850 mu l of supernatant through nitrogen flow, mixing the supernatant with 80 mu l of 50% methanol aqueous solution, oscillating for 1-5 min, centrifuging for 1-5 min under the conditions of 12000-15000 r/min and 4-20 ℃, and taking the supernatant for sample injection.

In a more preferred embodiment, the pretreated serum of the present invention is prepared as follows: putting 200 μ l serum into a 1.5ml centrifuge tube, adding 20 μ l internal standard working solution, 20 μ l0.2M sodium carbonate solution and 900 μ l methyl tert-butyl ether, shaking for 5min, and centrifuging at 14800r/min and 10 deg.C for 5 min; then 850 mul of supernatant is taken and dried by nitrogen flow, mixed with 80 mul of 50 percent methanol water solution, shaken for 3min, centrifuged for 3min under the conditions of 14800r/min and 10 ℃, and the supernatant is taken for sample injection.

In one scheme, the internal standard working solution provided by the invention is prepared according to the following method:

preparing the following internal standard mother liquor by using a methanol aqueous solution: 5-hydroxytryptamine-d 41 mg/ml, melatonin-d 40.01mg/ml;

respectively transferring each internal standard mother solution: 5-hydroxytryptamine-d 410 μ l, melatonin-d 44 μ l, and adding into 986 μ l methanol water solution to obtain 1ml mixed internal standard solution, which comprises: 5-hydroxytryptamine-d 410. mu.g/ml, melatonin-d 40.04. mu.g/ml.

Adding 10uL of the mixed internal standard solution into 0.99ml of pure methanol to obtain an internal standard working solution, wherein the internal standard working solution comprises: 5-hydroxytryptamine-d 4100 ng/ml, melatonin-d 40.4 ng/ml.

In a preferred embodiment, when preparing the internal standard mother liquor and the mixed internal standard solution, the selected methanol aqueous solution is 10% to 80% methanol aqueous solution, for example, the methanol aqueous solution is 50% methanol aqueous solution.

In a more preferred embodiment, the internal standard working solution mentioned in the invention is prepared according to the following method:

respectively preparing 5-hydroxytryptamine-d 4 and melatonin-d 4 internal standard mother liquor by using 50% methanol aqueous solution, adding the internal standard mother liquor into 986 mu l of 50% methanol aqueous solution, uniformly mixing to obtain 1ml of mixed internal standard solution, adding 10 mu l of the mixed internal standard solution into 0.99ml of pure methanol to obtain internal standard working solution, wherein the concentration is shown in the following table 4. The frozen food is recommended to be stored in a refrigerator at the temperature of 80 ℃ below zero and is taken out for use.

TABLE 4 internal standard working fluid preparation

In one embodiment, the standard mentioned in the present invention is prepared as follows:

5-hydroxytryptamine and melatonin are prepared into standard mother liquor with the following concentrations: 1mg/ml of 5-hydroxytryptamine and 0.01mg/ml of melatonin;

respectively transferring mother liquor of each standard product: 20 mul of 5-hydroxytryptamine and 2 mul of melatonin; then adding the mixture into 978 mu l of methanol water solution to obtain 1ml of mixed standard stock solution; the mixed standard stock solution comprises: 20 mu g/ml of 5-hydroxytryptamine and 0.02 mu g/ml of melatonin.

Preparing the mixed standard stock solution into a calibrator solution with seven different concentration points by using a blank serum matrix, wherein the seven concentration points of the calibrator solution are as follows:

seven concentration points of 5-hydroxytryptamine are as follows: 1ng/ml, 2.5ng/ml, 5ng/ml, 25ng/ml, 50ng/ml, 250ng/ml, 500 ng/ml;

the seven concentration points of melatonin are in order: 0.001ng/ml, 0.0025ng/ml, 0.005ng/ml, 0.025ng/ml, 0.05ng/ml, 0.25ng/ml, 0.5 ng/ml.

In a preferred embodiment, the mixed standard stock solution is prepared by selecting a 10% to 80% aqueous methanol solution, for example, a 50% aqueous methanol solution.

In a preferred embodiment, the blank serum matrix is 5% to 15% methanol aqueous solution, and more preferably, the blank serum matrix is 10% methanol aqueous solution.

In a more preferred embodiment, the standard solution is prepared as follows:

the standard mother liquors of 5-hydroxytryptamine and melatonin were removed, and added to 978 μ l of 50% methanol aqueous solution to obtain 1ml of mixed standard stock solution, the concentrations of which are shown in table 5 below.

TABLE 5 stock solutions of standards

The invention prepares the stock solution of the mixed standard substance into seven calibrator solutions with different concentration points by using a blank serum substrate (10% methanol aqueous solution), and the preparation process is as follows:

adding 10 μ l of the mixed standard solution into 390 μ l of 10% methanol aqueous solution as a first high-value concentration point; diluting 130 μ l of the first high-value concentration point with 130 μ l of 10% methanol aqueous solution to obtain a second high-value concentration point; diluting the first high-value concentration point with 9 times of 10% methanol aqueous solution to obtain a third high-value concentration point; diluting the second high-value concentration point with 9 times of 10% methanol aqueous solution to obtain a fourth high-value concentration point; diluting the third high-value concentration point with 9 times of 10% methanol aqueous solution to obtain a fifth high-value concentration point; diluting the fourth high-value concentration point with 9 times of 10% methanol aqueous solution to obtain a sixth high-value concentration point; and (4) diluting the fifth high-value concentration point with 10% methanol aqueous solution with 4 times volume to obtain a seventh high-value concentration point.

The invention adopts a gradient dilution method to prepare standard yeast, after a standard solution is taken out from a refrigerator at the temperature of 20 ℃ below zero, the standard solution is vortexed for 10s, the highest concentration point of the standard yeast is prepared by using the standard solution within 2min, and the standard yeast is stored at the temperature of 80 ℃ below zero after the standard yeast is prepared, and the specific process is shown in the following table 6 (unit: ng/ml).

TABLE 6 Standard preparation

Standard song	Pipetting solution (mu L)	Blank serum matrix (μ L)	5-hydroxytryptamine	Melatonin
					S7	Mixed Standard stock solution 10	390	500	0.5
S6	S7 130	130	250	0.25
					S5	S7 30	270	50	0.05
S4	S6 30	270	25	0.025
					S3	S5 30	270	5	0.005
S2	S4 30	270	2.5	0.0025
					S1	S3 50	200	1	0.001

Taking 200 mul of each concentration point of seven different calibrator samples, putting the samples into a 1.5ml centrifuge tube, adding 20 mul of internal standard working solution, 20 mul of 0.2M sodium carbonate solution and 900 mul of methyl tert-butyl ether, oscillating for 5min, and centrifuging for 5min at 14800r/min and 10 ℃; then 850 mul of supernatant is taken and dried by nitrogen flow, mixed with 80 mul of 50 percent methanol water solution, shaken for 3min, centrifuged for 3min at 14800r/min and 10 ℃, 65 mul of supernatant is taken, and 5 mul of sample injection is carried out.

The invention also comprises the preparation of a quality control product, wherein the quality control product is blank serum containing 5-hydroxytryptamine and melatonin, and the low, medium and high concentrations are QC (L), QC (M) and QC (H);

QC (L) is the above mixed standard stock solution diluted to 10000 times with blank serum base.

Qc (m) is a 1000-fold dilution of the above mixed standard stock solution in blank serum matrix.

Qc (h) was a 50-fold dilution of the above mixed standard stock solution in blank serum matrix.

For the purposes of the present invention, a serum blank matrix is a serum blank that does not contain the compound of interest. In a preferred embodiment, the blank serum matrix is 5% to 15% methanol in water, for example, the blank serum matrix is 10% methanol in water.

In a preferred embodiment, the quality control product is prepared according to the following method: the above mixed standard stock solution was mixed with a blank serum base (10% methanol aqueous solution) to prepare QC (L), QC (M), and QC (H) at three different concentrations, as shown in Table 7.

TABLE 7 concentration of quality control (unit: ng/ml)

QC (L) includes: 2ng/ml of 5-hydroxytryptamine and 0.002ng/ml of melatonin.

QC (M) comprises: 20ng/ml of 5-hydroxytryptamine and 0.02ng/ml of melatonin.

QC (H) includes: 400ng/ml of 5-hydroxytryptamine and 0.4ng/ml of melatonin.

By adopting the technical scheme of the invention, the advantages are as follows:

the invention provides a method for detecting the concentration of 5-hydroxytryptamine and melatonin in serum, which adopts sodium carbonate solution as a pH regulator and methyl tert-butyl ether as an extraction liquid in the pretreatment process of a serum sample, can enhance the extraction efficiency of the 5-hydroxytryptamine, screens out optimal chromatographic conditions such as a mobile phase, a gradient, a chromatographic column and the like, can simultaneously detect the 5-hydroxytryptamine and the melatonin in the serum at one time, has high sensitivity, strong specificity and simple pretreatment process, completes the separation and detection of the 5-hydroxytryptamine and the melatonin in the serum within 5.5 minutes, basically meets the requirements on accuracy and precision, can be used for the quantitative analysis of the 5-hydroxytryptamine and the melatonin in the serum clinically, and provides a simple and rapid detection method for the concentration monitoring of the 5-hydroxytryptamine and the melatonin in the clinically.

Drawings

FIG. 1 is an extracted ion flow spectrum of a 5-hydroxytryptamine and melatonin standard;

FIG. 2 is an ion flow diagram of 5-hydroxytryptamine and melatonin extraction from serum;

FIG. 3 is a graph showing the lower limit of quantitation of 5-hydroxytryptamine versus the response of a serum sample with different pretreatments;

FIG. 4 is a graph showing the comparison of melatonin quantitation limit and response of serum samples with different pretreatments;

FIG. 5 is a graph comparing the lower limit of quantitation of 5-hydroxytryptamine with the response of serum samples using different mobile phases;

fig. 6 is a graph comparing the lower limit of melatonin quantitation and the response of serum samples using different mobile phases.

Detailed Description

The invention will be better understood from the following examples. However, those skilled in the art will readily appreciate that the description of the embodiments is only for illustrating the present invention and should not be taken as limiting the invention as detailed in the claims.

Example 1:

first, experimental material and instrument

1. Material

The sample was obtained from serum samples collected from the 12 month 2020 ward of the first hospital affiliated with the university of medical science of china.

(1) The instrument comprises the following steps: xevo TQ-S triple quadrupole mass spectrometer (Waters Corporation); UPLC I-Class ultra high performance liquid chromatography system (with autosampler, Waters Corporation); SCILOGEX D2012 high speed bench top centrifuge (usa); ultra pure water meter (ELGA LabWater, uk); multi-tube Vortex mixer (Vortex genie2, usa); an adjustable pipettor (Eppendorf 0.5-10 mul, 10-100 mul, 100-1000 mul); glassware, graduated cylinders, and the like.

(2) Reagent consumables: MS grade methanol (Fisher, usa); MS grade formic acid (Fisher, usa); MS grade ammonium acetate (Sigma, usa); HPLC grade methyl tert-butyl ether (Fisher, usa); sodium carbonate (national medicine); the type of the chromatographic column: waters BEH C18 (2.1X 100mm,1.7 μm).

(3) And (3) standard substance: the standards and their corresponding internal standards are shown in table 8 below.

TABLE 8 Standard and internal standards

Serial number	Name of Chinese	Manufacturer of the product
			1	5-hydroxytryptamine	TRC
2	Melatonin	TRC
			3	5-hydroxytryptamine-d 4	TRC
4	Melatonin-d 4	TRC

(4) Quality control product: the blank serum containing 5-hydroxytryptamine and melatonin has low, medium and high concentrations of QC (L), QC (M) and QC (H), which are shown in Table 7.

Second, liquid condition

(1) Chromatographic conditions are as follows: mobile phase A: 0.1% formic acid-2 mM ammonium acetate in water; mobile phase B: methanol. The type of the chromatographic column: waters BEH C18 (2.1X 100mm,1.7 μm), using gradient elution, see Table 1 for details. The flow rate was 0.3ml/min, the column temperature was 40 ℃ and the injection volume was 5. mu.L.

(2) In an electrospray ionization positive ion detection mode, a mass spectrum scanning mode of multi-reaction monitoring is adopted, and the capillary voltage is 0.5kV (ESI +); the ion source temperature is 150 ℃; the desolventizing temperature is 400 ℃; the desolventizing gas flow rate is 800L/hr; the air flow rate of the taper hole is 150L/hr; the mass spectrum source parameters are shown in table 2, and the mass spectrum parameters of each target and the corresponding isotope internal standard thereof are monitored at the same time, and are shown in table 3.

Third, the experimental process

(1) Preparing a standard substance:

5-hydroxytryptamine and melatonin are prepared into standard mother liquor with the following concentrations: 1mg/ml of 5-hydroxytryptamine and 0.01mg/ml of melatonin;

respectively transferring mother liquor of each standard product: 20 mul of 5-hydroxytryptamine and 2 mul of melatonin; then added to 978. mu.l of 50% aqueous methanol to give 1ml of mixed standard stock solution. The mixed standard stock solution comprises: 20 mu g/ml of 5-hydroxytryptamine and 0.02 mu g/ml of melatonin, and the details are shown in Table 5.

The mixed standard stock solution was prepared into calibrator solutions at seven different concentration points with a blank serum base (10% methanol in water), as detailed in table 6, where the seven concentration points of the calibrator solution are:

seven concentration points of 5-hydroxytryptamine are as follows: 1ng/ml, 2.5ng/ml, 5ng/ml, 25ng/ml, 50ng/ml, 250ng/ml, 500 ng/ml;

the seven concentration points of melatonin are in order: 0.001ng/ml, 0.0025ng/ml, 0.005ng/ml, 0.025ng/ml, 0.05ng/ml, 0.25ng/ml, 0.5 ng/ml.

(2) Internal standard working fluid

Preparing the following internal standard mother liquor by using 50% methanol aqueous solution: 5-hydroxytryptamine-d 41 mg/ml, melatonin-d 40.01mg/ml;

respectively transferring internal standard mother liquor: 5-hydroxytryptamine-d 410 μ l, melatonin-d 44 μ l; further addition to 986. mu.l of 50% aqueous methanol gave 1ml of a mixed internal standard solution containing: 5-hydroxytryptamine-d 410. mu.g/ml, melatonin-d 40.04. mu.g/ml.

Adding 10 mul of the mixed internal standard solution into 0.99ml of pure methanol to obtain an internal standard working solution, wherein the internal standard working solution comprises: 5-hydroxytryptamine-d 4100 ng/ml, melatonin-d 40.4 ng/ml.

(3) Preparing a quality control product:

the standard stock solution was prepared into QC (L), QC (M), and QC (H) with three different concentrations by using a blank serum substrate (10% methanol aqueous solution), as shown in Table 7.

QC (L) includes: 2ng/ml of 5-hydroxytryptamine and 0.002ng/ml of melatonin.

QC (M) comprises: 20ng/ml of 5-hydroxytryptamine and 0.02ng/ml of melatonin.

QC (H) includes: 400ng/ml of 5-hydroxytryptamine and 0.4ng/ml of melatonin.

(4) Sample processing

1) Treating a standard substance: taking 200 mul of each concentration point of seven different calibrator samples, putting the samples into a 1.5ml centrifuge tube, adding 20 mul of internal standard working solution, 20 mul of 0.2M sodium carbonate solution and 900 mul of methyl tert-butyl ether, oscillating for 5min, and centrifuging for 5min at 14800r/min and 10 ℃; then 850 mul of supernatant is taken and dried by nitrogen flow, mixed with 80 mul of 50 percent methanol aqueous solution, shaken for 3min, centrifuged for 3min at 14800r/min at 10 ℃, 65 mul of supernatant is taken, and 5 mul of sample is injected.

2) Pretreatment of a serum sample: putting 200 μ l serum into a 1.5ml centrifuge tube, adding 20 μ l internal standard working solution, 20 μ l0.2M sodium carbonate solution and 900 μ l methyl tert-butyl ether, shaking for 5min, and centrifuging at 14800r/min and 10 deg.C for 5 min; then 850 mul of supernatant is taken and dried by nitrogen flow, mixed with 80 mul of 50 percent methanol water solution, shaken for 3min, centrifuged for 3min at 14800r/min and 10 ℃, 65 mul of supernatant is taken, and 5 mul of sample injection is carried out.

3) Pretreatment of quality control products: 200 μ l of each of the quality control solutions QC (L), QC (M), QC (H) were collected and placed in 1.5ml centrifuge tubes, and then the samples were pretreated in accordance with the serum samples, which is not described herein again.

Fourth, method verification

1. Extracting an ion current chromatogram: the peak shapes of the standard substance of 5-hydroxytryptamine and melatonin and the serum sample are symmetrical, and no peak interference exists, which indicates that good detection can be obtained under the condition, and fig. 1 is an ion flow chart of 5-hydroxytryptamine and melatonin standard substance extraction, and fig. 2 is an ion flow chart of 5-hydroxytryptamine and melatonin extraction in serum.

2. Calibration curve: and establishing a calibration curve by adopting an isotope internal standard quantitative method and utilizing TargetLynx software to calculate the concentration of the substance to be detected in the serum by taking the concentration ratio of the standard substance to the internal standard substance as an X axis and the peak area ratio of the standard substance to the internal standard substance as a Y axis. The linear fitting equation of the 5-hydroxytryptamine and the melatonin in the respective concentration ranges has good linearity, the correlation coefficient is more than 0.99, and the quantitative requirements are met, see table 9.

TABLE 95 linear regression equation and linear correlation coefficient for serotonin and melatonin

3. Accuracy survey: and evaluating the accuracy of the method by adopting a standard recovery rate test. A mixed blank serum sample is prepared, 3 concentrations of mixed standard substances of low, medium and high are respectively added, the treatment and the measurement are repeated for 5 times by the same steps, the result shows that the standard addition recovery rate of the 5-hydroxytryptamine and the melatonin is between 97.45 and 108.06 percent, the RSD of 5 repeated tests is in the range of 0.75 to 1.97 percent, and the statistical result is shown in a table 10.

TABLE 105 hydroxytryptamine and melatonin addition recovery results

4. And (3) precision test: taking an interference-free blank serum sample, adding 5-hydroxytryptamine and melatonin standard substances with different concentrations to obtain serum samples with low, medium and high concentrations, repeatedly processing 6 batches in one day, continuously processing for three days, quantitatively determining the concentrations of the 5-hydroxytryptamine and the melatonin by an internal standard method, wherein the internal precision is 0.75-3.00%, processing 3 batches in three days, calculating the precision between batches to be 1.57-2.86%, and obtaining results shown in Table 11.

TABLE 11 results of the precision test within and between batches

Fifth, discuss

The concentration of 5-hydroxytryptamine and melatonin in human serum is measured by an ID-UPLC-MS/MS method. Meanwhile, the method detects the peak time and the ion pair of the target object, has high sensitivity, can greatly eliminate matrix interference by adopting an isotope internal standard method for quantification, is not influenced by the conditions of pretreatment process, sample loading volume and flow and the like, and can achieve accurate quantification.

The result of the standard addition recovery rate test for evaluating the accuracy of the method shows that the standard addition recovery rate of the 5-hydroxytryptamine and the melatonin is that the standard addition recovery rate is between 97.45% and 108.06%, the RSD of 5 times of repeated tests is in the range of 0.75% to 1.97%, and the accuracy is good.

The reproducibility result of the method shows that the internal precision of the 5-hydroxytryptamine and the melatonin is 0.75-3.00%, the precision between the batches is 1.57-2.86% after 3 batches of treatment within three days. The pre-treatment process of the established serum sample is very simple, and the serum dosage is only 200 mu L.

Comparative example 1:

the method for detecting 5-hydroxytryptamine and melatonin in serum provided by the comparative example comprises the following steps:

1. liquid condition

(1) Mobile phase A: 0.1% formic acid-2 mM ammonium acetate in water; mobile phase B: methanol. The type of the chromatographic column: waters BEH C18 (2.1X 100mm,1.7 μm), using gradient elution, see Table 1 for details. The flow rate was 0.3ml/min, the column temperature was 40 ℃ and the injection volume was 5. mu.L.

(2) Mass spectrum conditions: in an electrospray ionization positive ion detection mode, a mass spectrum scanning mode of multi-reaction monitoring is adopted, and the capillary voltage is 0.5kV (ESI +); the ion source temperature is 150 ℃; the desolventizing temperature is 400 ℃; the desolventizing gas flow rate is 800L/hr; the air flow rate of the taper hole is 150L/hr; the mass spectrum source parameters are shown in table 2, and the mass spectrum parameters of each target and the corresponding isotope internal standard thereof are monitored at the same time, and are shown in table 3.

2. Procedure of experiment

(1) Preparing a standard substance:

5-hydroxytryptamine and melatonin are prepared into standard mother liquor with the following concentrations: 1mg/ml of 5-hydroxytryptamine and 0.01mg/ml of melatonin;

respectively transferring mother liquor of each standard product: 20 mul of 5-hydroxytryptamine and 2 mul of melatonin; then added to 978. mu.l of 50% aqueous methanol to give 1ml of mixed standard stock solution. The mixed standard stock solution comprises: 20 mu g/ml of 5-hydroxytryptamine and 0.02 mu g/ml of melatonin.

The mixed standard stock solution was prepared into 1ng/ml 5-hydroxytryptamine and 0.001ng/ml melatonin (lower limit sample) with a blank serum base (10% methanol aqueous solution).

(2) Internal standard working fluid

Preparing the following internal standard mother liquor by using 50% methanol aqueous solution: 5-hydroxytryptamine-d 41 mg/ml, melatonin-d 40.01mg/ml;

respectively transferring internal standard mother liquor: 5-hydroxytryptamine-d 410 μ l, melatonin-d 44 μ l; further addition to 986. mu.l of 50% aqueous methanol gave 1ml of a mixed internal standard solution containing: 5-hydroxytryptamine-d 410. mu.g/ml, melatonin-d 40.04. mu.g/ml.

Adding 10 mul of the mixed internal standard solution into 0.99ml of pure methanol to obtain an internal standard working solution, wherein the internal standard working solution comprises: 5-hydroxytryptamine-d 4100 ng/ml, melatonin-d 40.4 ng/ml.

(3) Sample processing

1) Pretreatment of a standard product 1: preparing 500 mu l of standard curve quantitative lower limit sample, adding 10 mu l of internal standard working solution, mixing for 60s, adding 100 mu l of NaOH solution (1mol/l) and 1ml of extract liquor (the volume ratio of n-hexane to ethyl acetate is 1:1), oscillating for 5min, centrifuging at 13000 r/m for 10min, and taking 800 mu l of supernatant; blowing dry with nitrogen, redissolving with 100 μ l of 10% methanol water solution, and oscillating for 5 min; centrifuging at 13000 rpm for 3min, and sampling the supernatant.

2) Pretreatment of a serum sample 1: taking 500 mu l of a serum sample, adding 10 mu l of internal standard working solution into the serum sample, mixing for 60s, adding 100 mu l of NaOH solution (1mol/l) and 1ml of extract liquor (the volume ratio of n-hexane to ethyl acetate is 1:1), oscillating for 5min, centrifuging for 10min at 13000 r/m, and taking 800 mu l of supernatant; blowing dry with nitrogen, redissolving with 100 μ l of 10% methanol water solution, and oscillating for 5 min; centrifuging at 13000 rpm for 3min, and sampling the supernatant.

3) Pretreatment of a standard product 2: preparing 200 μ l of standard yeast quantitative lower limit sample, adding internal standard working solution 20 μ l, 20 μ l of 0.2M sodium carbonate solution and 900 μ l of methyl tert-butyl ether, oscillating for 5min, centrifuging at 13000 rpm for 10min, and collecting supernatant 800 μ l; blowing with nitrogen, redissolving with 100 μ l of 50% methanol water solution, and oscillating for 5 min; centrifuging at 13000 rpm for 3min, and sampling the supernatant.

4) Pretreatment of a serum sample 2: taking 200 μ l of serum sample, adding internal standard working solution 20 μ l, 20 μ l of 0.2M sodium carbonate solution and 900 μ l of methyl tert-butyl ether, oscillating for 5min, centrifuging at 13000 rpm for 10min, and taking supernatant 800 μ l; blowing with nitrogen, redissolving with 100 μ l of 50% methanol water solution, and oscillating for 5 min; centrifuging at 13000 rpm for 3min, and sampling the supernatant.

The standard substance and serum sample in pretreatment 1 and the standard substance and serum sample in pretreatment 2 were taken and tested under the above chromatographic conditions, and the experimental results are shown in fig. 3 and 4.

The standard substance and the serum sample are respectively pretreated by adopting two treatment modes of pretreatment 1 and pretreatment 2, and the difference of melatonin and 5-hydroxytryptamine in the response intensity is examined. As can be seen from fig. 3 and 4, the melatonin showed little difference in response intensity, but the pretreatment 2 was performed in a slightly better manner; however, in terms of response intensity, the treatment efficiency of the pretreatment 2 is about 50 times higher than that of the pretreatment 1, and a remarkable effect is obtained, while the pretreatment 1 cannot satisfy quantitative analysis of the 5-hydroxytryptamine in the serum sample due to the low treatment efficiency, that is, the serum sample is treated by the pretreatment 1, and the 5-hydroxytryptamine and the melatonin in the serum cannot be simultaneously detected at one time.

Comparative example 2

The method for detecting 5-hydroxytryptamine and melatonin in serum provided by the comparative example has the same steps as those of the comparative example 1, and adopts a pretreatment mode 2, wherein the difference is only that the mobile phase A is different. Wherein, the mobile phase A1: 0.1% formic acid-2 mM ammonium acetate in water; mobile phase a 2: 0.05% aqueous formic acid.

The standard substance and serum sample in pretreatment 2 were taken and tested according to the chromatographic conditions in comparative example 1, and the experimental results are shown in fig. 5 and 6.

The standard substance and the serum sample are pretreated by adopting the treatment mode of pretreatment 2, the chromatographic conditions in comparative example 1 are referred for detection, and the difference of the melatonin and the 5-hydroxytryptamine in the response intensity is examined. As can be seen from fig. 5 and 6, in the same sample pretreatment mode, when the mobile phase a1 and the mobile phase a2 were used for the chromatographic analysis, the difference in the ionization efficiency of 5-hydroxytryptamine was not large, and the ionization efficiency was slightly better when the mobile phase a1 was used; however, the difference in ionization efficiency for 5-hydroxytryptamine is significant, and the ionization efficiency using mobile phase a1 is about 6 times higher than that of mobile phase a2, i.e., 0.1% formic acid-2 mM ammonium acetate aqueous solution-methanol as mixed mobile phase is significantly better than 0.05% formic acid aqueous solution-methanol as mixed mobile phase under the same pretreatment mode and substantially the same chromatographic conditions.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: modifications of the technical solutions described in the foregoing embodiments are still possible, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.